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Sample records for actuation levers driven

  1. Preliminary study of lever-based optical driven micro-actuator

    NASA Astrophysics Data System (ADS)

    Lin, Chih-Lang; Li, Yi-Hsiung; Lin, Chin-Te; Chiang, Chia-Chin; Liu, Yi-Jui; Chung, Tien-Tung; Baldeck, Patrice L.

    2012-04-01

    This study presents a novel type of optically driven lever-based micro-actuator fabricated using two-photon polymerization 3D-microfabrication technique. The lever is composed of a beam, an arch, and a sphere. First, optical tweezers is applied on the spheres to demonstrate the actuation of the lever. A spring is jointed at the lever for verifying the induced forces. Under the dragging by laser focusing, the lever simultaneously turns and results a torque like a mechanical arm. Then, the demonstration of a photo-driven micro-transducer with a mechanical arm and a gear is preformed. The experimental result indicates that our design enables precise manipulation of the mirco-actuator by optical tweezers at micron scale. This study provides a possibility for driving micron-sized structured mechanisms, such as connecting rods, valves. It is expected to contribute on the investigation of "Lab-on-a-chip".

  2. Preliminary study of lever-based optical driven micro-actuator

    NASA Astrophysics Data System (ADS)

    Lin, Chih-Lang; Li, Yi-Hsiung; Lin, Chin-Te; Chiang, Chia-Chin; Liu, Yi-Jui; Chung, Tien-Tung; Baldeck, Patrice L.

    2011-11-01

    This study presents a novel type of optically driven lever-based micro-actuator fabricated using two-photon polymerization 3D-microfabrication technique. The lever is composed of a beam, an arch, and a sphere. First, optical tweezers is applied on the spheres to demonstrate the actuation of the lever. A spring is jointed at the lever for verifying the induced forces. Under the dragging by laser focusing, the lever simultaneously turns and results a torque like a mechanical arm. Then, the demonstration of a photo-driven micro-transducer with a mechanical arm and a gear is preformed. The experimental result indicates that our design enables precise manipulation of the mirco-actuator by optical tweezers at micron scale. This study provides a possibility for driving micron-sized structured mechanisms, such as connecting rods, valves. It is expected to contribute on the investigation of "Lab-on-a-chip".

  3. Three-axis lever actuator with flexure hinges for an optical disk system

    NASA Astrophysics Data System (ADS)

    Han, Chang-Soo; Kim, Soo-Hyun

    2002-10-01

    A three-axis lever actuator with a flexure hinge has been designed and fabricated. This actuator is driven by electromagnetic force based on a coil-magnet system and can be used as a high precision actuator and, especially as a pickup head actuator in optical disks. High precision and low sensitivity to external vibration are the major advantages of this lever actuator. An analysis model was found and compared to the finite element method. Dynamic characteristics of the three-axis lever actuator were measured. The results are in very close agreement to those predicted by the model and finite element analysis.

  4. Stable electroosmotically driven actuators

    NASA Astrophysics Data System (ADS)

    Sritharan, Deepa; Motsebo, Mylene; Tumbic, Julia; Smela, Elisabeth

    2013-04-01

    We have previously presented "nastic" actuators based on electroosmotic (EO) pumping of fluid in microchannels using high electric fields for potential application in soft robotics. In this work we address two challenges facing this technology: applying EO to meso-scale devices and the stability of the pumping fluid. The hydraulic pressure achieved by EO increases with as 1/d2, where d is the depth of the microchannel, but the flow rate (which determines the stroke and the speed) is proportional to nd, where n is the number of channels. Therefore to get high force and high stroke the device requires a large number of narrow channels, which is not readily achievable using standard microfabrication techniques. Furthermore, for soft robotics the structure must be soft. In this work we present a method of fabricating a three-dimensional porous elastomer to serve as the array of channels based on a sacrificial sugar scaffold. We demonstrate the concept by fabricating small pumps. The flexible devices were made from polydimethylsiloxane (PDMS) and comprise the 3D porous elastomer flanked on either side by reservoirs containing electrodes. The second issue addressed here involves the pumping fluid. Typically, water is used for EO, but water undergoes electrolysis even at low voltages. Since EO takes place at kV, these systems must be open to release the gases. We have recently reported that propylene carbonate (PC) is pumped at a comparable rate as water and is also stable for over 30 min at 8 kV. Here we show that PC is, however, degraded by moisture, so future EO systems must prevent water from reaching the PC.

  5. Light-Driven Polymeric Bimorph Actuators

    NASA Technical Reports Server (NTRS)

    Adamovsky, Gregory; Sarkisov, Sergey S.; Curley, Michael J.

    2009-01-01

    Light-driven polymeric bimorph actuators are being developed as alternatives to prior electrically and optically driven actuators in advanced, highly miniaturized devices and systems exemplified by microelectromechanical systems (MEMS), micro-electro-optical-mechanical systems (MEOMS), and sensor and actuator arrays in smart structures. These light-driven polymeric bimorph actuators are intended to satisfy a need for actuators that (1) in comparison with the prior actuators, are simpler and less power-hungry; (2) can be driven by low-power visible or mid-infrared light delivered through conventional optic fibers; and (3) are suitable for integration with optical sensors and multiple actuators of the same or different type. The immediate predecessors of the present light-driven polymeric bimorph actuators are bimorph actuators that exploit a photorestrictive effect in lead lanthanum zirconate titanate (PLZT) ceramics. The disadvantages of the PLZT-based actuators are that (1) it is difficult to shape the PLZT ceramics, which are hard and brittle; (2) for actuation, it is necessary to use ultraviolet light (wavelengths < 380 nm), which must be generated by use of high-power, high-pressure arc lamps or lasers; (3) it is difficult to deliver sufficient ultraviolet light through conventional optical fibers because of significant losses in the fibers; (4) the response times of the PLZT actuators are of the order of several seconds unacceptably long for typical applications; and (5) the maximum mechanical displacements of the PLZT-based actuators are limited to those characterized by low strains beyond which PLZT ceramics disintegrate because of their brittleness. The basic element of a light-driven bimorph actuator of the present developmental type is a cantilever beam comprising two layers, at least one of which is a polymer that exhibits a photomechanical effect (see figure). The dominant mechanism of the photomechanical effect is a photothermal one: absorption of

  6. Tendon Driven Finger Actuation System

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Reich, David M. (Inventor); Bridgwater, Lyndon (Inventor); Linn, Douglas Martin (Inventor); Askew, Scott R. (Inventor); Diftler, Myron A. (Inventor); Platt, Robert (Inventor); Hargrave, Brian (Inventor); Valvo, Michael C. (Inventor); Abdallah, Muhammad E. (Inventor); Permenter, Frank Noble (Inventor); Mehling, Joshua S. (Inventor)

    2013-01-01

    A humanoid robot includes a robotic hand having at least one finger. An actuation system for the robotic finger includes an actuator assembly which is supported by the robot and is spaced apart from the finger. A tendon extends from the actuator assembly to the at least one finger and ends in a tendon terminator. The actuator assembly is operable to actuate the tendon to move the tendon terminator and, thus, the finger.

  7. Gear-Driven Turnbuckle Actuator

    NASA Technical Reports Server (NTRS)

    Rivera, Ricky N.

    2010-01-01

    This actuator design allows the extension and contraction of turnbuckle assemblies. It can be operated manually or remotely, and is extremely compact. It is ideal for turnbuckles that are hard to reach by conventional tools. The tool assembly design solves the problem of making accurate adjustments to the variable geometry guide vanes without having to remove and reinstall the actuator system back on the engine. The actuator does this easily by adjusting the length of the turnbuckles while they are still attached to the engine.

  8. Surface chemistry driven actuation in nanoporous gold

    SciTech Connect

    Biener, J; Wittstock, A; Zepeda-Ruiz, L; Biener, M M; Zielasek, V; Kramer, D; Viswanath, R N; Weissmuller, J; Baumer, M; Hamza, A V

    2008-04-14

    Although actuation in biological systems is exclusively powered by chemical energy, this concept has not been realized in man-made actuator technologies, as these rely on generating heat or electricity first. Here, we demonstrate that surface-chemistry driven actuation can be realized in high surface area materials such as nanoporous gold. For example, we achieve reversible strain amplitudes in the order of a few tenths of a percent by alternating exposure of nanoporous Au to ozone and carbon monoxide. The effect can be explained by adsorbate-induced changes of the surface stress, and can be used to convert chemical energy directly into a mechanical response thus opening the door to surface-chemistry driven actuator and sensor technologies.

  9. Microwave Driven Actuators Power Allocation and Distribution

    NASA Technical Reports Server (NTRS)

    Forbes, Timothy; Song, Kyo D.

    2000-01-01

    Design, fabrication and test of a power allocation and distribution (PAD) network for microwave driven actuators is presented in this paper. Development of a circuit that would collect power from a rectenna array amplify and distribute the power to actuators was designed and fabricated for space application in an actuator array driven by a microwave. A P-SPICE model was constructed initially for data reduction purposes, and was followed by a working real-world model. A voltage up - converter (VUC) is used to amplify the voltage from the individual rectenna. The testing yielded a 26:1 voltage amplification ratio with input voltage at 9 volts and a measured output voltage 230VDC. Future work includes the miniaturization of the circuitry, the use of microwave remote control, and voltage amplification technology for each voltage source. The objective of this work is to develop a model system that will collect DC voltage from an array of rectenna and propagate the voltage to an array of actuators.

  10. Quick-Release Pin With Lever Action

    NASA Technical Reports Server (NTRS)

    Trevino, Robert C.

    1995-01-01

    Lever-action quick-release pin operated more easily. Mechanism operated with gloved hand. In modified version, lever added to handle to facilitate actuation. Lever action reduces actuation force. Lever-action pin operated by squeezing on any point of moveable ends of lever and handle together between thumb and forefinger or by simply grasping and squeezing handle and lever with entire hand in more natural grasp.

  11. Design and experimental research of a novel inchworm type piezo-driven rotary actuator with the changeable clamping radius

    NASA Astrophysics Data System (ADS)

    Zhao, Hongwei; Fu, Lu; Ren, Luquan; Huang, Hu; Fan, Zunqiang; Li, Jianping; Qu, Han

    2013-01-01

    In this paper, a novel piezo-driven rotary actuator with the changeable clamping radius is developed based on the inchworm principle. This actuator mainly utilizes three piezoelectric actuators, a flexible gripper, a clamping block, and a rotor to achieve large stroke rotation with high resolution. The design process of the flexible gripper consisting of the driving unit and the clamping unit is described. Lever-type mechanisms were used to amplify the micro clamping displacements. The amplifying factor and parasitic displacement of the lever-type mechanism in the clamping unit was analyzed theoretically and experimentally. In order to investigate the rotation characteristics of the actuator, a series of experiments was carried out. Experimental results indicate that the actuator can rotate at a speed of 77 488 μrad/s with a driving frequency of 167 Hz. The rotation resolution and maximum load torque of the actuator are 0.25 μrad and 37 N mm, respectively. The gripper is movable along the z direction based on an elevating platform, and the clamping radius can change from 10.6 mm to 25 mm. Experimental results confirm that the actuator can achieve different rotation speeds by changing the clamping radius.

  12. Actuator Exerts Tensile Or Compressive Axial Load

    NASA Technical Reports Server (NTRS)

    Nozzi, John; Richards, Cuyler H.

    1994-01-01

    Compact, manually operated mechanical actuator applies controlled, limited tensile or compressive axial force. Designed to apply loads to bearings during wear tests in clean room. Intended to replace hydraulic actuator. Actuator rests on stand and imparts axial force to part attached to clevis inside or below stand. Technician turns control screw at one end of lever. Depending on direction of rotation of control screw, its end of lever driven downward (for compression) or upward (for tension). Lever pivots about clevis pin at end opposite of control screw; motion drives downward or upward link attached via shearpin at middle of lever. Link drives coupling and, through it, clevis attached to part loaded.

  13. Design of piezostack-driven trailing-edge flap actuator for helicopter rotors

    NASA Astrophysics Data System (ADS)

    Lee, Taeoh; Chopra, Inderjit

    2001-02-01

    A piezoelectric actuator is investigated to activate a trailing-edge flap mechanism for helicopter vibration suppression. This paper presents the development of a piezostack-based actuator with a new stroke amplification mechanism. A double-lever amplification concept is introduced, which is a dual-stage lever-fulcrum stroke amplifier that extends the capability of the conventional lever-fulcrum mechanism. Both the design and fabrication of the on-blade trailing-edge flap actuator are addressed. The first prototype actuator was designed and fabricated using two piezostack segments. An amplification factor of 19.4 and constant response covering up to 8/rev (52.3 Hz) were measured under non-rotating conditions, and a consistent actuator displacement of up to 600g of centrifugal loading was experimentally obtained for the vacuum spin testing. A major design refinement resulted in the second prototype actuator that uses five piezostack segments. The bench-top testing of the second prototype actuator showed 1.87 mm (73.7 mil) of free stroke, and uniform performance of up to 150 Hz. In vacuum spin testing, the second prototype actuator showed approximately 13% loss in actuation stroke at 700g of centrifugal loading, and no further degradation at 115% overloading condition. The double-lever amplification mechanism with piezostack actuation showed the potential for operation in a rotating environment.

  14. Hydrogel Actuation by Electric Field Driven Effects

    NASA Astrophysics Data System (ADS)

    Morales, Daniel Humphrey

    Hydrogels are networks of crosslinked, hydrophilic polymers capable of absorbing and releasing large amounts of water while maintaining their structural integrity. Polyelectrolyte hydrogels are a subset of hydrogels that contain ionizable moieties, which render the network sensitive to the pH and the ionic strength of the media and provide mobile counterions, which impart conductivity. These networks are part of a class of "smart" material systems that can sense and adjust their shape in response to the external environment. Hence, the ability to program and modulate hydrogel shape change has great potential for novel biomaterial and soft robotics applications. We utilized electric field driven effects to manipulate the interaction of ions within polyelectrolyte hydrogels in order to induce controlled deformation and patterning. Additionally, electric fields can be used to promote the interactions of separate gel networks, as modular components, and particle assemblies within gel networks to develop new types of soft composite systems. First, we present and analyze a walking gel actuator comprised of cationic and anionic gel legs attached by electric field-promoted polyion complexation. We characterize the electro-osmotic response of the hydrogels as a function of charge density and external salt concentration. The gel walkers achieve unidirectional motion on flat elastomer substrates and exemplify a simple way to move and manipulate soft matter devices in aqueous solutions. An 'ionoprinting' technique is presented with the capability to topographically structure and actuate hydrated gels in two and three dimensions by locally patterning ions induced by electric fields. The bound charges change the local mechanical properties of the gel to induce relief patterns and evoke localized stress, causing rapid folding in air. The ionically patterned hydrogels exhibit programmable temporal and spatial shape transitions which can be tuned by the duration and/or strength of

  15. Active catheter driven by a thermo-hydraulic actuation.

    PubMed

    Horovitz, Yonatan; Kosa, Gabor

    2015-01-01

    Catheters and flexible endoscopes are usually steered by mechanical wires that are driven from their base. Due to friction and buckling there is a need to place the driving actuator of the catheter at the catheter's tip. Such active catheter's manoeuvrability is much higher than wire-driven ones. A problem with active catheters is the difficulty to create high enough bending using micro-actuators placed at the catheter's tip. Our actuation method is an attempt to overcome this difficulty by using a novel thermo-hydraulic actuation method. The magnitude of the bending torque of our actuator is created by internal hydraulic pressure in the tube and the steering direction is controlled by the thermal micro-actuator embedded in the wall of the tube. In this paper we present the modelling, optimization, design and testing of an initial prototype of such an actuator. We found that a 4 mm OD actuator made of TPU can bend to ±12°. PMID:26738094

  16. A Study on a Microwave-Driven Smart Material Actuator

    NASA Technical Reports Server (NTRS)

    Choi, Sang H.; Chu, Sang-Hyon; Kwak, M.; Cutler, A. D.

    2001-01-01

    NASA s Next Generation Space Telescope (NGST) has a large deployable, fragmented optical surface (greater than or = 2 8 m in diameter) that requires autonomous correction of deployment misalignments and thermal effects. Its high and stringent resolution requirement imposes a great deal of challenge for optical correction. The threshold value for optical correction is dictated by lambda/20 (30 nm for NGST optics). Control of an adaptive optics array consisting of a large number of optical elements and smart material actuators is so complex that power distribution for activation and control of actuators must be done by other than hard-wired circuitry. The concept of microwave-driven smart actuators is envisioned as the best option to alleviate the complexity associated with hard-wiring. A microwave-driven actuator was studied to realize such a concept for future applications. Piezoelectric material was used as an actuator that shows dimensional change with high electric field. The actuators were coupled with microwave rectenna and tested to correlate the coupling effect of electromagnetic wave. In experiments, a 3x3 rectenna patch array generated more than 50 volts which is a threshold voltage for 30-nm displacement of a single piezoelectric material. Overall, the test results indicate that the microwave-driven actuator concept can be adopted for NGST applications.

  17. 49 CFR 236.764 - Locking, lever operated.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Locking, lever operated. 236.764 Section 236.764... Locking, lever operated. The mechanical locking of an interlocking machine which is actuated by means of the lever....

  18. 49 CFR 236.764 - Locking, lever operated.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Locking, lever operated. 236.764 Section 236.764... Locking, lever operated. The mechanical locking of an interlocking machine which is actuated by means of the lever....

  19. 49 CFR 236.764 - Locking, lever operated.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Locking, lever operated. 236.764 Section 236.764... Locking, lever operated. The mechanical locking of an interlocking machine which is actuated by means of the lever....

  20. 49 CFR 236.764 - Locking, lever operated.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Locking, lever operated. 236.764 Section 236.764... Locking, lever operated. The mechanical locking of an interlocking machine which is actuated by means of the lever....

  1. Light-driven actuation of fluids at microscale

    NASA Astrophysics Data System (ADS)

    Deshpande, Mandar; Saggere, Laxman

    2004-07-01

    This paper discusses the prospects of light-driven actuation particularly for actuating fluids at micro-scale for potential use in a novel retinal prosthesis and other drug delivery applications. The prosthesis is conceived to be comprised of an array of light-driven microfluidic-dispenser units, devices that eject very small amounts of fluids on the order of 1 picoliter per second in response to incident light energy in the range of 0.1-1 mW/cm2. A light-driven actuator, whose size will ideally be smaller than about 100 micrometers in diameter, independently powers each dispenser unit. Towards this application, various approaches for transducing light energy for actuation of fluids are explored. These approaches encompass both direct transduction of light energy to mechanical actuation of fluid and indirect transduction through an intermediary form of energy, for instance, light energy to thermal or electrical energy followed by mechanical actuation of fluid. Various existing schemes for such transduction are reviewed comprehensively and discussed from the standpoint of the application requirements. Direct transduction schemes exploiting recent developments in optically sensitive materials that exhibit direct strain upon illumination, particularly the photostrictive PLZT (Lanthanum modified Lead Zirconate Titanate), are studied for the current application, and results of some preliminary experiments involving measurement of photovoltage, photocurrent, and photo-induced strain in the meso-scale samples of the PLZT material are presented.

  2. An arm wrestling robot driven by dielectric elastomer actuators

    NASA Astrophysics Data System (ADS)

    Kovacs, Gabor; Lochmatter, Patrick; Wissler, Michael

    2007-04-01

    The first arm wrestling match between a human arm and a robotic arm driven by electroactive polymers (EAP) was held at the EAPAD conference in 2005. The primary objective was to demonstrate the potential of the EAP actuator technology for applications in the field of robotics and bioengineering. The Swiss Federal Laboratories for Materials Testing and Research (Empa) was one of the three organizations participating in this competition. The robot presented by Empa was driven by a system of rolled dielectric elastomer (DE) actuators. Based on the calculated stress condition in the rolled actuator, a low number of pre-strained DE film wrappings were found to be preferential for achieving the best actuator performance. Because of the limited space inside the robot body, more than 250 rolled actuators with small diameters were arranged in two groups according to the human agonist-antagonist muscle configuration in order to achieve an arm-like bidirectional rotation movement. The robot was powered by a computer-controlled high voltage amplifier. The rotary motion of the arm was activated and deactivated electrically by corresponding actuator groups. The entire development process of the robot is presented in this paper where the design of the DE actuators is of primary interest. Although the robot lost the arm wrestling contest against the human opponent, the DE actuators have demonstrated very promising performance as artificial muscles. The scientific knowledge gained during the development process of the robot has pointed out the challenges to be addressed for future improvement in the performance of rolled dielectric elastomer actuators.

  3. Position-movable lens driven by dielectric elastomer actuator

    NASA Astrophysics Data System (ADS)

    Jin, Boya; Ren, Hongwen

    2016-07-01

    A position-movable lens driven by a dielectric elastomer (DE) actuator is demonstrated. With the aid of stretching/contracting of the DE actuator, the lens can do a reciprocating motion in the direction perpendicular to its optical axis. For our DE with 1-mm thick, a voltage pulse of V=5.5 kV can cause the lens to shift ˜1.7 mm. The stretching time and contracting time of the actuator are ˜3.5 and ˜4 s, respectively. When the lens integrates with another solid lens, a variable focal length can be obtained. Although the driving voltage is relatively high, the actuator is electrically stable and the power consumption is extremely low. Our lens with movable position has potential applications in imaging, information storage, beam steering, and bifocal technology.

  4. A light-driven supramolecular nanowire actuator

    NASA Astrophysics Data System (ADS)

    Lee, Junho; Oh, Seungwhan; Pyo, Jaeyeon; Kim, Jong-Man; Je, Jung Ho

    2015-04-01

    A single photomechanical supramolecular nanowire actuator with an azobenzene-containing 1,3,5-tricarboxamide derivative is developed by employing a direct writing method. Single nanowires display photoinduced reversible bending and the bending behavior follows first-order kinetics associated with azobenzene photoisomerization. A wireless photomechanical nanowire tweezers that remotely manipulates a single micro-particle is also demonstrated.A single photomechanical supramolecular nanowire actuator with an azobenzene-containing 1,3,5-tricarboxamide derivative is developed by employing a direct writing method. Single nanowires display photoinduced reversible bending and the bending behavior follows first-order kinetics associated with azobenzene photoisomerization. A wireless photomechanical nanowire tweezers that remotely manipulates a single micro-particle is also demonstrated. Electronic supplementary information (ESI) available: Experimental details, X-ray powder diffraction (XRD) patterns of solution-crystallized sample, meniscus-guided microwires, and freeze-dried sample of Azo-1, Schematic of experimental set-up, 3D bending motion of Azo-1 nanowire, FE-SEM image of a bent Azo-1 nanowire after UV irradiation, real-time grazing incidence X-ray diffraction (GIXD) for an Azo-1 microwire, Imaging analyses, Absorption spectra of an Azo-1 film, and thermostability of Azo-1 nanowire. See DOI: 10.1039/c5nr01118c

  5. A parallel leaf spring structure driven by piezoelectric bimorph actuators

    NASA Astrophysics Data System (ADS)

    Seki, Hiroya; Gohda, Tomio; Shimokohbe, Akira

    A parallel leaf spring structure driven by piezoelectric bimorph actuator is modelled using a Rayleigh-Ritz formulation and model truncation is done for feedback controller design. Using a strain gauge sensor, a precise positioning of the end point mass is realized. The position of the strain gauge sensor is found to be an important factor in achieving a stable response with an estimator based feedback control system. Also excitation of higher structural modes, which becomes an obstacle to a wide servo bandwidth actuator, is discussed. Using multi electrodes arranged on the bimorph actuator and appropriately tuning the voltage ratio applied to them, pole-zero cancellation of the higher modes is experimentally demonstrated.

  6. A planar nano-positioner driven by shear piezoelectric actuators

    NASA Astrophysics Data System (ADS)

    Dong, W.; Li, H.; Du, Z.

    2016-08-01

    A planar nano-positioner driven by the shear piezoelectric actuators is proposed in this paper based on inertial sliding theory. The performance of the nano-positioner actuated by different driving signals is analyzed and discussed, e.g. the resolution and the average velocity which depend on the frequency, the amplitude and the wave form of the driving curves. Based on the proposed design, a prototype system of the nano-positioner is developed by using a capacitive sensor as the measurement device. The experiment results show that the proposed nano-positioner is capable of outputting two-dimensional motions within an area of 10 mm × 10 mm at a maximum speed of 0.25 mm/s. The corresponding resolution can be as small as 21 nm. The methodology outlined in this paper can be employed and extended to shear piezoelectric actuators involved in high precision positioning systems.

  7. Variable area nozzle for gas turbine engines driven by shape memory alloy actuators

    NASA Technical Reports Server (NTRS)

    Rey, Nancy M. (Inventor); Miller, Robin M. (Inventor); Tillman, Thomas G. (Inventor); Rukus, Robert M. (Inventor); Kettle, John L. (Inventor); Dunphy, James R. (Inventor); Chaudhry, Zaffir A. (Inventor); Pearson, David D. (Inventor); Dreitlein, Kenneth C. (Inventor); Loffredo, Constantino V. (Inventor)

    2001-01-01

    A gas turbine engine includes a variable area nozzle having a plurality of flaps. The flaps are actuated by a plurality of actuating mechanisms driven by shape memory alloy (SMA) actuators to vary fan exist nozzle area. The SMA actuator has a deformed shape in its martensitic state and a parent shape in its austenitic state. The SMA actuator is heated to transform from martensitic state to austenitic state generating a force output to actuate the flaps. The variable area nozzle also includes a plurality of return mechanisms deforming the SMA actuator when the SMA actuator is in its martensitic state.

  8. Body Levers.

    ERIC Educational Resources Information Center

    Chiappetta, Eugene L.

    1987-01-01

    Explains how the muscle and bone arrangement of the human body can be used in teaching the principles of simple machines. Presents an activity that investigates the lever system of the forearm. Includes background information on levers and suggests questions for classroom discussion. (ML)

  9. Moisture-driven actuators inspired by motility of plants

    NASA Astrophysics Data System (ADS)

    Shin, Beomjune; Lee, Minhee; Kim, Ho-Young

    2015-11-01

    We report design and fabrication of moisture-driven actuators mimicking pine cones, wild wheats and seeds of Erodium cicutarium, which can bend and even helically coil with variation of environmental humidity. The actuators adopt a bilayer configuration, one of whose layers is hygroscopically active while the other is inactive. In order to enhance the degree and speed of deformation which critically depends on moisture-responsivity of the active layer, nanofibers of hydrogel are directionally deposited on the inactive layer via electrospinning. As a result, several designs of soft robots are demonstrated which are capable of locomotion by harvesting environmental humidity energy. The dynamics of the robots are analyzed by coupling moisture diffusion kinetics and elastic theory of multi-layer bending. The theoretical predictions are compared with the experimental results, to lead to the optimal design to maximize the locomotion speed measured by travel distance normalized by body length per unit time.

  10. A small biomimetic quadruped robot driven by multistacked dielectric elastomer actuators

    NASA Astrophysics Data System (ADS)

    Nguyen, Canh Toan; Phung, Hoa; Dat Nguyen, Tien; Lee, Choonghan; Kim, Uikyum; Lee, Donghyouk; Moon, Hyungpil; Koo, Jachoon; Nam, Jae-do; Ryeol Choi, Hyouk

    2014-06-01

    A kind of dielectric elastomer (DE) material, called ‘synthetic elastomer’, has been developed based on acrylonitrile butadiene rubber (NBR) to be used as a dielectric elastomer actuator (DEA). By stacking single layers of synthetic elastomer, a linear actuator, called a multistacked actuator, is produced, and used by mechatronic and robotic systems to generate linear motion. In this paper, we demonstrate the application of the multistacked dielectric elastomer actuator in a biomimetic legged robot. A miniature robot driven by a biomimetic actuation system with four 2-DOF (two-degree-of-freedom) legged mechanisms is realized. Based on the experimental results, we evaluate the performance of the proposed robot and validate the feasibility of the multistacked actuator in a locomotion system as a replacement for conventional actuators.

  11. Hierarchically arranged helical fibre actuators driven by solvents and vapours

    NASA Astrophysics Data System (ADS)

    Chen, Peining; Xu, Yifan; He, Sisi; Sun, Xuemei; Pan, Shaowu; Deng, Jue; Chen, Daoyong; Peng, Huisheng

    2015-12-01

    Mechanical responsiveness in many plants is produced by helical organizations of cellulose microfibrils. However, simple mimicry of these naturally occurring helical structures does not produce artificial materials with the desired tunable actuations. Here, we show that actuating fibres that respond to solvent and vapour stimuli can be created through the hierarchical and helical assembly of aligned carbon nanotubes. Primary fibres consisting of helical assemblies of multiwalled carbon nanotubes are twisted together to form the helical actuating fibres. The nanoscale gaps between the nanotubes and micrometre-scale gaps among the primary fibres contribute to the rapid response and large actuation stroke of the actuating fibres. The compact coils allow the actuating fibre to rotate reversibly. We show that these fibres, which are lightweight, flexible and strong, are suitable for a variety of applications such as energy-harvesting generators, deformable sensing springs and smart textiles.

  12. Hierarchically arranged helical fibre actuators driven by solvents and vapours.

    PubMed

    Chen, Peining; Xu, Yifan; He, Sisi; Sun, Xuemei; Pan, Shaowu; Deng, Jue; Chen, Daoyong; Peng, Huisheng

    2015-12-01

    Mechanical responsiveness in many plants is produced by helical organizations of cellulose microfibrils. However, simple mimicry of these naturally occurring helical structures does not produce artificial materials with the desired tunable actuations. Here, we show that actuating fibres that respond to solvent and vapour stimuli can be created through the hierarchical and helical assembly of aligned carbon nanotubes. Primary fibres consisting of helical assemblies of multiwalled carbon nanotubes are twisted together to form the helical actuating fibres. The nanoscale gaps between the nanotubes and micrometre-scale gaps among the primary fibres contribute to the rapid response and large actuation stroke of the actuating fibres. The compact coils allow the actuating fibre to rotate reversibly. We show that these fibres, which are lightweight, flexible and strong, are suitable for a variety of applications such as energy-harvesting generators, deformable sensing springs and smart textiles. PMID:26367106

  13. Dealloying-driven nanoporous palladium with superior electrochemical actuation performance.

    PubMed

    Zhang, Jie; Bai, Qingguo; Zhang, Zhonghua

    2016-04-01

    Metal-hydrogen (in particular, Pd-H) interactions have been receiving considerable attention over the past 150 years within the scope of hydrogen storage, catalytic hydrogenation, hydrogen embrittlement and hydrogen-induced interfacial failure. Here, for the first time, we show that the coupling of hydrogen adsorption and absorption could trigger giant reversible strain in bulk nanoporous Pd (np-Pd) in a weakly adsorbed NaF electrolyte. The bulk np-Pd with a hierarchically porous structure and a ligament/channel size of ∼10 nm was fabricated using a dealloying strategy with compositional/structural design of the precursor. The np-Pd actuator exhibits a giant reversible strain of up to 3.28% (stroke of 137.8 μm), which is a 252% enhancement in comparison to the state-of-the-art value of 1.3% in np-AuPt. The strain rate (∼10(-5) s(-1)) of np-Pd is two orders of magnitude higher than that of current metallic actuators. Moreover, the volume-/mass-specific strain energy density (10.71 MJ m(-3)/3811 J kg(-1)) of np-Pd reaches the highest level compared with that of previously reported actuator materials. The outstanding actuation performance of np-Pd could be attributed to the coupling of hydrogen adsorption/absorption and its unique hierarchically nanoporous structure. Our findings provide valuable information for the design of novel high-performance metallic actuators. PMID:26975834

  14. Design and demonstration of a fish robot actuated by a SMA-driven actuation system

    NASA Astrophysics Data System (ADS)

    Le, Chan H.; Nguyen, Quang S.; Park, Hoon C.

    2010-04-01

    This paper presents a concept of a fish robot actuated by an SMA-based actuator. The bending-type actuator system is composed of a 0.1mm diameter SMA wire and a 0.5mm thick glass/epoxy strip. The SMA wire is installed to the bent composite strip. The actuator can produce about 200gf of blocking force and 3.5mm displacement at the center of the glass/epoxy strip. The bending motion of the actuator is converted into the tail-beat motion of a fish robot through a linkage system. The fish robot is evaluated by measuring the tail-beat angle, swimming speed and thrust produced by the fish robot. The tail-beat angle is about 20° and the maximum swimming speed is about 1.6cm/s. The measured thrust is about 0.4gf when the fish robot is operated at 0.9Hz.

  15. Micro-Ball-Lens Optical Switch Driven by SMA Actuator

    NASA Technical Reports Server (NTRS)

    Yang, Eui-Hyeok

    2003-01-01

    The figure is a simplified cross section of a microscopic optical switch that was partially developed at the time of reporting the information for this article. In a fully developed version, light would be coupled from an input optical fiber to one of two side-by-side output optical fibers. The optical connection between the input and the selected output fiber would be made via a microscopic ball lens. Switching of the optical connection from one output fiber to another would be effected by using a pair of thin-film shape-memory-alloy (SMA) actuators to toggle the lens between two resting switch positions. There are many optical switches some made of macroscopic parts by conventional fabrication techniques and some that are microfabricated and, hence, belong to the class of microelectromechanical systems (MEMS). Conventionally fabricated optical switches tend to be expensive. MEMS switches can be mass-produced at relatively low cost, but their attractiveness has been diminished by the fact that, heretofore, MEMS switches have usually been found to exhibit high insertion losses. The present switch is intended to serve as a prototype of low-loss MEMS switches. In addition, this is the first reported SMA-based optical switch. The optical fibers would be held in V grooves in a silicon frame. The lens would have a diameter of 1 m; it would be held by, and positioned between, the SMA actuators, which would be made of thin films of TiNi alloy. Although the SMA actuators are depicted here as having simple shapes for the sake of clarity of illustration, the real actuators would have complex, partly net-like shapes. With the exception of the lens and the optical fibers, the SMA actuators and other components of the switch would be made by microfabrication techniques. The components would be assembled into a sandwich structure to complete the fabrication of the switch. To effect switching, an electric current would be passed through one of the SMA actuators to heat it above

  16. Characteristics of an actuator-driven pulsed water jet generator to dissecting soft tissue.

    PubMed

    Seto, Takeshi; Yamamoto, Hiroaki; Takayama, Kazuyoshi; Nakagawa, Atsuhiro; Tominaga, Teiji

    2011-05-01

    This paper reports characteristics of an actuator-driven pulsed water jet generator applied, in particular, to dissect soft tissues. Results of experiments, by making use of high speed recording of optical visualization and varying nozzle diameter, actuator time interval, and their effects on dissection performance are presented. Jet penetration characteristics are compared with continuous water jet and hence potential assessment of pulsed water jets to clinical applications is performed. PMID:21639536

  17. Dealloying-driven nanoporous palladium with superior electrochemical actuation performance

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Bai, Qingguo; Zhang, Zhonghua

    2016-03-01

    Metal-hydrogen (in particular, Pd-H) interactions have been receiving considerable attention over the past 150 years within the scope of hydrogen storage, catalytic hydrogenation, hydrogen embrittlement and hydrogen-induced interfacial failure. Here, for the first time, we show that the coupling of hydrogen adsorption and absorption could trigger giant reversible strain in bulk nanoporous Pd (np-Pd) in a weakly adsorbed NaF electrolyte. The bulk np-Pd with a hierarchically porous structure and a ligament/channel size of ~10 nm was fabricated using a dealloying strategy with compositional/structural design of the precursor. The np-Pd actuator exhibits a giant reversible strain of up to 3.28% (stroke of 137.8 μm), which is a 252% enhancement in comparison to the state-of-the-art value of 1.3% in np-AuPt. The strain rate (~10-5 s-1) of np-Pd is two orders of magnitude higher than that of current metallic actuators. Moreover, the volume-/mass-specific strain energy density (10.71 MJ m-3/3811 J kg-1) of np-Pd reaches the highest level compared with that of previously reported actuator materials. The outstanding actuation performance of np-Pd could be attributed to the coupling of hydrogen adsorption/absorption and its unique hierarchically nanoporous structure. Our findings provide valuable information for the design of novel high-performance metallic actuators.Metal-hydrogen (in particular, Pd-H) interactions have been receiving considerable attention over the past 150 years within the scope of hydrogen storage, catalytic hydrogenation, hydrogen embrittlement and hydrogen-induced interfacial failure. Here, for the first time, we show that the coupling of hydrogen adsorption and absorption could trigger giant reversible strain in bulk nanoporous Pd (np-Pd) in a weakly adsorbed NaF electrolyte. The bulk np-Pd with a hierarchically porous structure and a ligament/channel size of ~10 nm was fabricated using a dealloying strategy with compositional/structural design of the

  18. A simulated actuator driven by motor cortical signals.

    PubMed

    Lukashin, A V; Amirikian, B R; Georgopoulos, A P

    1996-11-01

    One problem in motor control concerns the mechanism whereby the central nervous system translates the motor cortical command encoded in cell activity into a coordinated contraction of limb muscles to generate a desired motor output. This problem is closely related to the design of adaptive systems that transform neuronal signals chronically recorded from the motor cortex into the physiologically appropriate motor output of multijoint prosthetic limbs. In this study we demonstrated how this transformation can be carried out by an artificial neural network using as command signals the actual impulse activity obtained from recordings in the motor cortex of monkeys during the performance of a task that required the exertion of force in different directions. The network receives experimentally measured brain signals and recodes them into motor actions of a simulated actuator that mimics the primate arm. The actuator responds to the motor cortical commands with surprising fidelity, generating forces in close quantitative agreement with those exerted by trained monkeys, in both the temporal and spatial domains. Moreover, we show that the time-varying motor output may be controlled by the impulse activity of as few as 15 motor cortical cells. These results outline a potentially implementable computation scheme that utilizes raw neuronal signals to drive artificial mechanical systems. PMID:8981430

  19. Nonlinear Actuation Dynamics of Driven Casimir Oscillators with Rough Surfaces

    NASA Astrophysics Data System (ADS)

    Broer, Wijnand; Waalkens, Holger; Svetovoy, Vitaly B.; Knoester, Jasper; Palasantzas, George

    2015-11-01

    At separations below 100 nm, Casimir-Lifshitz forces strongly influence the actuation dynamics of microelectromechanical systems (MEMS) in dry vacuum conditions. For a micron-size plate oscillating near a surface, which mimics a frequently used setup in experiments with MEMS, we show that the roughness of the surfaces significantly influences the qualitative dynamics of the oscillator. Via a combination of analytical and numerical methods, it is shown that surface roughness leads to a clear increase of initial conditions associated with chaotic motion, that eventually lead to stiction between the surfaces. Since stiction leads to a malfunction of MEMS oscillators, our results are of central interest for the design of microdevices. Moreover, stiction is of significance for fundamentally motivated experiments performed with MEMS.

  20. Nanoporous-Gold-Based Hybrid Cantilevered Actuator Dealloyed and Driven by A Modified Rotary Triboelectric Nanogenerator

    PubMed Central

    Li, Xuequan; Liu, Mengmeng; Huang, Baisheng; Liu, Hong; Hu, Weiguo; Shao, Li-Hua; Wang, Zhong Lin

    2016-01-01

    We firstly designed an electrochemical system for dealloying to synthesize nanoporous gold (NPG) and also driving the novel NPG based actuator by utilizing a modified rotary triboelectric nanogenerator (TENG). Compared to the previous reported TENG whose outputs decline due to temperature rising resulting from electrodes friction, the modified TENG with a cooling system has stable output current and voltage increased by 14% and 20%, respectively. The novel cantilevered hybrid actuator characterised by light-weight (ca. 3 mg) and small volume (ca. 30 mm × 2 mm × 10 μm) is driven by a microcontroller modulated TENG with the displacement of 2.2 mm, which is about 106 times larger than that of traditional cantilever using planar surfaces. The energy conversion efficiencies defined as the energy consumed during dealloying and actuation compared with the output of TENG are 47% and 56.7%, respectively. PMID:27063987

  1. Nanoporous-Gold-Based Hybrid Cantilevered Actuator Dealloyed and Driven by A Modified Rotary Triboelectric Nanogenerator.

    PubMed

    Li, Xuequan; Liu, Mengmeng; Huang, Baisheng; Liu, Hong; Hu, Weiguo; Shao, Li-Hua; Wang, Zhong Lin

    2016-01-01

    We firstly designed an electrochemical system for dealloying to synthesize nanoporous gold (NPG) and also driving the novel NPG based actuator by utilizing a modified rotary triboelectric nanogenerator (TENG). Compared to the previous reported TENG whose outputs decline due to temperature rising resulting from electrodes friction, the modified TENG with a cooling system has stable output current and voltage increased by 14% and 20%, respectively. The novel cantilevered hybrid actuator characterised by light-weight (ca. 3 mg) and small volume (ca. 30 mm × 2 mm × 10 μm) is driven by a microcontroller modulated TENG with the displacement of 2.2 mm, which is about 10(6) times larger than that of traditional cantilever using planar surfaces. The energy conversion efficiencies defined as the energy consumed during dealloying and actuation compared with the output of TENG are 47% and 56.7%, respectively. PMID:27063987

  2. Nanoporous-Gold-Based Hybrid Cantilevered Actuator Dealloyed and Driven by A Modified Rotary Triboelectric Nanogenerator

    NASA Astrophysics Data System (ADS)

    Li, Xuequan; Liu, Mengmeng; Huang, Baisheng; Liu, Hong; Hu, Weiguo; Shao, Li-Hua; Wang, Zhong Lin

    2016-04-01

    We firstly designed an electrochemical system for dealloying to synthesize nanoporous gold (NPG) and also driving the novel NPG based actuator by utilizing a modified rotary triboelectric nanogenerator (TENG). Compared to the previous reported TENG whose outputs decline due to temperature rising resulting from electrodes friction, the modified TENG with a cooling system has stable output current and voltage increased by 14% and 20%, respectively. The novel cantilevered hybrid actuator characterised by light-weight (ca. 3 mg) and small volume (ca. 30 mm × 2 mm × 10 μm) is driven by a microcontroller modulated TENG with the displacement of 2.2 mm, which is about 106 times larger than that of traditional cantilever using planar surfaces. The energy conversion efficiencies defined as the energy consumed during dealloying and actuation compared with the output of TENG are 47% and 56.7%, respectively.

  3. Thermally Driven Photonic Actuator Based on Silica Opal Photonic Crystal with Liquid Crystal Elastomer.

    PubMed

    Xing, Huihui; Li, Jun; Shi, Yang; Guo, Jinbao; Wei, Jie

    2016-04-13

    We have developed a novel thermoresponsive photonic actuator based on three-dimensional SiO2 opal photonic crystals (PCs) together with liquid crystal elastomers (LCEs). In the process of fabrication of such a photonic actuator, the LCE precursor is infiltrated into the SiO2 opal PC followed by UV light-induced photopolymerization, thereby forming the SiO2 opal PC/LCE composite film with a bilayer structure. We find that this bilayer composite film simultaneously exhibits actuation behavior as well as the photonic band gap (PBG) response to external temperature variation. When the SiO2 opal PC/LCE composite film is heated, it exhibits a considerable bending deformation, and its PBG shifts to a shorter wavelength at the same time. In addition, this actuation is quite fast, reversible, and highly repeatable. The thermoresponsive behavior of the SiO2 opal PC/LCE composite films mainly derives from the thermal-driven change of nematic order of the LCE layer which leads to the asymmetric shrinkage/expansion of the bilayer structure. These results will be of interest in designing optical actuator systems for environment-temperature detection. PMID:26996608

  4. A chaotic self-oscillating sunlight-driven polymer actuator.

    PubMed

    Kumar, Kamlesh; Knie, Christopher; Bléger, David; Peletier, Mark A; Friedrich, Heiner; Hecht, Stefan; Broer, Dirk J; Debije, Michael G; Schenning, Albertus P H J

    2016-01-01

    Nature provides much inspiration for the design of materials capable of motion upon exposure to external stimuli, and many examples of such active systems have been created in the laboratory. However, to achieve continuous motion driven by an unchanging, constant stimulus has proven extremely challenging. Here we describe a liquid crystalline polymer film doped with a visible light responsive fluorinated azobenzene capable of continuous chaotic oscillatory motion when exposed to ambient sunlight in air. The presence of simultaneous illumination by blue and green light is necessary for the oscillating behaviour to occur, suggesting that the dynamics of continuous forward and backward switching are causing the observed effect. Our work constitutes an important step towards the realization of autonomous, persistently self-propelling machines and self-cleaning surfaces powered by sunlight. PMID:27375235

  5. A chaotic self-oscillating sunlight-driven polymer actuator

    PubMed Central

    Kumar, Kamlesh; Knie, Christopher; Bléger, David; Peletier, Mark A.; Friedrich, Heiner; Hecht, Stefan; Broer, Dirk J.; Debije, Michael G.; Schenning, Albertus P. H. J.

    2016-01-01

    Nature provides much inspiration for the design of materials capable of motion upon exposure to external stimuli, and many examples of such active systems have been created in the laboratory. However, to achieve continuous motion driven by an unchanging, constant stimulus has proven extremely challenging. Here we describe a liquid crystalline polymer film doped with a visible light responsive fluorinated azobenzene capable of continuous chaotic oscillatory motion when exposed to ambient sunlight in air. The presence of simultaneous illumination by blue and green light is necessary for the oscillating behaviour to occur, suggesting that the dynamics of continuous forward and backward switching are causing the observed effect. Our work constitutes an important step towards the realization of autonomous, persistently self-propelling machines and self-cleaning surfaces powered by sunlight. PMID:27375235

  6. A chaotic self-oscillating sunlight-driven polymer actuator

    NASA Astrophysics Data System (ADS)

    Kumar, Kamlesh; Knie, Christopher; Bléger, David; Peletier, Mark A.; Friedrich, Heiner; Hecht, Stefan; Broer, Dirk J.; Debije, Michael G.; Schenning, Albertus P. H. J.

    2016-07-01

    Nature provides much inspiration for the design of materials capable of motion upon exposure to external stimuli, and many examples of such active systems have been created in the laboratory. However, to achieve continuous motion driven by an unchanging, constant stimulus has proven extremely challenging. Here we describe a liquid crystalline polymer film doped with a visible light responsive fluorinated azobenzene capable of continuous chaotic oscillatory motion when exposed to ambient sunlight in air. The presence of simultaneous illumination by blue and green light is necessary for the oscillating behaviour to occur, suggesting that the dynamics of continuous forward and backward switching are causing the observed effect. Our work constitutes an important step towards the realization of autonomous, persistently self-propelling machines and self-cleaning surfaces powered by sunlight.

  7. Active Joint Mechanism Driven by Multiple Actuators Made of Flexible Bags: A Proposal of Dual Structural Actuator

    PubMed Central

    Inou, Norio

    2013-01-01

    An actuator is required to change its speed and force depending on the situation. Using multiple actuators for one driving axis is one of the possible solutions; however, there is an associated problem of output power matching. This study proposes a new active joint mechanism using multiple actuators. Because the actuator is made of a flexible bag, it does not interfere with other actuators when it is depressurized. The proposed joint achieved coordinated motion of multiple actuators. This report also discusses a new actuator which has dual cylindrical structure. The cylinders are composed of flexible bags with different diameters. The joint torque is estimated based on the following factors: empirical formula for the flexible actuator torque, geometric relationship between the joint and the actuator, and the principle of virtual work. The prototype joint mechanism achieves coordinated motion of multiple actuators for one axis. With this motion, small inner actuator contributes high speed motion, whereas large outer actuator generates high torque. The performance of the prototype joint is examined by speed and torque measurements. The joint showed about 30% efficiency at 2.0 Nm load torque under 0.15 MPa air input. PMID:24385868

  8. Active joint mechanism driven by multiple actuators made of flexible bags: a proposal of dual structural actuator.

    PubMed

    Kimura, Hitoshi; Matsuzaki, Takuya; Kataoka, Mokutaro; Inou, Norio

    2013-01-01

    An actuator is required to change its speed and force depending on the situation. Using multiple actuators for one driving axis is one of the possible solutions; however, there is an associated problem of output power matching. This study proposes a new active joint mechanism using multiple actuators. Because the actuator is made of a flexible bag, it does not interfere with other actuators when it is depressurized. The proposed joint achieved coordinated motion of multiple actuators. This report also discusses a new actuator which has dual cylindrical structure. The cylinders are composed of flexible bags with different diameters. The joint torque is estimated based on the following factors: empirical formula for the flexible actuator torque, geometric relationship between the joint and the actuator, and the principle of virtual work. The prototype joint mechanism achieves coordinated motion of multiple actuators for one axis. With this motion, small inner actuator contributes high speed motion, whereas large outer actuator generates high torque. The performance of the prototype joint is examined by speed and torque measurements. The joint showed about 30% efficiency at 2.0 Nm load torque under 0.15 MPa air input. PMID:24385868

  9. Development of Electrostatic Actuator, which enables the Stable Contact Resistance, Driven at Low Voltage

    NASA Astrophysics Data System (ADS)

    Masuda, Takahiro; Seki, Tomonori; Miyaji, Takaaki; Sato, Fumihiko

    The switches play an important role in making the multifunctional radio communication circuit and therefore, the high-performance microminiaturized high-frequency switches are urgently expected. RF-MEMS switch with mechanical switching structure is hoped to improve both high-frequency signal loss and isolation quality simultaneously and to provide better linearity on the performance and compatibility to silicon-based circuit elements. But considering the applications, such as cellular phone and wireless-LAN, lower driving voltage and smaller switch dimensions are required. In order to solve these requirements, a novel electrostatic actuator with a unique structure of movable electrodes which enables the stable contact resistance is developed for RF-MEMS switches. This actuator has slits between the movable electrodes and the restoring spring. The electrostatic actuator with a movable electrode area of 0.5mm2 was driven at low voltage of 9-11V. And no defect due to restoration shortage is observed during switching test up to 400million cycles. In this paper, the results of mechanical design of the electrostatic actuator, the simulation, the experiments, and the reliability test are described

  10. Method and apparatus for actuating vehicle transmission

    SciTech Connect

    Ishida, H.; Ishihara, M.; Uriuhara, M.

    1988-11-15

    This patent describes a method of actuating a vehicle parallel-gear transmission having gears and an internal lever for moving shift blocks connected with shift rods and shift forks for changing gear ratios of the transmission, a hydraulically controlled select actuator operatively connected to the internal lever for moving the internal lever in a select direction, a hydraulically controlled shift actuator operatively connected to the internal lever for moving the internal lever in a shift direction substantially normal to the select direction, a hydraulically controlled clutch actuator for connecting and disconnecting a clutch of the transmission, and a common fluid discharge passage connected to fluid discharge ports of the select and shift actuators and a fluid discharge port of the clutch actuator, the select and shift actuators being alternately actuatable to effect a gear changing operation.

  11. Bio-inspired Polymer Composite Actuator and Generator Driven by Water Gradients

    PubMed Central

    Ma, Mingming; Guo, Liang; Anderson, Daniel G.; Langer, Robert

    2013-01-01

    Here we describe the development of a water-responsive polymer film; combining both a rigid matrix (polypyrrole) and a dynamic network (polyol-borate), strong and flexible polymer films were developed that can exchange water with the environment to induce film expansion and contraction, resulting in rapid and continuous locomotion. The film actuator can generate contractile stress up to 27 MPa, lift objects 380 times heavier than itself, and transport cargo 10 times heavier than itself. We have assembled a generator by associating this actuator with a piezoelectric element. Driven by water gradients, this generator outputs alternating electricity at ∼0.3 Hz, with a peak voltage of ∼1.0 V. The electrical energy is stored in capacitors that could power micro- and nano-electronic devices. PMID:23307738

  12. A multi-responsive water-driven actuator with instant and powerful performance for versatile applications

    PubMed Central

    Mu, Jiuke; Hou, Chengyi; Zhu, Bingjie; Wang, Hongzhi; Li, Yaogang; Zhang, Qinghong

    2015-01-01

    Mechanical actuators driven by water that respond to multiple stimuli, exhibit fast responses and large deformations, and generate high stress have potential in artificial muscles, motors, and generators. Meeting all these requirements in a single device remains a challenge. We report a graphene monolayer paper that undergoes reversible deformation. Its graphene oxide cells wrinkle and extend in response to water desorption and absorption, respectively. Its fast (~0.3 s), powerful (>100 MPa output stress, 7.5 × 105 N kg−1 unit mass force), and controllable actuation can be triggered by moisture, heat, and light. The graphene monolayer paper has potential in artificial muscles, robotic hands, and electromagnetic-free generators. PMID:25826443

  13. An innovative ultra-capacitor driven shape memory alloy actuator with an embedded control system

    NASA Astrophysics Data System (ADS)

    Li, Peng; Song, Gangbing

    2014-08-01

    In this paper, an innovative ultra-capacitor driven shape memory alloy (SMA) actuator with an embedded control system is proposed targeting high power high-duty cycle SMA applications. The ultra-capacitor, which is capable of delivering massive amounts of instantaneous current in a compact dimension for high power applications, is chosen as the main component of the power supply. A specialized embedded system is designed from the ground up to control the ultra-capacitor driven SMA system. The control of the ultra-capacitor driven SMA is different from that of a regular constant voltage powered SMA system in that the energy and the voltage of the ultra-capacitor decrease as the system load increases. The embedded control system is also different from a computer-based control system in that it has limited computational power, and the control algorithm has to be designed to be simple while effective so that it can fit into the embedded system environment. The problem of a variable voltage power source induced by the use of the ultra-capacitor is solved by using a fuzzy PID (proportional integral and derivative) control. The method of using an ultra-capacitor to drive SMA actuators enabled SMA as a good candidate for high power high-duty cycle applications. The proposed embedded control system provides a good and ready-to-use solution for SMA high power applications.

  14. A new type of a direct-drive valve system driven by a piezostack actuator and sliding spool

    NASA Astrophysics Data System (ADS)

    Jeon, Juncheol; Han, Chulhee; Han, Young-Min; Choi, Seung-Bok

    2014-07-01

    A direct-drive valve (DDV) system is a kind of electrohydraulic servo valve system, in which the actuator directly drives the spool of the valve. In conventional DDV systems, the spool is generally driven by an electromagnetic actuator. Performance characteristics such as frequency bandwidth of DDV systems driven by the electromagnetic actuator are limited due to the actuator response property. In order to improve the performance characteristics of conventional DDV systems, in this work a new configuration for a direct-drive valve system actuated by a piezostack actuator with a flexible beam mechanism is proposed (in short, a piezo-driven DDV system). Its benefits are demonstrated through both simulation and experiment. After describing the geometric configuration and operational principle of the proposed valve system, a governing equation of the whole system is obtained by combining the dynamic equations of the fluid part and the structural parts: the piezostack, the flexible beam, and the spool. In the structural parts of the piezostack and flexible beam, a lumped parameter modeling method is used, while the conventional rule of the fluid momentum is used for the fluid part. In order to evaluate valve performances of the proposed system, an experimental apparatus consisting of a hydraulic circuit and the piezo-driven DDV system is established. The performance characteristics are evaluated in terms of maximum spool displacement, flow rate, frequency characteristics, and step response. In addition, in order to advocate the feasibility of the proposed dynamic model, a comparison between simulation and experiment is undertaken.

  15. Modeling and simulations of new electrostatically driven, bimorph actuator for high beam steering micromirror deflection angles

    NASA Astrophysics Data System (ADS)

    Walton, John P.; Coutu, Ronald A.; Starman, LaVern

    2015-02-01

    There are numerous applications for micromirror arrays seen in our everyday lives. From flat screen televisions and computer monitors, found in nearly every home and office, to advanced military weapon systems and space vehicles, each application bringing with it a unique set of requirements. The microelectromechanical systems (MEMS) industry has researched many ways micromirror actuation can be accomplished and the different constraints on performance each design brings with it. This paper investigates a new "zipper" approach to electrostatically driven micromirrors with the intent of improving duel plane beam steering by coupling large deflection angles, over 30°, and a fast switching speed. To accomplish this, an extreme initial deflection is needed which can be reached using high stress bimorph beams. Currently this requires long beams and high voltage for the electrostatic pull in or slower electrothermal switching. The idea for this "zipper" approach is to stack multiple beams of a much shorter length and allow for the deflection of each beam to be added together in order to reach the required initial deflection height. This design requires much less pull-in voltage because the pull-in of one short beam will in turn reduce the height of the all subsequent beams, making it much easier to actuate. Using modeling and simulation software to characterize operations characteristics, different bimorph cantilever beam configurations are explored in order to optimize the design. These simulations show that this new "zipper" approach increases initial deflection as additional beams are added to the assembly without increasing the actuation voltage.

  16. Laterally-actuated inside-driven RF MEMS switches fabricated by a SOG process

    NASA Astrophysics Data System (ADS)

    Wang, Li-Feng; Han, Lei; Tang, Jie-Ying; Huang, Qing-An

    2015-06-01

    This paper presents two RF MEMS switches, both of them are laterally-actuated and inside-driven. One is the push-pull type switch controlled by only one actuation signal, and the other is the low voltage three-state switch actuated by rhombic structures. To fabricate RF MEMS switches, the silicon on glass (SOG) based microwave transmission line is redesigned, and an electroplated gold layer is added to the standard SOG process flow. The measured insertion loss and isolation of the push-pull type switch at 6 GHz are -0.28 dB and -38.4 dB, respectively, and its measured pull-in voltage is 57 V. The measured insertion loss and isolation of the low voltage three-state switch at 6 GHz are -0.77 dB and -53 dB, respectively, and the measured pull-in voltage is only 15 V. Preliminary lifetime tests show the lifetimes of both switches exceed the magnitude of 107 cycles.

  17. Chitosan: a novel platform in proton-driven DNA strand rearrangement actuation.

    PubMed

    Lee, Dami; Singha, Kaushik; Jang, Mi-Kyeong; Nah, Jae-Woon; Park, In-Kyu; Kim, Won Jong

    2009-04-01

    Nanometre-scaled DNA machine based on molecular recognition properties of DNA has now become a powerful tool in nanodevices, miniaturized structure, and nanofabrication. The common principle behind designing a DNA nanomachine is DNA strand exchange or rearrangement, which is solely controlled by the stabilization through associative and dissociative forces arising from base pair interaction of DNA molecules. Thus, highly effective DNA reaction actuator will make DNA nanomachine more flexible, controllable, and powerful device. Here, we report the novel polymer-mediated platform in proton-driven DNA strand rearrangement actuation. This cationic low molecular weight water-soluble chitosan (LMWSC) exhibited pH-dependent complexation with oligodeoxynucleotides (ODN). It formed complex with ODN only at low pH and accelerated the DNA strand exchange (or rearrangement) reaction between dsDNA and its complementary ssDNA at pH 5.0. However, no complexation was observed between LMWSC and ODN at neutral pH. We assume that at physiological pH, LMWSC is not protonated enough for formation of complex with ODN. Therefore, it can not diminish the electrostatic repulsion among the negatively charged DNA strands of the three-stranded intermediate formed during the strand exchange reaction. In contrast, LMWSC becomes positively charged at acidic pH, and it stabilizes the three-stranded intermediate by spreading out the accumulated counter-ions and increasing the entropy of the system. This fascinating observation prompted us to believe that this intelligent proton-driven DNA reaction actuator has a potential for the precise control of DNA nanomachine and would be applied for operating and controlling nanoscaled machine. PMID:19396376

  18. Electromechanical Actuator Ribbons Driven by Electrically Conducting Spring-Like Fibers.

    PubMed

    Chen, Peining; He, Sisi; Xu, Yifan; Sun, Xuemei; Peng, Huisheng

    2015-09-01

    Electrically conducting fibers are woven into polymer ribbons to prepare electromechanical actuators. The ribbons generate a strain rate of more than 10(3) times that of typical electrochemical actuators, accompanied by a lower operating voltage and faster responsiveness compared to electrostatic and electrothermal actuators. Programmable actuation including bending, contraction, elongation, and rotation are shown with a high reversibility. PMID:26192453

  19. Thickness dependence of voltage-driven magnetization switching in FeCo/PI/piezoelectric actuator heterostructures

    NASA Astrophysics Data System (ADS)

    Cui, B. S.; Guo, X. B.; Wu, K.; Li, D.; Zuo, Y. L.; Xi, L.

    2016-03-01

    Strain mediated magnetization switching of ferromagnetic/substrate/piezoelectric actuator heterostructures has become a hot issue due to the advantage of low-power consumption. In this work, Fe65Co35 thin films were deposited on a flexible polyamides (PI) substrate, which has quite low Young’s module (~4 GPa for PI as compared to ~180 GPa for Si) and benefits from complete transfer of the strain from the piezoelectric actuator to magnetic thin films. A complete 90° transition of the magnetic easy axis was realized in 50 nm thick FeCo films under the voltage of 70 V, while a less than 90° rotation angle of the magnetic easy axis direction was observed in other samples, which was ascribed to the distribution of the anisotropy field and/or the orthogonal misalignment between stress induced anisotropy and original uniaxial anisotropy. A model considering two uniaxial anisotropies with orthogonal arrangement was used to quantitatively understand the observed results and the linear-like voltage dependent anisotropy field, especially for 10 nm FeCo films, in which the switching mechanism along the easy axis direction can be explained by the domain wall depinning model. It indicates that the magnetic domain-wall movement velocity may be controlled by strain through tuning the energy barrier of the pinning in heterostructures. Moreover, voltage-driven 90° magnetization switching with low-power consumption was achieved in this work.

  20. A tunable millimeter-wave phase shifter driven by dielectric elastomer actuators

    NASA Astrophysics Data System (ADS)

    Araromi, O. A.; Romano, P.; Rosset, S.; Perruisseau-Carrier, J.; Shea, H. R.

    2014-03-01

    We present the successful operation of the first dielectric elastomer actuator (DEA) driven tunable millimeter-wave phase shifter. The development of dynamically reconfigurable microwave/millimeter-wave (MW/MMW) antenna devices is becoming a prime need in the field of telecommunications and sensing. The real time updating of antenna characteristics such as coverage or operation frequency is particularly desired. However, in many circumstances currently available technologies suffer from high EM losses, increased complexity and cost. Conversely, reconfigurable devices based on DEAs offer low complexity, low electromagnetic (EM) losses and analogue operation. Our tunable phase shifter consists of metallic strips suspended a fixed distance above a coplanar waveguide (CPW) by planar DEAs. The planar actuators displace the metallic strips (10 mm in length) in-plane by 500 μm, modifying the EM field distribution, resulting in the desired phase shift. The demanding spacing (50 +/-5 μm between CPW and metallic strips) and parallel alignment criteria required for optimal device operation are successfully met in our device design and validated using bespoke methods. Our current device, approximately 60 mm x 60 mm in planar dimensions, meets the displacement requirements and we observe a considerable phase shift (~95° at 25 GHz) closely matching numerical simulations. Moreover, our device achieves state of the art performance in terms of phase shift per EM loss ~235°/dB (35 GHz), significantly out performing other phase shifter technologies, such as MMIC phase shifters.

  1. A new plasma-driven pulsed jet actuator for flow control

    NASA Astrophysics Data System (ADS)

    Bonnet, Jean-Paul; Acher, Gwenael; Lebedev, Anton; Benard, Nicolas; Moreau, Eric; Electro-Fluido Group Team

    2015-11-01

    Active flow control requires actuators with enough authority and high frequency response. Synthetic jets can have high frequency response but are rather limited in terms of authority providing the exit velocity is limited. Pressurized (flowing) jets have a very high potential in terms of authority particularly for high velocity flow control purposes. However, for most purposes, high frequency modulation (of order of several kHz) is required in order to excite most unstable modes and to operate in closed mode. Rapid mechanical valves are limited in terms of frequency (up to typically a few hundred of Hz). We develop a new generation of plasma-driven pulsation of flowing jet. The principle is to increase the temperature at the sonic throat through a plasma discharge located at the throat. The flow rate being proportional to the square root of the temperature for a perfect gas, for the same settling chamber pressure, the actuator flow rate can be varied. The frequency is then no limited by any mechanical constraint. A demonstrator has been tested with a 1mm sonic throat. The electric discharge is created by a 10 kV voltage applied between the anode and the throat acting as the cathode. Within these conditions, a 30% modulation of the flow rate can be obtained.

  2. Actuator-valve interface optimization. [Explosive actuators

    SciTech Connect

    Burchett, O.L.; Jones, R.L.

    1987-02-01

    The interface of explosive actuator driven valves can be optimized to maximize the velocity of the valve plunger by using the computer code Actuator-Valve Response. Details of the AVR model of the actuator driven valve plunger and the results of optimizing an actuator-valve interface with AVR are presented. 5 refs., 5 figs., 3 tabs.

  3. Omnidirectional Actuator Handle

    NASA Technical Reports Server (NTRS)

    Moetteli, John B.

    1995-01-01

    Proposed actuator handle comprises two normally concentric rings, cables, and pulleys arranged such that relative displacement of rings from concentricity results in pulling of cable and consequent actuation of associated mechanism. Unlike conventional actuator handles like levers on farm implements, actuated from one or two directions only, proposed handle reached from almost any direction and actuated by pulling or pushing inner ring in any direction with respect to outer ring. Flanges installed on inner ring to cover gap between inner ring and housing to prevent clothing from being caught.

  4. Combining Model-Based and Feature-Driven Diagnosis Approaches - A Case Study on Electromechanical Actuators

    NASA Technical Reports Server (NTRS)

    Narasimhan, Sriram; Roychoudhury, Indranil; Balaban, Edward; Saxena, Abhinav

    2010-01-01

    Model-based diagnosis typically uses analytical redundancy to compare predictions from a model against observations from the system being diagnosed. However this approach does not work very well when it is not feasible to create analytic relations describing all the observed data, e.g., for vibration data which is usually sampled at very high rates and requires very detailed finite element models to describe its behavior. In such cases, features (in time and frequency domains) that contain diagnostic information are extracted from the data. Since this is a computationally intensive process, it is not efficient to extract all the features all the time. In this paper we present an approach that combines the analytic model-based and feature-driven diagnosis approaches. The analytic approach is used to reduce the set of possible faults and then features are chosen to best distinguish among the remaining faults. We describe an implementation of this approach on the Flyable Electro-mechanical Actuator (FLEA) test bed.

  5. Auto-Gopher: A Wireline Deep Sampler Driven by Piezoelectric Percussive Actuator and EM Rotary Motor

    NASA Technical Reports Server (NTRS)

    Badescu, Mircea; Ressa, Aaron; Jae Lee, Hyeong; Bar-Cohen, Yoseph; Sherrit, Stewart; Zacny, Kris; Paulsen, Gale L.; Beegle, Luther; Bao, Xiaoqi

    2013-01-01

    The ability to penetrate subsurfaces and perform sample acquisition at depth of meters may be critical for future NASA in-situ exploration missions to bodies in the solar system, including Mars and Europa. A corer/sampler was developed with the goal of enabling acquisition of samples from depths of several meters where if used on Mars would be beyond the oxidized and sterilized zone. For this purpose, we developed a rotary-hammering coring drill, called Auto-Gopher, which employs a piezoelectric actuated percussive mechanism for breaking formations and an electric motor that rotates the bit to remove the powdered cuttings. This sampler is a wireline mechanism that can be fed into and retrieved from the drilled hole using a winch and a cable. It includes an inchworm anchoring mechanism allowing the drill advancement and weight on bit control without twisting the reeling and power cables. The penetration rate is being optimized by simultaneously activating the percussive and rotary motions of the Auto-Gopher. The percussive mechanism is based on the Ultrasonic/Sonic Drill/Corer (USDC) mechanism that is driven by piezoelectric stack and that was demonstrated to require low axial preload. The design and fabrication of this device were presented in previous publications. This paper presents the results of laboratory and field tests and lessons learned from this development.

  6. An instant multi-responsive porous polymer actuator driven by solvent molecule sorption

    NASA Astrophysics Data System (ADS)

    Zhao, Qiang; Dunlop, John W. C.; Qiu, Xunlin; Huang, Feihe; Zhang, Zibin; Heyda, Jan; Dzubiella, Joachim; Antonietti, Markus; Yuan, Jiayin

    2014-07-01

    Fast actuation speed, large-shape deformation and robust responsiveness are critical to synthetic soft actuators. A simultaneous optimization of all these aspects without trade-offs remains unresolved. Here we describe porous polymer actuators that bend in response to acetone vapour (24 kPa, 20 °C) at a speed of an order of magnitude faster than the state-of-the-art, coupled with a large-scale locomotion. They are meanwhile multi-responsive towards a variety of organic vapours in both the dry and wet states, thus distinctive from the traditional gel actuation systems that become inactive when dried. The actuator is easy-to-make and survives even after hydrothermal processing (200 °C, 24 h) and pressing-pressure (100 MPa) treatments. In addition, the beneficial responsiveness is transferable, being able to turn ‘inert’ objects into actuators through surface coating. This advanced actuator arises from the unique combination of porous morphology, gradient structure and the interaction between solvent molecules and actuator materials.

  7. Computational modeling and parametric study of a rotary actuator driven by piezoelectric composites

    NASA Astrophysics Data System (ADS)

    Li, Hing L.; Lee, ShiWei R.

    1998-07-01

    An innovative actuation principle was introduced in a previous study to drive a rotary actuator by piezoelectric composite laminate. The driving element is a three layer laminated beam with piezoceramics sandwiched between two antisymmetric composite laminae. By taking advantage of the structural coupling, a rotary actuator similar to ultrasonic motors can be implemented. A prototype of the mentioned actuator has been fabricated. The objective of this study is to model this device by finite element method. A commercial finite element code, ANSYS, was employed to simulate the rotary actuator. The piezoelectric laminate and the rotor were modeled by solid brick elements and special constraint element was used to account for the contact between two separate bodies. Static and transient dynamic analyses were conducted to simulate the deformation and the angular motion of the rotary actuator, respectively. Parametric study was performed by modal and harmonic analyses to investigate the dynamic response of the driving laminate. The results of this study confirmed the proposed actuation principle and the developed computational model may be used for the optimization of future design.

  8. Lightweight Seat Lever Operation Characteristics

    NASA Technical Reports Server (NTRS)

    Rajulu, Sudhakar

    1999-01-01

    In 1999, a Shuttle crew member was unable to operate the backrest lever for the lightweight seat in microgravity. It is essential that crew members can adjust this backrest lever, which is titled forward during launch and then moved backward upon reaching orbit. This adjustment is needed to cushion the crew members during an inadvertent crash landing situation. JSCs Anthropometry and Biomechanics Facility (ABF) performed an evaluation of the seat controls and provided recommendations on whether the seat lever positions and operations should be modified. The original Shuttle seats were replaced with new lightweight seats whose controls were moved, with one control at the front and the other at the back. The ABF designed a 12-person experiment to investigate the amount of pull force exerted by suited subjects, when controls were placed in the front and back of the lightweight seat. Each subject was asked to perform the pull test at least three times for each combination of lever position and suit pressure conditions. The results showed that, in general, the subjects were able to pull on the lever at the back position with only about half the amount of force that they were able to exert on the lever at the front position. In addition, the results also showed that subjects wearing the pressurized suit were unable to reach the seat lever when it was located at the back. The pull forces on the front lever diminished about 50% when subjects wore pressurized suits. Based on these results from this study, it was recommended that the levers should not be located in the back position. Further investigation is needed to determine whether the levers at the front of the seat could be modified or adjusted to increase the leverage for crew members wearing pressurized launch/escape suits.

  9. Aerospace induction motor actuators driven from a 20-kHz power link

    NASA Technical Reports Server (NTRS)

    Hansen, Irving G.

    1990-01-01

    Aerospace electromechanical actuators utilizing induction motors are under development in sizes up to 40 kW. While these actuators have immediate application to the Advanced Launch System (ALS) program, several potential applications are currently under study including the Advanced Aircraft Program. Several recent advances developed for the Space Station Freedom have allowed induction motors to be selected as a first choice for such applications. Among these technologies are bi-directional electronics and high frequency power distribution techniques. Each of these technologies are discussed with emphasis on their impact upon induction motor operation.

  10. Design and performance evaluation of a new jetting dispenser system using two piezostack actuators

    NASA Astrophysics Data System (ADS)

    Jeon, Juncheol; Hong, Seung-Min; Choi, Minkyu; Choi, Seung-Bok

    2015-01-01

    This paper presents a new jetting dispenser system which is adaptable to various packaging processes such as light emitting diode packaging and flip chip packaging. The proposed dispenser system is driven by piezostack actuators and a lever-hinge mechanism. In order to improve jetting performances such as accurate dispensed amount and adaptability to high viscosity fluid, two piezostack actuators are used. By activating the two actuators dually, the angular displacement of the lever can be controlled to produce a required motion of the needle. Firstly, the configuration and working principles of the proposed jetting system are explained, the design of the dispenser is then conducted and significant geometric dimensions of the dispenser are presented. In the design process, several operational requirements such as the maximum needle stroke, operational frequency, and amplification ratio of the lever-hinge are considered. The principal design parameters of the jetting dispenser system are determined from static and modal analysis using the finite element analysis. After obtaining the dimensional characteristics, the control logic for the dispensing operation is explained using a feed-forward controller. The piezostack-driven jetting dispenser system and control devices are then fabricated to evaluate the dispenser performance. It is shown experimentally that by changing the input voltage conditions, the amount of fluid dispensed by the proposed jetting system can be effectively controlled to achieve the desired jetting performance.

  11. Development of a tilt-positioning mechanism driven by flextensional piezoelectric actuators.

    PubMed

    Jing, Zijian; Xu, Minglong; Wu, Tonghui; Tian, Zheng

    2016-08-01

    Tilt-positioning mechanisms are required in optical systems for diverse applications. Compared to electromagnetic tilt-positioning mechanisms, piezoelectric tilters are superior with regard to high positioning resolution, cost-effectiveness, and no electromagnetic interference issues. But their applications are limited by small motion ranges. To overcome this problem, a novel piezoelectric tilt-positioning mechanism is proposed and developed in this paper, aiming to achieve a large output range in compact size. Serving this purpose, flextensional piezoelectric actuators (FPAs) are employed in this mechanism and their optimal structure is pursued. The existing approach to model and analyze the structure of FPAs is not perfect, making it challenging to exactly characterize and optimize actuator performance for its applications. To address this problem, a hybrid-body model of the FPAs is developed and based on this model, a governing equation is established to exactly and comprehensively characterize their kinematic performance. This equation allows the application requirement to be readily related to the actuator design, enabling the optimization of tilter design and the actuators. Using the optimized parameters, an experimental prototype is fabricated. This specimen achieved more than 15 mrad of angular travel at a small size of 35 × 42 × 42 mm, and the error between the analytical model and the experiment was less than 5%. These results support the accuracy of the hybrid-body model and indicate that the proposed tilter is very promising for practical applications. PMID:27587152

  12. Photothermally driven fast responding photo-actuators fabricated with comb-type hydrogels and magnetite nanoparticles

    PubMed Central

    Lee, Eunsu; Kim, Dowan; Kim, Haneul; Yoon, Jinhwan

    2015-01-01

    To overcome the slow kinetics of the volume phase transition of stimuli-responsive hydrogels as platforms for soft actuators, thermally responsive comb-type hydrogels were prepared using synthesized poly(N-isopropylacrylamide) macromonomers bearing graft chains. Fast responding light-responsive hydrogels were fabricated by combining a comb-type hydrogel matrix with photothermal magnetite nanoparticles (MNP). The MNPs dispersed in the matrix provide heat to stimulate the volume change of the hydrogel matrix by converting absorbed visible light to thermal energy. In this process, the comb-type hydrogel matrix exhibited a rapid response due to the free, mobile grafted chains. The comb-type hydrogel exhibited significantly enhanced light-induced volume shrinkage and rapid recovery. The comb-type hydrogels containing MNP were successfully used to fabricate a bilayer-type photo-actuator with fast bending motion. PMID:26459918

  13. Analysis of suitable geometrical parameters for designing a tendon-driven under-actuated mechanical finger

    NASA Astrophysics Data System (ADS)

    Penta, Francesco; Rossi, Cesare; Savino, Sergio

    2016-06-01

    This study aims to optimize the geometrical parameters of an under-actuated mechanical finger by conducting a theoretical analysis of these parameters. The finger is actuated by a flexion tendon and an extension tendon. The considered parameters are the tendon guide positions with respect to the hinges. By applying such an optimization, the correct kinematical and dynamical behavior of the closing cycle of the finger can be obtained. The results of this study are useful for avoiding the snapthrough and the single joint hyperflexion, which are the two breakdowns most frequently observed during experimentation on prototypes. Diagrams are established to identify the optimum values for the tendon guides position of a finger with specified dimensions. The findings of this study can serve as guide for future finger design.

  14. Real-time thickness measurement of biological tissues using a microfabricated magnetically-driven lens actuator.

    PubMed

    Mansoor, Hadi; Zeng, Haishan; Chiao, Mu

    2011-08-01

    A fiber optic confocal catheter with a micro scanning lens was developed for real-time and non-contact thickness measurement of biological tissue. The catheter has an outer diameter and rigid length of 4.75 mm and 30 mm respectively and is suitable for endoscopic applications. The catheter incorporates a lens actuator that is fabricated using microelectromechanical systems (MEMS) technology. The lens is mounted on a folded flexure made of nickel and is actuated by magnetic field. Thickness measurements are performed by positioning the catheter in front of the tissue and actuating the lens scanner in the out-of-plane direction. A single-mode optical fiber (SMF) is used to deliver a 785 nm laser beam to the tissue and relay back the reflected light from the tissue to a photomultiplier tube (PMT). When the focal point of the scanning lens passes tissue boundaries, intensity peaks are detected in the reflecting signal. Tissue thickness is calculated using its index of refraction and the lens displacement between intensity peaks. The utility of the confocal catheter was demonstrated by measuring the cornea and skin thicknesses of a mouse. Measurement uncertainty of 8.86 µm within 95% confidence interval has been achieved. PMID:21468630

  15. Design of IPMC actuator-driven valve-less micropump and its flow rate estimation at low Reynolds numbers

    NASA Astrophysics Data System (ADS)

    Lee, Sangki; Kim, Kwang J.

    2006-08-01

    This paper presents the design and flow rate predictions of an IPMC (ionic polymer-metal composite) actuator-driven valve-less micropump. It should be noted that IPMC is a promising material candidate for micropump applications since it can be operated with low input voltages and can produce large stroke volumes, while having controllable flow rates. The micropump manufacturing process with IPMC is also convenient; it is anticipated that the manufacturing cost of the IPMC micropump is competitive with other technologies. In order to design an effective IPMC diaphragm that functions as an actuating motor for a micropump, a finite element analysis (FEA) was utilized to optimize the electrode shape of the IPMC diaphragm and estimate its stroke volumes. In addition, the effect of the pump chamber pressure on the stroke volume was numerically investigated. Appropriate inlet and outlet nozzle/diffuser elements were also studied for the valve-less micropump. Based on the selected geometry of nozzle/diffuser elements and the estimated stroke volume of the IPMC diaphragm, the flow rate of the micropump was estimated at a low Reynolds number of about 50.

  16. Piezoelectrically Actuated Shutter for High Vacuum

    NASA Technical Reports Server (NTRS)

    Thompson, Robert; Klose, Gerhard

    2003-01-01

    A piezoelectrically actuated shutter is undergoing development for use in experiments on laser cooling of atoms. The shutter is required to be compatible with ultrahigh vacuum [pressure of 10(exp -9) torr (.1.3 x 10(exp -7) Pa) or less] and to be capable of performing reliably in the vacuum for at least one year. In operation, the shutter would enable the collection and launch of successive samples of cold atoms and would enable the interrogation of the immediately preceding sample while preventing disturbance of the atoms of that sample by light from the collection region. A major constraint is imposed on the design and operation of the shutter by a requirement that it not generate a magnetic field large enough to perturb an atomic clock. An electromagnetically actuated shutter could satisfy all requirements except this one. Hence, it was decided to use piezoelectric instead of electromagnetic actuation. The shutter (see figure) includes two commercial piezoelectrically driven flexure stages that produce a travel of 0.5 mm. Levers mechanically amplify the travel to the required level of 1 cm. Problems that remained to be addressed at the time of reporting the information for this article included lifetime testing and correction of a tendency for shutter blades to bounce open.

  17. Modeling of dielectric barrier discharge plasma actuators driven by repetitive nanosecond pulses

    SciTech Connect

    Likhanskii, Alexandre V.; Shneider, Mikhail N.; Macheret, Sergey O.; Miles, Richard B.

    2007-07-15

    A detailed physical model for an asymmetric dielectric barrier discharge (DBD) in air driven by repetitive nanosecond voltage pulses is developed. In particular, modeling of DBD with high voltage repetitive negative and positive nanosecond pulses combined with positive dc bias is carried out. Operation at high voltage is compared with operation at low voltage, highlighting the advantage of high voltages, however the effect of backward-directed breakdown in the case of negative pulses results in a decrease of the integral momentum transferred to the gas. The use of positive repetitive pulses with dc bias is demonstrated to be promising for DBD performance improvement. The effects of the voltage waveform not only on force magnitude, but also on the spatial profile of the force, are shown. The crucial role of background photoionization in numerical modeling of ionization waves (streamers) in DBD plasmas is demonstrated.

  18. Deep Drilling and Sampling via the Wireline Auto-Gopher Driven by Piezoelectric Percussive Actuator and EM Rotary Motor

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph; Badescu, Mircea; Sherrit, Stewart; Zacny, Kris; Paulsen, Gale L; Beegle, Luther; Bao, Xiaoqi

    2012-01-01

    The ability to penetrate subsurfaces and perform sample acquisition at depths of meters is critical for future NASA in-situ exploration missions to bodies in the solar system, including Mars and Europa. A corer/sampler was developed with the goal of acquiring pristine samples by reaching depths on Mars beyond the oxidized and sterilized zone. To developed rotary-hammering coring drill, called Auto-Gopher, employs a piezoelectric actuated percussive mechanism for breaking formations and an electric motor rotates the bit to remove the powdered cuttings. This sampler is a wireline mechanism that is incorporated with an inchworm mechanism allowing thru cyclic coring and core removal to reach great depths. The penetration rate is being optimized by simultaneously activating the percussive and rotary motions of the Auto-Gopher. The percussive mechanism is based on the Ultrasonic/Sonic Drill/Corer (USDC) mechanism that is driven by piezoelectric stack and that was demonstrated to require low axial preload. The Auto-Gopher has been produced taking into account the a lessons learned from the development of the Ultrasonic/Sonic Gopher that was designed as a percussive ice drill and was demonstrated in Antarctica in 2005 to reach about 2 meters deep. A field demonstration of the Auto-Gopher is currently being planned with objective of reaching as deep as 3 to 5 meters in tufa subsurface.

  19. Characteristics of sheath-driven tangential flow produced by a low-current DC surface glow discharge plasma actuator

    NASA Astrophysics Data System (ADS)

    Shin, Jichul; Shajid Rahman, Mohammad

    2014-08-01

    An experimental investigation of low-speed flow actuation at near-atmospheric pressure is presented. The flow actuation is achieved via low-current ( \\lesssim 1.0 mA) continuous or pulsed DC surface glow discharge plasma. The plasma actuator, consisting of two sharp-edged nickel electrodes, produces a tangential flow in a direction from anode to cathode, and is visualized using high-speed schlieren photography. The induced flow velocity estimated via the schlieren images reaches up to 5 m/s in test cases. The actuation capability increases with pressure and electrode gap distances, and the induced flow velocity increases logarithmically with the discharge power. Pulsed DC exhibits slightly improved actuation capability with better directionality. An analytic estimation of induced flow velocity obtained based on ion momentum in the cathode sheath and gas dynamics in one-dimensional flow yields values similar to those measured.

  20. Lever-Arm Pin Puller

    NASA Technical Reports Server (NTRS)

    Macmartin, Malcolm

    1994-01-01

    Mechanism holds retaining pins in place except when actuated to release pins quickly. Mechanism is integral part of cover designed to be removed with simple downward motion of hand. Before removal, mechanism secures cover in place. After removal, mechanism holds retaining pins for reuse.

  1. 14. INTERIOR OF MAIN DECKNOTE LEVERS FROM CEILING CONTROLLED BY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. INTERIOR OF MAIN DECK--NOTE LEVERS FROM CEILING CONTROLLED BY OPERATOR. LEFT HAND LEVER CONTROLLED THROTTLE, RIGHT HAND LEVER CONTROLLED SHOT GUN SWINGER. - Dredge CINCINNATI, Docked on Ohio River at foot of Lighthill Street, Pittsburgh, Allegheny County, PA

  2. Experimental investigation of dielectric barrier discharge plasma actuators driven by repetitive high-voltage nanosecond pulses with dc or low frequency sinusoidal bias

    NASA Astrophysics Data System (ADS)

    Opaits, Dmitry F.; Likhanskii, Alexandre V.; Neretti, Gabriele; Zaidi, Sohail; Shneider, Mikhail N.; Miles, Richard B.; Macheret, Sergey O.

    2008-08-01

    Experimental studies were conducted of a flow induced in an initially quiescent room air by a single asymmetric dielectric barrier discharge driven by voltage waveforms consisting of repetitive nanosecond high-voltage pulses superimposed on dc or alternating sinusoidal or square-wave bias voltage. To characterize the pulses and to optimize their matching to the plasma, a numerical code for short pulse calculations with an arbitrary impedance load was developed. A new approach for nonintrusive diagnostics of plasma actuator induced flows in quiescent gas was proposed, consisting of three elements coupled together: the schlieren technique, burst mode of plasma actuator operation, and two-dimensional numerical fluid modeling. The force and heating rate calculated by a plasma model was used as an input to two-dimensional viscous flow solver to predict the time-dependent dielectric barrier discharge induced flow field. This approach allowed us to restore the entire two-dimensional unsteady plasma induced flow pattern as well as characteristics of the plasma induced force. Both the experiments and computations showed the same vortex flow structures induced by the actuator. Parametric studies of the vortices at different bias voltages, pulse polarities, peak pulse voltages, and pulse repetition rates were conducted experimentally. The significance of charge buildup on the dielectric surface was demonstrated. The charge buildup decreases the effective electric field in the plasma and reduces the plasma actuator performance. The accumulated surface charge can be removed by switching the bias polarity, which leads to a newly proposed voltage waveform consisting of high-voltage nanosecond repetitive pulses superimposed on a high-voltage low frequency sinusoidal voltage. Advantages of the new voltage waveform were demonstrated experimentally.

  3. Theoretical model of adaptive fiber tip positioner based on flexible hinges and levers

    NASA Astrophysics Data System (ADS)

    Zhi, Dong; Ma, Yan-xing; Wang, Xiao-lin; Zhou, Pu; Si, Lei

    2015-10-01

    In this manuscript, we establish a model and theoretically investigate the novel structure of AFTP designed by ourselves. We analyze each sub-structure of the new type of AFTP and firstly use the software of ANSYS to simulate the deformation of the flexible hinge under the external force. The result shows that the deformation of the flexible hinge is mainly from and almost linear to the middle part. Further, after considering the influence of the levers and piezoelectric actuators, we setup the theoretical model in which the displacement is only relative to the ratio of the lever R. With the optimal value of R, we can get the relative largest displacement of the end cap when the other parameters are confirmed. As the maximal voltage applied on the piezoelectric stacks actuators (PSA) is finite, the largest displacement of the end cap is restricted. Neglecting the influence of the effective friction force (Ff) of inner-system, the relationship between the largest displacement of the end cap and the ratio (R) is derived numerically. From the calculated results, we get the largest displacement is about 67 μm with R of 6.9. This work provides a reference for structure optimization of AFTP based on flexible hinges and levers.

  4. Measuring How Muscles Function in Levers.

    ERIC Educational Resources Information Center

    DeMont, M. Edwin

    1996-01-01

    Presents an exercise that examines the lever systems that function in the chelae of the American lobster. Involves calculating the mechanical and distance advantages of the crusher and pincer chelae and estimating the actual forces generated by the contraction of the muscles and the magnitude of the forces transmitted around the fulcrum to the tip…

  5. DETAIL OF STANDARD INTERLOCKING MACHINE OPERATING LEVERS. LOCKING MECHANISM IS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL OF STANDARD INTERLOCKING MACHINE OPERATING LEVERS. LOCKING MECHANISM IS BELOW FLOOR. BOXES BEHIND SOME LEVERS HOUSE ELECTRICAL CONTACTS FOR SIGNALS. - Baltimore & Ohio Railroad, Z Tower, State Route 46, Keyser, Mineral County, WV

  6. Linear Actuator Has Long Stroke and High Resolution

    NASA Technical Reports Server (NTRS)

    Cook, Brant T.; Moore, Donald M.; Braun, David F.; Koenig, John S.; Hankins, Steve M.

    2009-01-01

    The term precision linear actuator, direct drive ( PLADD ) refers to a robust linear actuator designed to be capable of repeatedly performing, over a lifetime of the order of 5 to 10 years, positioning maneuvers that include, variously, submicron increments or slews of the order of a centimeter. The PLADD is capable of both long stroke (120 mm) and high resolution (repeatable increments of 20 nm). Unlike precise linear actuators of prior design, the PLADD contains no gears, levers, or hydraulic converters. The PLADD, now at the prototype stage of development, is intended for original use as a coarse-positioning actuator in a spaceborne interferometer. The PLADD could also be adapted to terrestrial applications in which there are requirements for long stroke and high resolution: potential applications include medical imaging and fabrication of semiconductor devices. The PLADD (see figure) includes a commercially available ball-screw actuator driven directly by a commercially available three-phase brushless DC motor. The ball-screw actuator comprises a spring-preloaded ball nut on a ball screw that is restrained against rotation as described below. The motor is coupled directly (that is, without an intervening gear train) to a drive link that, in turn, is coupled to the ball nut. By eliminating the gear train, the direct-drive design eliminates the complexity, backlash, and potential for misalignment associated with a gear train. To prevent inadvertent movement, there is a brake that includes flexured levers compressed against the drive link by preload springs. This is a power-off brake: There are also piezoelectric stacks that can be activated to oppose the springs and push the levers away from the drive link. Hence, power must be applied to the piezoelectric stacks to release the drive link from braking. To help ensure long operational life, all of the mechanical drive components are immersed in an oil bath within hermetically sealed bellows. The outer end of the

  7. Fabrication and characterization of solid-state, conducting polymer actuators

    SciTech Connect

    Xie, J.; Sansinena, J. M.; Gao, J.; Wang, H. L.

    2004-01-01

    We report here the fabrication and characterization of solid-state, conducting polymer actuators. The electrochemical activity of polyaniline (PANI) thin film coated with solid-state polyelectrolyte is very similar to the polyaniline thin film in an aqueous solution. The solid-state actuator is adhere to a lever arm of an force transducer and the force generation is measured in real time. The force generated by the actuator is found to be length dependent. However, the overall torques generated by the actuators with different lengths remains essentially the same. The effect of stimulation signals such as voltage, current, on the bending angle and displacement is also studied using square wave potential.

  8. Power lever apparatus for a turbine engine

    SciTech Connect

    McCombs Jr., H. L.

    1985-05-21

    In a turbine engine having a compressor with a bleed valve and a variable geometry apparatus is responsive to an operational control member for regulating the flow rate of fuel supplied the turbine engine as a function of atmospheric pressure and the temperature of air supplied to the compressor corresponding to movement of a power lever by an operator to a desired operation of the turbine engine. The power lever has an indicator member fluidically connected to a follower member linked to the operational control member. The fluidic connection is responsive to operational parameters of the turbine engine and limits the rotational input to the follower member when the rate of fuel flow could cause stalling and the development of an unacceptable operating temperature or overspeed condition in the turbine engine.

  9. Lever-press conditioning in the crab.

    PubMed

    Abramson, C I; Feinman, R D

    1990-08-01

    An operant chamber has been developed for studying lever-press conditioning in the green crab Carcinus maenas. In one series of experiments, animals were presented with a single bar and were reinforced with food for every bar press. Performance increased over time and high rates of responding were observed after 2 days of training. The response rate was always higher than that for a yoked (noncontingent) control group. When the contingencies were switched, the animals adjusted to the new conditions. Discrimination in the lever-press apparatus was demonstrated in a second experiment in which crabs had to choose between two bars, one (S+) caused food to be dispensed while the other (S-) was inactive. Experimental animals pressed the S+ bar at a significantly higher rate than the S- bar. When the contingencies associated with the lever were reversed, animals learned to switch to the correct bar by the second day. It was not necessary to reinforce every response: animals maintained high rates of responding on a schedule where every other response was reinforced. Animals used different methods of pressing the bar; the most common was extension of the claw, predominantly at the meropodite-carpopodite joint. PMID:2255730

  10. Note: Seesaw actuation of atomic force microscope probes for improved imaging bandwidth and displacement range

    SciTech Connect

    Torun, H.; Torello, D.; Degertekin, F. L.

    2011-08-15

    The authors describe a method of actuation for atomic force microscope (AFM) probes to improve imaging speed and displacement range simultaneously. Unlike conventional piezoelectric tube actuation, the proposed method involves a lever and fulcrum ''seesaw'' like actuation mechanism that uses a small, fast piezoelectric transducer. The lever arm of the seesaw mechanism increases the apparent displacement range by an adjustable gain factor, overcoming the standard tradeoff between imaging speed and displacement range. Experimental characterization of a cantilever holder implementing the method is provided together with comparative line scans obtained with contact mode imaging. An imaging bandwidth of 30 kHz in air with the current setup was demonstrated.

  11. A method for measurement of static lever arm

    NASA Astrophysics Data System (ADS)

    Ma, Xianglu; Qin, Shiqiao; Wang, Xingshu; Wu, Wei; Hu, Feng; Zheng, JiaXing

    2016-01-01

    Lever arm effect has to be considered in transfer alignment technology. Between static lever arm and dynamic lever arm, the former has larger amplitude, and it is the major error source in transfer alignment. How to measure and solve it become an important problem. This paper takes vehicle as a rigid body. Assume that static lever arm does not change in a short time, based on two inertial measurement units(IMU), data are measured and constituted several matrixes properly. After that, by using least square method, static lever arm is solved finally. Simulation experiments are implemented, results show that static lever arm can be solved effectively. Further study shows that, the precision of the method can be improved by preprocessing low pass filter.

  12. How does lever length and the position of its axis of rotation influence human performance during lever wheelchair propulsion?

    PubMed

    Fiok, Krzysztof; Mróz, Anna

    2015-10-01

    The purpose of this study was to investigate empirically how lever length and its axis of rotation position influences human performance during lever wheelchair propulsion. In order to fulfill this goal, a dedicated test stand allowing easy implementation of various lever positions was created. In the experiment, 10 young, healthy, male subjects performed 8 tests consisting of propulsion work with levers of different lengths and lever axis of rotation positions. During tests heart rate, oxygen consumption and EMG assessment of 6 muscles was carried out. Measurements of power output on the test stand were done as well. Together with oxygen consumption analysis, this allowed calculation of human work efficiency. The results show significant (p<0.05 and p<0.001) differences between lever configurations when comparing various parameters values. From the carried out experiments, the authors conclude that levers' length and their axis of rotation position significantly influence human performance during lever wheelchair propulsion. For the examined subjects, placing the levers' axis of rotation close behind the back wheels axis of rotation offered advantageous work conditions. PMID:26142018

  13. Simulation model of a lever-propelled wheelchair.

    PubMed

    Sasaki, Makoto; Ota, Yuki; Hase, Kazunori; Stefanov, Dimitar; Yamaguchi, Masaki

    2014-01-01

    Wheelchair efficiency depends significantly on the individual adjustment of the wheelchair propulsion interface. Wheelchair prescription involves reconfiguring the wheelchair to optimize it for specific user characteristics. Wheelchair tuning procedure is a complicated task that is performed usually by experienced rehabilitation engineers. In this study, we report initial results from the development of a musculoskeletal model of the wheelchair lever propulsion. Such a model could be used for the development of new advanced wheelchair approaches that allow wheelchair designers and practitioners to explore virtually, on a computer, the effects of the intended settings of the lever-propulsion interface. To investigate the lever-propulsion process, we carried out wheelchair lever propulsion experiments where joint angle, lever angle and three-directional forces and moments applied to the lever were recorded during the execution of defined propulsion motions. Kinematic and dynamic features of lever propulsion motions were extracted from the recorded data to be used for the model development. Five healthy male adults took part in these initial experiments. The analysis of the collected kinematic and dynamic motion parameters showed that lever propulsion is realized by a cyclical three-dimensional motion of upper extremities and that joint torque for propulsion is maintained within a certain range. The synthesized propulsion model was verified by computer simulation where the measured lever-angles were compared with the angles generated by the developed model simulation. Joint torque amplitudes were used to impose the torque limitation to the model joints. The results evidenced that the developed model can simulate successfully basic lever propulsion tasks such as pushing and pulling the lever. PMID:25571588

  14. Scissor thrust valve actuator

    DOEpatents

    DeWall, Kevin G.; Watkins, John C; Nitzel, Michael E.

    2006-08-29

    Apparatus for actuating a valve includes a support frame and at least one valve driving linkage arm, one end of which is rotatably connected to a valve stem of the valve and the other end of which is rotatably connected to a screw block. A motor connected to the frame is operatively connected to a motor driven shaft which is in threaded screw driving relationship with the screw block. The motor rotates the motor driven shaft which drives translational movement of the screw block which drives rotatable movement of the valve driving linkage arm which drives translational movement of the valve stem. The valve actuator may further include a sensory control element disposed in operative relationship with the valve stem, the sensory control element being adapted to provide control over the position of the valve stem by at least sensing the travel and/or position of the valve stem.

  15. Lever-type two-cycle internal combustion engine

    SciTech Connect

    Wenzel, E.C.; Wenzel, S.T.

    1991-06-25

    This patent describes a lever type internal combustion engine. It comprises power cylinders arranged in side-by-side opposed pairs and disposed in a first horizontal plane, each provided with a piston and a piston rod pivotally connected at an inner end with the piston, a crankshaft supported for rotation about an axis lying in a second horizontal plane disposed in spaced parallel relationship with and below the first horizontal plane, and a lever system whereby the power cylinder pistons drive the crankshaft, the lever system, one for each pair of opposed power cylinders, comprising an elongate level arm pivotally interconnected at a first end with the outer ends of the piston rods, means including guide members disposed below the crankshaft for constraining a second end of the lever arm for up and down movement in a direction perpendicular to the first and second horizontal planes, and means for operatively connecting the lever arm at a point intermediate its first and second ends to the crankshaft, whereby the lever arm functions as a lever of the second class between the piston rods and the crankshaft the constrained second end thereof functioning as the fulcrum therefor.

  16. Fail-safe electric actuator

    SciTech Connect

    Wright, J.J.

    1988-07-19

    In combination with a control mechanism characterized by the ability to be moved from inoperative to operative position and back, a fail-safe actuator device for automatically returning the control mechanism to inoperative position when interruption of electric power occurs is described which comprises: a fluid-driven vaned torque actuator: electric-motor-driven fluid power means for operating the torque actuator; electrically operated valve means for controlling the power fluid flow between the torque actuator and the fluid power generating means; at least one shaft projecting from the torque actuator; coupling means for operatively connecting the shaft to the control mechanism to be operated by the failsafe actuator device; reversible means for storing energy, the reversible means being operatively connected to the shaft; a limit-switch operating cam mounted on and rotable with the shaft; a limit switch positioned for activation by the limit-switch operating cam; and electric circuitry means for interconnecting the motordriven fluid power generating means, the valve means, and the limit switch.

  17. Improvements In Ball-Screw Linear Actuators

    NASA Technical Reports Server (NTRS)

    Iskenderian, Theodore; Joffe, Benjamin; Summers, Robert

    1996-01-01

    Report describes modifications of design of type of ball-screw linear actuator driven by dc motor, with linear-displacement feedback via linear variable-differential transformer (LVDT). Actuators used to position spacecraft engines to direct thrust. Modifications directed toward ensuring reliable and predictable operation during planned 12-year cruise and interval of hard use at end of cruise.

  18. 35. END VIEW, INTERIOR, SHOWING SWITCHING LEVERS, BERK SWITCH TOWER, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    35. END VIEW, INTERIOR, SHOWING SWITCHING LEVERS, BERK SWITCH TOWER, SOUTH NORWALK - New York, New Haven & Hartford Railroad, Automatic Signalization System, Long Island Sound shoreline between Stamford & New Haven, Stamford, Fairfield County, CT

  19. 16. VIEW OF LEVER CONNECTED TO CHAIN (BRIDGE IN CLOSED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. VIEW OF LEVER CONNECTED TO CHAIN (BRIDGE IN CLOSED POSITION), LOOKING WEST - Mystic River Drawbridge No. 7, Spanning Mystic River at Boston & Maine Railroad Eastern Route, Somerville, Middlesex County, MA

  20. Noninvasive determination of optical lever sensitivity in atomic force microscopy

    SciTech Connect

    Higgins, M.J.; Proksch, R.; Sader, J.E.; Polcik, M.; Mc Endoo, S.; Cleveland, J.P.; Jarvis, S.P.

    2006-01-15

    Atomic force microscopes typically require knowledge of the cantilever spring constant and optical lever sensitivity in order to accurately determine the force from the cantilever deflection. In this study, we investigate a technique to calibrate the optical lever sensitivity of rectangular cantilevers that does not require contact to be made with a surface. This noncontact approach utilizes the method of Sader et al. [Rev. Sci. Instrum. 70, 3967 (1999)] to calibrate the spring constant of the cantilever in combination with the equipartition theorem [J. L. Hutter and J. Bechhoefer, Rev. Sci. Instrum. 64, 1868 (1993)] to determine the optical lever sensitivity. A comparison is presented between sensitivity values obtained from conventional static mode force curves and those derived using this noncontact approach for a range of different cantilevers in air and liquid. These measurements indicate that the method offers a quick, alternative approach for the calibration of the optical lever sensitivity.

  1. Tension Stiffened and Tendon Actuated Manipulator

    NASA Technical Reports Server (NTRS)

    Doggett, William R. (Inventor); Dorsey, John T. (Inventor); Ganoe, George G. (Inventor); King, Bruce D. (Inventor); Jones, Thomas C. (Inventor); Mercer, Charles D. (Inventor); Corbin, Cole K. (Inventor)

    2015-01-01

    A tension stiffened and tendon actuated manipulator is provided performing robotic-like movements when acquiring a payload. The manipulator design can be adapted for use in-space, lunar or other planetary installations as it is readily configurable for acquiring and precisely manipulating a payload in both a zero-g environment and in an environment with a gravity field. The manipulator includes a plurality of link arms, a hinge connecting adjacent link arms together to allow the adjacent link arms to rotate relative to each other and a cable actuation and tensioning system provided between adjacent link arms. The cable actuation and tensioning system includes a spreader arm and a plurality of driven and non-driven elements attached to the link arms and the spreader arm. At least one cable is routed around the driven and non-driven elements for actuating the hinge.

  2. Mars Science Laboratory Rover Actuator Thermal Design

    NASA Technical Reports Server (NTRS)

    Novak, Keith S.; Liu, Yuanming; Lee, Chern-Jiin; Hendricks, Steven

    2010-01-01

    NASA will launch a 900 kg rover, part of the Mars Science Laboratory (MSL) mission, to Mars in October of 2011. The MSL rover is scheduled to land on Mars in August of 2012. The rover employs 31, electric-motor driven actuators to perform a variety of engineering and science functions including: mobility, camera pointing, telecommunications antenna steering, soil and rock sample acquisition and sample processing. This paper describes the MSL rover actuator thermal design. The actuators have stainless steel housings and planetary gearboxes that are lubricated with a "wet" lubricant. The lubricant viscosity increases with decreasing temperature. Warm-up heaters are required to bring the actuators up to temperature (above -55 C) prior to use in the cold wintertime environment of Mars (when ambient atmosphere temperatures are as cold as -113 C). Analytical thermal models of all 31 MSL actuators have been developed. The actuators have been analyzed and warm-up heaters have been designed to improve actuator performance in cold environments. Thermal hardware for the actuators has been specified, procured and installed. This paper presents actuator thermal analysis predicts, and describes the actuator thermal hardware and its operation. In addition, warm-up heater testing and thermal model correlation efforts for the Remote Sensing Mast (RSM) elevation actuator are discussed.

  3. Actuated atomizer

    NASA Technical Reports Server (NTRS)

    Tilton, Charles (Inventor); Weiler, Jeff (Inventor); Palmer, Randall (Inventor); Appel, Philip (Inventor)

    2008-01-01

    An actuated atomizer is adapted for spray cooling or other applications wherein a well-developed, homogeneous and generally conical spray mist is required. The actuated atomizer includes an outer shell formed by an inner ring; an outer ring; an actuator insert and a cap. A nozzle framework is positioned within the actuator insert. A base of the nozzle framework defines swirl inlets, a swirl chamber and a swirl chamber. A nozzle insert defines a center inlet and feed ports. A spool is positioned within the coil housing, and carries the coil windings having a number of turns calculated to result in a magnetic field of sufficient strength to overcome the bias of the spring. A plunger moves in response to the magnetic field of the windings. A stop prevents the pintle from being withdrawn excessively. A pintle, positioned by the plunger, moves between first and second positions. In the first position, the head of the pintle blocks the discharge passage of the nozzle framework, thereby preventing the atomizer from discharging fluid. In the second position, the pintle is withdrawn from the swirl chamber, allowing the atomizer to release atomized fluid. A spring biases the pintle to block the discharge passage. The strength of the spring is overcome, however, by the magnetic field created by the windings positioned on the spool, which withdraws the plunger into the spool and further compresses the spring.

  4. Q-factor enhancement for self-actuated self-sensing piezoelectric MEMS resonators applying a lock-in driven feedback loop

    NASA Astrophysics Data System (ADS)

    Kucera, M.; Manzaneque, T.; Sánchez-Rojas, J. L.; Bittner, A.; Schmid, U.

    2013-08-01

    This paper presents a robust Q-control approach based on an all-electrical feedback loop enhancing the quality factor of a resonant microstructure by using the self-sensing capability of a piezoelectric thin film actuator made of aluminium nitride. A lock-in amplifier is used to extract the feedback signal which is proportional to the piezoelectric current. The measured real part is used to replace the originally low-quality and noisy feedback signal to modulate the driving voltage of the piezoelectric thin-film actuator. Since the lock-in amplifier reduces the noise in the feedback signal substantially, the proposed enhancement loop avoids the disadvantage of a constant signal-to-noise ratio, which an analogue feedback circuit usually suffers from. The quality factor was increased from the intrinsic value of 1766 to a maximum of 34 840 in air. These promising results facilitate precise measurements for self-actuated and self-sensing MEMS cantilevers even when operated in static viscous media.

  5. Thermally Actuated Hydraulic Pumps

    NASA Technical Reports Server (NTRS)

    Jones, Jack; Ross, Ronald; Chao, Yi

    2008-01-01

    Thermally actuated hydraulic pumps have been proposed for diverse applications in which direct electrical or mechanical actuation is undesirable and the relative slowness of thermal actuation can be tolerated. The proposed pumps would not contain any sliding (wearing) parts in their compressors and, hence, could have long operational lifetimes. The basic principle of a pump according to the proposal is to utilize the thermal expansion and contraction of a wax or other phase-change material in contact with a hydraulic fluid in a rigid chamber. Heating the chamber and its contents from below to above the melting temperature of the phase-change material would cause the material to expand significantly, thus causing a substantial increase in hydraulic pressure and/or a substantial displacement of hydraulic fluid out of the chamber. Similarly, cooling the chamber and its contents from above to below the melting temperature of the phase-change material would cause the material to contract significantly, thus causing a substantial decrease in hydraulic pressure and/or a substantial displacement of hydraulic fluid into the chamber. The displacement of the hydraulic fluid could be used to drive a piston. The figure illustrates a simple example of a hydraulic jack driven by a thermally actuated hydraulic pump. The pump chamber would be a cylinder containing encapsulated wax pellets and containing radial fins to facilitate transfer of heat to and from the wax. The plastic encapsulation would serve as an oil/wax barrier and the remaining interior space could be filled with hydraulic oil. A filter would retain the encapsulated wax particles in the pump chamber while allowing the hydraulic oil to flow into and out of the chamber. In one important class of potential applications, thermally actuated hydraulic pumps, exploiting vertical ocean temperature gradients for heating and cooling as needed, would be used to vary hydraulic pressures to control buoyancy in undersea research

  6. T-Slide Linear Actuators

    NASA Technical Reports Server (NTRS)

    Vranish, John

    2009-01-01

    T-slide linear actuators use gear bearing differential epicyclical transmissions (GBDETs) to directly drive a linear rack, which, in turn, performs the actuation. Conventional systems use a rotary power source in conjunction with a nut and screw to provide linear motion. Non-back-drive properties of GBDETs make the new actuator more direct and simpler. Versions of this approach will serve as a long-stroke, ultra-precision, position actuator for NASA science instruments, and as a rugged, linear actuator for NASA deployment duties. The T slide can operate effectively in the presence of side forces and torques. Versions of the actuator can perform ultra-precision positioning. A basic T-slide actuator is a long-stroke, rack-and-pinion linear actuator that, typically, consists of a T-slide, several idlers, a transmission to drive the slide (powered by an electric motor) and a housing that holds the entire assembly. The actuator is driven by gear action on its top surface, and is guided and constrained by gear-bearing idlers on its other two parallel surfaces. The geometry, implemented with gear-bearing technology, is particularly effective. An electronic motor operating through a GBDET can directly drive the T slide against large loads, as a rack and pinion linear actuator, with no break and no danger of back driving. The actuator drives the slide into position and stops. The slide holes position with power off and no brake, regardless of load. With the T slide configuration, this GBDET has an entire T-gear surface on which to operate. The GB idlers coupling the other two T slide parallel surfaces to their housing counterpart surfaces provide constraints in five degrees-of-freedom and rolling friction in the direction of actuation. Multiple GB idlers provide roller bearing strength sufficient to support efficient, rolling friction movement, even in the presence of large, resisting forces. T-slide actuators can be controlled using the combination of an off

  7. Differential Acquisition of Lever Pressing in Inbred and Outbred Mice: Comparison of One-Lever and Two-Lever Procedures and Correlation with Differences in Locomotor Activity

    ERIC Educational Resources Information Center

    McKerchar, Todd L.; Zarcone, Troy J.; Fowler, Stephen C.

    2005-01-01

    Recent progress in mouse genetics has led to an increased interest in developing procedures for assessing mouse behavior, but relatively few of the behavioral procedures developed involve positively reinforced operant behavior. When operant methods are used, nose poking, not lever pressing, is the target response. In the current study differential…

  8. Microwave Power for Smart Membrane Actuators

    NASA Technical Reports Server (NTRS)

    Choi, Sang H.; Song, Kyo D.; Golembiewski, Walter T.; Chu, Sang-Hyon; King, Glen C.

    2002-01-01

    The concept of microwave-driven smart membrane actuators is envisioned as the best option to alleviate the complexity associated with hard-wired control circuitry. A large, ultra-light space structure, such as solar sails and Gossamer spacecrafts, requires a distribution of power into individual membrane actuators to control them in an effective way. A patch rectenna array with a high voltage output was developed to drive smart membrane actuators. Networked patch rectenna array receives and converts microwave power into a DC power for an array of smart actuators. To use microwave power effectively, the concept of a power allocation and distribution (PAD) circuit is developed and tested for networking a rectenna/actuator patch array. For the future development, the PAD circuit could be imbedded into a single embodiment of rectenna and actuator array with the thin-film microcircuit embodiment. Preliminary design and fabrication of PAD circuitry that consists of a sixteen nodal elements were made for laboratory testing.

  9. Rotary actuator

    NASA Technical Reports Server (NTRS)

    Brudnicki, Myron (Inventor)

    1995-01-01

    Rotary actuators and other mechanical devices incorporating shape memory alloys are provided herein. Shape memory alloys are a group of metals which when deformed at temperatures below their martensite temperatures, resume the shapes which they had prior to the deformation if they are heated to temperatures above their austensite temperatures. Actuators in which shape memory alloys are employed include bias spring types, in which springs deform the shape memory alloy (SMA), and differential actuators, which use two SMA members mechanically connected in series. Another type uses concentric cylindrical members. One member is in the form of a sleeve surrounding a cylinder, both being constructed of shape memory alloys. Herein two capstans are mounted on a shaft which is supported in a framework. Each capstan is capable of rotating the shaft. Shape memory wire, as two separate lengths of wire, is wrapped around each capstan to form a winding around that capstan. The winding on one capstan is so wrapped that the wire is in a prestretched state. The winding on the other capstan is so wrapped that the wire is in a taut, but not a prestretched, state. Heating one performs work in one direction, thus deforming the other one. When the other SMA is heated the action is reversed.

  10. Design of a MEMS-based motion stage based on a lever mechanism for generating large displacements and forces

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Sik; Shi, Hongliang; Dagalakis, Nicholas G.; Gupta, Satyandra K.

    2016-09-01

    Conventional miniaturized motion stages have a volume of 50–60 cm3 and a range of motion around 100 μm. Micro-electro-mechanical systems (MEMS)-based motion stages have been good alternatives in some applications for small footprint, micron-level accuracy, and a lower cost. However, existing MEMS-based motion stages are able to provide a force of μN level, small displacements (less than tens of microns), and need additional features for practical applications like a probe or a stage. In this paper, a single degree of freedom motion stage is designed and analyzed for a larger displacement, a larger output force, a smaller out-of-plane deformation, and a bigger moving stage for further applications. For these purposes, the presented motion stage is designed with a thermal actuator, folded springs, and a lever, and it is experimentally characterized. Furthermore, three different types of flexure joints are investigated to characterize their capabilities and suitability to serve as the revolute joint of the lever: a beam, a cartwheel, and a butterfly flexure. The presented motion stage has a moving stage of 15 mm  ×  15 mm and shows a maximum displacement over 80 μm, and out-of-plane deformation under a weight of 120 μN less than 2 μm. The force generated by the actuator is estimated to be 68.6 mN.

  11. Fast-acting valve actuator

    DOEpatents

    Cho, Nakwon

    1980-01-01

    A fast-acting valve actuator utilizes a spring driven pneumatically loaded piston to drive a valve gate. Rapid exhaust of pressurized gas from the pneumatically loaded side of the piston facilitates an extremely rapid piston stroke. A flexible selector diaphragm opens and closes an exhaust port in response to pressure differentials created by energizing and de-energizing a solenoid which controls the pneumatic input to the actuator as well as selectively providing a venting action to one side of the selector diaphragm.

  12. Performance study of a hydrogen powered metal hydride actuator

    NASA Astrophysics Data System (ADS)

    Mainul Hossain Bhuiya, Md; Kim, Kwang J.

    2016-04-01

    A thermally driven hydrogen powered actuator integrating metal hydride hydrogen storage reactor, which is compact, noiseless, and able to generate smooth actuation, is presented in this article. To test the plausibility of a thermally driven actuator, a conventional piston type actuator was integrated with LaNi5 based hydrogen storage system. Copper encapsulation followed by compaction of particles into pellets, were adopted to improve overall thermal conductivity of the reactor. The operation of the actuator was thoroughly investigated for an array of operating temperature ranges. Temperature swing of the hydride reactor triggering smooth and noiseless actuation over several operating temperature ranges were monitored for quantification of actuator efficiency. Overall, the actuator generated smooth and consistent strokes during repeated cycles of operation. The efficiency of the actuator was found to be as high as 13.36% for operating a temperature range of 20 °C-50 °C. Stress-strain characteristics, actuation hysteresis etc were studied experimentally. Comparison of stress-strain characteristics of the proposed actuator with traditional actuators, artificial muscles and so on was made. The study suggests that design modification and use of high pressure hydride may enhance the performance and broaden the application horizon of the proposed actuator in future.

  13. Modular droplet actuator drive

    NASA Technical Reports Server (NTRS)

    Pollack, Michael G. (Inventor); Paik, Philip (Inventor)

    2011-01-01

    A droplet actuator drive including a detection apparatus for sensing a property of a droplet on a droplet actuator; circuitry for controlling the detection apparatus electronically coupled to the detection apparatus; a droplet actuator cartridge connector arranged so that when a droplet actuator cartridge electronically is coupled thereto: the droplet actuator cartridge is aligned with the detection apparatus; and the detection apparatus can sense the property of the droplet on a droplet actuator; circuitry for controlling a droplet actuator coupled to the droplet actuator connector; and the droplet actuator circuitry may be coupled to a processor.

  14. Gear-shift lever having variable thickness walls

    SciTech Connect

    Tanaka, T.

    1988-01-03

    A one-piece elongated tubular transmission gear shift lever, is described comprising a tubular connector part at a first end of the gear shift lever, whereby the tubular connector part is adapted to be secured to a pivot means; a spherical part extending from the connector part, the connector part and the spherical part having a first wall thickness; a cylindrical part extending from the spherical part in a direction opposite the tubular connector part, the cylindrical part having a second wall thickness less than the first wall thickness; a tapered part extending from the cylindrical part; and a threaded part extending from the tapered part, the threaded part formed at a second end of the gear shift lever opposite the first end, whereby a gear shift knob may be attached.

  15. Acquisition of operant behavior in rats with delayed reinforcement: A retractable-lever procedure.

    PubMed

    McNamara, Andrew A; Johnson, Lyndsey E; Tate, Christopher; Chiang, Thomas; Byrne, Tom

    2015-02-01

    Experimentally naïve rats acquired lever pressing with delayed reinforcement when the immediate programmed consequence for lever pressing was the simultaneous retraction of two identical levers. Presses on one lever also produced access to sweetened condensed milk after a delay of 10s following retraction. Presses on the second lever resulted in retraction only. Lever retraction prevented the possibility of adventitious reinforcement of contacting the operanda during the reinforcement delays. Several measures indicated that the delayed reinforcers strengthened behavior. The majority of responses for all rats were on the lever that initiated reinforcer delivery. Responding for seven out of eight rats decreased during a subsequent extinction phase in which retraction was the only consequence arranged for lever pressing. Responding recovered rapidly when food reinforcement was available again. Furthermore, when contingencies on the two levers were switched, rats allocated their behavior accordingly, showing control by the delayed reinforcers. PMID:25464338

  16. Dielectric Actuation of Polymers

    NASA Astrophysics Data System (ADS)

    Niu, Xiaofan

    in tactile display is investigated by the prototyping of a large scale refreshable Braille display device. Braille is a critical way for the vision impaired community to learn literacy and improve life quality. Current piezoelectrics-based refreshable Braille display technologies are limited to up to 1 line of Braille text, due to the bulky size of bimorph actuators. Based on the unique actuation feature of BSEP, refreshable Braille display devices up to smartphone-size have been demonstrated by polymer sheet laminates. Dots in the devices can be individually controlled via incorporated field-driven BSEP actuators and Joule heater units. A composite material consisting of silver nanowires (AgNW) embedded in a polymer substrate is brought up as a compliant electrode candidate for BSEP application. The AgNW composite is highly conductive (Rs: 10 Ω/sq) and remains conductive at strains as high as 140% (Rs: <10 3 Ω/sq). The baseline conductivity has only small changes up to 90% strain, which makes it low enough for both field driving and stretchable Joule heating. An out-of-plane bistable area strain up to 68% under Joule heating is achieved.

  17. Carbon nanotube based NEMS actuators and sensors

    NASA Astrophysics Data System (ADS)

    Forney, Michael; Poler, Jordan

    2011-03-01

    Single-walled carbon nanotubes (SWNTs) have been widely studied due to superior mechanical and electrical properties. We have grown vertically aligned SWNTs (VA-SWNTs) onto microcantilever (MC) arrays, which provides an architecture for novel actuators and sensors. Raman spectroscopy confirms that the CVD-grown nanotubes are SWNTs and SEM confirms aligned growth. As an actuator, this hybrid MC/VA-SWNT system can be electrostatically modulated. SWNTs are excellent electron acceptors, so we can charge up the VA-SWNT array by applying a voltage. The electrostatic repulsion among the charged SWNTs provides a surface stress that induces MC deflection. Simulation results show that a few electrons per SWNT are needed for measureable deflections, and experimental actuators are being characterized by SEM, Raman, and an AFM optical lever system. The applied voltage is sinusoidally modulated, and deflection is measured with a lock-in amplifier. These actuators could be used for nano-manipulation, release of drugs from a capsule, or nano-valves. As a sensor, this MC/VA-SWNT system offers an improved sensitivity for chemical and bio-sensing compared to surface functionalized MC-based sensors. Those sensors only have a 2D sensing surface, but a MC/VA-SWNT system has significantly more sensing surface because the VA-SWNTs extend microns off the MC surface.

  18. Memory metal actuator

    NASA Technical Reports Server (NTRS)

    Ruoff, C. F. (Inventor)

    1985-01-01

    A mechanical actuator can be constructed by employing a plurality of memory metal actuator elements in parallel to control the amount of actuating force. In order to facilitate direct control by digital control signals provided by a computer or the like, the actuating elements may vary in stiffness according to a binary relationship. The cooling or reset time of the actuator elements can be reduced by employing Peltier junction cooling assemblies in the actuator.

  19. DETAIL OF TRACTION CABLE ENGAGEMENT DEVICE. SMALL, KNOBBED LEVER ON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL OF TRACTION CABLE ENGAGEMENT DEVICE. SMALL, KNOBBED LEVER ON BUCKET HANGER WAS PULLED DOWN BY A CAMEL (FIXED CAM RAIL AT CENTER) AS BUCKET ROLLED PAST IT, CAUSING A CLAMP TO CLOSE AGAINST TRACTION CABLE. A SIMILAR CAMEL (NO LONGER EXTANT) DISENGAGED CLAMP ON RECEIVING SIDE. - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO

  20. 26. VIEW FROM EAST IN BRIDGE TENDER'S HOUSE, LEVERS FOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. VIEW FROM EAST IN BRIDGE TENDER'S HOUSE, LEVERS FOR GASOLINE ENGINE OPERATION FOR BRIDGE AND THEIR CONNECTIONS TO CONTROL RODS ON DOWNSTREAM SIDE OF SWING-SPAN; new bridge located in background - Tipers Bridge, Spanning Great Wicomico River at State Route 200, Kilmarnock, Lancaster County, VA

  1. PHOTOCOPY OF HISTORIC PHOTOGRAPH, "LAWRENCE LEVERING BECKEL (BRIDGE BUILT BY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    PHOTOCOPY OF HISTORIC PHOTOGRAPH, "LAWRENCE LEVERING BECKEL (BRIDGE BUILT BY HIM AND HIS FATHER, CHAS. N. BECKEL AT EASTON)," original ca. 1885, photographer unknown. Collection of Historic Bethlehem Inc., Bethlehem, PA, Negative Nos. 3550 or 4504. - Walnut Street Bridge, Formerly spanning Saucon Creek, Hellertown, Northampton County, PA

  2. 25. VIEW EAST IN BRIDGE TENDER'S HOUSE, (left) ORIGINAL LEVERS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. VIEW EAST IN BRIDGE TENDER'S HOUSE, (left) ORIGINAL LEVERS FOR GASOLINE ENGINE OPERATION OF SWING-SPAN, (right) PANEL F ELECTRIC OPERATION OF GATES AND SWING-SPAN; new bridge located in background - Tipers Bridge, Spanning Great Wicomico River at State Route 200, Kilmarnock, Lancaster County, VA

  3. The Relationship between State Policy Levers and Student Mobility

    ERIC Educational Resources Information Center

    Gross, Jacob P. K.; Berry, Matthew S.

    2016-01-01

    To address conceptual and methodological shortcomings in the extant literature on student mobility, this study employs event history modeling to describe and explain how state policy levers, specifically state grant aid, relates to mobility and baccalaureate degree completion. We find that state grant aid reduces mobility, but less so than…

  4. 5. FLOOR 3; SHOWS BRAKE LEVER, BLOCK FORMERLY USED TO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. FLOOR 3; SHOWS BRAKE LEVER, BLOCK FORMERLY USED TO RAISE IT AND HOOK WHICH KEPT IT IN THE 'OFF' POSITION; ALSO SEEN ARE THE LARGE BLOCKS SUSPENDED FROM THE CAP FRAME WHICH HOLD THE TRUCK WHEELS TO CENTER THE CAP - Hayground Windmill, Windmill Lane, East Hampton, Suffolk County, NY

  5. 49 CFR 236.764 - Locking, lever operated.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Locking, lever operated. 236.764 Section 236.764 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL...

  6. SECOND FLOOR OF OPERATOR'S ROOM, WITH THROTTLE LEVER ABOVE TORQUE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SECOND FLOOR OF OPERATOR'S ROOM, WITH THROTTLE LEVER ABOVE TORQUE CONVERTER SWITCH, AT LEFT. MAGNETIC SOLENOID IS IN CENTER, HYDRAULIC BRAKE PUMP IS IN UPPER RIGHT, LOOKING WEST. - Mad River Glen, Single Chair Ski Lift, 62 Mad River Glen Resort Road, Fayston, Washington County, VT

  7. Electrostatic micromembrane actuator arrays as motion generator

    NASA Astrophysics Data System (ADS)

    Wu, X. T.; Hui, J.; Young, M.; Kayatta, P.; Wong, J.; Kennith, D.; Zhe, J.; Warde, C.

    2004-05-01

    A rigid-body motion generator based on an array of micromembrane actuators is described. Unlike previous microelectromechanical systems (MEMS) techniques, the architecture employs a large number (typically greater than 1000) of micron-sized (10-200 μm) membrane actuators to simultaneously generate the displacement of a large rigid body, such as a conventional optical mirror. For optical applications, the approach provides optical design freedom of MEMS mirrors by enabling large-aperture mirrors to be driven electrostatically by MEMS actuators. The micromembrane actuator arrays have been built using a stacked architecture similar to that employed in the Multiuser MEMS Process (MUMPS), and the motion transfer from the arrayed micron-sized actuators to macro-sized components was demonstrated.

  8. Biomimetic actuator

    NASA Astrophysics Data System (ADS)

    Bouda, Vaclav; Boudova, Lea; Haluzikova, Denisa

    2005-05-01

    The aim of the presentation is to propose an alternative model of mammalian skeletal muscle function, which reflects the simplicity of nature and can be applied in engineering. Van der Waals attractive and repulsive electrostatic forces are assumed to control the design of internal structures and functions of contractile units of the muscles - sarcomere. The role of myosin heads is crucial for the higher order formation. The model of the myosin head lattice is the working model for the sarcomere contraction interpretation. The contraction is interpreted as a calcium induced phase transition of the lattice, which results in relative actin-myosin sliding and/or force generation. The model should provide the engineering science with a simple analogy to technical actuators of high performance.

  9. Response Induction during the Acquisition and Maintenance of Lever Pressing with Delayed Reinforcement

    ERIC Educational Resources Information Center

    Escobar, Rogelio; Bruner, Carlos A.

    2007-01-01

    The acquisition of lever pressing by rats and the occurrence of unreinforced presses at a location different from that of the reinforced response were studied using different delays of reinforcement. An experimental chamber containing seven identical adjoining levers was used. Only presses on the central (operative) lever produced food pellets.…

  10. 49 CFR 236.340 - Electromechanical interlocking machine; locking between electrical and mechanical levers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... between electrical and mechanical levers. 236.340 Section 236.340 Transportation Other Regulations... Electromechanical interlocking machine; locking between electrical and mechanical levers. In electro-mechanical interlocking machine, locking between electric and mechanical levers shall be maintained so that...

  11. Piezoelectric multilayer actuator life test.

    PubMed

    Sherrit, Stewart; Bao, Xiaoqi; Jones, Christopher M; Aldrich, Jack B; Blodget, Chad J; Moore, James D; Carson, John W; Goullioud, Renaud

    2011-04-01

    Potential NASA optical missions such as the Space Interferometer Mission require actuators for precision positioning to accuracies of the order of nanometers. Commercially available multilayer piezoelectric stack actuators are being considered for driving these precision mirror positioning mechanisms. These mechanisms have potential mission operational requirements that exceed 5 years for one mission life. To test the feasibility of using these commercial actuators for these applications and to determine their reliability and the redundancy requirements, a life test study was undertaken. The nominal actuator requirements for the most critical actuators on the Space Interferometry Mission (SIM) in terms of number of cycles was estimated from the Modulation Optics Mechanism (MOM) and Pathlength control Optics Mechanism (POM) and these requirements were used to define the study. At a nominal drive frequency of 250 Hz, one mission life is calculated to be 40 billion cycles. In this study, a set of commercial PZT stacks configured in a potential flight actuator configuration (pre-stressed to 18 MPa and bonded in flexures) were tested for up to 100 billion cycles. Each test flexure allowed for two sets of primary and redundant stacks to be mechanically connected in series. The tests were controlled using an automated software control and data acquisition system that set up the test parameters and monitored the waveform of the stack electrical current and voltage. The samples were driven between 0 and 20 V at 2000 Hz to accelerate the life test and mimic the voltage amplitude that is expected to be applied to the stacks during operation. During the life test, 10 primary stacks were driven and 10 redundant stacks, mechanically in series with the driven stacks, were open-circuited. The stroke determined from a strain gauge, the temperature and humidity in the chamber, and the temperature of each individual stack were recorded. Other properties of the stacks, including the

  12. Powerful Electromechanical Linear Actuator

    NASA Technical Reports Server (NTRS)

    Cowan, John R.; Myers, William N.

    1994-01-01

    Powerful electromechanical linear actuator designed to replace hydraulic actuator that provides incremental linear movements to large object and holds its position against heavy loads. Electromechanical actuator cleaner and simpler, and needs less maintenance. Two principal innovative features that distinguish new actuator are use of shaft-angle resolver as source of position feedback to electronic control subsystem and antibacklash gearing arrangement.

  13. Flight control actuation system

    NASA Technical Reports Server (NTRS)

    Wingett, Paul T. (Inventor); Gaines, Louie T. (Inventor); Evans, Paul S. (Inventor); Kern, James I. (Inventor)

    2004-01-01

    A flight control actuation system comprises a controller, electromechanical actuator and a pneumatic actuator. During normal operation, only the electromechanical actuator is needed to operate a flight control surface. When the electromechanical actuator load level exceeds 40 amps positive, the controller activates the pneumatic actuator to offset electromechanical actuator loads to assist the manipulation of flight control surfaces. The assistance from the pneumatic load assist actuator enables the use of an electromechanical actuator that is smaller in size and mass, requires less power, needs less cooling processes, achieves high output forces and adapts to electrical current variations. The flight control actuation system is adapted for aircraft, spacecraft, missiles, and other flight vehicles, especially flight vehicles that are large in size and travel at high velocities.

  14. The Lever oscillator for use in high resistance resonator applications

    SciTech Connect

    Wessendorf, K.O.

    1993-07-01

    The Lever oscillator has been specifically designed for use with quartz resonator sensors. The use of quartz resonators as sensors is of particular interest and depending on the sensing environment, e.g., liquid, the oscillator design is both critical and difficult due to the wide dynamic range of resonator resistance possible due to damping of the resonator. Standard oscillator designs do not work well as sensor oscillators. An oscillator design will be presented that allows both frequency and loss (R{sub m}) of the resonator to be determined over a wide dynamic range of resonator loss. The Lever oscillator uses negative feedback in a differential amplifier configuration to actively and variably divide (or leverage) the resonator impedance such that the oscillator can maintain the phase and gain of the loop over a wide range of resonator resistance.

  15. Gain lever characterization in monolithically integrated diode lasers

    NASA Astrophysics Data System (ADS)

    Pocha, Michael; Bond, Tiziana; Welty, Rebecca; Vernon, Stephen; Kallman, Jeffrey; Behymer, Elaine

    2005-04-01

    Gain Lever, an effect for enhancing amplitude modulation (AM) efficiency in multisection laser diodes1, has been characterized in InGaAs DQW edge emitting lasers that are integrated with passive waveguides. Specifically designed structures which give a range of split ratios from 1:1 to 9:1 have been fabricated and measured to fully characterize the parameter space for operation in the gain lever mode. Additionally the experimental results are compared to a hybrid 3-D simulation involving effective index method (EIM) reduction to 2-D. Gains greater than 6 dB in the AM efficiency can be achieved within the appropriate operating range, but this gain drops rapidly as the parameter range is exceeded. High speed RF modulation with significant gain is, in principle, possible if proper biasing and modulation conditions are used. This phenomenon can also be useful for high-speed digital information transmission.

  16. Study of Unsteady Flow Actuation Produced by Surface Plasma Actuator on 2-D Airfoil

    NASA Astrophysics Data System (ADS)

    Phan, Minh Khang; Shin, Jichul

    2014-10-01

    Effect of flow actuation driven by low current continuous or pulsed DC surface glow discharge plasma actuator is studied. Schlieren image of induced flow on flat plate taken at a high repetition rate reveals that the actuation is mostly initiated near the cathode. Assuming that the actuation is mostly achieved by ions in the cathode sheath region, numerical model for the source of flow actuation is obtained by analytical estimation of ion pressure force created in DC plasma sheath near the cathode and added in momentum equation as a body force term. Modeled plasma flow actuator is simulated with NACA0012 airfoil oscillating over a certain range of angle of attack (AoA) at specific reduced frequencies of airfoil. By changing actuation authority according to the change in AoA, stabilization of unsteady flow field is improved and hence steady aerodynamic performance can be maintained. Computational result shows that plasma actuation is only effective in modifying aerodynamic characteristics of separated flow. It turns out that plasma pulse frequency should be tuned for optimal performance depending on phase angle and rotating speed. The actuation authority can be parameterized by a ratio between plasma pulse frequency and reduced frequency.

  17. Thermo-magnetic materials for use in designing intelligent actuators

    SciTech Connect

    Ohtani, Yoshimutsu; Yoshimura, Fumikatsu; Hatakeyama, Iwao; Ishii, Yoshikazu

    1994-12-31

    The authors present the concept of an intelligent thermal actuator designed by using thermally sensitive magnetic materials. The use of the magnetic transition of FeRh alloy is very effective in increasing the actuator functions. These functions are freedom of direction, tuning temperature, and increasing both sensitivity and power. Two new types of actuator, a remote controlled optical driven thermo-magnetic motor and a temperature sensitive spring-less valve, are proposed and experimental results are shown.

  18. Superconducting linear actuator

    NASA Technical Reports Server (NTRS)

    Johnson, Bruce; Hockney, Richard

    1993-01-01

    Special actuators are needed to control the orientation of large structures in space-based precision pointing systems. Electromagnetic actuators that presently exist are too large in size and their bandwidth is too low. Hydraulic fluid actuation also presents problems for many space-based applications. Hydraulic oil can escape in space and contaminate the environment around the spacecraft. A research study was performed that selected an electrically-powered linear actuator that can be used to control the orientation of a large pointed structure. This research surveyed available products, analyzed the capabilities of conventional linear actuators, and designed a first-cut candidate superconducting linear actuator. The study first examined theoretical capabilities of electrical actuators and determined their problems with respect to the application and then determined if any presently available actuators or any modifications to available actuator designs would meet the required performance. The best actuator was then selected based on available design, modified design, or new design for this application. The last task was to proceed with a conceptual design. No commercially-available linear actuator or modification capable of meeting the specifications was found. A conventional moving-coil dc linear actuator would meet the specification, but the back-iron for this actuator would weigh approximately 12,000 lbs. A superconducting field coil, however, eliminates the need for back iron, resulting in an actuator weight of approximately 1000 lbs.

  19. Multilayer Piezoelectric Stack Actuator Characterization

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Jones, Christopher M.; Aldrich, Jack B.; Blodget, Chad; Bao, Xioaqi; Badescu, Mircea; Bar-Cohen, Yoseph

    2008-01-01

    Future NASA missions are increasingly seeking to use actuators for precision positioning to accuracies of the order of fractions of a nanometer. For this purpose, multilayer piezoelectric stacks are being considered as actuators for driving these precision mechanisms. In this study, sets of commercial PZT stacks were tested in various AC and DC conditions at both nominal and extreme temperatures and voltages. AC signal testing included impedance, capacitance and dielectric loss factor of each actuator as a function of the small-signal driving sinusoidal frequency, and the ambient temperature. DC signal testing includes leakage current and displacement as a function of the applied DC voltage. The applied DC voltage was increased to over eight times the manufacturers' specifications to investigate the correlation between leakage current and breakdown voltage. Resonance characterization as a function of temperature was done over a temperature range of -180C to +200C which generally exceeded the manufacturers' specifications. In order to study the lifetime performance of these stacks, five actuators from one manufacturer were driven by a 60volt, 2 kHz sine-wave for ten billion cycles. The tests were performed using a Lab-View controlled automated data acquisition system that monitored the waveform of the stack electrical current and voltage. The measurements included the displacement, impedance, capacitance and leakage current and the analysis of the experimental results will be presented.

  20. Superfluid helium sloshing dynamics induced oscillations and fluctuations of angular momentum, force and moment actuated on spacecraft driven by gravity gradient or jitter acceleration associated with slew motion

    NASA Technical Reports Server (NTRS)

    Hung, R. J.

    1994-01-01

    The generalized mathematical formulation of sloshing dynamics for partially filled liquid of cryogenic superfluid helium II in dewar containers driven by the gravity gradient and jitter accelerations associated with slew motion for the purpose to perform scientific observation during the normal spacecraft operation are investigated. An example is given with the Advanced X-Ray Astrophysics Facility-Spectroscopy (AXAF-S) for slew motion which is responsible for the sloshing dynamics. The jitter accelerations include slew motion, spinning motion, atmospheric drag on the spacecraft, spacecraft attitude motions arising from machinery vibrations, thruster firing, pointing control of spacecraft, crew motion, etc. Explicit mathematical expressions to cover these forces acting on the spacecraft fluid systems are derived. The numerical computation of sloshing dynamics is based on the non-inertia frame spacecraft bound coordinate, and solve time-dependent, three-dimensional formulations of partial differential equations subject to initial and boundary conditions. The explicit mathematical expressions of boundary conditions to cover capillary force effect on the liquid-vapor interface in microgravity environments are also derived. The formulations of fluid moment and angular moment fluctuations in fluid profiles induced by the sloshing dynamics, together with fluid stress and moment fluctuations exerted on the spacecraft dewar containers have also been derived. Examples are also given for cases applicable to the AXAF-S spacecraft sloshing dynamics associated with slew motion.

  1. [Work physiological studies performed to optimate the lever propulsion and the seat position of a lever propelled wheelchair (author's transl)].

    PubMed

    Engel, P; Neikes, M; Bennedik, K; Hildebrandt, G; Rode, F W

    1976-11-01

    Spiroergometric examination with defined work loads and permanent records of the common circulatory and metabolic values were carried out on a group of healthy adults and one wheelchair occupant, using a fixed wheelchair simulator with lever propulsion, which was connected to an ergometer. Comparative studies were performed in three different seat positions in relation to the lever, as well as six different lengths of the connecting rod. The best values were measured, under steadystate conditions, with increasing lengths of the connecting rod and posterior placement of the seat unit. The results are in agreement with the experience gained by other authors with respect to arm work, and show that the optimal efficiency of hand lever work is obtained in the anterior position. In this context it proved to be particularly advantageious from the ergonomic viewpoint, if, when bending forward, as necessitated by a long connecting rod, both the upper part of the body and the trunk musculature are employed. The practical consequences of the simulator tests on an adequate wheelchair design and wheelchair prescription are discussed. PMID:137501

  2. Induced shear piezoelectric actuators for smart rotor blades

    NASA Astrophysics Data System (ADS)

    Centolanza, Louis Richard

    In the present work, an induced-shear piezoelectric tube actuator is used in conjunction with a simple lever/cusp hinge amplification device to generate a useful combination of trailing edge flap (or blade tip) deflections and hinge moments. A finite element model of the actuator tube and trailing edge flap (including aerodynamic and inertial loading) was used to guide the design of the actuator/flap system. Both a full scale and small scale tube actuator flap systems and a small scale tube actuator blade tip system were fabricated and experimental bench top testing was conducted to validate the analysis. Hinge moments that corresponded to various rotor speeds were applied to the actuator using mechanical springs. The experimental testing revealed that for an applied electric field of 3 kV/cm, the tube actuator deflected a representative full scale 12 inch flap +/-2.8° at 0 RPM and +/-1.4° for a hinge moment simulating a 400 RPM condition. The percent error between the predicted and experimental full scale flap deflections ranged from 4% (low RPM) to 12.5% (large RPM). Based on the design analysis, the tube actuator can deflect a 12 inch long flap +/-2.5° at a rotation speed of 400 RPM for an electric field of 4 kV/cm. In the experimental testing at an applied electric field of 4 kV/cm of the small scale induced shear tube actuator, a 1.5 inch long flap was deflected +/-12° in a no-load condition and +/-8.5° for a hinge moment simulating a rotor speed of 2000 RPM. The percent error between the predicted and experimental flap deflections ranged from 2% (low RPM) to 8% (large RPM). In addition, a small scale 10% radius blade tip (3.6 inches) was deflected +/-3.15° and +/-2.50° for hinge moments that simulated the 0 and 2000 RPM rotor speed conditions. A numerical analysis was also conducted to investigate the induced shear tube as an active blade twist actuator. Finally, a trade study was conducted to compare the performance of the piezoelectric tube actuator

  3. Efficient active actuation to imitate locomotion of gecko's toes using an ionic polymer-metal composite actuator enhanced by carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yu, Min; He, Qingsong; Yu, Dingshan; Zhang, Xiaoqing; Ji, Aihong; Zhang, Hao; Guo, Ce; Dai, Zhendong

    2012-10-01

    Active actuation of the adhesive pads is important for a gecko-robot climbing on walls. We demonstrate the fabrication of an ionic polymer-metal composite (IPMC) actuator enhanced with carbon nanotubes (CNTs) and its use for actively actuating an adhesive array to imitate the locomotion of gecko's toes. The as-fabricated IPMC actuator doped with CNTs exhibits a maximum blocking force of 3.59 gf driven at a low voltage of 3 V. It can be easily controlled by voltage signals to actuate an artificial gecko's toe to attach and detach from a surface. This will allow active, distributed actuation in a gecko robot.

  4. Simulation of sloshing dynamics induced forces and torques actuated on dewar container driven by gravity gradient and jitter accelerations in microgravity

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Pan, H. L.

    1993-01-01

    three levels of gravity jitter (10(exp -6), 10(exp -7), and 10(exp -8) g(sub 0)) each at three predominant frequencies (0.1, 1.0, and 10 Hz), combined with a gravity gradient appropriate for the GP-B orbit. Dynamical evolution of sloshing dynamics excited fluid forces and torque fluctuations exerted on the dewar container driven by the combined gravity gradient and jitter accelerations are also investigated and simulated.

  5. Micromachined electrostatic vertical actuator

    DOEpatents

    Lee, Abraham P.; Sommargren, Gary E.; McConaghy, Charles F.; Krulevitch, Peter A.

    1999-10-19

    A micromachined vertical actuator utilizing a levitational force, such as in electrostatic comb drives, provides vertical actuation that is relatively linear in actuation for control, and can be readily combined with parallel plate capacitive position sensing for position control. The micromachined electrostatic vertical actuator provides accurate movement in the sub-micron to micron ranges which is desirable in the phase modulation instrument, such as optical phase shifting. For example, compact, inexpensive, and position controllable micromirrors utilizing an electrostatic vertical actuator can replace the large, expensive, and difficult-to-maintain piezoelectric actuators. A thirty pound piezoelectric actuator with corner cube reflectors, as utilized in a phase shifting diffraction interferometer can be replaced with a micromirror and a lens. For any very precise and small amplitudes of motion` micromachined electrostatic actuation may be used because it is the most compact in size, with low power consumption and has more straightforward sensing and control options.

  6. Electromagnetic rotational actuation.

    SciTech Connect

    Hogan, Alexander Lee

    2010-08-01

    There are many applications that need a meso-scale rotational actuator. These applications have been left by the wayside because of the lack of actuation at this scale. Sandia National Laboratories has many unique fabrication technologies that could be used to create an electromagnetic actuator at this scale. There are also many designs to be explored. In this internship exploration of the designs and fabrications technologies to find an inexpensive design that can be used for prototyping the electromagnetic rotational actuator.

  7. AMSD Cryo Actuator Testing

    NASA Technical Reports Server (NTRS)

    Mullette, Mark; Matthews, Gary; Russell, Kevin (Technical Monitor)

    2002-01-01

    The actuator technology required for AMSD and subsequently NGST are critical in the successful development for future cryogenic systems. Kodak has undertaken an extensive test plan to determine the performance of the force actuators developed under the AMSD program. These actuators are currently in testing at MSFC and are expected to finish this test cycle in early June 2002.

  8. Subminiature hydraulic actuator

    NASA Technical Reports Server (NTRS)

    Sevart, F. D.

    1978-01-01

    Subminiature, single-vane rotary actuator for wind-tunnel test-model control-surface actuation systems presents severe torque and system band-pass requirements with stringent space and weight limitations. Actuator has very low leakage of fluid from one side to other, permitting use in precision position servo-systems.

  9. Dual drive actuators

    NASA Technical Reports Server (NTRS)

    Packard, D. T.

    1982-01-01

    A new class of electromechanical actuators is described. These dual drive actuators were developed for the NASA-JPL Galileo Spacecraft. The dual drive actuators are fully redundant and therefore have high inherent reliability. They can be used for a variety of tasks, and they can be fabricated quickly and economically.

  10. Novel applications of plasma actuators

    NASA Astrophysics Data System (ADS)

    Ozturk, Arzu Ceren

    The current study investigates the effectiveness of two different dielectric barrier discharge plasma actuator configurations, a 3-D annular geometry for use in micro thrusters and internal duct aerodynamics and a jet vectoring actuator that acts as a vortex generator and flow control device. The first configuration consists of a closed circumferential arrangement which yields a body force when a voltage difference is applied across the inner and outer electrodes separated by a dielectric. The primary flow is driven by this zero-net mass flux jet at the wall that then entrains fluid in the core of the duct. PIV experiments in both quiescent flow and freestream are conducted on tubes of different diameters while varying parameters such as the modulation frequency, duty cycle and tunnel speed. The values of the induced velocities increase with the forcing frequency and duty cycle although there is a peak value for the forcing frequency after which the velocity and thrust decrease for each thruster. The velocities and thrust increase as the inner diameter of the tubes are increased while the velocity profiles show a great difference with the (l/di) ratio; recirculation occurs after going below a critical value. Experiments in the wind tunnel illustrate that the jet exit characteristics significantly change upon actuation in freestream flow but the effect tends to diminish with increasing inner diameters and tunnel speeds. Using staged arrays of these thrusters result in higher velocities while operating at both in phase and out of phase. The jet vectoring configuration consists of a single embedded electrode separated from two exposed electrodes on either side by the dielectric. The embedded electrode is grounded while the exposed electrodes are driven with a high frequency high voltage input signal. PIV measurements of the actuator in a freestream show that vectoring the jet yields stronger vortices than a linear configuration and increasing the difference between

  11. Theory and applications of optical fiber lever sensors

    NASA Technical Reports Server (NTRS)

    Cuomo, F. W.

    1989-01-01

    The evolution of optical fiber lever concepts is illustrated leading to several designs found useful in air and water applications. In particular, this technology has led to the development of underwater detectors of the pressure and pressure gradient kind. In addition, an optical microphone with features not found in condenser microphones has been utilized in the measurement of pressure fluctuations in high speed boundary layers requiring sensors of small size, extended bandwidth, wide dynamic range, and high temperature capability. Finally, similar concepts have been applied to the design of scale model acoustic arrays intended for acoustic imaging applications in the megahertz frequency range.

  12. Comparison of dynamic lever STM and noncontact AFM

    NASA Astrophysics Data System (ADS)

    Guggisberg, M.; Bammerlin, M.; Lüthi, R.; Loppacher, C.; Battiston, F.; Lü, J.; Baratoff, A.; Meyer, E.; Güntherodt, H.-J.

    We investigate interaction effects which occur in scanning tunneling microscopy (STM) by performing local force spectroscopy with an oscillating tip while imaging Si(111)7×7 terraces in the dynamic lever STM mode (constant time-averaged current). It is found that true atomic resolution is achieved close to the minimum of the resonance frequency vs. distance curve and even closer to the sample. On the other hand true atomic resolution in noncontact AFM (constant frequency shift) is expected several nm away from this minimum, in the range where the frequency shift becomes more negative with decreasing distance.

  13. Nanoporous carbon actuator and methods of use thereof

    DOEpatents

    Biener, Juergen; Baumann, Theodore F.; Shao, Lihua; Weissmueller, Joerg

    2012-07-31

    An electrochemically driveable actuator according to one embodiment includes a nanoporous carbon aerogel composition capable of exhibiting charge-induced reversible strain when wetted by an electrolyte and a voltage is applied thereto. An electrochemically driven actuator according to another embodiment includes a nanoporous carbon aerogel composition wetted by an electrolyte; and a mechanism for causing charge-induced reversible strain of the composition. A method for electrochemically actuating an object according to one embodiment includes causing charge-induced reversible strain of a nanoporous carbon aerogel composition wetted with an electrolyte to actuate the object by the strain.

  14. Low backlash direct drive actuator

    DOEpatents

    Kuklo, T.C.

    1994-10-25

    A low backlash direct drive actuator is described which comprises a motor such as a stepper motor having at least 200 steps per revolution; a two part hub assembly comprising a drive hub coaxially attached to the shaft of the motor and having a plurality of drive pins; a driven hub having a plurality of bores in one end thereof in alignment with the drive pins in the drive hub and a threaded shaft coaxially mounted in an opposite end of the driven hub; and a housing having a central bore therein into which are fitted the drive hub and driven hub, the housing having a motor mount on one end thereof to which is mounted the stepper motor, and a closed end portion with a threaded opening therein coaxial with the central bore in the housing and receiving therein the threaded shaft attached to the driven hub. Limit switches mounted to the housing cooperate with an enlarged lip on the driven hub to limit the lateral travel of the driven hub in the housing, which also acts to limit the lateral travel of the threaded shaft which functions as a lead screw. 10 figs.

  15. Low backlash direct drive actuator

    DOEpatents

    Kuklo, Thomas C.

    1994-01-01

    A low backlash direct drive actuator is described which comprises a motor such as a stepper motor having at least 200 steps per revolution; a two part hub assembly comprising a drive hub coaxially attached to the shaft of the motor and having a plurality of drive pins; a driven hub having a plurality of bores in one end thereof in alignment with the drive pins in the drive hub and a threaded shaft coaxially mounted in an opposite end of the driven hub; and a housing having a central bore therein into which are fitted the drive hub and driven hub, the housing having a motor mount on one end thereof to which is mounted the stepper motor, and a closed end portion with a threaded opening therein coaxial with the central bore in the housing and receiving therein the threaded shaft attached to the driven hub. Limit switches mounted to the housing cooperate with an enlarged lip on the driven hub to limit the lateral travel of the driven hub in the housing, which also acts to limit the lateral travel of the threaded shaft which functions as a lead screw.

  16. Bimorphic polymeric photomechanical actuator

    NASA Technical Reports Server (NTRS)

    Sarkisov, Sergey S. (Inventor); Curley, Michael J. (Inventor); Adamovsky, Grigory (Inventor); Sarkisov, Jr., Sergey S. (Inventor); Fields, Aisha B. (Inventor)

    2006-01-01

    A bimorphic polymeric photomechanical actuator, in one embodiment using polyvinylidene fluoride (PVDF) as a photosensitive body, transmitting light over fiber optic cables, and controlling the shape and pulse duration of the light pulse to control movement of the actuator. Multiple light beams are utilized to generate different ranges of motion for the actuator from a single photomechanical body and alternative designs use multiple light beams and multiple photomechanical bodies to provide controlled movement. Actuator movement using one or more ranges of motion is utilized to control motion to position an actuating element in three dimensional space.

  17. Electrical and Optical Gain Lever Effects in InGaAs Double Quantum Well Diode Lasers

    SciTech Connect

    Pocha, M D; Goddard, L L; Bond, T C; Nikolic, R J; Vernon, S P; Kallman, J S; Behymer, E M

    2007-01-03

    In multisection laser diodes, the amplitude or frequency modulation (AM or FM) efficiency can be improved using the gain lever effect. To study gain lever, InGaAs double quantum well (DQW) edge emitting lasers have been fabricated with integrated passive waveguides and dual sections providing a range of split ratios from 1:1 to 9:1. Both the electrical and the optical gain lever have been examined. An electrical gain lever with greater than 7 dB enhancement of AM efficiency was achieved within the range of appropriate DC biasing currents, but this gain dropped rapidly outside this range. We observed a 4 dB gain in the optical AM efficiency under non-ideal biasing conditions. This value agreed with the measured gain for the electrical AM efficiency under similar conditions. We also examined the gain lever effect under large signal modulation for digital logic switching applications. To get a useful gain lever for optical gain quenched logic, a long control section is needed to preserve the gain lever strength and a long interaction length between the input optical signal and the lasing field of the diode must be provided. The gain lever parameter space has been fully characterized and validated against numerical simulations of a semi-3D hybrid beam propagation method (BPM) model for the coupled electron-photon rate equation. We find that the optical gain lever can be treated using the electrical injection model, once the absorption in the sample is known.

  18. Advances in shape-memory polymer actuation

    NASA Astrophysics Data System (ADS)

    Leng, Jinsong; Liu, Yanju; Lan, Xin

    2009-03-01

    Shape memory polymer (SMP) is a promising smart material, which is able to perform a large deformation upon applying an external stimulus, such as heat, light and moisture, etc. In recent years, many investigations have been advanced in thermo-responsive SMP actuation, and several novel actuations have been applied in SMP. In this paper, the mechanism and demonstration of three types of SMP actuations (infrared laser, physical swelling effect and electricity) are presented. These novel actuation approaches may help SMP to fully reach its potential application. Firstly, for the infrared laser-activated SMP, it is concerned about the drive of SMP by infrared light. The infrared laser, transmitted through the optical fiber embedded in the SMP matrix, was chosen to drive the SMP. The working frequency of infrared laser was installed in 3-4μm. Moreover, this paper presents a study on the effects of solution on the glass transition temperature (Tg). It shows that the hydrogen bonding of SMP was aroused by the absorbed solution that significantly reduces transition temperature of polymer. In this way, the shape memory effect (SME) can undergo solution-driven shape recovery. Finally, the actuation of two types of electro-active SMP composites filled with electrically conductive powders (carbon black, nickel powers) have been carried out, and the SMP composite can be driven by applying a relatively low voltage.

  19. Design of a bidirectional piezoelectric actuator for blade trailing-edge flap

    NASA Astrophysics Data System (ADS)

    Lee, Taeoh; Chopra, Inderjit

    2001-08-01

    The present research investigates the feasibility of a compact piezoelectric actuator mechanism to oscillate the rotorblade trailing-edge flap for active vibration suppression. The main components of the actuator are two piezostack segments and a dual-stage stroke amplifier. Each piezostack segment is fabricated by bonding five identical piezostacks. A bidirectional double-lever amplification concept is developed, that involves an extended dual-stage lever-fulcrum stroke amplifier and two parallel rows of piezostacks. Both design and fabrication of the trailing-edge flap actuator are addressed. The designed actuator is of size 8-inch length (spanwise), 1.25-inch width (chordwise), 0.75-inch height, and the weight of the prototype is 1.05 lbs. The bench-top test showed 94% of ideal displacement output. To validate the feasibility of the designed actuator, the spin test in the vacuum chamber is planned to evaluate the performance in rotating environment up to 700g of centrifugal loading.

  20. Networked Rectenna Array for Smart Material Actuators

    NASA Technical Reports Server (NTRS)

    Choi, Sang H.; Golembiewski, Walter T.; Song, Kyo D.

    2000-01-01

    The concept of microwave-driven smart material actuators is envisioned as the best option to alleviate the complexity associated with hard-wired control circuitry. Networked rectenna patch array receives and converts microwave power into a DC power for an array of smart actuators. To use microwave power effectively, the concept of a power allocation and distribution (PAD) circuit is adopted for networking a rectenna/actuator patch array. The PAD circuit is imbedded into a single embodiment of rectenna and actuator array. The thin-film microcircuit embodiment of PAD circuit adds insignificant amount of rigidity to membrane flexibility. Preliminary design and fabrication of PAD circuitry that consists of a few nodal elements were made for laboratory testing. The networked actuators were tested to correlate the network coupling effect, power allocation and distribution, and response time. The features of preliminary design are 16-channel computer control of actuators by a PCI board and the compensator for a power failure or leakage of one or more rectennas.

  1. Electropneumatic actuator, phase 1

    NASA Astrophysics Data System (ADS)

    Bloomfield, D. P.

    1989-10-01

    The program demonstrated the feasibility of an electropneumatic actuator which can be used in manufacturing applications. The electropneumatic actuator, an alternative to the electric, hydraulic, and pneumatic actuators used in industry, consists of an electrochemical compressor, a power supply, and an actuator. The electrochemical compressor working fluid is hydrogen and a solvent such as water or ammonia. The compressor has no moving parts and runs on low voltage DC. The actuator is a conventional, commercially available unit. Researchers designed, constructed, and tested the electrochemical compressor in conjunction with the actuator, power supply, and computerized control. The one inch actuator can lift a fifty pound weight a distance of ten inches in about 1.5 minutes. The electrochemically powered system is capable of driving its loaded actuator to a prescribed location at a controlled rate. A defined set of design changes will combine the compressor and actuator in the same housing, and will develop two orders of magnitude increased actuator speed at the same or higher force levels.

  2. Rotary stepping device with memory metal actuator

    NASA Technical Reports Server (NTRS)

    Jamieson, Robert S. (Inventor)

    1987-01-01

    A rotary stepping device includes a rotatable shaft which is driven by means of a coiled spring clutch which is alternately tightened to grip and rotate the shaft and released to return it to a resting position. An actuator formed of a memory metal is used to pull the spring clutch to tighten it and rotate the shaft. The actuator is activated by heating it above its critical temperature and is returned to an elongated configuration by means of the force of the spring cloth.

  3. Tuneable Auxiliary Control Mechanisms For RUM Actuators

    NASA Technical Reports Server (NTRS)

    Polites, Michael E.; Alhorn, Dean C.

    1995-01-01

    Tuneable auxiliary control mechanisms for rotating unbalanced-mass (RUM) actuators used to maximize scan amplitudes and/or minimize power consumption during changing conditions. This type of mechanism more sophisticated version of type of mechanism described in "Auxiliary Control Mechanisms for RUM Actuators" (MFS-28817). Torsional stiffness of torsionally flexible coupling made adjustable on command. Torsionally flexible coupling in tuneable version of auxiliary control mechanism adjustable by use of stepping-motor-driven worm-gear mechanism that varies bending length of flexible blade.

  4. MEMS fluidic actuator

    DOEpatents

    Kholwadwala, Deepesh K.; Johnston, Gabriel A.; Rohrer, Brandon R.; Galambos, Paul C.; Okandan, Murat

    2007-07-24

    The present invention comprises a novel, lightweight, massively parallel device comprising microelectromechanical (MEMS) fluidic actuators, to reconfigure the profile, of a surface. Each microfluidic actuator comprises an independent bladder that can act as both a sensor and an actuator. A MEMS sensor, and a MEMS valve within each microfluidic actuator, operate cooperatively to monitor the fluid within each bladder, and regulate the flow of the fluid entering and exiting each bladder. When adjacently spaced in a array, microfluidic actuators can create arbitrary surface profiles in response to a change in the operating environment of the surface. In an embodiment of the invention, the profile of an airfoil is controlled by independent extension and contraction of a plurality of actuators, that operate to displace a compliant cover.

  5. Electroactive polymer (EAP) actuators for planetary applications

    NASA Astrophysics Data System (ADS)

    Bar-Cohen, Yoseph; Leary, Sean P.; Shahinpoor, Mohsen; Harrison, Joycelyn S.; Smith, J.

    1999-05-01

    NASA is seeking to reduce the mass, size, consumed power, and cost of the instrumentation used in its future missions. An important element of many instruments and devices is the actuation mechanism and electroactive polymers (EAP) are offering an effective alternative to current actuators. In this study, two families of EAP materials were investigated, including bending ionomers and longitudinal electrostatically driven elastomers. These materials were demonstrated to effectively actuate manipulation devices and their performance is being enhanced in this on-going study. The recent observations are reported in this paper, include the operation of the bending-EAP at conditions that exceed the harsh environment on Mars, and identify the obstacles that its properties and characteristics are posing to using them as actuators. Analysis of the electrical characteristics of the ionomer EAP showed that it is a current driven material rather than voltage driven and the conductivity distribution on the surface of the material greatly influences the bending performance. An accurate equivalent circuit modeling of the ionomer EAP performance is essential for the design of effective drive electronics. The ionomer main limitations are the fact that it needs to be moist continuously and the process of electrolysis that takes place during activation. An effective coating technique using a sprayed polymer was developed extending its operation in air from a few minutes to about four months. The coating technique effectively forms the equivalent of a skin to protect the moisture content of the ionomer. In parallel to the development of the bending EAP, the development of computer control of actuated longitudinal EAP has been pursued. An EAP driven miniature robotic arm was constructed and it is controlled by a MATLAB code to drop and lift the arm and close and open EAP fingers of a 4-finger gripper.

  6. CMB cluster lensing: Cosmography with the longest lever arm

    SciTech Connect

    Hu, Wayne; Holz, Daniel E.; Vale, Chris

    2007-12-15

    We discuss combining gravitational lensing of galaxies and the cosmic microwave background by clusters to measure cosmographic distance ratios, and hence dark energy parameters. Advantages to using the cosmic microwave background as the second source plane, instead of galaxies, include a well-determined source distance, a longer lever arm for distance ratios, typically up to an order of magnitude higher sensitivity to dark energy parameters, and a decreased sensitivity to photometric redshift accuracy of the lens and galaxy sources. Disadvantages include higher statistical errors, potential systematic errors, and the need for disparate surveys that overlap on the sky. Ongoing and planned surveys, such as the South Pole Telescope in conjunction with the Dark Energy Survey, can potentially reach the statistical sensitivity to make interesting consistency tests of the standard cosmological constant model. Future measurements that reach 1% or better precision in the convergences can provide sharp tests for future supernovae distance measurements.

  7. High-temperature fiber-optic lever microphone

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J.; Cuomo, Frank W.; Nguyen, Trung D.; Rizzi, Stephen A.; Clevenson, Sherman A.

    1995-01-01

    The design and construction of a fiber-optic lever microphone, capable of operating continuously at temperatures up to 538 C (1000 F) are described. The design is based on the theoretical sensitivities of each of the microphone system components, namely, a cartridge containing a stretched membrane, an optical fiber probe, and an optoelectronic amplifier. Laboratory calibrations include the pistonphone sensitivity and harmonic distortion at ambient temperature, and frequency response, background noise, and optical power transmission at both ambient and elevated temperatures. A field test in the Thermal Acoustic Fatigue Apparatus at Langley Research Center, in which the microphone was subjected to overall sound-pressure levels in the range of 130-160 dB and at temperatures from ambient to 538 C, revealed good agreement with a standard probe microphone.

  8. 29 CFR 1926.305 - Jacks-lever and ratchet, screw, and hydraulic.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 8 2014-07-01 2014-07-01 false Jacks-lever and ratchet, screw, and hydraulic. 1926.305 Section 1926.305 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH... Power § 1926.305 Jacks—lever and ratchet, screw, and hydraulic. (a) General requirements. (1)...

  9. 29 CFR 1926.305 - Jacks-lever and ratchet, screw, and hydraulic.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 8 2012-07-01 2012-07-01 false Jacks-lever and ratchet, screw, and hydraulic. 1926.305 Section 1926.305 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH... Power § 1926.305 Jacks—lever and ratchet, screw, and hydraulic. (a) General requirements. (1)...

  10. 29 CFR 1926.305 - Jacks-lever and ratchet, screw, and hydraulic.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 8 2011-07-01 2011-07-01 false Jacks-lever and ratchet, screw, and hydraulic. 1926.305 Section 1926.305 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH... Power § 1926.305 Jacks—lever and ratchet, screw, and hydraulic. (a) General requirements. (1)...

  11. 29 CFR 1926.305 - Jacks-lever and ratchet, screw, and hydraulic.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 8 2013-07-01 2013-07-01 false Jacks-lever and ratchet, screw, and hydraulic. 1926.305 Section 1926.305 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH... Power § 1926.305 Jacks—lever and ratchet, screw, and hydraulic. (a) General requirements. (1)...

  12. 49 CFR 236.340 - Electromechanical interlocking machine; locking between electrical and mechanical levers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Electromechanical interlocking machine; locking... Electromechanical interlocking machine; locking between electrical and mechanical levers. In electro-mechanical interlocking machine, locking between electric and mechanical levers shall be maintained so that...

  13. 49 CFR 236.340 - Electromechanical interlocking machine; locking between electrical and mechanical levers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Electromechanical interlocking machine; locking... Electromechanical interlocking machine; locking between electrical and mechanical levers. In electro-mechanical interlocking machine, locking between electric and mechanical levers shall be maintained so that...

  14. 49 CFR 236.340 - Electromechanical interlocking machine; locking between electrical and mechanical levers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Electromechanical interlocking machine; locking... Electromechanical interlocking machine; locking between electrical and mechanical levers. In electro-mechanical interlocking machine, locking between electric and mechanical levers shall be maintained so that...

  15. 49 CFR 236.340 - Electromechanical interlocking machine; locking between electrical and mechanical levers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Electromechanical interlocking machine; locking... Electromechanical interlocking machine; locking between electrical and mechanical levers. In electro-mechanical interlocking machine, locking between electric and mechanical levers shall be maintained so that...

  16. Acquisition and Maintenance of Lever Pressing with Prolonged Exposure to Delayed Reinforcement

    ERIC Educational Resources Information Center

    Vansickel, Andrea; White, Victoria; Byrne, Tom

    2004-01-01

    The present study investigated acquisition and extinction of free-operant responding when rats' lever presses produced sucrose pellets after resetting delays of 10 or 20 s. Presses on a second lever cancelled any scheduled food deliveries. Although previous research using 60-s delays failed to demonstrate maintenance of responding across repeated…

  17. 29 CFR 1926.305 - Jacks-lever and ratchet, screw, and hydraulic.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Jacks-lever and ratchet, screw, and hydraulic. 1926.305... Power § 1926.305 Jacks—lever and ratchet, screw, and hydraulic. (a) General requirements. (1) The... secured at once. (ii) Hydraulic jacks exposed to freezing temperatures shall be supplied with an...

  18. Improved Electrohydraulic Linear Actuators

    NASA Technical Reports Server (NTRS)

    Hamtil, James

    2004-01-01

    A product line of improved electrohydraulic linear actuators has been developed. These actuators are designed especially for use in actuating valves in rocket-engine test facilities. They are also adaptable to many industrial uses, such as steam turbines, process control valves, dampers, motion control, etc. The advantageous features of the improved electrohydraulic linear actuators are best described with respect to shortcomings of prior electrohydraulic linear actuators that the improved ones are intended to supplant. The flow of hydraulic fluid to the two ports of the actuator cylinder is controlled by a servo valve that is controlled by a signal from a servo amplifier that, in turn, receives an analog position-command signal (a current having a value between 4 and 20 mA) from a supervisory control system of the facility. As the position command changes, the servo valve shifts, causing a greater flow of hydraulic fluid to one side of the cylinder and thereby causing the actuator piston to move to extend or retract a piston rod from the actuator body. A linear variable differential transformer (LVDT) directly linked to the piston provides a position-feedback signal, which is compared with the position-command signal in the servo amplifier. When the position-feedback and position-command signals match, the servo valve moves to its null position, in which it holds the actuator piston at a steady position.

  19. Comprehensive piezoceramic actuator review

    NASA Astrophysics Data System (ADS)

    Taylor, Chris J.; Washington, Gregory N.

    2002-07-01

    Piezoceramic actuation has become an area of increased interest in the past ten years. Having been used for many years as sensors in such applications as pressure transducers and smoke detectors, piezoceramics are now being used as prime movers in fuel injectors and valve lifters. In an effort to aid the engineering community, this paper will conduct a comprehensive review of several piezoceramic actuators. Classical design parameters will be derived for each actuator such as blocked force and free stroke. In addition, more esoteric entities such as mechanical efficiency and energy density will also be derived. The result will be design metrics of popular piezoceramic actuators containing vital design equations, validated with empirical data. Of the many different configurations of piezoceramic actuators, this paper will investigate the bimorph and unimorph bender. These actuator types are finding increased use in semi-active structural damping, energy harvesting and vibration control. The work in this paper will show experimental verification of various actuator types as well as theoretical derivations. In addition to unimorphs, bimorphs and stack actuators a novel type of unimorph bender, the THUNDER actuator (developed and licensed by NASA) will be included in the review.

  20. 77 FR 9890 - Solicitation of Input From Stakeholders Regarding the Smith-Lever 3(d) Children, Youth, and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-21

    ...-Lever 3(d) Children, Youth, and Families at Risk Sustainable Community Projects AGENCY: National... section 3(d) of the Smith-Lever Act (7 U.S.C. 343(d)) to provide the opportunity for 1862 and 1890...

  1. Apparatus for controlling an engine in a hydraulically driven vehicle

    SciTech Connect

    Kitada, T.

    1987-01-27

    An apparatus is described for controlling the internal combustion engine of a hydraulically driven vehicle comprising: a transmission mechanism for transmitting the operation of a fuel control lever to a governor control lever and having a loose spring mechanism with a loose spring therein: a hydraulic decelerator cylinder connected to the transmission mechanism and having a spring and piston therein. The deceleration cylinder spring has a slightly larger spring force than the loose spring in the loose spring mechanism and applies a force absorbing action, in the absence of hydraulic force acting on the piston, to set the governor control lever in its deceleration position when the fuel control lever is moved to its full engine speed position and for moving the governor control lever to its full engine speed position when hydraulic force is applied to the piston; an electromagnetic valve for applying fluid pressure from a control pump driven by the engine to the piston in the decelerator cylinder and releasing the fluid pressure; and an electric circuit including switches operationally associated with levers for operating a hydraulic valve.

  2. Precision Linear Actuator for Space Interferometry Mission (SIM) Siderostat Pointing

    NASA Technical Reports Server (NTRS)

    Cook, Brant; Braun, David; Hankins, Steve; Koenig, John; Moore, Don

    2008-01-01

    'SIM PlanetQuest will exploit the classical measuring tool of astrometry (interferometry) with unprecedented precision to make dramatic advances in many areas of astronomy and astrophysics'(1). In order to obtain interferometric data two large steerable mirrors, or Siderostats, are used to direct starlight into the interferometer. A gimbaled mechanism actuated by linear actuators is chosen to meet the unprecedented pointing and angle tracking requirements of SIM. A group of JPL engineers designed, built, and tested a linear ballscrew actuator capable of performing submicron incremental steps for 10 years of continuous operation. Precise, zero backlash, closed loop pointing control requirements, lead the team to implement a ballscrew actuator with a direct drive DC motor and a precision piezo brake. Motor control commutation using feedback from a precision linear encoder on the ballscrew output produced an unexpected incremental step size of 20 nm over a range of 120 mm, yielding a dynamic range of 6,000,000:1. The results prove linear nanometer positioning requires no gears, levers, or hydraulic converters. Along the way many lessons have been learned and will subsequently be shared.

  3. Remote control thermal actuator

    NASA Technical Reports Server (NTRS)

    Englund, D. R.; Harrigill, W. T.; Krsek, A.

    1969-01-01

    Thermal actuator makes precise changes in the position of one object with respect to another. Expansion of metal tubes located in the actuator changes the position of the mounting block. Capacitance probe measures the change in position of the block relative to the fixed target plate.

  4. Self-actuated device

    DOEpatents

    Hecht, Samuel L.

    1984-01-01

    A self-actuated device, of particular use as a valve or an orifice for nuclear reactor fuel and blanket assemblies, in which a gas produced by a neutron induced nuclear reaction gradually accumulates as a function of neutron fluence. The gas pressure increase occasioned by such accumulation of gas is used to actuate the device.

  5. Control surface actuator

    NASA Technical Reports Server (NTRS)

    Seidel, Gerhard E. (Inventor)

    1988-01-01

    A device which actuates aircraft control surfaces is disclosed. The actuator is disposed entirely within the control surface structure. This allows the gap between the wing structural box and the control surface to be reduced. Reducing the size of the gap is especially desirable for wings with high aspect ratio, wherein the volume of the structural box is at a premium.

  6. Fast electrochemical actuator

    NASA Astrophysics Data System (ADS)

    Uvarov, I. V.; Postnikov, A. V.; Svetovoy, V. B.

    2016-03-01

    Lack of fast and strong microactuators is a well-recognized problem in MEMS community. Electrochemical actuators can develop high pressure but they are notoriously slow. Water electrolysis produced by short voltage pulses of alternating polarity can overcome the problem of slow gas termination. Here we demonstrate an actuation regime, for which the gas pressure is relaxed just for 10 μs or so. The actuator consists of a microchamber filled with the electrolyte and covered with a flexible membrane. The membrane bends outward when the pressure in the chamber increases. Fast termination of gas and high pressure developed in the chamber are related to a high density of nanobubbles in the chamber. The physical processes happening in the chamber are discussed so as problems that have to be resolved for practical applications of this actuation regime. The actuator can be used as a driving engine for microfluidics.

  7. 77 FR 4982 - Solicitation of Input From Stakeholders Regarding the Smith-Lever 3(d) Extension Integrated Pest...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-01

    ...-Lever 3(d) Extension Integrated Pest Management Competitive Grants Program AGENCY: National Institute of...(d) of the Smith-Lever Act (7 U.S.C. 343(d)) to provide the ] opportunity for 1862 and 1890 Land... agency, CSREES, on October 6, 2008 and March 26, 2009 about the restructuring of the Smith-Lever 3(d)...

  8. Modeling actuation forces and strains in nastic structures

    NASA Astrophysics Data System (ADS)

    Matthews, Luke A.; Giurgiutiu, Victor

    2006-03-01

    Nastic structures are capable of three dimensional shape change using biological principles borrowed from plant motion. The plant motor cells increase or decrease in size through a change in osmotic pressure. When nonuniform cell swelling occurs, it causes the plant tissue to warp and change shape, resulting it net movement, known as nastic motion, which is the same phenomena that causes plants to angle their broad leaf and flower surfaces to face light sources. The nastic structures considered in this paper are composed of a bilayer of microactuator arrays with a fluid reservoir in between the two layers. The actuators are housed in a thin plate and expand when water from the fluid reservoir is pumped into the actuation chamber through a phospholipid bilayer with embedded active transport proteins, which move the water from the low pressure fluid reservoir into a high pressure actuation chamber. Increasing water pressure inside the actuator causes lateral expansion and axial bulging, and the non-uniform net volume change of actuators throughout the nastic structure results in twisting or bending shape change. Modifying the actuation displacement allows controlled volume change. This paper presents an analytical model of the driving and blocking forces involved in actuation, as well as stress and strain that occurs due to the pressure changes. Actuation is driven by increasing osmotic pressure, and blocking forces are taken into consideration to plan actuator response so that outside forces do not counteract the displacement of actuation. Nastic structures are designed with use in unmanned aerial vehicles in mind, so blocking forces are modeled to be similar to in-flight conditions. Stress in the system is modeled so that any residual strain or lasting deformation can be determined, as well as a lifespan before failure from repeated actuation. The long-term aim of our work is to determine the power and energy efficiency of nastic structures actuation mechanism.

  9. A magnetorheological actuation system: test and model

    NASA Astrophysics Data System (ADS)

    John, Shaju; Chaudhuri, Anirban; Wereley, Norman M.

    2008-04-01

    Self-contained actuation systems, based on frequency rectification of the high frequency motion of an active material, can produce high force and stroke output. Magnetorheological (MR) fluids are active fluids whose rheological properties can be altered by the application of a magnetic field. By using MR fluids as the energy transmission medium in such hybrid devices, a valving system with no moving parts can be implemented and used to control the motion of an output cylinder shaft. The MR fluid based valves are configured in the form of an H-bridge to produce bi-directional motion in an output cylinder by alternately applying magnetic fields in the two opposite arms of the bridge. The rheological properties of the MR fluid are modeled using both Bingham plastic and bi-viscous models. In this study, the primary actuation is performed using a compact terfenol-D rod driven pump and frequency rectification of the rod motion is done using passive reed valves. The pump and reed valve configuration along with MR fluidic valves form a compact hydraulic actuation system. Actuator design, analysis and experimental results are presented in this paper. A time domain model of the actuator is developed and validated using experimental data.

  10. Characterization of radiation-induced performance decrement using a two-lever shock-avoidance task

    SciTech Connect

    Burghardt, W.F. Jr.; Hunt, W.A.

    1985-07-01

    Rats were trained to perform a task involving responses on two levers. Responding on an avoidance lever delayed the onset of electrical footshock for 20 sec and responding on a warning lever turned on a light for 60 sec. When the light was on, the task on the avoidance lever was changed from unsignaled shock avoidance to signaled shock avoidance by preceding the shocks with 5-sec warning tones. The animals preferred the signaled avoidance condition. After 100 Gy of /sup 60/Co irradiation, the animals were less able to avoid shock, an effect from which the animals recovered somewhat over 90 min. The response rate on the avoidance lever remained at or above control rates, while the response rate on the warning lever showed an initial increase, followed by a decrease below baseline. The data suggest that under these experimental conditions a subject will not respond appropriately to avoid shock or acquire cues that can facilitate the avoidance of shock. The effects, however, do not reflect an inability to perform the required movements but instead appear to reflect some characteristic of the task associated with a particular lever.

  11. Functional implications of the staminal lever mechanism in Salvia cyclostegia (Lamiaceae)

    PubMed Central

    Zhang, Bo; Claßen-Bockhoff, Regine; Zhang, Zhi-Qiang; Sun, Shan; Luo, Yan-Jiang; Li, Qing-Jun

    2011-01-01

    Background and Aims Flower morphology and inflorescence architecture affect pollinator foraging behaviour and thereby influence the process of pollination and the reproductive success of plants. This study explored possible ecological functions of the lever-like stamens and the floral design in Salvia cyclostegia. Methods Flower construction was experimentally manipulated by removing either the lower lever arms or the upper fertile thecae of the two stamens from a flower. The two types of manipulated individuals were intermixed with the control ones and randomly distributed in the population. Key Results Removing the sterile lower lever arms significantly reduced handling time per flower of the main pollinator, Bombus personatus. Interestingly, this manipulation did not increase the number of flowers probed per plant visit, but instead reduced it, i.e. shortened the visit sequence of the bumble-bees. Both loss of staminal lever function by removing lower lever arms and exclusion of self pollen by removing upper fertile thecae significantly reduced seed set per flower and seed set per plant. Both the manipulations interacted significantly with inflorescence size for the effect on female reproductive output. Conclusions Though the intact flowers demand a long handling time for pollinators, the reversible staminal lever is of advantage by promoting dispersal of pollen and thus the male function. The particular floral design in S. cyclostegia contributes to the floral constancy of B. personatus bumble-bees, with the lower lever arms acting as an optical cue for foraging cognition. PMID:21292677

  12. [Acquisition of a lever press behavior by mice in a water reinforcement situation].

    PubMed

    Kaneto, H; Nanri, M

    1984-11-01

    An operant chamber for mice, consisting of two adjacent compartments of W 130 X L 120 X H 150 mm, with a liquid dispenser which is operated by lever press was prepared. Using the apparatus, the applicability of mice for the study of learning of lever press behavior in a water reinforcement situation was investigated. Animals were deprived of water in the home cage and water was only supplied in the operant chamber by the lever press. A session of 15 min training was performed daily. By continuous reinforcement schedule, animals learned the lever pressing by 3 sessions. With these trained animals which attained more than 150 responses further experiments with a fixed ratio (FR) schedule was made, from FR 1 to FR 20. The best increase in responses was observed when the FR was regularly and gradually stepped up from 1 to 20 by every 5 sessions. Scopolamine, 1 mg/kg ip, significantly suppressed the lever press at FR 1 sessions, and the latency time until the first lever press was also prolonged significantly in these sessions. Thus, the applicability of mice for the study of learning of lever press behavior and the experimental schedules were established. PMID:6534036

  13. Photostrictive actuators for photonic control of shallow spherical shells

    NASA Astrophysics Data System (ADS)

    Shih, Hui-Ru; Tzou, Horn-Sen

    2007-10-01

    Photostrictive materials, exhibiting light-induced strain, are of interest for the future generation of wireless remote control photo-actuators. Photostrictive actuators are expected to be used as the driving component in optically controlled flexible structures. In this paper, the photonic control of flexible spherical shells using discrete photostrictive actuators is investigated. This paper presents a coupled opto-piezothermoelastic shell theory that incorporates photovoltaic, pyroelectric and piezoelectric effects, and has the capability to predict the response of a spherical shell driven by the photostrictive actuators. In this study, the effects of actuator location as well as membrane and bending components on the control action have been analyzed. The results obtained indicate that the control forces are mode and location dependent. Analysis also shows that the membrane control action is much more significant than the bending control action.

  14. A Method for Evaluating the Electro-Mechanical Characteristics of Piezoelectric Actuators during Motion

    PubMed Central

    Jin, Tao; Takita, Akihiro; Djamal, Mitra; Hou, Wenmei; Jia, Hongzhi; Fujii, Yusaku

    2012-01-01

    The electro-mechanical characteristics of piezoelectric actuators which have being driven are evaluated in this paper. The force generated by actuators is measured as an inertial force of a corner cub prism which is attached to the actuators. The Doppler frequency shift of a laser beam, due to the motion of actuator, is accurately measured by a heterodyne interferometer. Subsequently, the mechanical quantities, such as velocity, acceleration, force, power and displacement, are calculated from the Doppler frequency shift. With the measurement results of current and voltage of the actuator, the relationships between electrical and mechanical characteristics are evaluated.

  15. Implementation and analysis of an innovative digital charge amplifier for hysteresis reduction in piezoelectric stack actuators

    SciTech Connect

    Bazghaleh, Mohsen Grainger, Steven; Cazzolato, Ben; Lu, Tien-Fu; Oskouei, Reza

    2014-04-15

    Smart actuators are the key components in a variety of nanopositioning applications, such as scanning probe microscopes and atomic force microscopes. Piezoelectric actuators are the most common smart actuators due to their high resolution, low power consumption, and wide operating frequency but they suffer hysteresis which affects linearity. In this paper, an innovative digital charge amplifier is presented to reduce hysteresis in piezoelectric stack actuators. Compared to traditional analog charge drives, experimental results show that the piezoelectric stack actuator driven by the digital charge amplifier has less hysteresis. It is also shown that the voltage drop of the digital charge amplifier is significantly less than the voltage drop of conventional analog charge amplifiers.

  16. Electro-Mechanical Actuators

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The electro-mechanical actuator, a new electronics technology, is an electronic system that provides the force needed to move valves that control the flow of propellant to the engine. It is proving to be advantageous for the main propulsion system plarned for a second generation reusable launch vehicle. Hydraulic actuators have been used successfully in rocket propulsion systems. However, they can leak when high pressure is exerted on such a fluid-filled hydraulic system. Also, hydraulic systems require significant maintenance and support equipment. The electro-mechanical actuator is proving to be low maintenance and the system weighs less than a hydraulic system. The electronic controller is a separate unit powering the actuator. Each actuator has its own control box. If a problem is detected, it can be replaced by simply removing one defective unit. The hydraulic systems must sustain significant hydraulic pressures in a rocket engine regardless of demand. The electro-mechanical actuator utilizes power only when needed. A goal of the Second Generation Reusable Launch Vehicle Program is to substantially improve safety and reliability while reducing the high cost of space travel. The electro-mechanical actuator was developed by the Propulsion Projects Office of the Second Generation Reusable Launch Vehicle Program at the Marshall Space Flight Center.

  17. Cryogenic Piezoelectric Actuator

    NASA Technical Reports Server (NTRS)

    Jiang, Xiaoning; Cook, William B.; Hackenberger, Wesley S.

    2009-01-01

    In this paper, PMN-PT single crystal piezoelectric stack actuators and flextensional actuators were designed, prototyped and characterized for space optics applications. Single crystal stack actuators with footprint of 10 mm x10 mm and the height of 50 mm were assembled using 10 mm x10mm x0.15mm PMN-PT plates. These actuators showed stroke > 65 - 85 microns at 150 V at room temperature, and > 30 microns stroke at 77 K. Flextensional actuators with dimension of 10mm x 5 mm x 7.6 mm showed stroke of >50 microns at room temperature at driving voltage of 150 V. A flextensional stack actuator with dimension of 10 mm x 5 mm x 47 mm showed stroke of approx. 285 microns at 150 V at room temperature and > 100 microns at 77K under driving of 150 V should be expected. The large cryogenic stroke and high precision of these actuators are promising for cryogenic optics applications.

  18. MEMS Actuated Deformable Mirror

    SciTech Connect

    Papavasiliou, A; Olivier, S; Barbee, T; Walton, C; Cohn, M

    2005-11-10

    This ongoing work concerns the creation of a deformable mirror by the integration of MEMS actuators with Nanolaminate foils through metal compression boning. These mirrors will use the advantages of these disparate technologies to achieve dense actuation of a high-quality, continuous mirror surface. They will enable advanced adaptive optics systems in large terrestrial telescopes. While MEMS actuators provide very dense actuation with high precision they can not provide large forces typically necessary to deform conventional mirror surfaces. Nanolaminate foils can be fabricated with very high surface quality while their extraordinary mechanical properties enable very thin, flexible foils to survive the rigors of fabrication. Precise metal compression bonding allows the attachment of the fragile MEMS actuators to the thin nanolaminate foils without creating distortions at the bond sites. This paper will describe work in four major areas: (1) modeling and design, (2) bonding development, (3) nanolaminate foil development, (4) producing a prototype. A first-principles analytical model was created and used to determine the design parameters. A method of bonding was determined that is both strong, and minimizes the localized deformation or print through. Work has also been done to produce nanolaminate foils that are sufficiently thin, flexible and flat to be deformed by the MEMS actuators. Finally a prototype was produced by bonding thin, flexible nanolaminate foils to commercially available MEMS actuators.

  19. Investigation of Creep Properties in RAINBOW High Displacement Actuators

    NASA Technical Reports Server (NTRS)

    Haertling, Gene; Furman, Eugene; Li, Guang; Barron, Bret; Moon, Youngwoo

    1997-01-01

    Results from this study on fatigue in Rainbow and Cerambow actuators show that these high displacement actuators have definite fatigue rates and lifetimes depending upon (1) the amount of displacement generated, (2) how hard they are driven electrically, and (3) the microstructure (grain size) of the ceramic material. Lifetimes for some actuators were on the order of 10(exp 7) cycles at near dc (1 Hz) frequencies while others still retained up to 74% of their displacement at 2.1 x 10(exp 7) Hz.

  20. Induced-shear piezoelectric actuators for rotor blade trailing edge flaps

    NASA Astrophysics Data System (ADS)

    Centolanza, Louis R.; Smith, Edward C.; Munsky, Brian

    2002-02-01

    Much of the current rotorcraft research is focused on improving performance by reducing unwanted helicopter noise and vibration. One of the most promising active rotorcraft vibration control systems is an active trailing edge flap. In this paper, an induced-shear piezoelectric tube actuator is used in conjunction with a simple lever-cusp hinge amplification device to generate a useful combination of trailing edge flap deflections and hinge moments. A finite-element model of the actuator tube and trailing edge flap (including aerodynamic and inertial loading) was used to guide the design of the actuator-flap system. A full-scale induced shear tube actuator flap system was fabricated and bench top testing was conducted to validate the analysis. Hinge moments corresponding to various rotor speeds were applied to the actuator using mechanical springs. The testing demonstrated that for an applied electric field of 3 kV cm-1, the tube actuator deflected a representative full-scale 12 inch flap +/-2.8° at 0 rpm and +/-1.4° for a hinge moment simulating a 400 rpm condition. The per cent error between the predicted and experimental full-scale flap deflections ranged from 4% (low rpm) to 12.5% (large rpm). Increasing the electric field to 4 kV cm-1 results in +/-2.5° flap deflection at a rotation speed of 400 rpm, according to the design analysis. A trade study was conducted to compare the performance of the piezoelectric tube actuator to the state of the art in trailing edge flap actuators and indicated that the induced-shear tube actuator shows promise as a trailing edge flap actuator.

  1. Fiber-optic raster scanning two-photon endomicroscope using a tubular piezoelectric actuator

    NASA Astrophysics Data System (ADS)

    Do, Dukho; Yoo, Hongki; Gweon, Dae-Gab

    2014-06-01

    A nonresonant, fiber-optic raster scanning endomicroscope was developed using a quarter-tubular piezoelectric (PZT) actuator. A fiber lever mechanism was utilized to enhance the small actuation range of the tubular PZT actuator and to increase its field-of-view. Finite element method simulation of the endoscopic probe was conducted for various conditions to maximize its scanning range. After fabricating the probe using a double clad fiber, we obtained two-photon fluorescence images using raster beam scanning of the fiber. The outer diameter of the probe was 3.5 mm and its rigid distal length was 30 mm including a high numerical aperture gradient index lens. These features are sufficient for input into the instrumental channel of a commercial colonoscope or gastroscope to obtain high resolution images in vivo.

  2. Lever arm extension of myosin VI is unnecessary for the adjacent binding state

    PubMed Central

    Ikezaki, Keigo; Komori, Tomotaka; Arai, Yoshiyuki; Yanagida, Toshio

    2015-01-01

    Myosin VI is a processive myosin that has a unique stepping motion, which includes three kinds of steps: a large forward step, a small forward step and a backward step. Recently, we proposed the parallel lever arms model to explain the adjacent binding state, which is necessary for the unique motion. In this model, both lever arms are directed the same direction. However, experimental evidence has not refuted the possibility that the adjacent binding state emerges from myosin VI folding its lever arm extension (LAE). To clarify this issue, we constructed a myosin VI/V chimera that replaces the myosin VI LAE with the IQ3-6 domains of the myosin V lever arm, which cannot fold, and performed single molecule imaging. Our chimera showed the same stepping patterns as myosin VI, indicating the LAE is not responsible for the adjacent binding state.

  3. Manual shift control lever device and self-contained electronic control for transmissions

    SciTech Connect

    Parker, F.F.

    1986-09-09

    A unitized shift control lever device is described for the remote activation of an electrically controlled transmission comprising: a housing; a manually operable range selector lever pivotally supported in the housing for selective movements to predetermined operating positions respectively indicative of a required operating condition of an associated electrically controlled transmission; means in the housing providing a source of radiations; radiation controlled switching means for generating discrete control signals in response to the presence and non-presence of the radiations; means interposed in the radiation path between the source and the switching means operable in response to the movement of the range selector lever for selectively determining the presence or non-presence of the radiations with respect to the switching means at each range selector position of the lever; and electronic circuit control means having input connections for receiving the generated signals and output connections adapted for connection with electrically activated condition controlling devices on the transmission.

  4. 20. VIEW OF NEWER 7LEVER INTERLOCKING MACHINE IN FOREGROUND, NEXT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. VIEW OF NEWER 7-LEVER INTERLOCKING MACHINE IN FOREGROUND, NEXT TO ORIGINAL INTERLOCKING MACHINE, THIRD FLOOR - South Station Tower No. 1 & Interlocking System, Dewey Square, Boston, Suffolk County, MA

  5. Magnetically Actuated Seal

    NASA Technical Reports Server (NTRS)

    Pinera, Alex

    2013-01-01

    This invention is a magnetically actuated seal in which either a single electromagnet, or multiple electromagnets, are used to control the seal's position. This system can either be an open/ close type of system or an actively controlled system.

  6. Rotary Series Elastic Actuator

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Mehling, Joshua S. (Inventor); Parsons, Adam H. (Inventor); Griffith, Bryan Kristian (Inventor); Radford, Nicolaus A. (Inventor); Permenter, Frank Noble (Inventor); Davis, Donald R. (Inventor); Ambrose, Robert O. (Inventor); Junkin, Lucien Q. (Inventor)

    2013-01-01

    A rotary actuator assembly is provided for actuation of an upper arm assembly for a dexterous humanoid robot. The upper arm assembly for the humanoid robot includes a plurality of arm support frames each defining an axis. A plurality of rotary actuator assemblies are each mounted to one of the plurality of arm support frames about the respective axes. Each rotary actuator assembly includes a motor mounted about the respective axis, a gear drive rotatably connected to the motor, and a torsion spring. The torsion spring has a spring input that is rotatably connected to an output of the gear drive and a spring output that is connected to an output for the joint.

  7. Rotary series elastic actuator

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Mehling, Joshua S. (Inventor); Parsons, Adam H. (Inventor); Griffith, Bryan Kristian (Inventor); Radford, Nicolaus A. (Inventor); Permenter, Frank Noble (Inventor); Davis, Donald R. (Inventor); Ambrose, Robert O. (Inventor); Junkin, Lucien Q. (Inventor)

    2012-01-01

    A rotary actuator assembly is provided for actuation of an upper arm assembly for a dexterous humanoid robot. The upper arm assembly for the humanoid robot includes a plurality of arm support frames each defining an axis. A plurality of rotary actuator assemblies are each mounted to one of the plurality of arm support frames about the respective axes. Each rotary actuator assembly includes a motor mounted about the respective axis, a gear drive rotatably connected to the motor, and a torsion spring. The torsion spring has a spring input that is rotatably connected to an output of the gear drive and a spring output that is connected to an output for the joint.

  8. Muscle Motion Solenoid Actuator

    NASA Astrophysics Data System (ADS)

    Obata, Shuji

    It is one of our dreams to mechanically recover the lost body for damaged humans. Realistic humanoid robots composed of such machines require muscle motion actuators controlled by all pulling actions. Particularly, antagonistic pairs of bi-articular muscles are very important in animal's motions. A system of actuators is proposed using the electromagnetic force of the solenoids with the abilities of the stroke length over 10 cm and the strength about 20 N, which are needed to move the real human arm. The devised actuators are based on developments of recent modern electro-magnetic materials, where old time materials can not give such possibility. Composite actuators are controlled by a high ability computer and software making genuine motions.

  9. Linear Proof Mass Actuator

    NASA Technical Reports Server (NTRS)

    Holloway, Sidney E., III

    1994-01-01

    This paper describes the mechanical design, analysis, fabrication, testing, and lessons learned by developing a uniquely designed spaceflight-like actuator. The linear proof mass actuator (LPMA) was designed to attach to both a large space structure and a ground test model without modification. Previous designs lacked the power to perform in a terrestrial environment while other designs failed to produce the desired accelerations or frequency range for spaceflight applications. Thus, the design for a unique actuator was conceived and developed at NASA Langley Research Center. The basic design consists of four large mechanical parts (mass, upper housing, lower housing, and center support) and numerous smaller supporting components including an accelerometer, encoder, and four drive motors. Fabrication personnel were included early in the design phase of the LPMA as part of an integrated manufacturing process to alleviate potential difficulties in machining an already challenging design. Operating testing of the LPMA demonstrated that the actuator is capable of various types of load functions.

  10. Linear Proof Mass Actuator

    NASA Technical Reports Server (NTRS)

    Holloway, S. E., III

    1995-01-01

    This paper describes the mechanical design, analysis, fabrication, testing, and lessons learned by developing a uniquely designed spaceflight-like actuator. The Linear Proof Mass Actuator (LPMA) was designed to attach to both a large space structure and a ground test model without modification. Previous designs lacked the power to perform in a terrestrial environment while other designs failed to produce the desired accelerations or frequency range for spaceflight applications. Thus, the design for a unique actuator was conceived and developed at NASA Langley Research Center. The basic design consists of four large mechanical parts (Mass, Upper Housing, Lower Housing, and Center Support) and numerous smaller supporting components including an accelerometer, encoder, and four drive motors. Fabrication personnel were included early in the design phase of the LPMA as part of an integrated manufacturing process to alleviate potential difficulties in machining an already challenging design. Operational testing of the LPMA demonstrated that the actuator is capable of various types of load functions.

  11. Configuration of a shear web based actuation system

    NASA Astrophysics Data System (ADS)

    Natterer, Franz Josef; Monner, Hans-Peter

    2010-04-01

    Shape adaptive systems and structural configurations are necessary to fulfill the demands of a future unmanned aerial vehicle structure. Predominantly the present approaches are based on a passive load-bearing structure having smart actuation systems deforming the passive structural configuration elastically in the wanted shape. Therefore the actuation system can be based on discrete actuators, like electrically driven motors using gearing systems to transform the displacement into the structure or on smart material configurations placed on the load bearing passive structure, deforming the structure within the elastic region into the wanted shape. Using smart materials within load-bearing structures, elastic and static strength properties vary between passive and active structures. Matching these properties is a great challenge for future structural configurations. This is a successful approach for certain applications, e.g. smart rotor blade. The availability of two-dimensional smart actuator configurations with distinct actuation orientation allows the definition of a distinct load bearing active structure. Therefore the so called "web" of a spar-equivalent configuration was substituted by such a smart material actuator also known as macro fiber composite (MFC). Activating the web of the active cantilevered spar-configuration is resulting in a free end displacement. The main advantage lies in the fact that this approach will allow larger active displacements in comparison to a passive structural configuration with applied smart material actuators. Within the paper the process of developing the shear web based actuation system with configuration details will be illustrated and future steps will be proposed.

  12. Electrostatic actuators for portable microfluidic systems

    NASA Astrophysics Data System (ADS)

    Tice, Joshua

    Both developed and developing nations have an urgent need to diagnose disease cheaply, reliably, and independently of centralized facilities. Microfulidic platforms are well-positioned to address the need for portable diagnostics, mainly due to their obvious advantage in size. However, most microfluidic methods rely on equipment outside of the chip either for driving fluid flow (e.g., syringe pumps) or for taking measurements (e.g., lasers or microscopes). The energy and space requirements of the whole system inhibit portability and contribute to costs. To capitalize on the strengths of microfluidic platforms and address the serious needs of society, system components need to be miniaturized. Also, miniaturization should be accomplished as simply as possible, considering that simplicity is usually requisite for achieving truly transformative technology. Herein, I attempt to address the issue of controlling fluid flow in portable microfluidic systems. I focus on systems that are driven by elastomer-based membrane valves, since these valves are inherently simple, yet they are capable of sophisticated fluid manipulation. Others have attempted to modify pneumatic microvalves for portable applications, e.g., by transitioning to electromagnetic, thermopneumatic, or piezoelectric actuation principles. However, none of these strategies maintain the proper balance of simplicity, functionality, and ease of integration. My research centers on electrostatic actuators, due to their conceptual simplicity and the efficacy of electrostatic forces on the microscale. To ensure easy integration with polymer-based systems, and to maintain simplicity in the fabrication procedure, the actuators were constructed solely from poly(dimethylsiloxane) and multi-walled carbon nanotubes. In addition, the actuators were fabricated exclusively with soft-lithographic techniques. A mathematical model was developed to identify actuator parameters compatible with soft-lithography, and also to

  13. Laser Initiated Actuator study

    SciTech Connect

    Watson, B.

    1991-06-27

    The program task was to design and study a laser initiated actuator. The design of the actuator is described, it being comprised of the fiber and body subassemblies. The energy source for all experiments was a Spectra Diode 2200-H2 laser diode. The diode is directly coupled to a 100 micron core, 0.3 numerical aperture fiber optic terminated with an SMA connector. The successful testing results are described and recommendations are made.

  14. Inertial Linear Actuators

    NASA Technical Reports Server (NTRS)

    Laughlin, Darren

    1995-01-01

    Inertial linear actuators developed to suppress residual accelerations of nominally stationary or steadily moving platforms. Function like long-stroke version of voice coil in conventional loudspeaker, with superimposed linear variable-differential transformer. Basic concept also applicable to suppression of vibrations of terrestrial platforms. For example, laboratory table equipped with such actuators plus suitable vibration sensors and control circuits made to vibrate much less in presence of seismic, vehicular, and other environmental vibrational disturbances.

  15. Combustion powered linear actuator

    DOEpatents

    Fischer, Gary J.

    2007-09-04

    The present invention provides robotic vehicles having wheeled and hopping mobilities that are capable of traversing (e.g. by hopping over) obstacles that are large in size relative to the robot and, are capable of operation in unpredictable terrain over long range. The present invention further provides combustion powered linear actuators, which can include latching mechanisms to facilitate pressurized fueling of the actuators, as can be used to provide wheeled vehicles with a hopping mobility.

  16. Compact electrostatic comb actuator

    DOEpatents

    Rodgers, M. Steven; Burg, Michael S.; Jensen, Brian D.; Miller, Samuel L.; Barnes, Stephen M.

    2000-01-01

    A compact electrostatic comb actuator is disclosed for microelectromechanical (MEM) applications. The actuator is based upon a plurality of meshed electrostatic combs, some of which are stationary and others of which are moveable. One or more restoring springs are fabricated within an outline of the electrostatic combs (i.e. superposed with the moveable electrostatic combs) to considerably reduce the space required for the actuator. Additionally, a truss structure is provided to support the moveable electrostatic combs and prevent bending or distortion of these combs due to unbalanced electrostatic forces or external loading. The truss structure formed about the moveable electrostatic combs allows the spacing between the interdigitated fingers of the combs to be reduced to about one micron or less, thereby substantially increasing the number of active fingers which can be provided in a given area. Finally, electrostatic shields can be used in the actuator to substantially reduce unwanted electrostatic fields to further improve performance of the device. As a result, the compact electrostatic comb actuator of the present invention occupies only a fraction of the space required for conventional electrostatic comb actuators, while providing a substantial increase in the available drive force (up to one-hundred times).

  17. Hybrid electromechanical actuator and actuation system

    NASA Technical Reports Server (NTRS)

    Su, Ji (Inventor); Xu, Tian-Bing (Inventor)

    2008-01-01

    A hybrid electromechanical actuator has two different types of electromechanical elements, one that expands in a transverse direction when electric power is applied thereto and one that contracts in a transverse direction when electric power is applied thereto. The two electromechanical elements are (i) disposed in relation to one another such that the transverse directions thereof are parallel to one another, and (ii) mechanically coupled to one another at least at two opposing edges thereof. Electric power is applied simultaneously to the elements.

  18. Direct measurements of the coordination of lever arm swing and the catalytic cycle in myosin V

    PubMed Central

    Trivedi, Darshan V.; Muretta, Joseph M.; Swenson, Anja M.; Davis, Jonathon P.; Thomas, David D.; Yengo, Christopher M.

    2015-01-01

    Myosins use a conserved structural mechanism to convert the energy from ATP hydrolysis into a large swing of the force-generating lever arm. The precise timing of the lever arm movement with respect to the steps in the actomyosin ATPase cycle has not been determined. We have developed a FRET system in myosin V that uses three donor–acceptor pairs to examine the kinetics of lever arm swing during the recovery and power stroke phases of the ATPase cycle. During the recovery stroke the lever arm swing is tightly coupled to priming the active site for ATP hydrolysis. The lever arm swing during the power stroke occurs in two steps, a fast step that occurs before phosphate release and a slow step that occurs before ADP release. Time-resolved FRET demonstrates a 20-Å change in distance between the pre- and postpower stroke states and shows that the lever arm is more dynamic in the postpower stroke state. Our results suggest myosin binding to actin in the ADP.Pi complex triggers a rapid power stroke that gates the release of phosphate, whereas a second slower power stroke may be important for mediating strain sensitivity. PMID:26553992

  19. Powered glove with electro-pneumatic actuation unit for the disabled

    NASA Astrophysics Data System (ADS)

    Kawakami, Kosuke; Kumano, Shinichi; Moromugi, Shunji; Ishimatsu, Takakazu

    2007-12-01

    Authors have been developing a powered glove for people suffering from paralysis on their fingers to support their daily activity. Small air cylinders are used as actuators for this glove. Pneumatically-driven system has high advantages in case soft actuation is preferable. However, there are some problems to be solved in the pneumatically-driven system if the system is supposed to be used in our daily life. Huge air compressor is needed and solenoid valves emit loud sound for example. These problems are hurdles to commercialize the powered glove. To solve these problems authors have developed a new actuation unit by integrating an electric cylinder and an air cylinder. This actuation unit has advantages of both the electric actuation and the pneumatic actuation. Its advanced grip control ability has demonstrated through several experiments. The experimental results are reported in this paper.

  20. S-IV-B Aft Swing Arm Cam Lever Stop Strain Guage

    NASA Technical Reports Server (NTRS)

    1967-01-01

    The Marshall Space Flight Center (MSFC) played a crucial role in the development of the huge Saturn rockets that delivered humans to the moon in the 1960s. Many unique facilities existed at MSFC for the development and testing of the Saturn rockets. Affectionately nicknamed 'The Arm Farm', the Random Motion/ Lift-Off Simulator was one of those unique facilities. This facility was developed to test the swing arm mechanisms that were used to hold the rocket in position until liftoff. The Arm Farm provided the capability of testing the detachment and reconnection of various arms under brutally realistic conditions. The 18-acre facility consisted of more than a half dozen arm test positions and one position for testing access arms used by the Apollo astronauts. Each test position had two elements: a vehicle simulator for duplicating motions during countdown and launch; and a section duplicating the launch tower. The vehicle simulator duplicated the portion of the vehicle skin that contained the umbilical connections and personnel access hatches. Driven by a hydraulic servo system, the vehicle simulator produced relative motion between the vehicle and tower. On the Arm Farm, extreme environmental conditions (such as a launch scrub during an approaching Florida thunderstorm) could be simulated. The dramatic scenes that the Marshall engineers and technicians created at the Arm Farm permitted the gathering of crucial technical and engineering data to ensure a successful real time launch from the Kennedy Space Center. This photo depicts a close up of the S-IV-B aft swing arm cam lever stop strain guage.

  1. Non-collinear valve actuator

    NASA Technical Reports Server (NTRS)

    Richard, James A. (Inventor)

    2012-01-01

    A non-collinear valve actuator includes a primary actuating system and a return spring system with each applying forces to a linkage system in order to regulate the flow of a quarter-turn valve. The primary actuating system and return spring system are positioned non-collinearly, which simply means the primary actuating system and return spring system are not in line with each other. By positioning the primary actuating system and return spring system in this manner, the primary actuating system can undergo a larger stroke while the return spring system experiences significantly less displacement. This allows the length of the return spring to be reduced due to the minimization of displacement thereby reducing the weight of the return spring system. By allowing the primary actuating system to undergo longer strokes, the weight of the primary actuating system may also be reduced. Accordingly, the weight of the non-collinear valve actuator is reduced.

  2. Digital Actuator Technology

    SciTech Connect

    Ken Thomas; Ted Quinn; Jerry Mauck; Richard Bockhorst

    2014-09-01

    There are significant developments underway in new types of actuators for power plant active components. Many of these make use of digital technology to provide a wide array of benefits in performance of the actuators and in reduced burden to maintain them. These new product offerings have gained considerable acceptance in use in process plants. In addition, they have been used in conventional power generation very successfully. This technology has been proven to deliver the benefits promised and substantiate the claims of improved performance. The nuclear industry has been reluctant to incorporate digital actuator technology into nuclear plant designs due to concerns due to a number of concerns. These could be summarized as cost, regulatory uncertainty, and a certain comfort factor with legacy analog technology. The replacement opportunity for these types of components represents a decision point for whether to invest in more modern technology that would provide superior operational and maintenance benefits. Yet, the application of digital technology has been problematic for the nuclear industry, due to qualification and regulatory issues. With some notable exceptions, the result has been a continuing reluctance to undertake the risks and uncertainties of implementing digital actuator technology when replacement opportunities present themselves. Rather, utilities would typically prefer to accept the performance limitations of the legacy analog actuator technologies to avoid impacts to project costs and schedules. The purpose of this report is to demonstrate that the benefits of digital actuator technology can be significant in terms of plant performance and that it is worthwhile to address the barriers currently holding back the widespread development and use of this technology. It addresses two important objectives in pursuit of the beneficial use of digital actuator technology for nuclear power plants: 1. To demonstrate the benefits of digital actuator

  3. Thermally actuated mechanical systems

    NASA Astrophysics Data System (ADS)

    Sul, Onejae

    This thesis will discuss the generation of controlled sub-micron motions using novel micro actuators. Our research focuses on the development of an arm-type actuator and a free-motion locomotive walking device. Nano-science and nano-technology focuses on the creation of novel functional materials and also at the development of new fabrication techniques incorporating them. In the fields of novel fabrication techniques, manipulations of micron or sub-micron objects by micro actuators have been suggested in the science and engineering societies for mainly two reasons. From a scientific standpoint, new tools enable new prospective sciences, as is evident from the development of the atomic force microscope. From an engineering standpoint, the miniaturization of manipulation tools will require less material and less energy during a material's production. In spite of such importance, progress in the actuator miniaturization is in a primitive state, especially for the micro mobile devices. The thesis will be a key step in pursuit of this goal with an emphasis on generating motions. Our static actuator uses the excellent elastic properties of multiwall carbon nanotubes as a template for a bimorph system. Deflections in response to temperature variations are demonstrated. The mobile device itself is a bimorph system consisting of thin metal films. Control mechanisms for its velocity and steering are discussed. Finally, fundamental limits on the capabilities of the two devices in a more general sense are discussed under via laws of physics.

  4. Flexible low-mass robotic arm actuated by electroactive polymers

    NASA Astrophysics Data System (ADS)

    Bar-Cohen, Yoseph; Xue, T.; Shahinpoor, Mohsen; Harrison, Joycelyn S.; Smith, Joseph G.

    1998-07-01

    Miniature, lightweight, low-cost actuators that consume low- power can be used to develop unmatched robotic devices to make an impact on many technology areas. Electroactive polymers (EAP) actuators offer the potential to produce such devices and they induce relatively large bending and longitudinal actuation strains. This reported study is concentrating on the development of effective EAPs and the resultant enabling mechanisms employing their unique characteristics. Several EAP driven mechanisms, which emulate human hand, were developed including a gripper, manipulator arm and surface wiper. The manipulator arm was made of a composite rod with a lifting actuator consisting of a scrolled rope that is activated longitudinally by an electrostatic field. A gripper was made to serve as an end effector and it consisted of multiple bending EAP fingers for grabbing and holding such objects as rocks. An EAP surface wiper was developed to operate like a human finger and to demonstrate the potential to remove dust from optical and IR windows as well as solar cells. These EAP driven devices are taking advantage of the large actuation displacement of these materials for applications that have limited requirement for actuation force capability.

  5. Torsional Ratcheting Actuating System

    SciTech Connect

    BARNES,STEPHEN MATTHEW; MILLER,SAMUEL L.; RODGERS,M. STEVEN; BITSIE,FERNANDO

    2000-01-24

    A new type of surface micromachined ratcheting actuation system has been developed at the Microelectronics Development Laboratory at Sandia National Laboratories. The actuator uses a torsional electrostatic comb drive that is coupled to an external ring gear through a ratcheting scheme. The actuator can be operated with a single square wave, has minimal rubbing surfaces, maximizes comb finger density, and can be used for open-loop position control. The prototypes function as intended with a minimum demonstrated operating voltage of 18V. The equations of motion are developed for the torsional electrostatic comb drive. The resonant frequency, voltage vs. displacement and force delivery characteristics are predicted and compared with the fabricated device's performance.

  6. Tetherless thermobiochemically actuated microgrippers

    PubMed Central

    Leong, Timothy G.; Randall, Christina L.; Benson, Bryan R.; Bassik, Noy; Stern, George M.; Gracias, David H.

    2009-01-01

    We demonstrate mass-producible, tetherless microgrippers that can be remotely triggered by temperature and chemicals under biologically relevant conditions. The microgrippers use a self-contained actuation response, obviating the need for external tethers in operation. The grippers can be actuated en masse, even while spatially separated. We used the microgrippers to perform diverse functions, such as picking up a bead on a substrate and the removal of cells from tissue embedded at the end of a capillary (an in vitro biopsy). PMID:19139411

  7. Fault tolerant linear actuator

    DOEpatents

    Tesar, Delbert

    2004-09-14

    In varying embodiments, the fault tolerant linear actuator of the present invention is a new and improved linear actuator with fault tolerance and positional control that may incorporate velocity summing, force summing, or a combination of the two. In one embodiment, the invention offers a velocity summing arrangement with a differential gear between two prime movers driving a cage, which then drives a linear spindle screw transmission. Other embodiments feature two prime movers driving separate linear spindle screw transmissions, one internal and one external, in a totally concentric and compact integrated module.

  8. Hydraulic involute cam actuator

    DOEpatents

    Love, Lonnie J.; Lind, Randall F.

    2011-11-01

    Mechanical joints are provided in which the angle between a first coupled member and a second coupled member may be varied by mechanical actuators. In some embodiments the angle may be varied around a pivot axis in one plane and in some embodiments the angle may be varied around two pivot axes in two orthogonal planes. The joints typically utilize a cam assembly having two lobes with an involute surface. Actuators are configured to push against the lobes to vary the rotation angle between the first and second coupled member.

  9. Deformable mirrors: design fundamentals for force actuation of continuous facesheets

    NASA Astrophysics Data System (ADS)

    Ravensbergen, S. K.; Hamelinck, R. F. H. M.; Rosielle, P. C. J. N.; Steinbuch, M.

    2009-08-01

    Adaptive Optics is established as essential technology in current and future ground based (extremely) large telescopes to compensate for atmospheric turbulence. Deformable mirrors for astronomic purposes have a high number of actuators (> 10k), a relatively large stroke (> 10μm) on a small spacing (< 10mm) and a high control bandwidth (> 100Hz). The availability of piezoelectric ceramics as an actuator principle has driven the development of many adaptive deformable mirrors towards inappropriately stiff displacement actuation. This, while the use of force actuation supersedes piezos in performance and longevity while being less costly per channel by a factor of 10-20. This paper presents a model which is independent of the actuator type used for actuation of continuous facesheet deformable mirrors, to study the design parameters such as: actuator spacing & coupling, influence function, peak-valley stroke, dynamical behavior: global & local, etc. The model is validated using finite element simulations and its parameters are used to derive design fundamentals for optimization.

  10. Transfer Function Identification of an Electro-Rheological Actuator

    NASA Astrophysics Data System (ADS)

    Brookfield, D. J.; Dlodlo, Z. B.

    A fluid clutch utilising an Electro-Rheological (ER) suspension provides a controlled torque coupling between input and output through the control of the applied electric field. If the input is driven at constant speed the device can be considered as an ER torque actuator and thus be used to drive robot links or other mechanisms requiring precise positioning. Such an ER torque actuator can replace a DC servo-motor in robotic applications with the benefits of low time constant and smooth output torque unaffected by cogging (i.e. variation in torque of a DC motor as the magnetic reluctance of the armature-stator path changes with rotation). Although the ER actuator has many benefits, it suffers from a non-linear and time varying relationship between input voltage and output torque. These undesirable characteristics can be mitigated by providing a local closed loop controller around the system. The design of such a controller requires a knowledge of the relationship between the applied voltage and output torque; i.e. the transfer function of the actuator. This transfer function has been determined by observing the response of an ER torque actuator in the frequency domain. It is shown that a linear transfer function model reasonable represents the actuator behaviour, that the actuator is a stable second order system and that the time constant of the clutch studied is sufficiently short to hold considerable promise for robotic applications. Furthermore, the maximum torque capability is shown to be sufficient for many medium scale industrial robots.

  11. Tough Nanocomposite Ionogel-based Actuator Exhibits Robust Performance

    PubMed Central

    Liu, Xinhua; He, Bin; Wang, Zhipeng; Tang, Haifeng; Su, Teng; Wang, Qigang

    2014-01-01

    Ionogel electrolytes can be fabricated for electrochemical actuators with many desirable advantages, including direct low-voltage control in air, high electrochemical and thermal stability, and complete silence during actuation. However, the demands for active actuators with above features and load-driving ability remain a challenge; much work is necessary to enhance the mechanical strength of electrolyte materials. Herein, we describe a cross-linked supramolecular approach to prepare tough nanocomposite gel electrolytes from HEMA, BMIMBF4, and TiO2 via self-initiated UV polymerization. The tough and stable ionogels are emerging to fabricate electric double-layer capacitor-like soft actuators, which can be driven by electrically induced ion migration. The ionogel-based actuator shows a displacement response of 5.6 mm to the driving voltage of 3.5 V. After adding the additional mass weight of the same as the actuator, it still shows a large displacement response of 3.9 mm. Furthermore, the actuator can not only work in harsh temperature environments (100°C and −10°C) but also realize the goal of grabbing an object by adjusting the applied voltage. PMID:25327414

  12. Soft linear electroactive polymer actuators based on polypyrrole

    NASA Astrophysics Data System (ADS)

    Maziz, Ali; Khaldi, Alexandre; Persson, Nils-Krister; Jager, Edwin W. H.

    2015-04-01

    There is a growing demand for human-friendly robots that can interact and work closely with humans. Such robots need to be compliant, lightweight and equipped with silent and soft actuators. Electroactive polymers such as conducting polymers (CPs) are "smart" materials that deform in response to electrical simulation and are often addressed as artificial muscles due to their functional similarity with natural muscles. They offer unique possibilities and are perfect candidates for such actuators since they are lightweight, silent, and driven at low voltages. Most CP actuators are fabricated using electrochemical oxidative synthesis. We have developed new CP based fibres employing both vapour phase and liquid phase electrochemical synthesis. We will present the fabrication and characterisation of these fibres as well as their performance as linear actuators.

  13. Conceptual hermetically sealed elbow actuator

    NASA Technical Reports Server (NTRS)

    Wuenscher, H. F.

    1968-01-01

    Electrically or hydraulically powered, hermetically sealed angular or rotary actuator deflects mechanical members over a range of plus or minus 180 degrees. The actuator design provides incremental flexures which keep the local deflection rate within elastic limits.

  14. Low-Shock Pyrotechnic Actuator

    NASA Technical Reports Server (NTRS)

    Lucy, M. H.

    1984-01-01

    Miniature 1-ampere, 1-watt pyrotechnic actuator enclosed in flexible metal bellows. Bellows confines outgassing products, and pyrotechnic shock reduction achieved by action of bellows, gas cushion within device, and minimum use of pyrotechnic material. Actuator inexpensive, compact, and lightweight.

  15. Applications of dielectric elastomer actuators

    NASA Astrophysics Data System (ADS)

    Pelrine, Ron; Sommer-Larsen, Peter; Kornbluh, Roy D.; Heydt, Richard; Kofod, Guggi; Pei, Qibing; Gravesen, Peter

    2001-07-01

    Dielectric elastomer actuators, based on the field-induced deformation of elastomeric polymers with compliant electrodes, can produce a large strain response, combined with a fast response time and high electromechanical efficiency. This unique performance, combined with other factors such as low cost, suggests many potential applications, a wide range of which are under investigation. Applications that effectively exploit the properties of dielectric elastomers include artificial muscle actuators for robots; low-cost, lightweight linear actuators; solid- state optical devices; diaphragm actuators for pumps and smart skins; acoustic actuators; and rotary motors. Issues that may ultimately determine the success or failure of the actuation technology for specific applications include the durability of the actuator, the performance of the actuator under load, operating voltage and power requirements, and electronic driving circuitry, to name a few.

  16. Unimolecular Submersible Nanomachines. Synthesis, Actuation, and Monitoring.

    PubMed

    García-López, Víctor; Chiang, Pinn-Tsong; Chen, Fang; Ruan, Gedeng; Martí, Angel A; Kolomeisky, Anatoly B; Wang, Gufeng; Tour, James M

    2015-12-01

    Unimolecular submersible nanomachines (USNs) bearing light-driven motors and fluorophores are synthesized. NMR experiments demonstrate that the rotation of the motor is not quenched by the fluorophore and that the motor behaves in the same manner as the corresponding motor without attached fluorophores. No photo or thermal decomposition is observed. Through careful design of control molecules with no motor and with a slow motor, we found using single molecule fluorescence correlation spectroscopy that only the molecules with fast rotating speed (MHz range) show an enhancement in diffusion by 26% when the motor is fully activated by UV light. This suggests that the USN molecules give ∼9 nm steps upon each motor actuation. A non-unidirectional rotating motor also results in a smaller, 10%, increase in diffusion. This study gives new insight into the light actuation of motorized molecules in solution. PMID:26540377

  17. Torque control in lingual orthodontics with lever arm mechanics: a case report.

    PubMed

    Aravind, M; Shivaprakash, G; Ramesh, G C

    2013-01-01

    The aim of this report is to illustrate treatment mechanics for torque control in lingual mechanotherapy using a lever arm and transpalatal arch (TPA) tab system during en masse retraction of anterior teeth. An 18-year-old female with bimaxillary dentoalveolar proclination with crowding was treated with a lever arm-TPA tab system. The retraction tabs bent into the TPA placed across the maxillary second molars were used as anchorage. The retraction force on the maxillary anterior teeth was applied using lever arm hooks soldered between the lateral incisors and canines on a lingual mushroom archwire. By applying a retraction force to the lever arm hooks, the maxillary anterior teeth experienced greater palatal root movement as compared to the conventional retraction forces applied at the crown level. The tabs, placed high in the TPA, produced a distal tipping moment on the maxillary second molars, reinforcing their anchorage. The retraction force applied to the long lever arm hooks from the TPA tabs at the level of center of resistance (CRes) of anterior and posterior teeth is advantageous mainly in two aspects. First, it reinforces the anchorage, and second, it favors the palatal root movement of anterior teeth, thus obtaining better control over the torque during en masse retraction. PMID:23646329

  18. Robot Arm with Tendon Connector Plate and Linear Actuator

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Diftler, Myron A. (Inventor); Bridgwater, Lyndon (Inventor); Nguyen, Vienny (Inventor); Millerman, Alexander (Inventor)

    2014-01-01

    A robotic system includes a tendon-driven end effector, a linear actuator, a flexible tendon, and a plate assembly. The linear actuator assembly has a servo motor and a drive mechanism, the latter of which translates linearly with respect to a drive axis of the servo motor in response to output torque from the servo motor. The tendon connects to the end effector and drive mechanism. The plate assembly is disposed between the linear actuator assembly and the tendon-driven end effector and includes first and second plates. The first plate has a first side that defines a boss with a center opening. The second plate defines an accurate through-slot having tendon guide channels. The first plate defines a through passage for the tendon between the center opening and a second side of the first plate. A looped end of the flexible tendon is received within the tendon guide channels.

  19. Field emission microplasma actuation for microchannel flows

    NASA Astrophysics Data System (ADS)

    Sashank Tholeti, Siva; Shivkumar, Gayathri; Alexeenko, Alina A.

    2016-06-01

    Microplasmas offer attractive flow control methodology for gas transport in microsystems where large viscous losses make conventional pumping methods highly inefficient. We study microscale flow actuation by dielectric-barrier discharge (DBD) with field emission (FE) of electrons, which allows lowering the operational voltage from kV to a few hundred volts and below. A feasibility study of FE-DBD for flow actuation is performed using 2D particle-in-cell method with Monte Carlo collisions (PIC/MCC) at 10 MHz in nitrogen at atmospheric pressure. The free diffusion dominated, high velocity field emission electrons create a large positive space charge and a body force on the order of 106 N m‑3. The body force and Joule heat decrease with increase in dielectric thickness and electrode thickness. The body force also decreases at lower pressures. The plasma body force distribution along with the Joule heating is then used in the Navier–Stokes simulations to quantify the flow actuation in a microchannel. Theoretical analysis and simulations for plasma actuated planar Poiseuille flow show that the gain in flow rate is inversely proportional to Reynolds number. This theoretical analysis is in good agreement with the simulations for a microchannel with closely placed actuators under incompressible conditions. Flow rate of FE-DBD driven 2D microchannel is around 100 ml min‑1 mm‑1 for an input power of 64 μW mm‑1. The gas temperature rises by 1500 K due to the Joule heating, indicating FE-DBD’s potential for microcombustion, micropropulsion and chemical sensing in addition to microscale pumping and mixing applications.

  20. Angular-Momentum-Compensating Actuator

    NASA Technical Reports Server (NTRS)

    Wiktor, Peter J.

    1988-01-01

    Reactionless actuator developed for instrument-pointing platforms on flexible spacecraft; by eliminating reactions, actuator changes aiming angle of platform without inducing vibrations in spacecraft, eliminateing vibrations in point angle of instrument platform. Actuator used on Earth in such systems as helicopter platforms for television cameras in law enforcement and news telecasts.

  1. Electromechanical flight control actuator

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The feasibility of using an electromechanical actuator (EMA) as the primary flight control equipment in aerospace flight is examined. The EMA motor design is presented utilizing improved permanent magnet materials. The necessary equipment to complete a single channel EMA using the single channel power electronics breadboard is reported. The design and development of an improved rotor position sensor/tachometer is investigated.

  2. Bistable microelectromechanical actuator

    DOEpatents

    Fleming, J.G.

    1999-02-02

    A bistable microelectromechanical (MEM) actuator is formed on a substrate and includes a stressed membrane of generally rectangular shape that upon release assumes a curvilinear cross-sectional shape due to attachment at a midpoint to a resilient member and at opposing edges to a pair of elongate supports. The stressed membrane can be electrostatically switched between a pair of mechanical states having mirror-image symmetry, with the MEM actuator remaining in a quiescent state after a programming voltage is removed. The bistable MEM actuator according to various embodiments of the present invention can be used to form a nonvolatile memory element, an optical modulator (with a pair of mirrors supported above the membrane and moving in synchronism as the membrane is switched), a switchable mirror (with a single mirror supported above the membrane at the midpoint thereof) and a latching relay (with a pair of contacts that open and close as the membrane is switched). Arrays of bistable MEM actuators can be formed for applications including nonvolatile memories, optical displays and optical computing. 49 figs.

  3. Bistable microelectromechanical actuator

    DOEpatents

    Fleming, James G.

    1999-01-01

    A bistable microelectromechanical (MEM) actuator is formed on a substrate and includes a stressed membrane of generally rectangular shape that upon release assumes a curvilinear cross-sectional shape due to attachment at a midpoint to a resilient member and at opposing edges to a pair of elongate supports. The stressed membrane can be electrostatically switched between a pair of mechanical states having mirror-image symmetry, with the MEM actuator remaining in a quiescent state after a programming voltage is removed. The bistable MEM actuator according to various embodiments of the present invention can be used to form a nonvolatile memory element, an optical modulator (with a pair of mirrors supported above the membrane and moving in synchronism as the membrane is switched), a switchable mirror (with a single mirror supported above the membrane at the midpoint thereof) and a latching relay (with a pair of contacts that open and close as the membrane is switched). Arrays of bistable MEM actuators can be formed for applications including nonvolatile memories, optical displays and optical computing.

  4. Actuators Acting without Actin.

    PubMed

    Geitmann, Anja

    2016-06-30

    Plant actuators move organs, allowing the plant to respond to environmental cues or perform other mechanical tasks. In Cardamine hursuta the dispersal of seeds is accomplished by explosive opening of the fruit. The biomechanical mechanism relies on a complex interplay between turgor regulation and cell wall mechanical properties. PMID:27368097

  5. "Mighty Worm" Piezoelectric Actuator

    NASA Technical Reports Server (NTRS)

    Bamford, Robert M.; Wada, Ben K.; Moore, Donald M.

    1994-01-01

    "Mighty Worm" piezoelectric actuator used as adjustable-length structural member, active vibrator or vibration suppressor, and acts as simple (fixed-length) structural member when inactive. Load force not applied to piezoelectric element in simple-structural-member mode. Piezoelectric element removed from load path when not in use.

  6. Electro-Active Polymer (EAP) Actuators for Planetary Applications

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Y.; Leary, S.; Shahinpoor, M.; Harrison, J. O.; Smith, J.

    1999-01-01

    NASA is seeking to reduce the mass, size, consumed power, and cost of the instrumentation used in its future missions. An important element of many instruments and devices is the actuation mechanism and electroactive polymers (EAP) are offering an effective alternative to current actuators. In this study, two families of EAP materials were investigated, including bending ionomers and longitudinal electrostatically driven elastomers. These materials were demonstrated to effectively actuate manipulation devices and their performance is being enhanced in this on-going study. The recent observations are reported in this paper, include the operation of the bending-EAP at conditions that exceed the harsh environment on Mars, and identify the obstacles that its properties and characteristics are posing to using them as actuators. Analysis of the electrical characteristics of the ionomer EAP showed that it is a current driven material rather than voltage driven and the conductivity distribution on the surface of the material greatly influences the bending performance. An accurate equivalent circuit modeling of the ionomer EAP performance is essential for the design of effective drive electronics. The ionomer main limitations are the fact that it needs to be moist continuously and the process of electrolysis that takes place during activation. An effective coating technique using a sprayed polymer was developed extending its operation in air from a few minutes to about four months. The coating technique effectively forms the equivalent of a skin to protect the moisture content of the ionomer. In parallel to the development of the bending EAP, the development of computer control of actuated longitudinal EAP has been pursued. An EAP driven miniature robotic arm was constructed and it is controlled by a MATLAB code to drop and lift the arm and close and open EAP fingers of a 4-finger gripper. Keywords: Miniature Robotics, Electroactive Polymers, Electroactive Actuators, EAP

  7. The Lever Arm Effects a Mechanical Asymmetry of the Myosin-V-Actin Bond

    PubMed Central

    Gebhardt, J. Christof M.; Ökten, Zeynep; Rief, Matthias

    2010-01-01

    Myosin-V is a two-headed molecular motor taking multiple ATP-dependent steps toward the plus end (forward) of actin filaments. At high mechanical loads, the motor processively steps toward the minus end (backward) even in the absence of ATP, whereas analogous forward steps cannot be induced. The detailed mechanism underlying this mechanical asymmetry is not known. We investigate the effect of force on individual single headed myosin-V constructs bound to actin in the absence of ATP. If pulled forward, the myosin-V head dissociates at forces twice as high than if pulled backward. Moreover, backward but not forward distances to the unbinding barrier are dependent on the lever arm length. This asymmetry of unbinding force distributions in a single headed myosin forms the basis of the two-headed asymmetry. Under load, the lever arm functions as a true lever in a mechanical sense. PMID:20338849

  8. Single-Lever Power Control for General Aviation Aircraft Promises Improved Efficiency and Simplified Pilot Controls

    NASA Technical Reports Server (NTRS)

    Musgrave, Jeffrey L.

    1997-01-01

    General aviation research is leading to major advances in internal combustion engine control systems for single-engine, single-pilot aircraft. These advances promise to increase engine performance and fuel efficiency while substantially reducing pilot workload and increasing flight safety. One such advance is a single-lever power control (SLPC) system, a welcome departure from older, less user-friendly, multilever engine control systems. The benefits of using single-lever power controls for general aviation aircraft are improved flight safety through advanced engine diagnostics, simplified powerplant operations, increased time between overhauls, and cost-effective technology (extends fuel burn and reduces overhaul costs). The single-lever concept has proven to be so effective in preliminary studies that general aviation manufacturers are making plans to retrofit current aircraft with the technology and are incorporating it in designs for future aircraft.

  9. Switched capacitor charge pump reduces hysteresis of piezoelectric actuators over a large frequency range.

    PubMed

    Huang, Liang; Ma, Yu Ting; Feng, Zhi Hua; Kong, Fan Rang

    2010-09-01

    Piezoelectric actuators exhibit large hysteresis between the applied voltage and their displacement. A switched capacitor charge pump is proposed to reduce hysteresis and linearize the movement of piezoelectric actuators. By pumping the same amount of charges into the piezoelectric actuator quantitatively, the actuator will be forced to change its length with constant step. Compared with traditional voltage and charge driving, experimental results demonstrated that the piezoelectric stack driven by the charge pump had less hysteresis over a large frequency range, especially at ultralow frequencies. A hysteresis of less than 2.01% was achieved over a frequency range of 0.01-20 Hz using the charge pump driver. PMID:20886997

  10. New Insights into the Functional Morphology of the Lever Mechanism of Salvia pratensis (Lamiaceae)

    PubMed Central

    Reith, Martin; Baumann, Gisela; Claßen-Bockhoff, Regine; Speck, Thomas

    2007-01-01

    Background and Aims The functional morphology of Salvia pratensis flowers was re-investigated, after new insights revealed that pollen dispensing is one of the main functions of the staminal lever. In particular, no detailed information was available regarding the process of pollen transfer and the forces arising between the pollen-bearing thecae and the pollinating bee's body. The assumption was made that these forces play a significant role in pollen dispensing. Methods The functional morphology of S. pratensis flowers and the interaction between flowers and bees (Apis mellifera) were studied by reconstructing stress and strains by using qualitative and semi-quantitative theoretical analysis. Flowers were manipulated to study the spatial arrangement of the filament and lever, and of the head and proboscis of the visiting bee inside the tube. Photographs and films of bee visits on flowers were used to analyse the interaction of pollinator and staminal lever. Key Results The spoon-shaped lower lever of S. pratensis has a small hole through which a bee introduces its proboscis into the corolla tube. Although mentioned for the first time by Kerner von Marilaun in 1891, presented here is the first drawing and the first photograph showing this interaction in detail. The analysis of the interaction of flower visitor and the lever mechanism revealed that the position of bees on different flowers is spatially very similar. Flower morphology constrains postures of legitimately nectar-probing bees within narrow bounds. A theoretical discussion on structural elements and force progression in the flower allows the principles of lightweight architecture in flower morphology to be recognized. Conclusions The staminal lever of S. pratensis is a pollen-dispensing device. It seems to influence the amount of pollen deposited on pollinators by determining the forces arising between the pollinator and the pollen. The relevant forces occur either during the first, dynamic phase or

  11. Myosin VI: an innovative motor that challenged the swinging lever arm hypothesis

    PubMed Central

    Spudich, James A.; Sivaramakrishnan, Sivaraj

    2010-01-01

    The swinging crossbridge hypothesis states that energy from ATP hydrolysis is transduced to mechanical movement of the myosin head while bound to actin. The light chain-binding region of myosin is thought to act as a lever arm that amplifies movements near the catalytic site. This model has been challenged by findings that myosin VI takes larger steps along actin filaments than early interpretations of its structure seem to allow. We now know that myosin VI does indeed operate by an unusual ~ 180° lever arm swing and achieves its large step size using special structural features in its tail domain. PMID:20094053

  12. Micromechanism linear actuator with capillary force sealing

    DOEpatents

    Sniegowski, Jeffry J.

    1997-01-01

    A class of micromachine linear actuators whose function is based on gas driven pistons in which capillary forces are used to seal the gas behind the piston. The capillary forces also increase the amount of force transmitted from the gas pressure to the piston. In a major subclass of such devices, the gas bubble is produced by thermal vaporization of a working fluid. Because of their dependence on capillary forces for sealing, such devices are only practical on the sub-mm size scale, but in that regime they produce very large force times distance (total work) values.

  13. Ergonomic Evaluation of Space Shuttle Light-Weight Seat Lever Position and Operation

    NASA Technical Reports Server (NTRS)

    Maida, J.; Rajulu, Sudhakar L.; Bond, Robert L. (Technical Monitor)

    2000-01-01

    During a Shuttle flight in the early part of 1999, one of the crewmembers was unable to operate the backrest lever for the light-weight seat in microgravity. It is essential that the crewmembers are able to adjust this back-rest lever, which is titled forward 2 degrees from vertical during launch and then moved backwards to 10 degrees aft of vertical upon reaching orbit. This adjustment is needed to cushion the crewmembers during an inadvertent crash landing situation. The original Shuttle seats, which had seat controls located on the front left and right sides of the seat, were replaced recently with the new light-weight seats. The controls for these new, seats were moved to the night side with one control at the front and the other at the back. While it was uncertain whether the problem encountered was unique to that crewmember or not it was clear to the personnel responsible for maintaining the Shuttle seats that not knowing the cause of the problem posed a safety concern for NASA. Hence the Anthropometry and Biomechanics Facility (ABF) of the Johnson Space Center was requested to perform an evaluation of the seat controls and provide NASA with appropriate recommendations on whether the seat lever positions and operations should be modified. The ABF designed an experiment to investigate the amount of pull force exerted by subjects, wearing an unpressurized or pressurized crew launch escape suit, when controls were placed in the front and back (on the right side) of the light-weight seat. Single-axis load cells were attached to the seat levers, which measured the maximum static pull forces that were exerted by the subjects. Twelve subjects, six male and six female, participated in this study. Each subject was asked to perform the pull test at least three times for each combination of lever position and suit pressure conditions. The results from this study showed that as a whole (or in general), the subjects were able to pull on the lever at the back position with

  14. A linear actuator for precision positioning of dual objects

    NASA Astrophysics Data System (ADS)

    Peng, Yuxin; Cao, Jie; Guo, Zhao; Yu, Haoyong

    2015-12-01

    In this paper, a linear actuator for precision positioning of dual objects is proposed based on a double friction drive principle using a single piezoelectric element (PZT). The linear actuator consists of an electromagnet and a permanent magnet, which are connected by the PZT. The electromagnet serves as an object 1, and another object (object 2) is attached on the permanent magnet by the magnetic force. For positioning the dual objects independently, two different friction drive modes can be alternated by an on-off control of the electromagnet. When the electromagnet releases from the guide way, it can be driven by impact friction force generated by the PZT. Otherwise, when the electromagnet clamps on the guide way and remains stationary, the object 2 can be driven based on the principle of smooth impact friction drive. A prototype was designed and constructed and experiments were carried out to test the basic performance of the actuator. It has been verified that with a compact size of 31 mm (L) × 12 mm (W) × 8 mm (H), the two objects can achieve long strokes on the order of several millimeters and high resolutions of several tens of nanometers. Since the proposed actuator allows independent movement of two objects by a single PZT, the actuator has the potential to be constructed compactly.

  15. Microfabricated therapeutic actuators

    SciTech Connect

    Lee, Abraham P.; Northrup, M. Allen; Ciarlo, Dino R.; Krulevitch, Peter A.; Benett, William J.

    1999-01-01

    Microfabricated therapeutic actuators are fabricated using a shape memory polymer (SMP), a polyurethane-based material that undergoes a phase transformation at a specified temperature (Tg). At a temperature above temperature Tg material is soft and can be easily reshaped into another configuration. As the temperature is lowered below temperature Tg the new shape is fixed and locked in as long as the material stays below temperature Tg. Upon reheating the material to a temperature above Tg, the material will return to its original shape. By the use of such SMP material, SMP microtubing can be used as a release actuator for the delivery of embolic coils through catheters into aneurysms, for example. The microtubing can be manufactured in various sizes and the phase change temperature Tg is determinate for an intended temperature target and intended use.

  16. Microfabricated therapeutic actuators

    DOEpatents

    Lee, A.P.; Northrup, M.A.; Ciarlo, D.R.; Krulevitch, P.A.; Benett, W.J.

    1999-06-15

    Microfabricated therapeutic actuators are fabricated using a shape memory polymer (SMP), a polyurethane-based material that undergoes a phase transformation at a specified temperature (Tg). At a temperature above temperature Tg material is soft and can be easily reshaped into another configuration. As the temperature is lowered below temperature Tg the new shape is fixed and locked in as long as the material stays below temperature Tg. Upon reheating the material to a temperature above Tg, the material will return to its original shape. By the use of such SMP material, SMP microtubing can be used as a release actuator for the delivery of embolic coils through catheters into aneurysms, for example. The microtubing can be manufactured in various sizes and the phase change temperature Tg is determinate for an intended temperature target and intended use. 8 figs.

  17. Electrical Actuation Technology Bridging

    NASA Technical Reports Server (NTRS)

    Hammond, Monica (Compiler); Sharkey, John (Compiler)

    1993-01-01

    This document contains the proceedings of the NASA Electrical Actuation Technology Bridging (ELA-TB) Workshop held in Huntsville, Alabama, September 29-October 1, 1992. The workshop was sponsored by the NASA Office of Space Systems Development and Marshall Space Flight Center (MSFC). The workshop addressed key technologies bridging the entire field of electrical actuation including systems methodology, control electronics, power source systems, reliability, maintainability, and vehicle health management with special emphasis on thrust vector control (TVC) applications on NASA launch vehicles. Speakers were drawn primarily from industry with participation from universities and government. In addition, prototype hardware demonstrations were held at the MSFC Propulsion Laboratory each afternoon. Splinter sessions held on the final day afforded the opportunity to discuss key issues and to provide overall recommendations. Presentations are included in this document.

  18. Microfabricated therapeutic actuator mechanisms

    DOEpatents

    Northrup, Milton A.; Ciarlo, Dino R.; Lee, Abraham P.; Krulevitch, Peter A.

    1997-01-01

    Electromechanical microstructures (microgrippers), either integrated circuit (IC) silicon-based or precision machined, to extend and improve the application of catheter-based interventional therapies for the repair of aneurysms in the brain or other interventional clinical therapies. These micromechanisms can be specifically applied to release platinum coils or other materials into bulging portions of the blood vessels also known as aneurysms. The "micro" size of the release mechanism is necessary since the brain vessels are the smallest in the body. Through a catheter more than one meter long, the micromechanism located at one end of the catheter can be manipulated from the other end thereof. The microgripper (micromechanism) of the invention will also find applications in non-medical areas where a remotely actuated microgripper or similar actuator would be useful or where micro-assembling is needed.

  19. Microfabricated therapeutic actuator mechanisms

    DOEpatents

    Northrup, M.A.; Ciarlo, D.R.; Lee, A.P.; Krulevitch, P.A.

    1997-07-08

    Electromechanical microstructures (microgrippers), either integrated circuit (IC) silicon-based or precision machined, to extend and improve the application of catheter-based interventional therapies for the repair of aneurysms in the brain or other interventional clinical therapies. These micromechanisms can be specifically applied to release platinum coils or other materials into bulging portions of the blood vessels also known as aneurysms. The ``micro`` size of the release mechanism is necessary since the brain vessels are the smallest in the body. Through a catheter more than one meter long, the micromechanism located at one end of the catheter can be manipulated from the other end thereof. The microgripper (micromechanism) of the invention will also find applications in non-medical areas where a remotely actuated microgripper or similar actuator would be useful or where micro-assembling is needed. 22 figs.

  20. A Lever for Life: How I Lost 150 Pounds and Learned the Catalytic Power of School Community

    ERIC Educational Resources Information Center

    Ebner, Steven J.

    2011-01-01

    The quotation, attributed to the Greek mathematician Archimedes, about the power of levers to move the world has been quoted many times with slight variations, but usually the point is the same: "With the right lever, one can move the earth." However, the actual quotation attributed to Archimedes comes in the writings of another Greek…

  1. Thermally actuated thermionic switch

    DOEpatents

    Barrus, D.M.; Shires, C.D.

    1982-09-30

    A thermally actuated thermionic switch which responds to an increase of temperature by changing from a high impedance to a low impedance at a predictable temperature set point. The switch has a bistable operation mode switching only on temperature increases. The thermionic material may be a metal which is liquid at the desired operation temperature and held in matrix in a graphite block reservoir, and which changes state (ionizes, for example) so as to be electrically conductive at a desired temperature.

  2. Thermally actuated thermionic switch

    DOEpatents

    Barrus, Donald M.; Shires, Charles D.

    1988-01-01

    A thermally actuated thermionic switch which responds to an increase of temperature by changing from a high impedance to a low impedance at a predictable temperature set point. The switch has a bistable operation mode switching only on temperature increases. The thermionic material may be a metal which is liquid at the desired operation temperature and held in matrix in a graphite block reservoir, and which changes state (ionizes, for example) so as to be electrically conductive at a desired temperature.

  3. Passively actuated valve

    SciTech Connect

    Modro, S. Michael; Ougouag, Abderrafi M.

    2005-09-20

    A passively actuated valve for isolating a high pressure zone from a low pressure zone and discontinuing the isolation when the pressure in the high pressure zone drops below a preset threshold. If the pressure in the high pressure zone drops below the preset threshold, the valve opens and allows flow from the high pressure zone to the low pressure zone. The valve remains open allowing pressure equalization and back-flow should a pressure inversion between the two pressure zone occur.

  4. Shape memory alloy actuator

    DOEpatents

    Varma, Venugopal K.

    2001-01-01

    An actuator for cycling between first and second positions includes a first shaped memory alloy (SMA) leg, a second SMA leg. At least one heating/cooling device is thermally connected to at least one of the legs, each heating/cooling device capable of simultaneously heating one leg while cooling the other leg. The heating/cooling devices can include thermoelectric and/or thermoionic elements.

  5. Dissolution actuated sample container

    DOEpatents

    Nance, Thomas A.; McCoy, Frank T.

    2013-03-26

    A sample collection vial and process of using a vial is provided. The sample collection vial has an opening secured by a dissolvable plug. When dissolved, liquids may enter into the interior of the collection vial passing along one or more edges of a dissolvable blocking member. As the blocking member is dissolved, a spring actuated closure is directed towards the opening of the vial which, when engaged, secures the vial contents against loss or contamination.

  6. Microelectromechanical (MEM) thermal actuator

    DOEpatents

    Garcia, Ernest J.; Fulcher, Clay W. G.

    2012-07-31

    Microelectromechanical (MEM) buckling beam thermal actuators are disclosed wherein the buckling direction of a beam is constrained to a desired direction of actuation, which can be in-plane or out-of-plane with respect to a support substrate. The actuators comprise as-fabricated, linear beams of uniform cross section supported above the substrate by supports which rigidly attach a beam to the substrate. The beams can be heated by methods including the passage of an electrical current through them. The buckling direction of an initially straight beam upon heating and expansion is controlled by incorporating one or more directional constraints attached to the substrate and proximal to the mid-point of the beam. In the event that the beam initially buckles in an undesired direction, deformation of the beam induced by contact with a directional constraint generates an opposing force to re-direct the buckling beam into the desired direction. The displacement and force generated by the movement of the buckling beam can be harnessed to perform useful work, such as closing contacts in an electrical switch.

  7. Single Piezo-Actuator Rotary-Hammering Drill

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Bao, Xiaoqi; Badescu, Mircea; Bar-Cohen, Yoseph

    2011-01-01

    This innovation comprises a compact drill that uses low-axial preload, via vibrations, that fractures the rock under the bit kerf, and rotates the bit to remove the powdered cuttings while augmenting the rock fracture via shear forces. The vibrations fluidize the powered cuttings inside the flutes around the bit, reducing the friction with the auger surface. These combined actions reduce the consumed power and the heating of the drilled medium, helping to preserve the pristine content of the produced samples. The drill consists of an actuator that simultaneously impacts and rotates the bit by applying force and torque via a single piezoelectric stack actuator without the need for a gearbox or lever mechanism. This reduces the development/fabrication cost and complexity. The piezoelectric actuator impacts the surface and generates shear forces, fragmenting the drilled medium directly under the bit kerf by exceeding the tensile and/or shear strength of the struck surface. The percussive impact action of the actuator leads to penetration of the medium by producing a zone of finely crushed rock directly underneath the struck location. This fracturing process is highly enhanced by the shear forces from the rotation and twisting action. To remove the formed cuttings, the bit is constructed with an auger on its internal or external surface. One of the problems with pure hammering is that, as the teeth become embedded in the sample, the drilling efficiency drops unless the teeth are moved away from the specific footprint location. By rotating the teeth, they are moved to areas that were not fragmented, and thus the rock fracturing is enhanced via shear forces. The shear motion creates ripping or chiseling action to produce larger fragments to increase the drilling efficiency, and to reduce the required power. The actuator of the drill consists of a piezoelectric stack that vibrates the horn. The stack is compressed by a bolt between the backing and the horn in order to

  8. A small and fast piezo-actuated legged robot

    NASA Astrophysics Data System (ADS)

    Yumaryanto, Abdul A.; An, Jaebum; Lee, Sangyoon

    2007-04-01

    In this paper we present the development of a small and fast LIPCA-actuated mobile robot. LIPCA (Lightweight Piezoceramic Composite curved Actuator) is a piezo-composite actuator that uses a PZT layer sandwiched between composite materials of carbon/epoxy and glass/epoxy layers to amplify the displacement. Three versions of LIPCA robots have been developed thus far to implement a small and autonomous robot. The design of the first prototype was inspired by a six-legged insect like a cockroach. Its maximum speed is 173 mm/sec with the voltage input of 400 Vpp at 40 Hz frequency. As the result of a slight modification in the design, a faster LIPCA robot was developed. However their structures are not strong enough to carry a load heavier than 20 gram, which can be a major obstacle to implementing autonomous robots. By several changes in the mechanism, the LIPCA-actuated robot has been improved such that it is able to carry a weight as much as 60 gram. For all the prototypes we used two LIPCA strips that are placed oppositely in the middle of the robot body. The LIPCA strips are driven by a square signal function of high AC voltage with the phase difference of 180°. All the experimental results show a possibility of a small and fast walking robot actuated by LIPCA without using any conventional electromagnetic actuator.

  9. Cylindrical Piezoelectric Fiber Composite Actuators

    NASA Technical Reports Server (NTRS)

    Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.

    2008-01-01

    The use of piezoelectric devices has become widespread since Pierre and Jacques Curie discovered the piezoelectric effect in 1880. Examples of current applications of piezoelectric devices include ultrasonic transducers, micro-positioning devices, buzzers, strain sensors, and clocks. The invention of such lightweight, relatively inexpensive piezoceramic-fiber-composite actuators as macro fiber composite (MFC) actuators has made it possible to obtain strains and displacements greater than those that could be generated by prior actuators based on monolithic piezoceramic sheet materials. MFC actuators are flat, flexible actuators designed for bonding to structures to apply or detect strains. Bonding multiple layers of MFC actuators together could increase force capability, but not strain or displacement capability. Cylindrical piezoelectric fiber composite (CPFC) actuators have been invented as alternatives to MFC actuators for applications in which greater forces and/or strains or displacements may be required. In essence, a CPFC actuator is an MFC or other piezoceramic fiber composite actuator fabricated in a cylindrical instead of its conventional flat shape. Cylindrical is used here in the general sense, encompassing shapes that can have circular, elliptical, rectangular or other cross-sectional shapes in the planes perpendicular to their longitudinal axes.

  10. Expanded Lever Rule for Phase Volume Fraction Calculation of High-Strength Low-Alloy Steel in Thermal Simulation

    NASA Astrophysics Data System (ADS)

    Lei, Xuanwei; Huang, Jihua; Chen, Shuhai; Zhao, Xingke

    2016-06-01

    The principle of the lever rule on the dilatation curve and its application to the corresponding differential dilatation curve were introduced in a nonoverlapped two-phase continuous cooling process. The lever rule was further expanded in the case of an overlapped two-phase process. The application of the expanded lever rule was based on the approximate symmetry treatment on the differential dilatation curve, which shows reasonably both on the theoretical calculation and in the experimental results. High-strength low-alloy steels were thermal simulated with Gleeble 3500. The transformed phase volume fractions in different cooling processes were calculated by the expanded lever rule and metallography analysis. The results showed the expanded lever rule could calculate reliable phase volume fractions as metallography analysis.

  11. "Modernisation" and the Role of Policy Levers in the Learning and Skills Sector

    ERIC Educational Resources Information Center

    Steer, Richard; Spours, Ken; Hodgson, Ann; Finlay, Ian; Coffield, Frank; Edward, Sheila; Gregson, Maggie

    2007-01-01

    This paper examines the changing use of policy levers in the English postcompulsory education and training system, often referred to as the learning and skills sector (LSS). Policy steering by governments has increased significantly in recent years, bringing with it the development of new forms of arms-length regulation. In the English context,…

  12. [Equivalent Lever Principle of Ossicular Chain and Amplitude Reduction Effect of Internal Ear Lymph].

    PubMed

    Zhao, Xiaoyan; Qin, Renjia

    2015-04-01

    This paper makes persuasive demonstrations on some problems about the human ear sound transmission principle in existing physiological textbooks and reference books, and puts forward the authors' view to make up for its literature. Exerting the knowledge of lever in physics and the acoustics theory, we come up with an equivalent simplified model of manubrium mallei which is to meet the requirements as the long arm of the lever. We also set up an equivalent simplified model of ossicular chain--a combination of levers of ossicular chain. We disassemble the model into two simple levers, and make full analysis and demonstration on them. Through the calculation and comparison of displacement amplitudes in both external auditory canal air and internal ear lymph, we may draw a conclusion that the key reason, which the sound displacement amplitude is to be decreased to adapt to the endurance limit of the basement membrane, is that the density and sound speed in lymph is much higher than those in the air. PMID:26211249

  13. Haptic Feedback and Students' Learning about Levers: Unraveling the Effect of Simulated Touch

    ERIC Educational Resources Information Center

    Wiebe, Eric N.; Minogue, James; Jones, M. Gail; Cowley, Jennifer; Krebs, Denise

    2009-01-01

    While there has been extensive experimental research on haptics, less has been conducted on cross-modal interactions between visual and haptic perception and even less still on cross-modal applications in instructional settings. This study looks at a simulation on the principles of levers using both visual and haptic feedback: one group received…

  14. Mediation, Translation and Local Ecologies: Understanding the Impact of Policy Levers on FE Colleges

    ERIC Educational Resources Information Center

    Spours, Ken; Coffield, Frank; Gregson, Maggie

    2007-01-01

    This article reports the views of managers and tutors on the role of policy "levers" on teaching, learning, and inclusion in colleges of Further Education (FE) in our research project, "The impact of policy on learning and inclusion in the Learning and Skills Sector (LSS)." Using data from five research visits conducted over two years in eight FE…

  15. Connection Levers: Supports for Building Teachers' Confidence and Commitment to Teach Mathematics and Statistics through Inquiry

    ERIC Educational Resources Information Center

    Makar, Katie

    2007-01-01

    Gaps between teaching practices and research recommendations have been well documented. One challenge for research is in understanding the processes and systems that promote a bridging of these gaps. A year-long study with four primary teachers documented ten support mechanisms, or connection levers, that the teachers raised as important for…

  16. In Vivo Orientation of Single Myosin Lever Arms in Zebrafish Skeletal Muscle

    PubMed Central

    Sun, Xiaojing; Ekker, Stephen C.; Shelden, Eric A.; Takubo, Naoko; Wang, Yihua; Burghardt, Thomas P.

    2014-01-01

    Cardiac and skeletal myosin assembled in the muscle lattice power contraction by transducing ATP free energy into the mechanical work of moving actin. Myosin catalytic/lever-arm domains comprise the transduction/mechanical coupling machinery that move actin by lever-arm rotation. In vivo, myosin is crowded and constrained by the fiber lattice as side chains are mutated and otherwise modified under normal, diseased, or aging conditions that collectively define the native myosin environment. Single-myosin detection uniquely defines bottom-up characterization of myosin functionality. The marriage of in vivo and single-myosin detection to study zebrafish embryo models of human muscle disease is a multiscaled technology that allows one-to-one registration of a selected myosin molecular alteration with muscle filament-sarcomere-cell-fiber-tissue-organ- and organism level phenotypes. In vivo single-myosin lever-arm orientation was observed at superresolution using a photoactivatable-green-fluorescent-protein (PAGFP)-tagged myosin light chain expressed in zebrafish skeletal muscle. By simultaneous observation of multiphoton excitation fluorescence emission and second harmonic generation from myosin, we demonstrated tag specificity for the lever arm. Single-molecule detection used highly inclined parallel beam illumination and was verified by quantized photoactivation and photobleaching. Single-molecule emission patterns from relaxed muscle in vivo provided extensive superresolved dipole orientation constraints that were modeled using docking scenarios generated for the myosin (S1) and GFP crystal structures. The dipole orientation data provided sufficient constraints to estimate S1/GFP coordination. The S1/GFP coordination in vivo is rigid and the lever-arm orientation distribution is well-ordered in relaxed muscle. For comparison, single myosins in relaxed permeabilized porcine papillary muscle fibers indicated slightly differently oriented lever arms and rigid S1

  17. Shoulder Muscular Demand During Lever-Activated Vs Pushrim Wheelchair Propulsion in Persons With Spinal Cord Injury

    PubMed Central

    Requejo, Philip Santos; Lee, Sharon E; Mulroy, Sara J; Haubert, Lisa Lighthall; Bontrager, Ernest L; Gronley, JoAnne K; Perry, Jacquelin

    2008-01-01

    Background/Objective: The high demand on the upper limbs during manual wheelchair (WC) use contributes to a high prevalence of shoulder pathology in people with spinal cord injury (SCI). Lever-activated (LEVER) WCs have been presented as a less demanding alternative mode of manual WC propulsion. The objective of this study was to evaluate the shoulder muscle electromyographic activity and propulsion characteristics in manual WC users with SCI propelling a standard pushrim (ST) and LEVER WC design. Methods: Twenty men with complete injuries (ASIA A or B) and tetraplegia (C6, n = 5; C7, n = 7) or paraplegia (n = 8) secondary to SCI propelled ST and LEVER WCs at 3 propulsion conditions on a stationary ergometer: self-selected free, self-selected fast, and simulated graded resistance. Average velocity, cycle distance, and cadence; median and peak electromyographic intensity; and duration of electromyography of anterior deltoid, pectoralis major, supraspinatus, and infraspinatus muscles were compared between LEVER and ST WC propulsion. Results: Significant decreases in pectoralis major and supraspinatus activity were recorded during LEVER compared with ST WC propulsion. However, anterior deltoid and infraspinatus intensities tended to increase during LEVER WC propulsion. Participants with tetraplegia had similar or greater anterior deltoid, pectoralis major, and infraspinatus activity for both ST and LEVER WC propulsion compared with the men with paraplegia. Conclusions: Use of the LEVER WC reduced and shifted the shoulder muscular demands in individuals with paraplegia and tetraplegia. Further studies are needed to determine the impact of LEVER WC propulsion on long-term shoulder function. PMID:19086715

  18. Dielectric barrier discharge plasma actuator for flow control

    NASA Astrophysics Data System (ADS)

    Opaits, Dmitry Florievich

    Electrohydrodynamic (EHD) and magnetohydrodynamic phenomena are being widely studied for aerodynamic applications. The major effects of these phenomena are heating of the gas, body force generation, and enthalpy addition or extraction, [1, 2, 3]. In particular, asymmetric dielectric barrier discharge (DBD) plasma actuators are known to be effective EHD device in aerodynamic control, [4, 5]. Experiments have demonstrated their effectiveness in separation control, acoustic noise reduction, and other aeronautic applications. In contrast to conventional DBD actuators driven by sinusoidal voltages, we proposed and used a voltage profile consisting of nanosecond pulses superimposed on dc bias voltage. This produces what is essentially a non-self-sustained discharge: the plasma is generated by repetitive short pulses, and the pushing of the gas occurs primarily due to the bias voltage. The advantage of this non-self-sustained discharge is that the parameters of ionizing pulses and the driving bias voltage can be varied independently, which adds flexibility to control and optimization of the actuators performance. Experimental studies were conducted of a flow induced in a quiescent room air by a single DBD actuator. A new approach for non-intrusive diagnostics of plasma actuator induced flows in quiescent gas was proposed, consisting of three elements coupled together: the Schlieren technique, burst mode of plasma actuator operation, and 2-D numerical fluid modeling. During the experiments, it was found that DBD performance is severely limited by surface charge accumulation on the dielectric. Several ways to mitigate the surface charge were found: using a reversing DC bias potential, three-electrode configuration, slightly conductive dielectrics, and semi conductive coatings. Force balance measurements proved the effectiveness of the suggested configurations and advantages of the new voltage profile (pulses+bias) over the traditional sinusoidal one at relatively low

  19. Telescoping cylindrical piezoelectric fiber composite actuator assemblies

    NASA Technical Reports Server (NTRS)

    Allison, Sidney G. (Inventor); Shams, Qamar A. (Inventor); Fox, Robert L. (Inventor); Fox, legal representative, Christopher L. (Inventor); Fox Chattin, legal representative, Melanie L. (Inventor)

    2010-01-01

    A telescoping actuator assembly includes a plurality of cylindrical actuators in a concentric arrangement. Each cylindrical actuator is at least one piezoelectric fiber composite actuator having a plurality of piezoelectric fibers extending parallel to one another and to the concentric arrangement's longitudinal axis. Each cylindrical actuator is coupled to concentrically-adjacent ones of the cylindrical actuators such that the plurality of cylindrical actuators can experience telescopic movement. An electrical energy source coupled to the cylindrical actuators applies actuation energy thereto to generate the telescopic movement.

  20. Cellular Pressure-Actuated Joint

    NASA Technical Reports Server (NTRS)

    McGuire, John R.

    2003-01-01

    A modification of a pressure-actuated joint has been proposed to improve its pressure actuation in such a manner as to reduce the potential for leakage of the pressurizing fluid. The specific joint for which the modification is proposed is a field joint in a reusable solid-fuel rocket motor (RSRM), in which the pressurizing fluid is a mixture of hot combustion gases. The proposed modification could also be applicable to other pressure-actuated joints of similar configuration.

  1. Direct drive field actuator motors

    DOEpatents

    Grahn, A.R.

    1998-03-10

    A positive-drive field actuator motor is described which includes a stator carrying at least one field actuator which changes in dimension responsive to application of an energy field, and at least one drive shoe movable by the dimensional changes of the field actuator to contact and move a rotor element with respect to the stator. Various embodiments of the motor are disclosed, and the rotor element may be moved linearly or arcuately. 62 figs.

  2. Fault-tolerant rotary actuator

    DOEpatents

    Tesar, Delbert

    2006-10-17

    A fault-tolerant actuator module, in a single containment shell, containing two actuator subsystems that are either asymmetrically or symmetrically laid out is provided. Fault tolerance in the actuators of the present invention is achieved by the employment of dual sets of equal resources. Dual resources are integrated into single modules, with each having the external appearance and functionality of a single set of resources.

  3. Direct drive field actuator motors

    DOEpatents

    Grahn, Allen R.

    1998-01-01

    A positive-drive field actuator motor including a stator carrying at least one field actuator which changes in dimension responsive to application of an energy field, and at least one drive shoe movable by the dimensional changes of the field actuator to contact and move a rotor element with respect to the stator. Various embodiments of the motor are disclosed, and the rotor element may be moved linearly or arcuately.

  4. Development of a smart trailing-edge flap actuator with multistage stroke amplifier for a rotor blade

    NASA Astrophysics Data System (ADS)

    Lee, Taeoh; Chopra, Inderjit

    2000-06-01

    The present research experimentally investigates the feasibility of a trailing-edge flap mechanism actuated in a helicopter rotor by piezoelectric stacks in conjunction with a dual-stage mechanical stroke amplifier to actively control vibration. A new mechanical leverage amplification concept was developed to extend the capability of a simple lever-fulcrum stroke amplifier. A refined prototype actuator and flap mechanism were designed and fabricated using five piezostacks. The bench-top test of the actuator showed 73.7 mils of free stroke and uniform displacement output up to a frequency of 150 Hz. Spin testing was performed in the vacuum chamber to evaluate the performance in rotating environment, and the refined prototype actuator showed approximately 13% loss in actuation stroke at 710 g of full-scale centrifugal loading. In the Open-Jet wind tunnel testing to simulate the aerodynamic loading environment, the peak-to-peak flap deflections above 8 degrees for freestream velocity of 120 ft/sec were obtained at different excitation frequencies. It demonstrated the capability of the refined prototype actuator in rotating environment to potentially reduce helicopter vibration.

  5. Compact, Low-Force, Low-Noise Linear Actuator

    NASA Technical Reports Server (NTRS)

    Badescu, Mircea; Sherrit, Stewart; Bar-Cohen, Yoseph

    2012-01-01

    Actuators are critical to all the robotic and manipulation mechanisms that are used in current and future NASA missions, and are also needed for many other industrial, aeronautical, and space activities. There are many types of actuators that were designed to operate as linear or rotary motors, but there is still a need for low-force, low-noise linear actuators for specialized applications, and the disclosed mechanism addresses this need. A simpler implementation of a rotary actuator was developed where the end effector controls the motion of a brush for cleaning a thermal sensor. The mechanism uses a SMA (shape-memory alloy) wire for low force, and low noise. The linear implementation of the actuator incorporates a set of springs and mechanical hard-stops for resetting and fault tolerance to mechanical resistance. The actuator can be designed to work in a pull or push mode, or both. Depending on the volume envelope criteria, the actuator can be configured for scaling its volume down to 4x2x1 cu cm. The actuator design has an inherent fault tolerance to mechanical resistance. The actuator has the flexibility of being designed for both linear and rotary motion. A specific configuration was designed and analyzed where fault-tolerant features have been implemented. In this configuration, an externally applied force larger than the design force does not damage the active components of the actuator. The actuator housing can be configured and produced using cost-effective methods such as injection molding, or alternatively, its components can be mounted directly on a small circuit board. The actuator is driven by a SMA -NiTi as a primary active element, and it requires energy on the order of 20 Ws(J) per cycle. Electrical connections to points A and B are used to apply electrical power in the resistive NiTi wire, causing a phase change that contracts the wire on the order of 5%. The actuation period is of the order of a second for generating the stroke, and 4 to 10

  6. Compact, Low-Force, Low-Noise Linear Actuator

    NASA Technical Reports Server (NTRS)

    Badescu, Mircea; Sherrit, Stewart; Bar-Cohen, Yoseph

    2012-01-01

    Actuators are critical to all the robotic and manipulation mechanisms that are used in current and future NASA missions, and are also needed for many other industrial, aeronautical, and space activities. There are many types of actuators that were designed to operate as linear or rotary motors, but there is still a need for low-force, low-noise linear actuators for specialized applications, and the disclosed mechanism addresses this need. A simpler implementation of a rotary actuator was developed where the end effector controls the motion of a brush for cleaning a thermal sensor. The mechanism uses a SMA (shape-memory alloy) wire for low force, and low noise. The linear implementation of the actuator incorporates a set of springs and mechanical hard-stops for resetting and fault tolerance to mechanical resistance. The actuator can be designed to work in a pull or push mode, or both. Depending on the volume envelope criteria, the actuator can be configured for scaling its volume down to 4 2 1 cm3. The actuator design has an inherent fault tolerance to mechanical resistance. The actuator has the flexibility of being designed for both linear and rotary motion. A specific configuration was designed and analyzed where fault-tolerant features have been implemented. In this configuration, an externally applied force larger than the design force does not damage the active components of the actuator. The actuator housing can be configured and produced using cost-effective methods such as injection molding, or alternatively, its components can be mounted directly on a small circuit board. The actuator is driven by a SMA -NiTi as a primary active element, and it requires energy on the order of 20 Ws(J) per cycle. Electrical connections to points A and B are used to apply electrical power in the resistive NiTi wire, causing a phase change that contracts the wire on the order of 5%. The actuation period is of the order of a second for generating the stroke, and 4 to 10 seconds

  7. Strain actuated aeroelastic control

    NASA Technical Reports Server (NTRS)

    Lazarus, Kenneth B.

    1992-01-01

    Viewgraphs on strain actuated aeroelastic control are presented. Topics covered include: structural and aerodynamic modeling; control law design methodology; system block diagram; adaptive wing test article; bench-top experiments; bench-top disturbance rejection: open and closed loop response; bench-top disturbance rejection: state cost versus control cost; wind tunnel experiments; wind tunnel gust alleviation: open and closed loop response at 60 mph; wind tunnel gust alleviation: state cost versus control cost at 60 mph; wind tunnel command following: open and closed loop error at 60 mph; wind tunnel flutter suppression: open loop flutter speed; and wind tunnel flutter suppression: closed loop state cost curves.

  8. Compact valve actuation mechanism

    NASA Technical Reports Server (NTRS)

    Brogdon, James William (Inventor); Gill, David Keith (Inventor)

    2000-01-01

    A valve actuation device. The device may include a free floating valve bridge movably supported within a cavity in the engine housing. The bridge may be provided with a cavity and an orifice arrangement for pumping gases entrained with lubricating fluid toward the piston stems as the bridge reciprocates back and forth. The device may also include a rocker arm that has a U-shaped cross-sectional shape for receiving at least a portion of the valve bridge, valve stem valve spring and spring retainer therein. The rocker arm may be provided with lubrication passages for directing lubrication to the point wherein it is pivotally affixed to the engine housing.

  9. Lead screw linear actuator

    NASA Technical Reports Server (NTRS)

    Perkins, Gerald S. (Inventor)

    1980-01-01

    A linear actuator which can apply high forces is described, which includes a reciprocating rod having a threaded portion engaged by a nut that is directly coupled to the rotor of an electric motor. The nut is connected to the rotor in a manner that minimizes loading on the rotor, by the use of a coupling that transmits torque to the nut but permits it to shift axially and radially with respect to the rotor. The nut has a threaded hydrostatic bearing for engaging the threaded rod portion, with an oilcarrying groove in the nut being interrupted.

  10. Piezoelectric actuated gimbal

    DOEpatents

    Tschaggeny, Charles W.; Jones, Warren F.; Bamberg, Eberhard

    2011-09-13

    A gimbal is described and which includes a fixed base member defining an axis of rotation; a second member concentrically oriented relative to the axis of rotation; a linear actuator oriented in immediate, adjoining force transmitting relation relative to the base member or to the second member, and which applies force along a linear axis which is tangential to the axis of rotation so as to cause the second member to rotate coaxially relative to the fixed base member; and an object of interest mounted to the second member such that the object of interest is selectively moved relative to the base member about the axis of rotation.

  11. Robotic Arm Actuated by Electroactie Polymers

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Y.; Xue, T.; Shaninpoor, M.; Simpson, J. O.; Smith, J.

    1998-01-01

    Actuators are used for many planetary and space applications. To meet the NASA goal to reduce the actuators size, mass, cost and power consumption, electroactie polymers (EAP) are being developed to induce large bending and longitudinal actuation strains.

  12. Grasp Assist Device with Shared Tendon Actuator Assembly

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Bergelin, Bryan J. (Inventor); Bridgwater, Lyndon (Inventor)

    2015-01-01

    A grasp assist device includes a glove with first and second tendon-driven fingers, a tendon, and a sleeve with a shared tendon actuator assembly. Tendon ends are connected to the respective first and second fingers. The actuator assembly includes a drive assembly having a drive axis and a tendon hook. The tendon hook, which defines an arcuate surface slot, is linearly translatable along the drive axis via the drive assembly, e.g., a servo motor thereof. The flexible tendon is routed through the surface slot such that the surface slot divides the flexible tendon into two portions each terminating in a respective one of the first and second ends. The drive assembly may include a ball screw and nut. An end cap of the actuator assembly may define two channels through which the respective tendon portions pass. The servo motor may be positioned off-axis with respect to the drive axis.

  13. Control of Systems With Slow Actuators Using Time Scale Separation

    NASA Technical Reports Server (NTRS)

    Stepanyan, Vehram; Nguyen, Nhan

    2009-01-01

    This paper addresses the problem of controlling a nonlinear plant with a slow actuator using singular perturbation method. For the known plant-actuator cascaded system the proposed scheme achieves tracking of a given reference model with considerably less control demand than would otherwise result when using conventional design techniques. This is the consequence of excluding the small parameter from the actuator dynamics via time scale separation. The resulting tracking error is within the order of this small parameter. For the unknown system the adaptive counterpart is developed based on the prediction model, which is driven towards the reference model by the control design. It is proven that the prediction model tracks the reference model with an error proportional to the small parameter, while the prediction error converges to zero. The resulting closed-loop system with all prediction models and adaptive laws remains stable. The benefits of the approach are demonstrated in simulation studies and compared to conventional control approaches.

  14. Actuator operated microvalves

    NASA Technical Reports Server (NTRS)

    Okojie, Robert S. (Inventor)

    2008-01-01

    An actuator operated microvalve and the method of making same is disclosed and claimed. The microvalve comprises a SiC housing which includes a first lower portion and a second upper portion. The lower portion of the SiC housing includes a passageway therethrough, a microvalve seat, and a moveable SiC diaphragm. The SiC diaphragm includes a centrally located boss and radially extending corrugations which may be sinusoidally shaped. The boss of the SiC diaphragm moves and modulates in a range of positions between a closed position wherein the boss interengages said microvalve seat prohibiting communication of fluid through the passageway and a fully open position when the boss is spaced apart from the seat at its maximum permitting communication of fluid through said passageway. The actuator includes a SiC top plate affixed to the boss of the diaphragm and a first electrode and the second upper portion of the SiC housing further includes a second electrode.

  15. Actuated Hybrid Mirror Telescope

    NASA Technical Reports Server (NTRS)

    Hickey, Gregory; Redding, David; Lowman, Andrew; Cohen, David; Ohara, Catherine

    2005-01-01

    The figure depicts the planned Actuated Hybrid Mirror Telescope (AHMT), which is intended to demonstrate a new approach to the design and construction of wide-aperture spaceborne telescopes for astronomy and Earth science. This technology is also appropriate for Earth-based telescopes. The new approach can be broadly summarized as using advanced lightweight mirrors that can be manufactured rapidly at relatively low cost. More specifically, it is planned to use precise replicated metallic nanolaminate mirrors to obtain the required high-quality optical finishes. Lightweight, dimensionally stable silicon carbide (SiC) structures will support the nanolaminate mirrors in the required surface figures. To enable diffraction- limited telescope performance, errors in surface figures will be corrected by use of mirror-shape-control actuators that will be energized, as needed, by a wave-front-sensing and control system. The concepts of nanolaminate materials and mirrors made from nanolaminate materials were discussed in several previous NASA Tech Briefs articles. Nanolaminates constitute a relatively new class of materials that can approach theoretical limits of stiffness and strength. Nanolaminate mirrors are synthesized by magnetron sputter deposition of metallic alloys and/or compounds on optically precise master surfaces to obtain optical-quality reflector surfaces backed by thin shell structures. As an integral part of the deposition process, a layer of gold that will constitute the reflective surface layer is deposited first, eliminating the need for a subsequent and separate reflective-coating process. The crystallographic textures of the nanolaminate will be controlled to optimize the performance of the mirror. The entire deposition process for making a nanolaminate mirror takes less than 100 hours, regardless of the mirror diameter. Each nanolaminate mirror will be bonded to its lightweight SiC supporting structure. The lightweight nanolaminate mirrors and Si

  16. Bi-stable optical actuator

    DOEpatents

    Holdener, Fred R.; Boyd, Robert D.

    2000-01-01

    The present invention is a bi-stable optical actuator device that is depowered in both stable positions. A bearing is used to transfer motion and smoothly transition from one state to another. The optical actuator device may be maintained in a stable position either by gravity or a restraining device.

  17. Dynamic properties of a metal photo-thermal micro-actuator.

    PubMed

    Shi, B; Zhang, H J; Wang, B; Yi, F T; Jiang, J Z; Zhang, D X

    2015-02-20

    This work presents the design, modeling, simulation, and characterization of a metal bent-beam photo-thermal micro-actuator. The mechanism of actuation is based on the thermal expansion of the micro-actuator which is irradiated by a laser, achieving noncontact control of the power supply. Models for micro-actuators were established and finite-element simulations were carried out to investigate the effects of various parameters on actuation properties. It is found that the thermal expansion coefficient, thermal conductivity, and the geometry size largely affected actuation behavior whereas heat capacity, density, and Young's modulus did not. Experiments demonstrated the dynamic properties of a Ni micro-actuator fabricated via LIGA technology with 1100/30/100 μm (long/wide/thick) arms. The tip displacement of the micro-actuator could achieve up to 42 μm driven by a laser beam (1064 nm wavelength, 1.2 W power, and a driving frequency of 1 HZ). It is found that the tip displacement decreases with increasing laser driving frequency. For 8 Hz driving frequency, 17 μm (peak-valley value) can be still reached, which is large enough for the application as micro-electro-mechanical systems. Metal photo-thermal micro actuators have advantages such as large displacement, simple structure, and large temperature tolerance, and therefore they will be promising in the fields of micro/nanotechnology. PMID:25968201

  18. Actuator-valve interface optimization

    SciTech Connect

    Burchett, O.L.; Jones, R.L.

    1986-01-01

    A computer code, Actuator Valve Response (AVR), has been developed to optimize the explosive actuator-valve interface parameters so that the valve plunger velocity is at a maximum when the plunger reaches the valve tubes. The code considers three forces to act on the valve plunger before the plunger reaches the valve tubes. These are the pressure force produced by the actuator, the shear force necessary to shear the seal disks on the actuator and the valve plunger, and the friction force caused by friction between the plunger and the plunger bore. The three forces are modeled by expressions that are explicitly functions of the plunger displacement. A particular actuator-valve combination was analyzed with the computer code AVR with four different combinations of valve plunger seal disk shear strength and initial friction force. (LEW)

  19. Electrostatic charge sensor based on a micromachined resonator with dual micro-levers

    NASA Astrophysics Data System (ADS)

    Zhao, Jiuxuan; Ding, Hong; Xie, Jin

    2015-06-01

    This paper describes an electrostatic charge sensor based on a microelectromechanical systems (MEMS) resonator with dual micro-levers to improve sensitivity. The device comprises a double-ended tuning fork resonant element working at out-of-phase mode with a quality factor (Q) of about 4900 under operating pressure of 40 mTorr. The resonant frequency shifts in proportion to an axial force induced by charge additions and then transformed by dual micro-levers with an amplification factor over 8. The measured responsivity is 1.3 × 10 - 3 Hz / fC 2 , which matches well with the results from analytical models and finite element method. The sensitivity of the charge sensor is 21 fC under 4 ppm frequency fluctuation. Additionally, electrostatic spring softening and nonlinear feature of the resonator are also investigated.

  20. Characterizing piezoscanner hysteresis and creep using optical levers and a reference nanopositioning stage

    SciTech Connect

    Xie, H.; Regnier, S.

    2009-04-15

    A method using atomic force microscope (AFM) optical levers and a reference nanopositioning stage has been developed to characterize piezoscanner hysteresis and creep. The piezoscanner is fixed on a closed-loop nanopositioning stage, both of which have the same arrangement on each axis of the three spatial directions inside the AFM-based nanomanipulation system. In order to achieve characterization, the optical lever is used as a displacement sensor to measure the relative movement between the nanopositioning stage and the piezoscanner by lateral tracking a well-defined slope with the tapping mode of the AFM cantilever. This setup can be used to estimate a piezoscanner's voltage input with a reference displacement from the nanopositioning stage. The hysteresis and creep were accurately calibrated by the method presented, which use the current setup of the AFM-based nanomanipulation system without any modification or additional devices.

  1. Coupling of lever arm swing and biased Brownian motion in actomyosin.

    PubMed

    Nie, Qing-Miao; Togashi, Akio; Sasaki, Takeshi N; Takano, Mitsunori; Sasai, Masaki; Terada, Tomoki P

    2014-04-01

    An important unresolved problem associated with actomyosin motors is the role of Brownian motion in the process of force generation. On the basis of structural observations of myosins and actins, the widely held lever-arm hypothesis has been proposed, in which proteins are assumed to show sequential structural changes among observed and hypothesized structures to exert mechanical force. An alternative hypothesis, the Brownian motion hypothesis, has been supported by single-molecule experiments and emphasizes more on the roles of fluctuating protein movement. In this study, we address the long-standing controversy between the lever-arm hypothesis and the Brownian motion hypothesis through in silico observations of an actomyosin system. We study a system composed of myosin II and actin filament by calculating free-energy landscapes of actin-myosin interactions using the molecular dynamics method and by simulating transitions among dynamically changing free-energy landscapes using the Monte Carlo method. The results obtained by this combined multi-scale calculation show that myosin with inorganic phosphate (Pi) and ADP weakly binds to actin and that after releasing Pi and ADP, myosin moves along the actin filament toward the strong-binding site by exhibiting the biased Brownian motion, a behavior consistent with the observed single-molecular behavior of myosin. Conformational flexibility of loops at the actin-interface of myosin and the N-terminus of actin subunit is necessary for the distinct bias in the Brownian motion. Both the 5.5-11 nm displacement due to the biased Brownian motion and the 3-5 nm displacement due to lever-arm swing contribute to the net displacement of myosin. The calculated results further suggest that the recovery stroke of the lever arm plays an important role in enhancing the displacement of myosin through multiple cycles of ATP hydrolysis, suggesting a unified movement mechanism for various members of the myosin family. PMID:24762409

  2. Integration, control, and applications of multifunctional linear actuators

    NASA Astrophysics Data System (ADS)

    Ma, Kougen; Ghasemi-Nejhad, Mehrdad N.

    2008-03-01

    The integration, analysis, control, and application of a linear actuator are investigated. The linear actuator has super-precision, large stroke, and simultaneous precision positioning and vibration suppression capabilities. It is an integration of advanced electro-mechanical technology, smart materials technology, sensing technology, and control technology. Based on the electromechanical technology, a DC-motor driven leading screw ensures the large stroke of motion and coarse positioning. The smart piezoelectric technology makes the fine positioning and vibration suppression over a wide frequency range possible. The advanced control strategy greatly compensates the hysteresis characteristics such as backlash and/or dead zone, and enables the excellent performance of the actuator. Several sensors such as load cells, displacement sensors, and encoders are also integrated for various applications. Controller design and testing of this linear actuator are also conducted. The applications of the linear actuator are also explored in precision positioning and vibration suppression of a flexible manipulator and smart composite platform for thrust vector control of satellites.

  3. A practical multilayered conducting polymer actuator with scalable work output

    NASA Astrophysics Data System (ADS)

    Ikushima, Kimiya; John, Stephen; Yokoyama, Kazuo; Nagamitsu, Sachio

    2009-09-01

    Household assistance robots are expected to become more prominent in the future and will require inherently safe design. Conducting polymer-based artificial muscle actuators are one potential option for achieving this safety, as they are flexible, lightweight and can be driven using low input voltages, unlike electromagnetic motors; however, practical implementation also requires a scalable structure and stability in air. In this paper we propose and practically implement a multilayer conducting polymer actuator which could achieve these targets using polypyrrole film and ionic liquid-soaked separators. The practical work density of a nine-layer multilayer actuator was 1.4 kJ m-3 at 0.5 Hz, when the volumes of the electrolyte and counter electrodes were included, which approaches the performance of mammalian muscle. To achieve air stability, we analyzed the effect of air-stable ionic liquid gels on actuator displacement using finite element simulation and it was found that the majority of strain could be retained when the elastic modulus of the gel was kept below 3 kPa. As a result of this work, we have shown that multilayered conducting polymer actuators are a feasible idea for household robotics, as they provide a substantial practical work density in a compact structure and can be easily scaled as required.

  4. Predicting bite force in mammals: two-dimensional versus three-dimensional lever models.

    PubMed

    Davis, J L; Santana, S E; Dumont, E R; Grosse, I R

    2010-06-01

    Bite force is a measure of whole-organism performance that is often used to investigate the relationships between performance, morphology and fitness. When in vivo measurements of bite force are unavailable, researchers often turn to lever models to predict bite forces. This study demonstrates that bite force predictions based on two-dimensional (2-D) lever models can be improved by including three-dimensional (3-D) geometry and realistic physiological cross-sectional areas derived from dissections. Widely used, the 2-D method does a reasonable job of predicting bite force. However, it does so by over predicting physiological cross-sectional areas for the masseter and pterygoid muscles and under predicting physiological cross-sectional areas for the temporalis muscle. We found that lever models that include the three dimensional structure of the skull and mandible and physiological cross-sectional areas calculated from dissected muscles provide the best predictions of bite force. Models that accurately represent the biting mechanics strengthen our understanding of which variables are functionally relevant and how they are relevant to feeding performance. PMID:20472771

  5. Transparent actuator made with few layer graphene electrode and dielectric elastomer, for variable focus lens

    NASA Astrophysics Data System (ADS)

    Hwang, Taeseon; Kwon, Hyeok-Yong; Oh, Joon-Suk; Hong, Jung-Pyo; Hong, Seung-Chul; Lee, Youngkwan; Ryeol Choi, Hyouk; Jin Kim, Kwang; Hossain Bhuiya, Mainul; Nam, Jae-Do

    2013-07-01

    A transparent dielectric elastomer actuator driven by few-layer-graphene (FLG) electrode was experimentally investigated. The electrodes were made of graphene, which was dispersed in N-methyl-pyrrolidone. The transparent actuator was fabricated from developed FLG electrodes. The FLG electrode with its sheet resistance of 0.45 kΩ/sq (80 nm thick) was implemented to mask silicone elastomer. The developed FLG-driven actuator exhibited an optical transparency of over 57% at a wavenumber of 600 nm and produced bending displacement performance ranging from 29 to 946 μm as functions of frequency and voltage. The focus variation was clearly demonstrated under actuation to study its application-feasibility in variable focus lens and various opto-electro-mechanical devices.

  6. Rontgen's electrode-free elastomer actuators without electromechanical pull-in instability.

    PubMed

    Keplinger, Christoph; Kaltenbrunner, Martin; Arnold, Nikita; Bauer, Siegfried

    2010-03-01

    Electrical actuators made from films of dielectric elastomers coated on both sides with stretchable electrodes may potentially be applied in microrobotics, tactile and haptic interfaces, as well as in adaptive optical elements. Such actuators with compliant electrodes are sensitive to the pull-in electromechanical instability, limiting operational voltages and attainable deformations. Electrode-free actuators driven by sprayed-on electrical charges were first studied by Röntgen in 1880. They withstand much higher voltages and deformations and allow for electrically clamped (charge-controlled) thermodynamic states preventing electromechanical instabilities. The absence of electrodes allows for direct optical monitoring of the actuated elastomer, as well as for designing new 3D actuator configurations and adaptive optical elements. PMID:20173097

  7. Design and driving characteristics of a novel ‘pusher’ type piezoelectric actuator

    NASA Astrophysics Data System (ADS)

    Wang, Shupeng; Zhang, Zhihui; Ren, Luquan; Zhao, Hongwei; Liang, Yunhong; Zhu, Bing

    2016-01-01

    This study proposes a novel ‘pusher’ type piezoelectric actuator based on clamping blocks, where a solid mover can be driven at a high resolution and with a designed stroke of 4 mm. The working principle of the actuator is presented and the design process of its key component ‘stator’ is described. Via finite element simulation, the rationality of the structure of the device was analyzed. The prototype actuator was manufactured and its main performance was tested. The driving characteristics of the proposed actuator produced the following experimental results. The movement resolution was 31.5 nm, the maximum speed was 248 μm s-1 and the maximum loading capacity was 123.5 N, verifying that it could meet the needs of precise positioning with a high resolution and a large load capacity. The actuator was also found to achieve various step speeds when the driving voltage and working frequency were changed.

  8. Nuclear radiation actuated valve

    DOEpatents

    Christiansen, David W.; Schively, Dixon P.

    1985-01-01

    A nuclear radiation actuated valve for a nuclear reactor. The valve has a valve first part (such as a valve rod with piston) and a valve second part (such as a valve tube surrounding the valve rod, with the valve tube having side slots surrounding the piston). Both valve parts have known nuclear radiation swelling characteristics. The valve's first part is positioned to receive nuclear radiation from the nuclear reactor's fuel region. The valve's second part is positioned so that its nuclear radiation induced swelling is different from that of the valve's first part. The valve's second part also is positioned so that the valve's first and second parts create a valve orifice which changes in size due to the different nuclear radiation caused swelling of the valve's first part compared to the valve's second part. The valve may be used in a nuclear reactor's core coolant system.

  9. Pneumatic actuator with hydraulic control

    NASA Astrophysics Data System (ADS)

    Everett, Hobart R., Jr.

    1992-11-01

    The present invention provides a pneumatically powered actuator having hydraulic control for both locking and controlling the velocity of an output rod without any sponginess. The invention includes a double-acting pneumatic actuator having a bore, a piston slidably engaged within the bore, and a control rod connected to the piston. The double-acting pneumatic actuator is mounted to a frame. A first double-acting hydraulic actuator having a bore, a piston slidably engaged within the bore, and a follower rod mounted to the piston is mounted to the frame such that the follower rod is fixedly connected to the control rod. The maximum translation of the piston within the bore of the first double-acting hydraulic actuator provides a volumetric displacement V1. The present invention also includes a second double-acting hydraulic actuator having a bore, a piston slidably engaged within the bore, and an output rod mounted to the piston. The maximum translation of the piston within the bore of the second double-acting hydraulic actuator provides a volumetric displacement V2, where V2=V1. A pair of fluid ports in each of the first and second double-acting hydraulic cylinders are operably connected by fluid conduits, one of which includes a valve circuit which may be used to control the velocity of the output rod or to lock the output rod in a static position by regulating the flow of hydraulic fluid between the double-acting cylinders.

  10. Elliptical modelling of hysteresis operating characteristics in a dielectric elastomer tubular actuator

    NASA Astrophysics Data System (ADS)

    Tian, Pengfei; Jones, Richard W.; Yu, Fei

    2016-07-01

    A dielectric elastomer (DE) tubular actuator, based on compliant metal electrode technology, exhibits hysteresis-like characteristics when driven with a low power rated high voltage power supply (HVPS). This behavior occurs mainly because the DE actuator acts as a capacitive load compromising the ‘slew rate’ of the HVPS during the actuator’s operation. The motivation of this contribution is to investigate the use of elliptical modelling approaches for capturing the hysteresis characteristics exhibited by the DE tubular actuator when it is driven by a low cost low power rated HVPS. The DE tubular actuator considered in this work demonstrates asymmetric hysteresis behaviour due to the nonlinear voltage–strain behaviour of the actuator. A linearization filter placed in series with the actuator (during its operation) ensures a symmetric hysteresis characteristic that can then be modelled using an ellipse-based approach. Elliptical models come in many forms with the two most popular being the constrained general conic form and the general parametric form. Elliptical-based hysteresis model fits are carried out on experimental data obtained from the application of periodic input voltages, at a number of different low-frequencies, to the tubular actuator. The range of frequencies used is related to the possible use of the tubular actuator for attenuating low frequency vibration during DE actuator-based load positioning applications. Constrained conic and general parametric forms of elliptical model are used for modelling the hysteresis characteristics of the DE actuator and rate dependent models developed based on both approaches. The sensitivity of both of these rate dependent models to small inaccuracies in model parameters was then investigated. The general parametric form was found to be more robust in this respect.

  11. Electromechanical actuator for the tongs of a servomanipulator

    DOEpatents

    Martin, H. Lee; Killough, Stephen M.

    1986-01-01

    Computer-augmented electromechanical system is provided for controlling the tongs of a servomanipulator. The mechanical tongs are motor-driven through the remote slave arm of the manipulator, and the motor control current is supplied by a position sensor which senses the position of a spring-loaded trigger in the master arm handle on the manipulator. The actuator for the tongs provides the operator with artificial force reflection in a unilateral force-force control loop.

  12. Electrically controlled polymeric gel actuators

    DOEpatents

    Adolf, Douglas B.; Shahinpoor, Mohsen; Segalman, Daniel J.; Witkowski, Walter R.

    1993-01-01

    Electrically controlled polymeric gel actuators or synthetic muscles capable of undergoing substantial expansion and contraction when subjected to changing pH environments, temperature, or solvent. The actuators employ compliant containers for the gels and their solvents. The gels employed may be cylindrical electromechanical gel fibers such as polyacrylamide fibers or a mixture of poly vinyl alcohol-polyacrylic acid arranged in a parallel aggregate and contained in an electrolytic solvent bath such as salt water. The invention includes smart, electrically activated devices exploiting this phenomenon. These devices are capable of being manipulated via active computer control as large displacement actuators for use in adaptive structure such as robots.

  13. Electrically controlled polymeric gel actuators

    DOEpatents

    Adolf, D.B.; Shahinpoor, M.; Segalman, D.J.; Witkowski, W.R.

    1993-10-05

    Electrically controlled polymeric gel actuators or synthetic muscles are described capable of undergoing substantial expansion and contraction when subjected to changing pH environments, temperature, or solvent. The actuators employ compliant containers for the gels and their solvents. The gels employed may be cylindrical electromechanical gel fibers such as polyacrylamide fibers or a mixture of poly vinyl alcohol-polyacrylic acid arranged in a parallel aggregate and contained in an electrolytic solvent bath such as salt water. The invention includes smart, electrically activated devices exploiting this phenomenon. These devices are capable of being manipulated via active computer control as large displacement actuators for use in adaptive structure such as robots. 11 figures.

  14. Preliminary study, analysis and design for a power switch for digital engine actuators

    NASA Technical Reports Server (NTRS)

    Beattie, E. C.; Zickwolf, H. C., Jr.

    1979-01-01

    Innovative control configurations using high temperature switches to operate actuator driving solenoids were studied. The impact on engine control system life cycle costs and reliability of electronic control and (ECU) heat dissipation due to power conditioning and interface drivers were addressed. Various power supply and actuation schemes were investigated, including optical signal transmission and electronics on the actuator, engine driven alternator, and inside the ECU. The use of a switching shunt power conditioner results in the most significant decrease in heat dissipation within the ECU. No overall control system reliability improvement is projected by the use of remote high temperature switches for solenoid drivers.

  15. Enzyme actuated bioresponsive hydrogels

    NASA Astrophysics Data System (ADS)

    Wilson, Andrew Nolan

    Bioresponsive hydrogels are emerging with technological significance in targeted drug delivery, biosensors and regenerative medicine. Conferred with the ability to respond to specific biologically derived stimuli, the design challenge is in effectively linking the conferred biospecificity with an engineered response tailored to the needs of a particular application. Moreover, the fundamental phenomena governing the response must support an appropriate dynamic range and limit of detection. The design of these systems is inherently complicated due to the high interdependency of the governing phenomena that guide the sensing, transduction, and the actuation response of hydrogels. To investigate the dynamics of these materials, model systems may be used which seek to interrogate the system dynamics by uni-variable experimentation and limit confounding phenomena such as: polymer-solute interactions, polymer swelling dynamics and biomolecular reaction-diffusion concerns. To this end, a model system, alpha-chymotrypsin (Cht) (a protease) and a cleavable peptide-chromogen (pro-drug) covalently incorporated into a hydrogel, was investigated to understand the mechanisms of covalent loading and release by enzymatic cleavage in bio-responsive delivery systems. Using EDC and Sulfo-NHS, terminal carboxyl groups of N-succinyl-Ala-Ala-Pro-Phe p-nitroanilide, a cleavable chromogen, were conjugated to primary amines of a hydrated poly(HEMA)-based hydrogel. Hydrogel discs were incubated in buffered Cht causing enzyme-mediated cleavage of the peptide and concomitant release of the chromophore for monitoring. To investigate substrate loading and the effects of hydrogel morphology on the system, the concentration of the amino groups (5, 10, 20, and 30 mol%) and the cross-linked density (1, 5, 7, 9 and 12 mol%) were independently varied. Loading-Release Efficiency of the chromogen was shown to exhibit a positive relation to increasing amino groups (AEMA). The release rates demonstrated a

  16. Variable Valve Actuation

    SciTech Connect

    Jeffrey Gutterman; A. J. Lasley

    2008-08-31

    Many approaches exist to enable advanced mode, low temperature combustion systems for diesel engines - such as premixed charge compression ignition (PCCI), Homogeneous Charge Compression Ignition (HCCI) or other HCCI-like combustion modes. The fuel properties and the quantity, distribution and temperature profile of air, fuel and residual fraction in the cylinder can have a marked effect on the heat release rate and combustion phasing. Figure 1 shows that a systems approach is required for HCCI-like combustion. While the exact requirements remain unclear (and will vary depending on fuel, engine size and application), some form of substantially variable valve actuation is a likely element in such a system. Variable valve actuation, for both intake and exhaust valve events, is a potent tool for controlling the parameters that are critical to HCCI-like combustion and expanding its operational range. Additionally, VVA can be used to optimize the combustion process as well as exhaust temperatures and impact the after treatment system requirements and its associated cost. Delphi Corporation has major manufacturing and product development and applied R&D expertise in the valve train area. Historical R&D experience includes the development of fully variable electro-hydraulic valve train on research engines as well as several generations of mechanical VVA for gasoline systems. This experience has enabled us to evaluate various implementations and determine the strengths and weaknesses of each. While a fully variable electro-hydraulic valve train system might be the 'ideal' solution technically for maximum flexibility in the timing and control of the valve events, its complexity, associated costs, and high power consumption make its implementation on low cost high volume applications unlikely. Conversely, a simple mechanical system might be a low cost solution but not deliver the flexibility required for HCCI operation. After modeling more than 200 variations of the

  17. Hydraulically actuated well shifting tool

    SciTech Connect

    Roth, B.A.

    1992-10-20

    This patent describes a hydraulically actuated shifting tool for actuating a sliding member in a well tool. It comprises: a housing having a hydraulic fluid bore therein; shifting dog means positioned on the housing for movement away and toward the housing; locking dog means positioned on the housing for movement away and toward the body; shifting dog hydraulic actuating means in fluid communication with the bore for causing engagement of the shifting dogs with the sliding member; locking dog hydraulic actuating means in communication with the bore for causing engagement of the locking dogs with the locking means; and hydraulic shifting means in communication with the bore for causing relative movement between the shifting dog means and the locking dog means for shifting the sliding sleeve.

  18. Firewater system inadvertent actuation frequencies

    SciTech Connect

    Schroeder, J.A.; Eide, S.A.

    1993-04-01

    This paper presents some recommended generic values for fire protection system inadvertent actuation frequencies. The frequencies are based on actual data from Department of Energy and commercial reactor plant facilities.

  19. Firewater system inadvertent actuation frequencies

    SciTech Connect

    Schroeder, J.A. ); Eide, S.A. )

    1993-01-01

    This paper presents some recommended generic values for fire protection system inadvertent actuation frequencies. The frequencies are based on actual data from Department of Energy and commercial reactor plant facilities.

  20. The actuated latch pin and its development

    NASA Technical Reports Server (NTRS)

    Lawlor, P. J.

    1980-01-01

    An actuated latch pin developed to meet the need for a reusable locking device is described. The unit can function as a pin puller or as a pin pusher latch. Initial prototype testing demonstrated the feasibility of the device with the unit being driven from a 28 V dc supply and using 15 W to drive a 12 mm diameter pin through a stroke of 10 mm with a side load of 100 N in 120 ms. High wear rates with a MOS2 lubrication on the ballscrew and angular contact bearings have necessitated the reduction in the duty cycle from 1000 cycles in air and vacuum to 100 in air and 1000 in vacuum.

  1. Stress compensation for arbitrary curvature control in vanadium dioxide phase transition actuators

    NASA Astrophysics Data System (ADS)

    Dong, Kaichen; Lou, Shuai; Choe, Hwan Sung; Liu, Kai; You, Zheng; Yao, Jie; Wu, Junqiao

    2016-07-01

    Due to its thermally driven structural phase transition, vanadium dioxide (VO2) has emerged as a promising material for micro/nano-actuators with superior volumetric work density, actuation amplitude, and repetition frequency. However, the high initial curvature of VO2 actuators severely obstructs the actuation performance and application. Here, we introduce a "seesaw" method of fabricating tri-layer cantilevers to compensate for the residual stress and realize nearly arbitrary curvature control of VO2 actuators. By simply adjusting the thicknesses of the individual layers, cantilevers with positive, zero, or negative curvatures can be engineered. The actuation amplitude can be decoupled from the curvature and controlled independently as well. Based on the experimentally measured residual stresses, we demonstrate sub-micron thick VO2 actuators with nearly zero final curvature and a high actuation amplitude simultaneously. This "seesaw" method can be further extended to the curvature engineering of other microelectromechanical system multi-layer structures where large stress-mismatch between layers are inevitable.

  2. Characterization of synthetic jet actuators used for jet noise reduction by flow control

    NASA Astrophysics Data System (ADS)

    Zelenyak, Alexis; Berger, Zachary; Berry, Matthew; Shea, Patrick; Glauser, Mark

    2013-11-01

    The issue of jet noise introduces various opportunities for advancements in flow control and fluid dynamics. One such method for jet noise reduction involves the use of synthetic jet actuators as shear layer excitation on the flow produced by a fully compressible, turbulent jet. A set of eight zero-net-mass flux actuators are organized around the periphery of the jet in an actuation glove fitting on the nozzle. As some noise reduction has been achieved through the use of this actuation system, further characterization of the system is necessary to fully quantify its capabilities and understand its effect on the flow physics in the shear layer. The synthetic jet actuators are driven by several different frequencies based on the Helmholtz resonance of the cavities, with measurements taken at several locations along the actuator orifice. Velocity profiles are then constructed from the measured response using hot wire anemometry. Such experimental results provide vital insight into the flow field created by the synthetic jet actuator system, allowing for more effective modification to the actuation glove.

  3. Sensors, actuators, and smart materials

    NASA Astrophysics Data System (ADS)

    Troiler-McKinstry, S.; Newnham, R. E.

    1993-04-01

    Electroceramic materials are presently noted to have a wide array of sensing and actuating functions which can be incorporated into smart-material designs. The sensor types extend to temperature, piezoelectricity and piezoresistivity, and the presence of oxygen. Attention is given to the prospects for developing composite smart materials that encompass various sensing and actuating functions; these may ultimately reach a level of complexity and sophistication that may be termed 'biomimetric' in its approximation to the functions of the living tissues of organisms.

  4. Dielectric Elastomers for Actuation and Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Brochu, Paul A.

    The first part of this work focuses on free-standing linear soft silicone actuators as this configuration is the most relevant for real applications. A particular soft silicone has been isolated a good candidate and was extensively tested in a free-standing linear actuator configuration to determine the effects of pre-stretch and the application of mechanical loads on its actuation performance. It is shown that when the mechanical loads are properly applied, large linear actuation strains of 120% and work density of 0.5 J/cm3 can be obtained. Furthermore, we demonstrate that when coupled with single wall carbon nanotube (SWNT) compliant electrodes, fault-tolerance is introduced via self-clearing leading to significantly improved operational reliability. Driven at moderate electric fields, the actuators display relatively high linear actuation strain (25%) without degradation of the electromechanical performance even after 85,000 cycles. The high performance of the aforementioned soft silicone actuators requires the application of rather large levels of prestrain. In order to eliminate this requirement a novel all-silicone prestrain-locked interpenetrating polymer network (S-IPN) elastomer was developed. The elastomer is fabricated using a combination of two silicones: a soft room temperature vulcanizing silicone that serves as the host elastomer matrix, and a more rigid high temperature vulcanizing silicone that acts to preserve the prestrain in the host network. The free-standing prestrain-locked silicones show a more than twofold performance improvement over standard free-standing silicone films, with a linear strain of 25% and an area strain of 45% when tested in a diaphragm configuration. The S-IPN procedure was leveraged to improve electrode adhesion and stability as well as improve the interlayer adhesion in multilayer actuators. It is demonstrated that strongly bonded SWNT electrodes are capable of fault tolerance through self-clearing, even in multilayer

  5. Thermally actuated piston micromirror arrays

    NASA Astrophysics Data System (ADS)

    Cowan, William D.; Bright, Victor M.

    1997-07-01

    This paper reports design and characterization testing of thermally actuated piston micromirror arrays. The micromirrors were fabricated in the DARPA-sponsored MUMPs polysilicon surface micromachining process. The power averaging characteristic of thermal actuation is exploited in a novel line addressing scheme which reduces wiring for an n2 array to 2n wires. Mirror deflections were measured with a microscope laser interferometer system equipped with a vacuum chamber. Data presented includes device uniformity, frequency response, and deflection versus drive power for varied ambient pressure. Initial test results confirm that thermally actuated piston micromirrors offer several advantages over more common electrostatic designs. Thermally actuated micromirrors offer greater deflections at drive voltages compatible with CMOS circuitry. Measured thermal piston micromirror deflection versus drive voltage is nonlinear, but does not exhibit the 'snap through instability' characteristic of electrostatic devices. Operation of thermally actuated devices in rarefied ambient significantly decreases power dissipation. For a given deflection range, the power reduction facilitated by vacuum operation makes large arrays feasible. Frequency response of thermally actuated devices is limited by the ability of the device to dissipate heat, but operation at 1 kHz rates is feasible.

  6. Explosive actuated valve

    DOEpatents

    Byrne, Kenneth G.

    1983-01-01

    1. A device of the character described comprising the combination of a housing having an elongate bore and including a shoulder extending inwardly into said bore, a single elongate movable plunger disposed in said bore including an outwardly extending flange adjacent one end thereof overlying said shoulder, normally open conduit means having an inlet and an outlet perpendicularly piercing said housing intermediate said shoulder and said flange and including an intermediate portion intersecting and normally openly communicating with said bore at said shoulder, normally closed conduit means piercing said housing and intersecting said bore at a location spaced from said normally open conduit means, said elongate plunger including a shearing edge adjacent the other end thereof normally disposed intermediate both of said conduit means and overlying a portion of said normally closed conduit means, a deformable member carried by said plunger intermediate said flange and said shoulder and normally spaced from and overlying the intermediate portion of said normally open conduit means, and means on the housing communicating with the bore to retain an explosive actuator for moving said plunger to force the deformable member against the shoulder and extrude a portion of the deformable member out of said bore into portions of the normally open conduit means for plugging the same and to effect the opening of said normally closed conduit means by the plunger shearing edge substantially concomitantly with the plugging of the normally open conduit means.

  7. Nanotube Nano-actuators

    NASA Astrophysics Data System (ADS)

    Jennifer, Sippel; Arnason, Steve; Baughman, Ray; Rinzler, Andrew

    2002-03-01

    In 1999 it was found that a thin sheet of single wall carbon nanotubes (buckypaper) can act as an electromechanical transducer (an actuator), converting an applied voltage into a dimensional change, with the potential to do work.[1] The mechanism proposed for the effect is quite fundamental, relying on modification of the nearest neighbor carbon-carbon distance due to charge injected into the nanotube pi-orbital system. Because the experiment relied on buckypaper, which possesses nanoscale pores (where gas generation might also account for dimensional changes), as well as creep (where ropes sliding against one another make it difficult to determine the magnitude of the effect in the fundamental unit), the demonstration was less than ideal. Using an atomic force microscope for detection, we have now performed corresponding measurements on individual ropes of nanotubes tethered across micromachined trenches in silicon substrates. The experiment and results will be described. 1. R. H. Baughman, C. X. Cui, A. A. Zakhidov, Z. Iqbal, J. N. Barisci, G. M. Spinks, G. G. Wallace, A. Mazzoldi, D DeRossi, A. G. Rinzler, O. Jaschinski, S. Roth, M. Kertesz, Science, 284, 1340 (1999).

  8. Quick actuating closure

    NASA Technical Reports Server (NTRS)

    White, III, Dorsey E. (Inventor); Updike, deceased, Benjamin T. (Inventor); Allred, Johnny W. (Inventor)

    1989-01-01

    A quick actuating closure for a pressure vessel 80 in which a wedge ring 30 with a conical outer surface 31 is moved forward to force shear blocks 40, with conical inner surfaces 41, radially outward to lock an end closure plug 70 within an opening 81 in the pressure vessel 80. A seal ring 60 and a preload ramp 50 sit between the shear blocks 40 and the end closure plug 70 to provide a backup sealing capability. Conical surfaces 44 and 55 of the preload ramp 50 and the shear blocks 40 interact to force the seal ring 60 into shoulders 73 and 85 in the end closure plug 70 and opening 81 to form a tight seal. The end closure plug 70 is unlocked by moving the wedge ring 30 rearward, which causes T-bars 32 of the wedge ring 30 riding within T -slots 42 of the shear blocks 40 to force them radially inward. The end closure plug 70 is then removed, allowing access to the interior of the pressure vessel 80.

  9. Carbon nanotube array actuators

    NASA Astrophysics Data System (ADS)

    Geier, S.; Mahrholz, T.; Wierach, P.; Sinapius, M.

    2013-09-01

    Experimental investigations of highly vertically aligned carbon nanotubes (CNTs), also known as CNT-arrays, are the main focus of this paper. The free strain as result of an active material behavior is analyzed via a novel experimental setup. Previous test experiences of papers made of randomly oriented CNTs, also called Bucky-papers, reveal comparably low free strain. The anisotropy of aligned CNTs promises better performance. Via synthesis techniques like chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD), highly aligned arrays of multi-walled carbon nanotubes (MWCNTs) are synthesized. Two different types of CNT-arrays are analyzed, morphologically first, and optically tested for their active characteristics afterwards. One type of the analyzed arrays features tube lengths of 750-2000 μm with a large variety of diameters between 20 and 50 nm and a wave-like CNT-shape. The second type features a maximum, almost uniform, length of 12 μm and a constant diameter of 50 nm. Different CNT-lengths and array types are tested due to their active behavior. As result of the presented tests, it is reported that the quality of orientation is the most decisive property for excellent active behavior. Due to their alignment, CNT-arrays feature the opportunity to clarify the actuation mechanism of architectures made of CNTs.

  10. Multiple switch actuator

    DOEpatents

    Beyer, Edward T.

    1976-01-06

    The present invention relates to switches and switch actuating devices to be operated for purposes of arming a bomb or other missile as it is dropped or released from an aircraft. The particular bomb or missile in which this invention is applied is one in which there is a plurality of circuits which are to be armed by the closing of switches upon dropping or releasing of the bomb. The operation of the switches to closed position is normally accomplished by means of a pull-out wire; that is, a wire which is withdrawn from the bomb or missile at the time of release of the bomb, one end of the wire being attached to the aircraft. The conditions to be met are that the arming switches must be positively and surely maintained in open position until the bomb is released and the arming action is effected. The action of the pull-out wire in achieving the arming action must be sure and positive with minimum danger of malfunctioning, jamming or binding.

  11. Single Myosin Cross-Bridge Orientation in Cardiac Papillary Muscle Detects Lever-Arm Shear Strain in Transduction

    PubMed Central

    Burghardt, Thomas P.; Josephson, Matthew P.; Ajtai, Katalin

    2011-01-01

    Myosin motors transduce ATP free energy into mechanical work. Transduction models allocate specific functions to motor structural domains beginning with ATP hydrolysis in the active site and ending in a lever-arm rotating power-stroke. Myosin light chains, regulatory (RLC) and essential (ELC), bind IQ-domains on the lever-arm and track its movement. Strong evidence exists that light chains stabilize the lever-arm and that light chain mutation undermines stability. Human ventricular RLC tagged with photoactivatable GFP (HCRLC-PAGFP) replaces native RLC in porcine papillary muscle fibers, restores native contractility, and situates PAGFP for single molecule orientation tracking within the crowded fiber lattice. The spatial emission pattern from single photoactivated PAGFP tagged myosins was observed in z-stacks fitted simultaneously to maximize accuracy in estimated dipole orientation. Emitter dipole polar and azimuthal angle pair scatter plots identified an area where steric and molecular crowding constraints depopulated orientations unfavorable for actin interaction. Transitions between pre- and post-power-stroke states represent the lever-arm trajectory sampled by the data and quantify lever-arm shear strain in transduction at three tension levels. These data identify forces acting on myosin in the in situ fiber system due to crowding, steric hindrance, and actomyosin interaction. They induce lever-arm shear strain observed with single molecule orientation detection. A single myosin work histogram reveals discretized power-stroke substates reminiscent of the Huxley–Simmons model for myosin based contraction [Huxley and Simmons (1971) Nature 233, 533]. RLC or ELC mutation, should it impact lever-arm shear strain, will be detected as changes in single myosin shear strain or power-stroke substate distribution. PMID:21819137

  12. Sensing cantilever beam bending by the optical lever technique and its application to surface stress.

    PubMed

    Evans, Drew R; Craig, Vincent S J

    2006-03-23

    Cantilever beams, both microscopic and macroscopic, are used as sensors in a great variety of applications. An optical lever system is commonly employed to determine the deflection and thereby the profile of the cantilever under load. The sensitivity of the optical lever must be calibrated, and this is usually achieved by application of a known load or deflection to the free end of the cantilever. When the sensing operation involves a different type of load or a combination of types of loadings, the calibration and the deflection values derived from it become invalid. Here we develop a master equation that permits the true deflection of the cantilever to be obtained simply from the measurement of the apparent deflection for uniformly distributed loadings and end-moment loadings. These loadings are relevant to the uniform adsorption or application of material to the cantilever or the application of a surface stress to the cantilever and should assist experimentalists using the optical lever, such as in the atomic force microscope, to measure cantilever deflections in a great variety of sensing applications. We then apply this treatment to the experimental evaluation of surface stress. Three forms of Stoney's equation that relate the apparent deflection to the surface stress, which is valid for both macroscopic and microscopic experiments, are derived. Analysis of the errors arising from incorrect modeling of the loading conditions of the cantilever currently applied in experiments is also presented. It is shown that the reported literature values for surface stress in microscopic experiments are typically 9% smaller than their true value. For macroscopic experiments, we demonstrate that the added mass of the film or coating generally dominates the measured deflection and must be accounted for accurately if surface stress measurements are to be made. Further, the reported measurements generally use a form of Stoney's equation that is in error, resulting in an

  13. Evolution of levers and linkages in the feeding mechanisms of fishes.

    PubMed

    Westneat, Mark W

    2004-11-01

    The evolution of feeding mechanisms in the ray-finned fishes (Actinopterygii) is a compelling example of transformation in a musculoskeletal complex involving multiple skeletal elements and numerous muscles that power skull motion. Biomechanical models of jaw force and skull kinetics aid our understanding of these complex systems and enable broad comparison of feeding mechanics across taxa. Mechanical models characterize how muscles move skeletal elements by pulling bones around points of rotation in lever mechanisms, or by transmitting force through skeletal elements connected in a linkage. Previous work has focused on the feeding biomechanics of several lineages of fishes, but a broader survey of skull function in the context of quantitative models has not been attempted. This study begins such a survey by examining the diversity of mechanical design of the oral jaws in 35 species of ray-finned fishes with three main objectives: (1) analyze lower jaw lever models in a broad phylogenetic range of taxa, (2) identify the origin and evolutionary patterns of change in the linkage systems that power maxillary rotation and upper jaw protrusion, and (3) analyze patterns of change in feeding design in the context of actinopterygian phylogeny. The mandibular lever is present in virtually all actinopterygians, and the diversity in lower jaw closing force transmission capacity, with mechanical advantage ranging from 0.04 to 0.68, has important functional consequences. A four-bar linkage for maxillary rotation arose in the Amiiformes and persists in various forms in many teleost species. Novel mechanisms for upper jaw protrusion based on this linkage for maxillary rotation have evolved independently at least five times in teleosts. The widespread anterior jaws linkage for jaw protrusion in percomorph fishes arose initially in Zeiformes and subsequently radiated into a wide range of premaxillary protrusion capabilities. PMID:21676723

  14. Displacement response, detection limit, and dynamic range of fiber-optic lever sensors

    NASA Technical Reports Server (NTRS)

    He, Gang; Cuomo, Frank W.

    1991-01-01

    The authors present the evaluation of the displacement response, detection limit, and dynamic range of fiber-optic lever sensors in a general format to establish their dependence on fiber sizes, optoelectronic detector specifications, input power, and other relevant parameters. The formations for the normalized reflected optical power change are derived for the evaluation of the optimal sensor response, the linearity range, and the minimum detectable displacement. The theoretical models are verified by an experiment which determines sensor response, modulation index, reflected optical power change, and linear response range through dynamic measurement. The application of this theoretical model to the study of a fiber-optic microphone for acoustic pressure detection is considered.

  15. Long-Lever-Arm Manipulation Under Anesthesia With Resultant Traumatic Anterior Shoulder Dislocation.

    PubMed

    Roubal, Paul J; Placzek, Jeffrey D

    2016-08-01

    The patient was a 61-year-old woman who underwent long-lever manipulation under anesthesia (MUA) for adhesive capsulitis. Two weeks following MUA, the constellation of clinical findings raised concern for possible adverse outcomes. Radiographs were obtained, as well as subsequent magnetic resonance imaging and computed tomography scans. Images revealed anterior shoulder dislocation with Bankart and Hill-Sachs lesions, and an anterior rotator cuff tear. J Orthop Sports Phys Ther 2016;46(8):707. doi:10.2519/jospt.2016.0412. PMID:27477474

  16. Physical analysis of intravascular low-reation-lever laser irradiation therapy on improving the hemorheologic characteristics

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoran; Lu, Jian; Wang, Yawei; Ni, Xiaowu

    1999-09-01

    Many clinical results showed that intravascular low-reaction- lever laser irradiation therapy (ILLLI) could improve the hemorheologic characteristics. The red blood cell (RBC) aggregation index, the blood viscosity and the erythrocyte sedimentation rate (ESR) were reduced significantly by treatment with ILLLI. In this paper, a physical process is proposed that laser makes the H-bond parted, which would give rise to a decrease in the RBC aggregation index. According to the principle of hemorheologic characteristics, the blood viscosity and the ESR reduce with the decrease in the RBC aggregation index.

  17. Study of hybrid driven micromirrors for 3-D variable optical attenuator applications.

    PubMed

    Koh, Kah How; Soon, Bo Woon; Tsai, Julius Minglin; Danner, Aaron J; Lee, Chengkuo

    2012-09-10

    Aluminium-coated micromirrors driven by electrothermal and electromagnetic actuations have been demonstrated for 3-D variable optical attenuation applications. Three types of attenuation schemes based on electrothermal, electromagnetic and hybrid, i.e. combination of electrothermal and electromagnetic, actuations have been developed. In addition, two different designs have been fabricated and characterized to investigate the effects of the variations made to both the actuators on the optical attenuation performances of the micromirror. Our unique design of using both ET and EM actuators simultaneously to achieve attenuation is the first demonstration of such hybrid driven CMOS compatible MEMS VOA device. PMID:23037278

  18. 3-D Separation Control using Spatially-Compact, Pulsed Actuation

    NASA Astrophysics Data System (ADS)

    Woo, George T. K.; Glezer, Ari

    2013-11-01

    The dynamics of controlled 3-D transitory attachment of stalled flow over a dynamically pitching 2-D airfoil are investigated in wind tunnel experiments. Pulsed actuation is effected over a spanwise fraction of the separated domain on a time scale that is an order of magnitude shorter than the airfoil's characteristic convective time scale using surface-integrated pulsed, combustion-driven actuator jets. The formation, evolution, and advection of vorticity concentrations over the airfoil and in its near wake are computed from high-resolution, phase-locked PIV measurements of the flow field in multiple cross-stream planes. It is shown that transitory attachment spreads toward the outboard, unactuated flow domains and exceeds the spanwise width of the actuation. The attachment is preceded by the formation of 3-D vortical structures that are advected and shed into the near wake. The effect of the actuation on the variation of the lift and pitching moment during the pitching cycle is altered significantly with its phase delay relative to the airfoil's pitching motion and can significantly mitigate the adverse aerodynamic effects of the dynamic stall. Supported by AFOSR.

  19. Electro-active paper for a durable biomimetic actuator

    NASA Astrophysics Data System (ADS)

    Yun, Sung-Ryul; Yun, Gyu Young; Kim, Jung Hwan; Chen, Yi; Kim, Jaehwan

    2009-02-01

    Cellulose electro-active paper (EAPap), known as a smart material, has merits in terms of low voltage operation, light weight, dryness, low power consumption, biodegradability, abundance and low price. Since EAPap requires low power consumption, a remotely driven actuator has been proposed using microwave power transmission. This concept is attractive for many biomimetic systems such as crawling micro-insect robots, flying objects like dragon flies and smart wallpapers. However, the actuation performance of EAPap is sensitive to humidity and degrades with time. Thus, in this paper, a durable EAPap is studied. The fabrication of EAPap is explained and the actuation performance is shown with applied electric field, frequency, humidity level and time. The fabrication process includes dissolving cellulose fibers, eliminating solvent and Li ions with a mixture of deionized water and isopropyl alcohol, washing with water, drying and coating with gold. The morphology of the fabricated EAPap is analyzed by taking scanning electron microscope images and x-ray diffractograms. The actuation performance is tested in terms of bending displacement with frequency, time and humidity level

  20. Mixing Layer Excitation by Dielectric Barrier Discharge Plasma Actuators

    NASA Astrophysics Data System (ADS)

    Ely, Richard; Little, Jesse

    2012-11-01

    The response of a mixing layer with velocity ratio 0.28 to perturbations near the high-speed side (U2=11 m/s, ReL = 0.26 × 106) of its origin from dielectric barrier discharge plasma actuators is studied experimentally. Both alternating current (ac) and nanosecond (ns) pulse driven plasma are investigated in an effort to clarify the mechanisms associated with each technique as well as the more general physics associated with flow control via momentum-based versus thermal actuation. Ac-DBD plasma actuators, which function through electrohydrodynamic effects, are found to generate an increase in mixing layer momentum thickness that is strongly dependent on forcing frequency. Results are qualitatively similar to previous archival literature on the topic employing oscillating flaps. Ns-DBD plasma, which is believed to function through thermal effects, has no measureable influence on the mixing layer profile at similar forcing conditions. In the context of previous archival literature, these results suggest different physical mechanisms govern active control via ac- and ns-DBD plasma actuation and more generally, momentum versus thermal perturbations. Further investigation of these phenomena will be provided through variation of the boundary/mixing layer properties and forcing parameters in the context of spatially and temporally resolved experimental data. Supported by: AFOSR and Raytheon Missile Systems.

  1. Cryogenic actuator for subnanometer positioning

    NASA Astrophysics Data System (ADS)

    Bree, B. v.; Janssen, H.; Paalvast, S.; Albers, R.

    2012-09-01

    This paper discusses the development, realization, and qualification of a positioning actuator concept specifically for cryogenic environments. Originally developed for quantum physics research, the actuator also has many applications in astronomic cryogenic instruments to position optical elements with nanometer level accuracy and stability. Typical applications include the correction of thermally induced position errors of optical components after cooling down from ambient to cryogenic temperatures or sample positioning in microscopes. The actuator is nicknamed the ‘PiezoKnob’ because it is piezo based and it is compatible with the typical manipulator knob often found in standard systems for optical benches, such as linear stages or tip/tilt lens holders. Actuation with high stiffness piezo elements enables the Piezoknob to deliver forces up to 50 Newton which allows relatively stiff guiding mechanisms or large pre-loads. The PiezoKnob has been qualified at 77 Kelvin and was shown to work down to 2 Kelvin. As part of the qualification program, the custom developed driving electronics and set point profile have been fine-tuned, by combing measurements with predictions from a dynamic model, thus maximizing efficiency and minimizing power dissipation. Furthermore, the actuator holds its position without power and thanks to its mechanical layout it is absolutely insensitive to drift of the piezo elements or the driving electronics.

  2. Temperature-memory polymer actuators

    PubMed Central

    Behl, Marc; Kratz, Karl; Noechel, Ulrich; Sauter, Tilman; Lendlein, Andreas

    2013-01-01

    Reading out the temperature-memory of polymers, which is their ability to remember the temperature where they were deformed recently, is thus far unavoidably linked to erasing this memory effect. Here temperature-memory polymer actuators (TMPAs) based on cross-linked copolymer networks exhibiting a broad melting temperature range (ΔTm) are presented, which are capable of a long-term temperature-memory enabling more than 250 cyclic thermally controlled actuations with almost constant performance. The characteristic actuation temperatures Tacts of TMPAs can be adjusted by a purely physical process, guiding a directed crystallization in a temperature range of up to 40 °C by variation of the parameter Tsep in a nearly linear correlation. The temperature Tsep divides ΔTm into an upper Tm range (T > Tsep) forming a reshapeable actuation geometry that determines the skeleton and a lower Tm range (T < Tsep) that enables the temperature-controlled bidirectional actuation by crystallization-induced elongation and melting-induced contraction. The macroscopic bidirectional shape changes in TMPAs could be correlated with changes in the nanostructure of the crystallizable domains as a result of in situ X-ray investigations. Potential applications of TMPAs include heat engines with adjustable rotation rate and active building facades with self-regulating sun protectors. PMID:23836673

  3. The LDCM actuator for vibration suppression

    NASA Technical Reports Server (NTRS)

    Ide, Eric N.; Lindner, Douglas K.

    1988-01-01

    A linear dc motor (LDCM) has been proposed as an actuator for the COFS I mast and the COFS program ground test Mini-Mast. The basic principles of operation of the LDCM as an actuator for vibration suppression in large flexible structures are reviewed. Because of force and stroke limitations, control loops are required to stabilize the actuator, which results in a non-standard actuator-plant configuration. A simulation model that includes LDCM actuator control loops and a finite element model of the Mast is described, with simulation results showing the excitation capability of the actuator.

  4. Pneumatic artificial muscle actuators for compliant robotic manipulators

    NASA Astrophysics Data System (ADS)

    Robinson, Ryan Michael

    Robotic systems are increasingly being utilized in applications that require interaction with humans. In order to enable safe physical human-robot interaction, light weight and compliant manipulation are desirable. These requirements are problematic for many conventional actuation systems, which are often heavy, and typically use high stiffness to achieve high performance, leading to large impact forces upon collision. However, pneumatic artificial muscles (PAMs) are actuators that can satisfy these safety requirements while offering power-to-weight ratios comparable to those of conventional actuators. PAMs are extremely lightweight actuators that produce force in response to pressurization. These muscles demonstrate natural compliance, but have a nonlinear force-contraction profile that complicates modeling and control. This body of research presents solutions to the challenges associated with the implementation of PAMs as actuators in robotic manipulators, particularly with regard to modeling, design, and control. An existing PAM force balance model was modified to incorporate elliptic end geometry and a hyper-elastic constitutive relationship, dramatically improving predictions of PAM behavior at high contraction. Utilizing this improved model, two proof-of-concept PAM-driven manipulators were designed and constructed; design features included parallel placement of actuators and a tendon-link joint design. Genetic algorithm search heuristics were employed to determine an optimal joint geometry; allowing a manipulator to achieve a desired torque profile while minimizing the required PAM pressure. Performance of the manipulators was evaluated in both simulation and experiment employing various linear and nonlinear control strategies. These included output feedback techniques, such as proportional-integral-derivative (PID) and fuzzy logic, a model-based control for computed torque, and more advanced controllers, such as sliding mode, adaptive sliding mode, and

  5. Sensor/Actuator Selection for Gust and Turbulence Control

    NASA Technical Reports Server (NTRS)

    Kincaid, Rex K.

    1998-01-01

    From aircraft fuselages and space stations to vacuum cleaners and automobiles, active control of noise and/or vibration has come of age. Determining the number of active control devices (e.g. actuators) to be placed and where they are to be placed is the prototypical location problem. However, unlike typical location problems, where the customer is readily identified and is actively engaged in the assessment of the performance of the chosen locations, the customers that active control devices serve are not so easily identified and their impact on system performance issues may be unclear. For example, consider the problem of where to locate actuators to attenuate cabin noise in a propeller driven aircraft. Clearly, the ultimate customers are the passengers who will travel in these aircraft. But to decide whether one set of actuator locations is better than another it is unlikely we will ask passengers to fly in the aircraft and fill out a questionnaire about noise levels. Instead a set of sensors (pseudo-customers) are placed and the system performance of the actuators, as measured by these sensors, is recorded. Hence, we have yet another location problem. How many sensors should there be and where should they be located? In many instances collocation of sensors and actuators is the answer but in other instances it is not. A variety of approaches have been taken to address these sensor/actuator location problems. With regard to damping vibrations in truss structures (space station prototypes) it was formulated a new noxious location problem and generated high-quality solutions with a combination of LP-relaxations and heuristic search procedures. Other related efforts are summarized the actuator location problem for a single frequency interior noise control problem was examined for an idealized aircraft cabin. A tabu search procedure was shown to generate better locations for the actuators than a modal decomposition approach. The model was extended to include multi

  6. H∞ filter for flexure deformation and lever arm effect compensation in M/S INS integration

    NASA Astrophysics Data System (ADS)

    Liu, Xixiang; Xu, Xiaosu; Wang, Lihui; Li, Yinyin; Liu, Yiting

    2014-09-01

    On ship, especially on large ship, the flexure deformation between Master (M)/Slave (S) Inertial Navigation System (INS) is a key factor which determines the accuracy of the integrated system of M/S INS. In engineering this flexure deformation will be increased with the added ship size. In the M/S INS integrated system, the attitude error between MINS and SINS cannot really reflect the misalignment angle change of SINS due to the flexure deformation. At the same time, the flexure deformation will bring the change of the lever arm size, which further induces the uncertainty of lever arm velocity, resulting in the velocity matching error. To solve this problem, a H∞ algorithm is proposed, in which the attitude and velocity matching error caused by deformation is considered as measurement noise with limited energy, and measurement noise will be restrained by the robustness of H∞ filter. Based on the classical "attitude plus velocity" matching method, the progress of M/S INS information fusion is simulated and compared by using three kinds of schemes, which are known and unknown flexure deformation with standard Kalman filter, and unknown flexure deformation with H∞ filter, respectively. Simulation results indicate that H∞ filter can effectively improve the accuracy of information fusion when flexure deformation is unknown but non-ignorable

  7. Time of supplemental feeding alters the effects of cocaine on lever pressing of rats.

    PubMed

    Ross, Linda; Schaal, David W

    2002-03-01

    The present experiment assessed the effects of cocaine on the lever pressing of 4 rats maintained during 15-min sessions by a fixed-ratio 50 schedule of food reinforcement. Across phases, supplemental food was provided either immediately or 2 hr after sessions. Two rats began the experiment in the delayed-feeding condition, and 2 began the experiment in the immediate-feeding condition. Rates of lever pressing of 2 rats sometimes decreased to low levels near the ends of sessions when supplemental feeding was provided immediately, but were consistently high throughout sessions when supplemental feeding was delayed. Cocaine (1.0 to 17.0 or 30.0 mg/kg) was administered intraperitoneally 15 min prior to test sessions. In most cases, cocaine suppressed response rates at lower doses under immediate-feeding conditions. Decreases in overall response rates were correlated with dosedependent increases in the time rats spent not responding. It is suggested that delaying the time of postsession feeding increased response strength, as indicated by greater resistance to the rate-suppressive effects of cocaine. PMID:11936252

  8. Two Essential Light Chains Regulate the MyoA Lever Arm To Promote Toxoplasma Gliding Motility

    PubMed Central

    Williams, Melanie J.; Alonso, Hernan; Enciso, Marta; Egarter, Saskia; Sheiner, Lilach; Meissner, Markus; Striepen, Boris; Smith, Brian J.

    2015-01-01

    ABSTRACT Key to the virulence of apicomplexan parasites is their ability to move through tissue and to invade and egress from host cells. Apicomplexan motility requires the activity of the glideosome, a multicomponent molecular motor composed of a type XIV myosin, MyoA. Here we identify a novel glideosome component, essential light chain 2 (ELC2), and functionally characterize the two essential light chains (ELC1 and ELC2) of MyoA in Toxoplasma. We show that these proteins are functionally redundant but are important for invasion, egress, and motility. Molecular simulations of the MyoA lever arm identify a role for Ca2+ in promoting intermolecular contacts between the ELCs and the adjacent MLC1 light chain to stabilize this domain. Using point mutations predicted to ablate either the interaction with Ca2+ or the interface between the two light chains, we demonstrate their contribution to the quality, displacement, and speed of gliding Toxoplasma parasites. Our work therefore delineates the importance of the MyoA lever arm and highlights a mechanism by which this domain could be stabilized in order to promote invasion, egress, and gliding motility in apicomplexan parasites. PMID:26374117

  9. Band stop vibration suppression using a passive X-shape structured lever-type isolation system

    NASA Astrophysics Data System (ADS)

    Liu, Chunchuan; Jing, Xingjian; Chen, Zhaobo

    2016-02-01

    In the paper, band-stop vibration suppression property using a novel X-shape structured lever-type isolation system is studied. The geometrical nonlinear property of an X-shape supporting structure is used to improve the band-stop characteristics in the low frequency range of the lever-type vibration isolator. With the dynamics modeling of this hybrid structural system, it is shown that the proposed hybrid vibration system has very beneficial nonlinear stiffness and damping properties which are helpful to achieve much wider stop bandwidth. Theoretical results demonstrate that the anti-resonant frequencies, width and magnitude of the stop band can all be flexibly designed with structural parameters, and the parameters of the X-shape supporting structure are very critical for designing the band-stop frequency to achieve excellent low-frequency isolation performance. The results in the study provide a new approach to the design of the passive vibration suppression system in the low frequency region.

  10. Visualizing key hinges and a potential major source of compliance in the lever arm of myosin

    SciTech Connect

    Brown, J.H.; Robinson, H.; Senthil Kumar, V. S.; O'Neall-Hennessey, E.; Reshetnikova, L.; Nguyen-McCarty, M.; Szent-Gyorgyi, A. G.; Cohen, C.

    2011-01-04

    We have determined the 2.3-{angstrom}-resolution crystal structure of a myosin light chain domain, corresponding to one type found in sea scallop catch ('smooth') muscle. This structure reveals hinges that may function in the 'on' and 'off' states of myosin. The molecule adopts two different conformations about the heavy chain 'hook' and regulatory light chain (RLC) helix D. This conformational change results in extended and compressed forms of the lever arm whose lengths differ by 10 {angstrom}. The heavy chain hook and RLC helix D hinges could thus serve as a potential major and localized source of cross-bridge compliance during the contractile cycle. In addition, in one of the molecules of the crystal, part of the RLC N-terminal extension is seen in atomic detail and forms a one-turn alpha-helix that interacts with RLC helix D. This extension, whose sequence is highly variable in different myosins, may thus modulate the flexibility of the lever arm. Moreover, the relative proximity of the phosphorylation site to the helix D hinge suggests a potential role for conformational changes about this hinge in the transition between the on and off states of regulated myosins.

  11. Visualizing Key Hinges and a Potential Major Source of Compliance in the Lever Arm of Myosin

    SciTech Connect

    J Brown; V Senthil Kumar; E ONeall-Hennessey; L Reshetnikova; H Robinson; M Nguyen-McCarty; A Szent-Gyorgyi; C Cohen

    2011-12-31

    We have determined the 2.3-{angstrom}-resolution crystal structure of a myosin light chain domain, corresponding to one type found in sea scallop catch ('smooth') muscle. This structure reveals hinges that may function in the 'on' and 'off' states of myosin. The molecule adopts two different conformations about the heavy chain 'hook' and regulatory light chain (RLC) helix D. This conformational change results in extended and compressed forms of the lever arm whose lengths differ by 10 {angstrom}. The heavy chain hook and RLC helix D hinges could thus serve as a potential major and localized source of cross-bridge compliance during the contractile cycle. In addition, in one of the molecules of the crystal, part of the RLC N-terminal extension is seen in atomic detail and forms a one-turn alpha-helix that interacts with RLC helix D. This extension, whose sequence is highly variable in different myosins, may thus modulate the flexibility of the lever arm. Moreover, the relative proximity of the phosphorylation site to the helix D hinge suggests a potential role for conformational changes about this hinge in the transition between the on and off states of regulated myosins.

  12. Electromechanical propellant control system actuator

    NASA Technical Reports Server (NTRS)

    Myers, W. Neill; Weir, Rae Ann

    1990-01-01

    New control mechanism technologies are currently being sought to provide alternatives to hydraulic actuation systems. The Propulsion Laboratory at Marshall Space Flight Center (MSFC) is involved in the development of electromechanical actuators (EMA's) for this purpose. Through this effort, an in-house designed electromechanical propellant valve actuator has been assembled and is presently being evaluated. This evaluation will allow performance comparisons between EMA and hydraulics systems. The in-house design consists of the following hardware: a three-phase brushless motor, a harmonic drive, and an output spline which will mate with current Space Shuttle Main Engine (SSME) propellant control valves. A resolver and associated electronics supply position feedback for the EMA. System control is provided by a solid-state electronic controller and power supply. Frequency response testing has been performed with further testing planned as hardware and test facilities become available.

  13. A Parylene Bellows Electrochemical Actuator

    PubMed Central

    Li, Po-Ying; Sheybani, Roya; Gutierrez, Christian A.; Kuo, Jonathan T. W.; Meng, Ellis

    2011-01-01

    We present the first electrochemical actuator with Parylene bellows for large-deflection operation. The bellows diaphragm was fabricated using a polyethylene-glycol-based sacrificial molding technique followed by coating in Parylene C. Bellows were mechanically characterized and integrated with a pair of interdigitated electrodes to form an electrochemical actuator that is suitable for low-power pumping of fluids. Pump performance (gas generation rate and pump efficiency) was optimized through a careful examination of geometrical factors. Overall, a maximum pump efficiency of 90% was achieved in the case of electroplated electrodes, and a deflection of over 1.5 mm was demonstrated. Real-time wireless operation was achieved. The complete fabrication process and the materials used in this actuator are bio-compatible, which makes it suitable for biological and medical applications. PMID:21318081

  14. Self-actuated, self-sensing cantilever for fast CD measurement

    NASA Astrophysics Data System (ADS)

    Ahmad, Ahmad; Ivanov, Tzvetan; Reum, Alexander; Guliyev, Elshad; Angelov, Tihomir; Schuh, Andreas; Kaestner, Marcus; Atanasov, Ivaylo; Hofer, Manuel; Holz, Mathias; Rangelow, Ivo W.

    2015-03-01

    The conventional optical lever detection technique involves optical components and its precise mechanical alignment. An additional technical limit is the weight of the optical system, in case a top-scanner is used in high speed and high precision metrology. An alternative represents the application of self-actuated AFM cantilevers with integrated 2DEG piezoresistive deflection sensors. A significant improvement in performance of such cantilevers with respect to deflection sensitivity and temperature stability has been achieved by using an integrated Wheatstone bridge configuration. Due to employing effective cross-talk isolation and temperature drift compensation the performance of these cantilevers was significantly improved. In order to enhance the speed of AFM measurements we are presenting a fast cantilever-approach technology, Q-factor-control and novel adaptive scanning speed procedure. Examples of AFM measurements with high scanning speed (up to 200 lines/s) committed to advanced lithography process development are shown.

  15. Electrostatically actuatable light modulating device

    DOEpatents

    Koehler, Dale R.

    1991-01-01

    The electrostatically actuatable light modulator utilizes an opaque substrate plate patterned with an array of aperture cells, the cells comprised of physically positionable dielectric shutters and electrostatic actuators. With incorporation of a light source and a viewing screen, a projection display system is effected. Inclusion of a color filter array aligned with the aperture cells accomplishes a color display. The system is realized in terms of a silicon based manufacturing technology allowing fabrication of a high resolution capability in a physically small device which with the utilization of included magnification optics allows both large and small projection displays.

  16. Transparent actuators and robots based on single-layer superaligned carbon nanotube sheet and polymer composites.

    PubMed

    Chen, Luzhuo; Weng, Mingcen; Zhang, Wei; Zhou, Zhiwei; Zhou, Yi; Xia, Dan; Li, Jiaxin; Huang, Zhigao; Liu, Changhong; Fan, Shoushan

    2016-03-28

    Transparent actuators have been attracting emerging interest recently, as they demonstrate potential applications in the fields of invisible robots, tactical displays, variable-focus lenses, and flexible cellular phones. However, previous technologies did not simultaneously realize macroscopic transparent actuators with advantages of large-shape deformation, low-voltage-driven actuation and fast fabrication. Here, we develop a fast approach to fabricate a high-performance transparent actuator based on single-layer superaligned carbon nanotube sheet and polymer composites. Various advantages of single-layer nanotube sheets including high transparency, considerable conductivity, and ultra-thin dimensions together with selected polymer materials completely realize all the above required advantages. Also, this is the first time that a single-layer nanotube sheet has been used to fabricate actuators with high transparency, avoiding the structural damage to the single-layer nanotube sheet. The transparent actuator shows a transmittance of 72% at the wavelength of 550 nm and bends remarkably with a curvature of 0.41 cm(-1) under a DC voltage for 5 s, demonstrating a significant advance in technological performances compared to previous conventional actuators. To illustrate their great potential usage, a transparent wiper and a humanoid robot "hand" were elaborately designed and fabricated, which initiate a new direction in the development of high-performance invisible robotics and other intelligent applications with transparency. PMID:26959343

  17. Actuation properties of electrochemically driven polypyrrole free-standing films

    SciTech Connect

    Chiarelli, P.; De Rossi, D. |; Della Santa, A.; Mazzoldi, A.

    1994-12-31

    In this paper the authors report about investigations on coupled electrochemomechanical phenomena in polypyrrole (PPy) free-standing films. Quantitative measurements of isotonic length and relaxed elastic modulus changes are performed on PPy samples during cyclic voltammetry and square-wave amperometry. The link between dimensional and mechanical changes in the samples and doping salt exchange kinetics is investigated and a possible interpretation is proposed.

  18. SPRING DRIVEN ACTUATING MECHANISM FOR NUCLEAR REACTOR CONTROL

    DOEpatents

    Bevilacqua, F.; Uecker, D.F.; Groh, E.F.

    1962-01-23

    l962. rod in a nuclear reactor to shut it down. The control rod or an extension thereof is wound on a drum as it is withdrawn from the reactor. When an emergency occurs requiring the reactor to be shut down, the drum is released so as to be free to rotate, and the tendency of the control rod or its extension coiled on the drum to straighten itself is used for quickly returning the control rod to the reactor. (AEC)

  19. Large-Deformation Curling Actuators Based on Carbon Nanotube Composite: Advanced-Structure Design and Biomimetic Application.

    PubMed

    Chen, Luzhuo; Weng, Mingcen; Zhou, Zhiwei; Zhou, Yi; Zhang, Lingling; Li, Jiaxin; Huang, Zhigao; Zhang, Wei; Liu, Changhong; Fan, Shoushan

    2015-12-22

    In recent years, electroactive polymers have been developed as actuator materials. As an important branch of electroactive polymers, electrothermal actuators (ETAs) demonstrate potential applications in the fields of artificial muscles, biomimetic devices, robotics, and so on. Large-shape deformation, low-voltage-driven actuation, and ultrafast fabrication are critical to the development of ETA. However, a simultaneous optimization of all of these advantages has not been realized yet. Practical biomimetic applications are also rare. In this work, we introduce an ultrafast approach to fabricate a curling actuator based on a newly designed carbon nanotube and polymer composite, which completely realizes all of the above required advantages. The actuator shows an ultralarge curling actuation with a curvature greater than 1.0 cm(-1) and bending angle larger than 360°, even curling into a tubular structure. The driving voltage is down to a low voltage of 5 V. The remarkable actuation is attributed not only to the mismatch in the coefficients of thermal expansion but also to the mechanical property changes of materials during temperature change. We also construct an S-shape actuator to show the possibility of building advanced-structure actuators. A weightlifting walking robot is further designed that exhibits a fast-moving motion while lifting a sample heavier than itself, demonstrating promising biomimetic applications. PMID:26512734

  20. Miniature linear-to-rotary motion actuator

    NASA Technical Reports Server (NTRS)

    Sorokach, Michael R., Jr.

    1993-01-01

    A miniature hydraulic actuation system capable of converting linear actuator motion to control surface rotary motion has been designed for application to active controls on dynamic wind tunnel models. Due to space constraints and the torque requirements of an oscillating control surface at frequencies up to 50 Hertz, a new actuation system was developed to meet research objectives. This new actuation system was designed and developed to overcome the output torque limitations and fluid loss/sealing difficulties associated with an existing vane type actuator. Static control surface deflections and dynamic control surface oscillations through a given angle are provided by the actuation system. The actuator design has been incorporated into a transonic flutter model with an active trailing edge flap and two active spoilers. The model is scheduled for testing in the LaRC 16 Foot Transonic Dynamics Tunnel during Summer 1993. This paper will discuss the actuation system, its design, development difficulties, test results, and application to aerospace vehicles.

  1. New electrode materials for dielectric elastomer actuators

    NASA Astrophysics Data System (ADS)

    Yuan, Wei; Lam, Tuling; Biggs, James; Hu, Liangbing; Yu, Zhibin; Ha, Soonmok; Xi, Dongjuan; Senesky, Matthew K.; Grüner, George; Pei, Qibing

    2007-04-01

    Dielectric elastomer actuators exert strain due to an applied electric field. With advantageous properties such as high efficiency and their light weight, these actuators are attractive for a variety of applications ranging from biomimetic robots, medical prosthetics to conventional pumps and valves. The performance and reliability however, are limited by dielectric breakdown which occurs primarily from localized defects inherently present in the polymer film during actuation. These defects lead to electric arcing, causing a short circuit that shuts down the entire actuator and can lead to actuator failure at fields significantly lower than the intrinsic strength of the material. This limitation is particularly a problem in actuators using large-area films. Our recent studies have shown that the gap between the strength of the intrinsic material and the strength of large-area actuators can be reduced by electrically isolating defects in the dielectric film. As a result, the performance and reliability of dielectric elastomers actuators can be substantially improved.

  2. Electrodynamic actuators for rocket engine valves

    NASA Technical Reports Server (NTRS)

    Fiet, O.; Doshi, D.

    1972-01-01

    Actuators, employed in acoustic loudspeakers, operate liquid rocket engine valves by replacing light paper cones with flexible metal diaphragms. Comparative analysis indicates better response time than solenoid actuators, and improved service life and reliability.

  3. Flight Control System Design with Rate Saturating Actuators

    NASA Technical Reports Server (NTRS)

    Hess, R. A.; Snell, S. A.

    1997-01-01

    Actuator rate saturation is an important factor adversely affecting the stability and performance of aircraft flight control systems. It has been identified as a catalyst in pilot-induced oscillations, some of which have been catastrophic. A simple design technique is described that utilizes software rate limiters to improve the performance of control systems operating in the presence of actuator rate saturation. As described, the technique requires control effectors to be ganged such that any effector is driven by only a single compensated error signal. Using an analysis of the steady-state behavior of the system, requirements are placed upon the type of the loop transmissions and compensators in the proposed technique. Application of the technique to the design of a multi-input/multi-output, lateral-directional control system for a simple model of a high-performance fighter is demonstrated as are the stability and performance improvements that can accrue with the technique.

  4. Underwater propulsion of an internally actuated elastic plate

    NASA Astrophysics Data System (ADS)

    Yeh, Peter; Cen, Lejun; Erturk, Alper; Alexeev, Alexander

    2013-03-01

    Combining experiments and numerical simulations we examine underwater locomotion of an active (internally powered) flexible bimorph composite. We use Macro-Fiber Composite (MFC) piezoelectric laminates that are actuated by a sinusoidally varying voltage generating thrust similar to that of a flapping fin in carangiform motion. In our fully-coupled three dimensional simulations, we model this MFC bimorph fin as a thin, elastic plate that is actuated by a time-varying internal moment producing periodic fin bending and oscillations. The steady state swim velocity and thrust are experimentally measured and compared to the theoretical predictions. Our simulations provide detailed information about the flow structures around the swimming fin and show how they affect the forward motion. The results are useful for designing self-propelling fish-like robots driven by internally powered fins.

  5. Distributed structural control using multilayered piezoelectric actuators

    NASA Technical Reports Server (NTRS)

    Cudney, Harley H.; Inman, Daniel J.; Oshman, Yaakov

    1990-01-01

    A method of segmenting piezoelectric sensors and actuators is proposed which can preclude the currently experienced cancelation of sensor signals, or the reduction of actuator effectiveness, due to the integration of the property undergoing measurement or control. The segmentation method is demonstrated by a model developed for beam structures, to which multiple layers of piezoelectric materials are attached. A numerical study is undertaken of increasing active and passive damping of a beam using the segmented sensors and actuators over unsegmented sensors and actuators.

  6. Piezoelectric Actuators On A Cold Finger

    NASA Technical Reports Server (NTRS)

    Kuo, Chin-Po; Garba, John A.; Glaser, Robert J.

    1995-01-01

    Developmental system for active suppression of vibrations of cold finger includes three piezoelectric actuators bonded to outer surface. Actuators used to suppress longitudinal and lateral vibrations of upper end of cold finger by applying opposing vibrations. Cold finger in question is part of a cryogenic system associated with an infrared imaging detector. When fully developed, system would be feedback sensor/control/actuator system automatically adapting to changing vibrational environment and suppresses pressure-induced vibrations by imposing compensatory vibrations via actuators.

  7. Dielectric Barrier Discharge Plasma Actuator for Flow Control

    NASA Technical Reports Server (NTRS)

    Opaits, Dmitry, F.

    2012-01-01

    This report is Part II of the final report of NASA Cooperative Agreement contract no. NNX07AC02A. It includes a Ph.D. dissertation. The period of performance was January 1, 2007 to December 31, 2010. Part I of the final report is the overview published as NASA/CR-2012- 217654. Asymmetric dielectric barrier discharge (DBD) plasma actuators driven by nanosecond pulses superimposed on dc bias voltage are studied experimentally. This produces non-self-sustained discharge: the plasma is generated by repetitive short pulses, and the pushing of the gas occurs primarily due to the bias voltage. The parameters of ionizing pulses and the driving bias voltage can be varied independently, which adds flexibility to control and optimization of the actuators performance. The approach consisted of three elements coupled together: the Schlieren technique, burst mode of plasma actuator operation, and 2-D numerical fluid modeling. During the experiments, it was found that DBD performance is severely limited by surface charge accumulation on the dielectric. Several ways to mitigate the surface charge were found: using a reversing DC bias potential, three-electrode configuration, slightly conductive dielectrics, and semi conductive coatings. Force balance measurements proved the effectiveness of the suggested configurations and advantages of the new voltage profile (pulses+bias) over the traditional sinusoidal one at relatively low voltages. In view of practical applications certain questions have been also addressed, such as electrodynamic effects which accompany scaling of the actuators to real size models, and environmental effects of ozone production by the plasma actuators.

  8. Inflated Soft Actuators with Reversible Stable Deformations.

    PubMed

    Hines, Lindsey; Petersen, Kirstin; Sitti, Metin

    2016-05-01

    Most soft robotic systems are currently dependent on bulky compressors or pumps. A soft actuation method is presented combining hyperelastic membranes and dielectric elastomer actuators to switch between stable deformations of sealed chambers. This method is capable of large repeatable deformations, and has a number of stable states proportional to the number of actuatable membranes in the chamber. PMID:27008455

  9. Carbon nanotube-polymer composite actuators

    DOEpatents

    Gennett, Thomas; Raffaelle, Ryne P.; Landi, Brian J.; Heben, Michael J.

    2008-04-22

    The present invention discloses a carbon nanotube (SWNT)-polymer composite actuator and method to make such actuator. A series of uniform composites was prepared by dispersing purified single wall nanotubes with varying weight percents into a polymer matrix, followed by solution casting. The resulting nanotube-polymer composite was then successfully used to form a nanotube polymer actuator.

  10. Shape memory actuated release devices

    NASA Astrophysics Data System (ADS)

    Carpenter, Bernie F.; Clark, Cary R.; Weems, Weyman

    1996-05-01

    Spacecraft require a variety of separation and release devices to accomplish mission related functions. Current off-the-shelf devices such as pyrotechnics, gas-discharge systems, paraffin wax actuators, and other electro-mechanical devices may not be able to meet future design needs. The use of pyrotechnics on advanced lightweight spacecraft, for example, will expose fragile sensors and electronics to high shock levels and sensitive optics might be subject to contamination. Other areas of consideration include reliability, safety, and cost reduction. Shape memory alloys (SMA) are one class of actuator material that provides a solution to these design problems. SMA's utilize a thermally activated reversible phase transformation to recover their original heat treated shape (up to 8% strain) or to generate high recovery stresses (> 700 Mpa) when heated above a critical transition temperature. NiTiCu alloy actuators have been fabricated to provide synchronized, shockless separation within release mechanisms. In addition, a shape memory damper has been incorporated to absorb the elastic energy of the preload bolt and to electrically reset the device during ground testing. Direct resistive heating of the SMA actuators was accomplished using a programmable electric control system. Release times less than 40 msec have been determined using 90 watt-sec of power. Accelerometer data indicate less than 500 g's of shock were generated using a bolt preload of 1350 kgs.

  11. Electro-active paper actuators

    NASA Astrophysics Data System (ADS)

    Kim, Jaehwan; Seo, Yung B.

    2002-06-01

    In this paper, the actuation mechanism of electro-active paper (EAPap) actuators is addressed and the potential of the actuators is demonstrated. EAPap is a paper that produces large displacement with small force under an electrical excitation. EAPap is made with a chemically treated paper by constructing thin electrodes on both sides of the paper. When electrical voltage is applied on the electrodes the EAPap produces bending displacement. However, the displacement output has been unstable and degraded with timescale. To improve the bending performance of EAPap, different paper fibers - softwood, hardwood, bacteria cellulose, cellophane, carbon mixture paper, electrolyte containing paper and Korean traditional paper, in conjunction with additive chemicals, were tested. Two attempts were made to construct the electrodes: the direct use of aluminum foil and the gold sputtering technique. It was found that a cellophane paper exhibits a remarkable bending performance. When 2 MV m-1 excitation voltage was applied to the paper actuator, more than 3 mm tip displacement was observed from the 30 mm long paper beam. This is quite a low excitation voltage compared with that of other EAPs. Details of the experiments and results are addressed.

  12. Status of Electrical Actuator Applications

    NASA Technical Reports Server (NTRS)

    Roth, Mary Ellen; Taylor, Linda M.; Hansen, Irving G.

    1996-01-01

    An ever increasing number of actuation functions historically performed by hydraulics or pneumatics are being accomplished by electric actuation. If 'end to end' systems are considered, electric actuators (EA's) are potentially lighter and more efficient. In general, system redundancies may be more easily implemented and operationally monitored. Typically, electrical components exhibit longer mean times to failure and projected lifetime costs of EA's are potentially much lower than those of other options. EA's have certain characteristics which must be considered in their application. The actual mechanical loadings must be established, for the more easily controlled EA may be operated much closer to its full capabilities. At higher rates of motion, EA's are operating as constant power devices. Therefore, it may be possible to start a movement that can not be stopped. The incorporation of high power electronics into remote locations introduces new concerns of EMI and thermal control. It is the management of these and other characteristics that forms the engineering design challenges. Work is currently in progress on EA's for aircraft and expendable launch vehicles. These applications span from ten to 40+ horsepower. The systematics and status of these actuators will be reported along with current technical trends in this area.

  13. Smart patch piezoceramic actuator issues

    NASA Technical Reports Server (NTRS)

    Griffin, Steven F.; Denoyer, Keith K.; Yost, Brad

    1993-01-01

    The Phillips Laboratory is undertaking the challenge of finding new and innovative ways to integrate sensing, actuation, and the supporting control and power electronics into a compact self-contained unit to provide vibration suppression for a host structure. This self-contained unit is commonly referred to as a smart patch. The interfaces to the smart patch will be limited to standard spacecraft power and possibly a communications line. The effort to develop a smart patch involves both contractual and inhouse programs which are currently focused on miniaturization of the electronics associated with vibrational control using piezoceramic sensors and actuators. This paper is comprised of two distinct parts. The first part examines issues associated with bonding piezoceramic actuators to a host structure. Experimental data from several specimens with varying flexural stiffness are compared to predictions from two piezoelectric/substructure coupling models, the Blocked Force Model and the Uniform Strain Model with Perfect Bonding. The second part of the paper highlights a demonstration article smart patch created using the insights gained from inhouse efforts at the Phillips Laboratory. This demonstration article has self contained electronics on the same order of size as the actuator powered by a voltage differential of approximately 32 volts. This voltage is provided by four rechargeable 8 volt batteries.

  14. Ball Aerospace Actuator Cryogenic Testing

    NASA Technical Reports Server (NTRS)

    Kingsbury, Lana; Lightsey, Paul; Quigley, Phil; Rutkowski, Joel; Russell, J. Kevin (Technical Monitor)

    2002-01-01

    The ambient testing characterizing step size and repeatability for the Ball Aerospace Cryogenic Nano-Positioner actuators for the AMSD (Advanced Mirror System Demonstrator) program has been completed and are presented. Current cryogenic testing is underway. Earlier cryogenic test results for a pre-cursor engineering model are presented.

  15. Smart patch piezoceramic actuator issues

    NASA Astrophysics Data System (ADS)

    Griffin, Steven F.; Denoyer, Keith K.; Yost, Brad

    1993-02-01

    The Phillips Laboratory is undertaking the challenge of finding new and innovative ways to integrate sensing, actuation, and the supporting control and power electronics into a compact self-contained unit to provide vibration suppression for a host structure. This self-contained unit is commonly referred to as a smart patch. The interfaces to the smart patch will be limited to standard spacecraft power and possibly a communications line. The effort to develop a smart patch involves both contractual and inhouse programs which are currently focused on miniaturization of the electronics associated with vibrational control using piezoceramic sensors and actuators. This paper is comprised of two distinct parts. The first part examines issues associated with bonding piezoceramic actuators to a host structure. Experimental data from several specimens with varying flexural stiffness are compared to predictions from two piezoelectric/substructure coupling models, the Blocked Force Model and the Uniform Strain Model with Perfect Bonding. The second part of the paper highlights a demonstration article smart patch created using the insights gained from inhouse efforts at the Phillips Laboratory. This demonstration article has self contained electronics on the same order of size as the actuator powered by a voltage differential of approximately 32 volts. This voltage is provided by four rechargeable 8 volt batteries.

  16. Piezoelectrically-driven Thermoacoustic Refrigerator

    NASA Astrophysics Data System (ADS)

    Chinn, Daniel George

    Thermoacoustic refrigeration is an emerging refrigeration technology which does not require any moving parts or harmful refrigerants in its operation. This technology uses acoustic waves to pump heat across a temperature gradient. The vast majority of thermoacoustic refrigerators to date have used electromagnetic loudspeakers to generate the acoustic input. In this thesis, the design, construction, operation, and modeling of a piezoelectrically-driven thermoacoustic refrigerator are detailed. This refrigerator demonstrates the effectiveness of piezoelectric actuation in moving 0.3 W of heat across an 18 degree C temperature difference with an input power of 7.6 W. The performance characteristics of this class of thermoacoustic-piezoelectric refrigerators are modeled by using DeltaEC software and the predictions are experimentally validated. The obtained results confirm the validity of the developed model. Furthermore, the potential of piezoelectric actuation as effective means for driving thermoacoustic refrigerators is demonstrated as compared to the conventional electromagnetic loudspeakers which are heavy and require high actuation energy. The developed theoretical and experimental tools can serve as invaluable means for the design and testing of other piezoelectrically-driven thermoacoustic refrigerator configurations.

  17. Fast-Response-Time Shape-Memory-Effect Foam Actuators

    NASA Technical Reports Server (NTRS)

    Jardine, Peter

    2010-01-01

    Bulk shape memory alloys, such as Nitinol or CuAlZn, display strong recovery forces undergoing a phase transformation after being strained in their martensitic state. These recovery forces are used for actuation. As the phase transformation is thermally driven, the response time of the actuation can be slow, as the heat must be passively inserted or removed from the alloy. Shape memory alloy TiNi torque tubes have been investigated for at least 20 years and have demonstrated high actuation forces [3,000 in.-lb (approximately equal to 340 N-m) torques] and are very lightweight. However, they are not easy to attach to existing structures. Adhesives will fail in shear at low-torque loads and the TiNi is not weldable, so that mechanical crimp fits have been generally used. These are not reliable, especially in vibratory environments. The TiNi is also slow to heat up, as it can only be heated indirectly using heater and cooling must be done passively. This has restricted their use to on-off actuators where cycle times of approximately one minute is acceptable. Self-propagating high-temperature synthesis (SHS) has been used in the past to make porous TiNi metal foams. Shape Change Technologies has been able to train SHS derived TiNi to exhibit the shape memory effect. As it is an open-celled material, fast response times were observed when the material was heated using hot and cold fluids. A methodology was developed to make the open-celled porous TiNi foams as a tube with integrated hexagonal ends, which then becomes a torsional actuator with fast response times. Under processing developed independently, researchers were able to verify torques of 84 in.-lb (approximately equal to 9.5 Nm) using an actuator weighing 1.3 oz (approximately equal to 37 g) with very fast (less than 1/16th of a second) initial response times when hot and cold fluids were used to facilitate heat transfer. Integrated structural connections were added as part of the net shape process, eliminating

  18. Single Piezo-Actuator Rotary-Hammering (SPaRH) Drill

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Domm, Lukas; Bao, Xiaoqi; Bar-Cohen, Yoseph; Chang, Zensheu; Badescu, Mircea

    2012-01-01

    The search for present or past life in the Universe is one of the most important objectives of NASA's exploration missions. Drills for subsurface sampling of rocks, ice and permafrost are an essential tool for astrobiology studies on other planets. Increasingly, it is recognized that drilling via a combination of rotation and hammering offers an efficient and effective rapid penetration mechanism. The rotation provides an intrinsic method for removal of cuttings from the borehole while the impact and shear forces aids in the fracturing of the penetrated medium. Conventional drills that use a single actuator are based on a complex mechanism with many parts and their use in future mission involves greater risk of failure and/or may require lubrication that can introduce contamination. In this paper, a compact drill is reported that uses a single piezoelectric actuator to produce hammering and rotation of the bit. A horn with asymmetric grooves was design to impart a longitudinal (hammering) and transverse force (rotation) to a keyed free mass. The drill requires low axial pre-load since the hammering-impacts fracture the rock under the bit kerf and rotate the bit to remove the powdered cuttings while augmenting the rock fracture via shear forces. The vibrations 'fluidize' the powdered cuttings inside the flutes reducing the friction with the auger surface. This action reduces the consumed power and heating of the drilled medium helping to preserve the pristine content of the acquired samples. The drill consists of an actuator that simultaneously impacts and rotates the bit by applying force and torque via a single piezoelectric stack actuator without the need for a gearbox or lever mechanism. This can reduce the development/fabrication cost and complexity. In this paper, the drill mechanism will be described and the test results will be reported and discussed.

  19. Single piezo-actuator rotary-hammering (SPaRH) drill

    NASA Astrophysics Data System (ADS)

    Sherrit, Stewart; Domm, Lukas; Bao, Xiaoqi; Bar-Cohen, Yoseph; Chang, Zensheu; Badescu, Mircea

    2012-04-01

    The search for present or past life in the Universe is one of the most important objectives of NASA's exploration missions. Drills for subsurface sampling of rocks, ice and permafrost are an essential tool for astrobiology studies on other planets. Increasingly, it is recognized that drilling via a combination of rotation and hammering offers an efficient and effective rapid penetration mechanism. The rotation provides an intrinsic method for removal of cuttings from the borehole while the impact and shear forces aid in the fracturing of the penetrated medium. Conventional drills that use a single actuator are based on a complex mechanism with many parts and their use in future mission involves greater risk of failure and/or may require lubrication that can introduce contamination. In this paper, a compact drill is reported that uses a single piezoelectric actuator to produce hammering and rotation of the bit. A horn with asymmetric grooves was designed to impart a longitudinal (hammering) and transverse force (rotation) to a keyed free mass. The drill requires low axial pre-load since the hammering-impacts fracture the rock under the bit kerf and rotate the bit to remove the powdered cuttings while augmenting the rock fracture via shear forces. The vibrations 'fluidize' the powdered cuttings inside the flutes reducing the friction with the auger surface. This action reduces the consumed power and heating of the drilled medium helping to preserve the pristine content of the acquired samples. The drill consists of an actuator that simultaneously impacts and rotates the bit by applying force and torque via a single piezoelectric stack actuator without the need for a gearbox or lever mechanism. This can reduce the development/fabrication cost and complexity. In this paper, the drill mechanism will be described and the test results will be reported and discussed.

  20. Design and performance of a sub-nanoradian resolution autocollimating optical lever

    SciTech Connect

    Cowsik, R.; Srinivasan, R.; Kasturirengan, S.; Kumar, A. Senthil; Wagoner, K.

    2007-03-15

    Precision goniometry using optics has the advantage that it does not impose much stress on the object of investigation and, as such, is adopted extensively in gravitational wave detection, in torsion balances investigating fundamental forces, in specialized studies of biological samples, and it has potential applications in condensed matter physics. In this article we present the considerations that go into designing optical levers and discuss the performance of the instrument we have constructed. We motivate the design by considering an idealized setup and the limitations to the angular resolution induced by statistical fluctuations of the photon count rate and diffraction at the apertures. The effects of digitization of the count rate and of the spatial location of the photons on the image plane motivating the actual design are discussed next. Based on these considerations, we have developed an autocollimating optical lever which has a very high resolution and dynamic range. An array of 110 slits, of 90 {mu}m width and a pitch of 182 {mu}m, is located in the focal plane of a field lens, of focal length 1000 mm, and is illuminated by a CCFL tube. This array is imaged back onto the focal plane after retroreflection from a mirror placed just beyond the lens. The image is recorded on a linear charge-coupled device array at the rate of 1000 images/s and is processed through a special algorithm to obtain the centroid. The instrument has a centroid stability of {approx}3x10{sup -10} rad Hz{sup -1/2} and a dynamic range of {approx}10{sup 7}.

  1. Novel piezoelectric actuation mechanism for a gimbal-less mirror in 2D raster scanning applications

    NASA Astrophysics Data System (ADS)

    How Koh, Kah; Kobayashi, Takeshi; Xie, Jin; Yu, Aibin; Lee, Chengkuo

    2011-07-01

    In this paper, we present the design, fabrication and measurement results of a 2D scanning mirror actuated by 1 × 10 piezoelectric Pb(Zr,Ti)O3 (PZT) cantilever actuators integrated on a thin silicon beam. A combination of bulk silicon micromachining based on a silicon-on-insulator (SOI) substrate and thin-film surface micromachining on a 5 µm thick Si device layer is used to fabricate the device. Multi-layers of Pt/Ti/PZT/Pt/Ti are deposited as electrode materials. A large silicon mirror plate (5 mm × 5 mm) and a 1 × 10 PZT cantilever array arranged in parallel are formed after the backside release process. The ten PZT cantilever actuators are electrically isolated from one another. The device can operate in three modes: bending, torsional and mixed (or combinational) modes. In bending mode, the first resonant frequency was measured to be 30 Hz and an optical deflection angle of ±8° was obtained when all ten cantilevers were actuated at 9 Vpp. In torsional mode, the resonant frequency was measured to be 89 Hz and an optical deflection angle of ±4.6° was obtained by applying a gradually declining ac voltage started at 8 Vpp to two sets of actuators, where each set comprises five cantilever actuators of the said 1 × 10 array, i.e. 1-5 and 6-10. A 2D raster scanning pattern was achieved in the mixed mode when the bending mode was carried out by cantilever actuators of 4-7 and the torsional modes were exercised by two different sets of cantilever actuators, i.e. 1-3 and 8-10, under opposite biasing direction. This mixed mode operation mechanism demonstrates the first 2D raster scanning mirror-driven beam actuators.

  2. Oxygen reduction reaction induced pH-responsive chemo-mechanical hydrogel actuators.

    PubMed

    Yu, Cunjiang; Yuan, Peixi; Erickson, Evan M; Daly, Christopher M; Rogers, John A; Nuzzo, Ralph G

    2015-10-28

    We describe and characterize elementary designs for electrochemical micro- and macro-scale chemomechanical hydrogel actuators. The actuation of a pH-sensitive cross-linked polyacrylic acid (PAA) hydrogel is driven in the model devices through the oxygen reduction reaction (ORR) occurring at the electrodes of an embedded Au mesh micro-electrochemical array. Proton consumption by the ORR at the cathode of the embedded electrochemical cell leads to the formation of a localized pH gradient that in turn drives the strain response in the composite actuators. The dynamics result from the ionization of the carboxylic acid moieties of the PAA network in the high pH region, yielding an osmotic pressure that drives a volumetric expansion due to water imbibition. This system actuates both stably and reversibly; when the electrochemically-induced ORR is halted, the localized pH gradient dissipates due to diffusive mixing, which in turn relaxes the induced strains. Two approaches to the fabrication of hydrogel actuators were examined in this work. The first method adopted a design based on small flagella (∼0.2 mm × 1.5 mm × 60 μm, width × length × height) in which the actuating PAA structures are molded atop a set of fixed electrodes mounted on a supporting substrate. These hydrogel actuators show fast, large-amplitude, and largely reversible responses in the ORR mediated chemomechanical dynamics. We also investigated larger hydrogel actuators (∼4.5 mm × 11 mm × 1 mm, width × length × height), based on an autonomous design that embeds an open mesh stretchable micro-electrode array within the hydrogel. The significant and design-dependent impacts of mass transfer on the chemomechanical dynamics are evidenced in each case, a feature examined to elucidate more efficient mesoscopic design rules for actuators of this form. PMID:26323563

  3. Composite flight-control actuator development

    NASA Technical Reports Server (NTRS)

    Bott, Richard; Ching, Fred

    1992-01-01

    The composite actuator is 'jam resistant', satisfying a survivability requirement for the Navy. Typically, the push-pull force needed to drive through the wound area of the composite actuator is 73 percent less than that of an all-metal actuator. In addition to improving the aircraft's combat survivability, significant weight savings were realized. The current design of the survivable, composite actuator cylinder is 36 percent lighter than that of the production steel cylinder, which equates to a 15 percent overall actuator weight savings.

  4. Trying to Make a Lever Work at Ages 1 to 4: The Development of "Functions" (Logico-Mathematical Thinking)

    ERIC Educational Resources Information Center

    Kamii, Constance; Miyakawa, Yoko; Kato, Tsuguhiko

    2007-01-01

    To find out if children could make functions before age 4, 73 children aged 1 to 4 were encouraged to imitate the use of a lever to make a beanbag fly up. Functions are mental relationships that preoperational children can make between 2 things at a time in a unidirectional way (Piaget, Grize, Szeminska, & Bang, 1968/1977). The child's…

  5. Electron microscopic evidence for the myosin head lever arm mechanism in hydrated myosin filaments using the gas environmental chamber.

    PubMed

    Minoda, Hiroki; Okabe, Tatsuhiro; Inayoshi, Yuhri; Miyakawa, Takuya; Miyauchi, Yumiko; Tanokura, Masaru; Katayama, Eisaku; Wakabayashi, Takeyuki; Akimoto, Tsuyoshi; Sugi, Haruo

    2011-02-25

    Muscle contraction results from an attachment-detachment cycle between the myosin heads extending from myosin filaments and the sites on actin filaments. The myosin head first attaches to actin together with the products of ATP hydrolysis, performs a power stroke associated with release of hydrolysis products, and detaches from actin upon binding with new ATP. The detached myosin head then hydrolyses ATP, and performs a recovery stroke to restore its initial position. The strokes have been suggested to result from rotation of the lever arm domain around the converter domain, while the catalytic domain remains rigid. To ascertain the validity of the lever arm hypothesis in muscle, we recorded ATP-induced movement at different regions within individual myosin heads in hydrated myosin filaments, using the gas environmental chamber attached to the electron microscope. The myosin head were position-marked with gold particles using three different site-directed antibodies. The amplitude of ATP-induced movement at the actin binding site in the catalytic domain was similar to that at the boundary between the catalytic and converter domains, but was definitely larger than that at the regulatory light chain in the lever arm domain. These results are consistent with the myosin head lever arm mechanism in muscle contraction if some assumptions are made. PMID:21281603

  6. Effects of ketamine, a noncompetitive NMDA antagonist, on the acquisition of the lever-press response in rats.

    PubMed

    Pallarés, M A; Nadal, R A; Silvestre, J S; Ferré, N S

    1995-02-01

    We analyzed the effects of ketamine, a noncompetitive NMDA antagonist, on the acquisition of the lever-press response in the Skinner box and on motor performance both in the open field and in the inclined screen. Ninety-six adult male Wistar rats were assigned at random to eight different groups (n = 12). The first four groups received an acute intraperitoneal (IP) injection of: (a) physiological saline, (b) 4 mg/kg ketamine, (c) 8 mg/kg ketamine, or (d) 12 mg/kg ketamine, and the subjects were tested in a free lever-press response shaping in the Skinner box. The second four groups received the same substances and doses as the first four, but the subjects were tested for locomotor activity in an open field and tested immediately afterwards for motor performance in an 80 degrees inclined screen. Results showed that ketamine impaired the acquisition of the lever-press response in a dose-dependent manner, with no effects on ambulation in the open field nor on length of stay in the inclined screen. These results suggest that ketamine effects on the acquisition of the lever-press response cannot be attributed to a motor impairment, indicating a possible specific effect of ketamine on the associative learning acquisition. PMID:7716221

  7. Photogated humidity-driven motility

    NASA Astrophysics Data System (ADS)

    Zhang, Lidong; Liang, Haoran; Jacob, Jolly; Naumov, Panče

    2015-06-01

    Hygroinduced motion is a fundamental process of energy conversion that is essential for applications that require contactless actuation in response to the day-night rhythm of atmospheric humidity. Here we demonstrate that mechanical bistability caused by rapid and anisotropic adsorption and desorption of water vapour by a flexible dynamic element that harnesses the chemical potential across very small humidity gradients for perpetual motion can be effectively modulated with light. A mechanically robust material capable of rapid exchange of water with the surroundings is prepared that undergoes swift locomotion in effect to periodic shape reconfiguration with turnover frequency of <150 min-1. The element can lift objects ~85 times heavier and can transport cargos ~20 times heavier than itself. Having an azobenzene-containing conjugate as a photoactive dopant, this entirely humidity-driven self-actuation can be controlled remotely with ultraviolet light, thus setting a platform for next-generation smart biomimetic hybrids.

  8. Photogated humidity-driven motility

    PubMed Central

    Zhang, Lidong; Liang, Haoran; Jacob, Jolly; Naumov, Panče

    2015-01-01

    Hygroinduced motion is a fundamental process of energy conversion that is essential for applications that require contactless actuation in response to the day–night rhythm of atmospheric humidity. Here we demonstrate that mechanical bistability caused by rapid and anisotropic adsorption and desorption of water vapour by a flexible dynamic element that harnesses the chemical potential across very small humidity gradients for perpetual motion can be effectively modulated with light. A mechanically robust material capable of rapid exchange of water with the surroundings is prepared that undergoes swift locomotion in effect to periodic shape reconfiguration with turnover frequency of <150 min−1. The element can lift objects ∼85 times heavier and can transport cargos ∼20 times heavier than itself. Having an azobenzene-containing conjugate as a photoactive dopant, this entirely humidity-driven self-actuation can be controlled remotely with ultraviolet light, thus setting a platform for next-generation smart biomimetic hybrids. PMID:26067649

  9. Fabrication and Characterization of a Micromachined Swirl-Shaped Ionic Polymer Metal Composite Actuator with Electrodes Exhibiting Asymmetric Resistance

    PubMed Central

    Feng, Guo-Hua; Liu, Kim-Min

    2014-01-01

    This paper presents a swirl-shaped microfeatured ionic polymer-metal composite (IPMC) actuator. A novel micromachining process was developed to fabricate an array of IPMC actuators on a glass substrate and to ensure that no shortcircuits occur between the electrodes of the actuator. We demonstrated a microfluidic scheme in which surface tension was used to construct swirl-shaped planar IPMC devices of microfeature size and investigated the flow velocity of Nafion solutions, which formed the backbone polymer of the actuator, within the microchannel. The unique fabrication process yielded top and bottom electrodes that exhibited asymmetric surface resistance. A tool for measuring surface resistance was developed and used to characterize the resistances of the electrodes for the fabricated IPMC device. The actuator, which featured asymmetric electrode resistance, caused a nonzero-bias current when the device was driven using a zero-bias square wave, and we propose a circuit model to describe this phenomenon. Moreover, we discovered and characterized a bending and rotating motion when the IPMC actuator was driven using a square wave. We observed a strain rate of 14.6% and a displacement of 700 μm in the direction perpendicular to the electrode surfaces during 4.5-V actuation. PMID:24824370

  10. Development of micro inchworm robot actuated by electrostrictive polymer actuator

    NASA Astrophysics Data System (ADS)

    Cho, Sunghwi; Ryew, Sungmoo; Jeon, Jaewook; Kim, Hunmo; Nam, Jaedo; Choi, Hyoukryeol

    2001-07-01

    In previous works, the possibility of the electrostrictive polymer as the actuator use has been proved. In this paper we address an actual design of an actuator and an inchworm type robotic mechanism using the electrostrictive polymer. The robot will be developed to move horizontally, vertically with steering capability, aiming for navigation in small tubular structures such as flexible pipes but now in this stage a simple bellows type robot capable of accomplishing the linear movement like that of an inchworm is introduced. The issues about the mechanism design of the prototype, which has already been developed and under the consideration of reduction in size, are discussed and preliminary results of experiments are given.

  11. [Actuator placement for active sound and vibration control

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Two refereed journal publications and ten talks given at conferences, seminars, and colloquia resulted from research supported by NASA. They are itemized in this report. The two publications were entitled "Reactive Tabu and Search Sensor Selection in Active Structural Acoustic Control Problems" and "Quelling Cabin Noise in Turboprop Aircraft via Active Control." The conference presentations covered various aspects of actuator placement, including location problems, for active sound and vibration control of cylinders, of commuter jets, of propeller driven or turboprop aircraft, and for quelling aircraft cabin or interior noise.

  12. Efficient Hybrid Actuation Using Solid-State Actuators

    NASA Technical Reports Server (NTRS)

    Leo, Donald J.; Cudney, Harley H.; Horner, Garnett (Technical Monitor)

    2001-01-01

    Piezohydraulic actuation is the use of fluid to rectify the motion of a piezoelectric actuator for the purpose of overcoming the small stroke limitations of the material. In this work we study a closed piezohydraulic circuit that utilizes active valves to rectify the motion of a hydraulic end affector. A linear, lumped parameter model of the system is developed and correlated with experiments. Results demonstrate that the model accurately predicts the filtering of the piezoelectric motion caused by hydraulic compliance. Accurate results are also obtained for predicting the unidirectional motion of the cylinder when the active valves are phased with respect to the piezoelectric actuator. A time delay associated with the mechanical response of the valves is incorporated into the model to reflect the finite time required to open or close the valves. This time delay is found to be the primary limiting factor in achieving higher speed and greater power from the piezohydraulic unit. Experiments on the piezohydraulic unit demonstrate that blocked forces on the order of 100 N and unloaded velocities of 180 micrometers/sec are achieved.

  13. Fuel cutoff apparatus for engine-driven vehicle

    SciTech Connect

    Watanabe, T.; Miyata, K.

    1988-05-03

    A fuel cutoff apparatus for use in an engine-driven vehicle is described comprising: an ignition switch having an off-position and an on-position; a fuel supply means for supplying fuel to the engine of the vehicle and comprising a fuel supply solenoid which, when energized, supplies fuel to the engine and, when deenergized, stops the supply of fuel; a normally-closed hydraulically actuated switch means; a fuel cutoff control means comprising an electric circuit including the fuel supply solenoid, and a warning means actuated independently of the driver coil by the hydraulically actuated switch means moving to its closed position.

  14. Electron microscopic evidence for the myosin head lever arm mechanism in hydrated myosin filaments using the gas environmental chamber

    SciTech Connect

    Minoda, Hiroki; Okabe, Tatsuhiro; Inayoshi, Yuhri; Miyakawa, Takuya; Miyauchi, Yumiko; Tanokura, Masaru; Katayama, Eisaku; Wakabayashi, Takeyuki; Akimoto, Tsuyoshi; Sugi, Haruo

    2011-02-25

    Research highlights: {yields} We succeeded in recording structural changes of hydrated myosin cross-bridges. {yields} We succeeded in position-marking the cross-bridges with site-directed antibodies. {yields} We recorded cross-bridge movement at different regions in individual cross-bridge. {yields} The movement was smallest at the cross-bridge-subfragment two boundary. {yields} The results provide evidence for the cross-bridge lever arm mechanism. -- Abstract: Muscle contraction results from an attachment-detachment cycle between the myosin heads extending from myosin filaments and the sites on actin filaments. The myosin head first attaches to actin together with the products of ATP hydrolysis, performs a power stroke associated with release of hydrolysis products, and detaches from actin upon binding with new ATP. The detached myosin head then hydrolyses ATP, and performs a recovery stroke to restore its initial position. The strokes have been suggested to result from rotation of the lever arm domain around the converter domain, while the catalytic domain remains rigid. To ascertain the validity of the lever arm hypothesis in muscle, we recorded ATP-induced movement at different regions within individual myosin heads in hydrated myosin filaments, using the gas environmental chamber attached to the electron microscope. The myosin head were position-marked with gold particles using three different site-directed antibodies. The amplitude of ATP-induced movement at the actin binding site in the catalytic domain was similar to that at the boundary between the catalytic and converter domains, but was definitely larger than that at the regulatory light chain in the lever arm domain. These results are consistent with the myosin head lever arm mechanism in muscle contraction if some assumptions are made.

  15. Reliable quantification of bite-force performance requires use of appropriate biting substrate and standardization of bite out-lever.

    PubMed

    Lappin, A Kristopher; Jones, Marc E H

    2014-12-15

    Bite-force performance is an ecologically important measure of whole-organism performance that shapes dietary breadth and feeding strategies and, in some taxa, determines reproductive success. It also is a metric that is crucial to testing and evaluating biomechanical models. We reviewed nearly 100 published studies of a range of taxa that incorporate direct in vivo measurements of bite force. Problematically, methods of data collection and processing vary considerably among studies. In particular, there is little consensus on the appropriate substrate to use on the biting surface of force transducers. In addition, the bite out-lever, defined as the distance from the fulcrum (i.e. jaw joint) to the position along the jawline at which the jaws engage the transducer, is rarely taken into account. We examined the effect of bite substrate and bite out-lever on bite-force estimates in a diverse sample of lizards. Results indicate that both variables have a significant impact on the accuracy of measurements. Maximum bite force is significantly greater using leather as the biting substrate compared with a metal substrate. Less-forceful bites on metal are likely due to inhibitory feedback from mechanoreceptors that prevent damage to the feeding apparatus. Standardization of bite out-lever affected which trial produced maximum performance for a given individual. Indeed, maximum bite force is usually underestimated without standardization because it is expected to be greatest at the minimum out-lever (i.e. back of the jaws), which in studies is rarely targeted with success. We assert that future studies should use a pliable substrate, such as leather, and use appropriate standardization for bite out-lever. PMID:25359934

  16. Actuator placement for active sound and vibration control of cylinders

    NASA Technical Reports Server (NTRS)

    Kincaid, Rex K.

    1995-01-01

    Active structural acoustic control is a method in which the control inputs (used to reduce interior noise) are applied directly to a vibrating structural acoustic system. The control concept modeled in this work is the application of in-plane force inputs to piezoceramic patches bonded to the wall of a vibrating cylinder. The cylinder is excited by an exterior noise source -- an acoustic monopole -- located near the outside of the cylinder wall. The goal is to determine the force inputs and sites for the piezoelectric actuators so that (1) the interior noise is effectively damped; (2) the level of vibration of the cylinder shell is not increased; and (3) the power requirements needed to drive the actuators are not excessive. We studied external monopole excitations at two frequencies. A cylinder resonance of 100 Hz, where the interior acoustic field is driven in multiple, off-resonance cylinder cavity modes, and a cylinder resonance of 200 Hz are characterized by both near and off-resonance cylinder vibration modes which couple effectively with a single, dominant, low-order acoustic cavity mode at resonance. Previous work has focused almost exclusively on meeting objective (1) and solving a complex least-squares problem to arrive at an optimal force vector for a given set of actuator sites. In addition, it has been noted that when the cavity mode couples with cylinder vibration modes (our 200 Hz case) control spillover may occur in higher order cylinder shell vibrational modes. How to determine the best set of actuator sites to meet objectives (1)-(3) is the main contribution of our research effort. The selection of the best set of actuator sites from a set of potential sites is done via two metaheuristics -- simulated annealing and tabu search. Each of these metaheuristics partitions the set of potential actuator sites into two disjoint sets: those that are selected to control the noise (on) and those that are not (off). Next, each metaheuristic attempts to

  17. Flexible Low-Mass Devices and Mechanisms Actuated by Electroactive Polymers

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Y; Leary, S.; Shahinpoor, M.; Harrison, J. O.; Smith, J.

    1999-01-01

    Miniature, lightweight, miser actuators that operate similar to biological muscles can be used to develop robotic devices with unmatched capabilities to impact many technology areas. Electroactive polymers (EAP) offer the potential to producing such actuators and their main attractive feature is their ability to induce relatively large bending or longitudinal strain. Generally, these materials produce a relatively low force and the applications that can be considered at the current state of the art are relatively limited. This reported study is concentrating on the development of effective EAPs and the resultant enabling mechanisms employing their unique characteristics. Several EAP driven mechanisms, which emulate human hand, were developed including a gripper, manipulator arm and surface wiper. The manipulator arm was made of a composite rod with an EAP actuator consisting of a scrolled rope that is activated longitudinally by an electrostatic field. A gripper was made to serve as an end effector and it consisted of multiple bending EAP fingers for grabbing and holding such objects as rocks. An EAP surface wiper was developed to operate like a human finger and to demonstrate the potential to remove dust from optical and IR windows as well as solar cells. These EAP driven devices are taking advantage of the large actuation displacement of these materials but there is need for a significantly greater actuation force capability.

  18. Piezoelectric aluminum nitride nanoelectromechanical actuators

    NASA Astrophysics Data System (ADS)

    Sinha, Nipun; Wabiszewski, Graham E.; Mahameed, Rashed; Felmetsger, Valery V.; Tanner, Shawn M.; Carpick, Robert W.; Piazza, Gianluca

    2009-08-01

    This letter reports the implementation of ultrathin (100 nm) aluminum nitride (AlN) piezoelectric layers for the fabrication of vertically deflecting nanoactuators. The films exhibit an average piezoelectric coefficient (d31˜-1.9 pC/N), which is comparable to its microscale counterpart. This allows vertical deflections as large as 40 nm from 18 μm long and 350 nm thick multilayer cantilever bimorph beams with 2 V actuation. Furthermore, in-plane stress and stress gradients have been simultaneously controlled. The films exhibit leakage currents lower than 2 nA/cm2 at 1 V, and have an average relative dielectric constant of approximately 9.2 (as in thicker films). These material characteristics and actuation results make the AlN nanofilms ideal candidates for the realization of nanoelectromechanical switches for low power logic applications.

  19. Hydraulically amplified PZT mems actuator

    DOEpatents

    Miles, Robin R.

    2004-11-02

    A hydraulically amplified microelectromechanical systems actuator. A piece of piezoelectric material or stacked piezo bimorph is bonded or deposited as a thin film. The piece is operatively connected to a primary membrane. A reservoir is operatively connected to the primary membrane. The reservoir contains a fluid. A membrane is operatively connected to the reservoir. In operation, energizing the piezoelectric material causing the piezoelectric material to bow. Bowing of the piezoelectric material causes movement of the primary membrane. Movement of the primary membrane results in a force in being transmitted to the liquid in the reservoir. The force in the liquid causes movement of the membrane. Movement of the membrane results in an operating actuator.

  20. Piezoelectric step-motion actuator

    DOEpatents

    Mentesana; Charles P.

    2006-10-10

    A step-motion actuator using piezoelectric material to launch a flight mass which, in turn, actuates a drive pawl to progressively engage and drive a toothed wheel or rod to accomplish stepped motion. Thus, the piezoelectric material converts electrical energy into kinetic energy of the mass, and the drive pawl and toothed wheel or rod convert the kinetic energy of the mass into the desired rotary or linear stepped motion. A compression frame may be secured about the piezoelectric element and adapted to pre-compress the piezoelectric material so as to reduce tensile loads thereon. A return spring may be used to return the mass to its resting position against the compression frame or piezoelectric material following launch. Alternative embodiment are possible, including an alternative first embodiment wherein two masses are launched in substantially different directions, and an alternative second embodiment wherein the mass is eliminated in favor of the piezoelectric material launching itself.

  1. Impact micro-positioning actuator

    NASA Technical Reports Server (NTRS)

    Cuerden, Brian (Inventor); Angel, J. Roger P. (Inventor); Burge, James H. (Inventor); DeRigne, Scott T. (Inventor)

    2006-01-01

    An impact micro-positioning actuator. In one aspect of the invention, a threaded shaft is threadably received in a nut and the nut is impacted by an impacting device, causing the nut first to rotate relative to the shaft by slipping as a result of shaft inertia and subsequently to stick to the shaft as a result of the frictional force therebetween. The nut is returned to its initial position by a return force provided by a return mechanism after impact. The micro-positioning actuator is further improved by controlling at least one and preferably all of the following: the friction, the impact provided by the impacting device, the return force provided by the return mechanism, and the inertia of the shaft. In another aspect of the invention, a threaded shaft is threadably received in a nut and the shaft is impacted by an impacting device, causing the shaft to rotate relative to the nut.

  2. Actuator device for artificial leg

    NASA Technical Reports Server (NTRS)

    Burch, J. L. (Inventor)

    1976-01-01

    An actuator device is described for moving an artificial leg of a person having a prosthesis replacing an entire leg and hip joint. The device includes a first articulated hip joint assembly carried by the natural leg and a second articulated hip joint assembly carried by the prosthesis whereby energy from the movement of the natural leg is transferred by a compressible fluid from the first hip joint assembly to the second hip joint assembly for moving the artificial leg.

  3. Enhancing the force capability of permanent magnet latching actuators for electromechanical valve actuation systems

    NASA Astrophysics Data System (ADS)

    Rens, J.; Clark, R. E.; Jewell, G. W.; Howe, D.

    2005-05-01

    This article introduces a topology of parallel-polarized permanent magnet latching actuator for use in electromagnetic valve actuation systems for internal combustion engines. The actuator has a number of advantages over reluctance actuators, commonly employed in such systems, in terms of reduced starting currents and fail-safe capability. The influence of a number of design features on actuator performance, such as tooth tapering, additional magnets to improve the main magnet flux path and prevent the onset of saturation, and mechanical clearances required to protect the permanent magnet from shock loads are investigated. The design study findings are verified by measurements on a prototype actuator.

  4. Actuators for a space manipulator

    NASA Technical Reports Server (NTRS)

    Chun, W.; Brunson, P.

    1987-01-01

    The robotic manipulator can be decomposed into distinct subsytems. One particular area of interest of mechanical subsystems is electromechanical actuators (or drives). A drive is defined as a motor with an appropriate transmission. An overview is given of existing, as well as state-of-the-art drive systems. The scope is limited to space applications. A design philosophy and adequate requirements are the initial steps in designing a space-qualified actuator. The focus is on the d-c motor in conjunction with several types of transmissions (harmonic, tendon, traction, and gear systems). The various transmissions will be evaluated and key performance parameters will be addressed in detail. Included in the assessment is a shuttle RMS joint and a MSFC drive of the Prototype Manipulator Arm. Compound joints are also investigated. Space imposes a set of requirements for designing a high-performance drive assembly. Its inaccessibility and cryogenic conditions warrant special considerations. Some guidelines concerning these conditions are present. The goal is to gain a better understanding in designing a space actuator.

  5. The application of polypyrrole trilayer actuators in microfluidics and robotics

    NASA Astrophysics Data System (ADS)

    Kiefer, Rudolf; Mandviwalla, Xerxes; Archer, Rosalind; Tjahyono, Sungkono Surya; Wang, Han; MacDonald, Bruce; Bowmaker, Graham A.; Kilmartin, Paul A.; Travas-Sejdic, Jadranka

    2008-03-01

    Trilayer actuators were constructed using polypyrrole (PPy) films doped with dodecylbenzene sulfonate (DBS). Identical 5-20 μm PPy/DBS films were grown on either side of a 110 μm poly(vinylidene fluoride) (PVDF) membrane to serve as working and counter electrodes with respect to each other. The performance of the trilayer actuator was tested using potential step experiments between -0.8 and +0.8 V at different frequencies (0.03 to 10 Hz) and trilayer lengths (1 to 2.5 cm), and the extent of deflection was measured using a CCD camera. Satisfactory deflections in the range of 1-3 mm were observed for 10 μm thick PPy layers on trilayers 1.5 to 2.5 cm in length when operated at 1-5 Hz for over 40,000 cycles. The trilayer actuators were examined in a fluidics channels, and mathematical modelling using finite element analysis was used to predict overall fluid movement and flow rates. The trilayers were also used to construct a 'fish-tail' positioned at the back of a self-driven robotic fish.

  6. Osmotic actuation modelling for innovative biorobotic solutions inspired by the plant kingdom.

    PubMed

    Sinibaldi, E; Puleo, G L; Mattioli, F; Mattoli, V; Di Michele, F; Beccai, L; Tramacere, F; Mancuso, S; Mazzolai, B

    2013-06-01

    Osmotic-driven plant movements are widely recognized as impressive examples of energy efficiency and low power consumption. These aspects motivate the interest in developing an original biomimetic concept of new actuators based on the osmotic principle exploited by plants. This study takes a preliminary step in this direction, by modelling the dynamic behaviour of two exemplificative yet relevant implementations of an osmotic actuator concept. In more detail, the considered implementations differ from each other in the way actuation energy storage is achieved (through a piston displacement in the former case, through membrane bulging in the latter). The dynamic problem is analytically solved for both cases; scaling laws for the actuation figures of merit (namely characteristic time, maximum force, maximum power, power density, cumulated work and energy density) as a function of model parameters are obtained for the bulging implementation. Starting from such performance indicators, a preliminary dimensioning of the envisaged osmotic actuator is exemplified, based on design targets/constraints (such as characteristic time and/or maximum force). Moreover, model assumptions and limitations are discussed towards effective prototypical development and experimental testing. Nonetheless, this study takes the first step towards the design of new actuators based on the natural osmotic principle, which holds potential for disruptive innovation in many fields, including biorobotics and ICT solutions. PMID:23648821

  7. An investigation of electrochemomechanical actuation of conductive Polyacrylonitrile (PAN) nanofiber composites

    NASA Astrophysics Data System (ADS)

    Gonzalez, Mark A.; Walter, Wayne W.

    2014-03-01

    A polymer-based nanofiber composite actuator designed for contractile actuation was fabricated by electrospinning, stimulated by electrolysis, and characterized by electrochemical and mechanical testing to address performance limitations and understand the activation processing effects on actuation performance. Currently, Electroactive polymers (EAPs) have provided uses in sensory and actuation technology, but have either low force output or expand rather than contract, falling short in capturing the natural kinetics and mechanics of muscle needed to provide breakthroughs in the bio-medical and robotic fields. In this study, activated Polyacrylonitrile (PAN) fibers have demonstrated biomimetic functionalities similar to the sarcomere contraction responsible for muscle function. Activated PAN has also been shown to contract and expand by electrolysis when in close vicinity to the anode and cathode, respectively. PAN nanofibers (~500 nm) especially show faster response to changes in environmental pH and improved mechanical properties compared to larger diameter fibers. Tensile testing was conducted to examine changes in mechanical properties between annealing and hydrolysis processing. Voltage driven transient effects of localized pH were examined to address pHdefined actuation thresholds of PAN fibers. Electrochemical contraction rates of the PAN/Graphite composite actuator demonstrated up to 25%/min. Strains of 58.8%, ultimate stresses up to 77.1 MPa, and moduli of 0.21 MPa were achieved with pure PAN nanofiber mats, surpassing mechanical properties of natural muscles. Further improvements, however, to contraction rates and Young's moduli were found essential to capture the function and performance of skeletal muscles appropriately.

  8. A spongy graphene based bimorph actuator with ultra-large displacement towards biomimetic application.

    PubMed

    Hu, Ying; Lan, Tian; Wu, Guan; Zhu, Zicai; Chen, Wei

    2014-11-01

    Bimorph actuators, consisting of two layers with asymmetric expansion and generating bending displacement, have been widely researched. Their actuation performances greatly rely on the difference of coefficients of thermal expansion (CTE) between the two material layers. Here, by introducing a spongy graphene (sG) paper with a large negative CTE as well as high electrical-to-thermal properties, an electromechanical sG/PDMS bimorph actuator is designed and fabricated, showing an ultra-large bending displacement output under low voltage stimulation (curvature of about 1.2 cm(-1) at 10 V for 3 s), a high displacement-to-length ratio (∼0.79), and vibration motion at AC voltage (up to 10 Hz), which is much larger and faster than that of the other electromechanical bimorph actuators. Based on the sG/PDMS bimorph serving as the "finger", a mechanical gripper is constructed to realize the fast manipulation of the objects under 0.1 Hz square wave voltage stimulation (0-8 V). The designed bimorph actuator coupled with ultra-large bending displacement, low driven voltage, and the ease of fabrication may open up substantial possibilities for the utilization of electromechanical actuators in practical biomimetic device applications. PMID:25220910

  9. Design of high performance piezo composites actuators

    NASA Astrophysics Data System (ADS)

    Almajid, Abdulhakim A.

    Design of high performance piezo composites actuators are developed. Functionally Graded Microstructure (FGM) piezoelectric actuators are designed to reduce the stress concentration at the middle interface existed in the standard bimorph actuators while maintaining high actuation performance. The FGM piezoelectric laminates are composite materials with electroelastic properties varied through the laminate thickness. The elastic behavior of piezo-laminates actuators is developed using a 2D-elasticity model and a modified classical lamination theory (CLT). The stresses and out-of-plane displacements are obtained for standard and FGM piezoelectric bimorph plates under cylindrical bending generated by an electric field throughout the thickness of the laminate. The analytical model is developed for two different actuator geometries, a rectangular plate actuator and a disk shape actuator. The limitations of CLT are investigated against the 2D-elasticity model for the rectangular plate geometry. The analytical models based on CLT (rectangular and circular) and 2D-elasticity are compared with a model based on Finite Element Method (FEM). The experimental study consists of two FGM actuator systems, the PZT/PZT FGM system and the porous FGM system. The electroelastic properties of each layer in the FGM systems were measured and input in the analytical models to predict the FGM actuator performance. The performance of the FGM actuator is optimized by manipulating the thickness of each layer in the FGM system. The thickness of each layer in the FGM system is made to vary in a linear or non-linear manner to achieve the best performance of the FGM piezoelectric actuator. The analytical and FEM results are found to agree well with the experimental measurements for both rectangular and disk actuators. CLT solutions are found to coincide well with the elasticity solutions for high aspect ratios while the CLT solutions gave poor results compared to the 2D elasticity solutions for

  10. Rover Wheel-Actuated Tool Interface

    NASA Technical Reports Server (NTRS)

    Matthews, Janet; Ahmad, Norman; Wilcox, Brian

    2007-01-01

    A report describes an interface for utilizing some of the mobility features of a mobile robot for general-purpose manipulation of tools and other objects. The robot in question, now undergoing conceptual development for use on the Moon, is the All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) rover, which is designed to roll over gentle terrain or walk over rough or steep terrain. Each leg of the robot is a six-degree-of-freedom general purpose manipulator tipped by a wheel with a motor drive. The tool interface includes a square cross-section peg, equivalent to a conventional socket-wrench drive, that rotates with the wheel. The tool interface also includes a clamp that holds a tool on the peg, and a pair of fold-out cameras that provides close-up stereoscopic images of the tool and its vicinity. The field of view of the imagers is actuated by the clamp mechanism and is specific to each tool. The motor drive can power any of a variety of tools, including rotating tools for helical fasteners, drills, and such clamping tools as pliers. With the addition of a flexible coupling, it could also power another tool or remote manipulator at a short distance. The socket drive can provide very high torque and power because it is driven by the wheel motor.

  11. Policy initiation and political levers in health policy: lessons from Ghana’s health insurance

    PubMed Central

    2012-01-01

    Background Understanding the health policy formulation process over the years has focused on the content of policy to the neglect of context. This had led to several policy initiatives having a still birth or ineffective policy choices with sub-optimal outcomes when implemented. Sometimes, the difficulty has been finding congruence between different values and interests of the various stakeholders. How can policy initiators leverage the various subtle mechanisms that various players draw on to leverage their interests during policy formulation. This paper attempts to conceptualise these levers of policy formulation to enhance an understanding of this field of work based on lived experience. Methodology This is a qualitative participant observation case study based on retrospective recollection of the policy process and political levers involved in developing the Ghana National Health Insurance Scheme. The study uses a four-concept framework which is agenda setting, symbols manipulation, constituency preservation and coalition building to capture the various issues, negotiations and nuanced approaches used in arriving at desired outcomes. Results Technical experts, civil society, academicians and politicians all had significant influence on setting the health insurance agenda. Each of these various stakeholders carefully engaged in ways that preserved their constituency interests through explicit manoeuvres and subtle engagements. Where proposals lend themselves to various interpretations, stakeholders were quick to latch on the contentious issues to preserve their constituency and will manipulate the symbols that arise from the proposals to their advantage. Where interests are contested and the price of losing out will leave government worse off which will favour its political opponent, it will push for divergent interests outside parliamentary politics through intense negotiations to build coalitions so a particular policy may pass. Conclusions This paper has

  12. TECHNICAL NOTE: Multiple-degrees-of-freedom electroelastomer roll actuators

    NASA Astrophysics Data System (ADS)

    Pei, Qibing; Rosenthal, Marcus; Stanford, Scott; Prahlad, Harsha; Pelrine, Ron

    2004-10-01

    Electroelastomers (electroactive elastomers) such as the 3M VHB 4910 acrylic adhesive films have exhibited up to 380% strain in area expansion at 5 6 kV when they are highly prestrained. By rolling highly prestrained electroelastomer films around a compression spring, we have demonstrated multifunctional electroelastomer rolls (MERs, or spring rolls) that combine load bearing, actuation, and sensing functions. We extended the design to two-degree-of-freedom (2-DOF) and 3-DOF spring rolls by patterning the electrodes to align radially on two and four circumferential spans of the rolls, respectively. Multiple-DOF spring rolls retain the linear actuation of 1-DOF spring rolls with additional bending actuation. Mathematical equations are derived to correlate the bending angle and lateral force of the rolls with the actuated stroke in one of the electroded spans. Two-DOF spring rolls with a 1.4 cm outside diameter, 6.8 cm axial length, and 11 g weight have been fabricated; these rolls have a 90° maximum actuation bending angle, 0.7 N maximum lateral force, and up to 15 N blocked axial force. Three-DOF spring rolls with a 2.3 cm outside diameter, 9.0 cm axial length, and 29 g weight exhibit a 35° maximum bending angle and 1.0 N maximum lateral force. These specifications can be modified by variations in roll parameters according to the equations. Multi-DOF spring rolls are easy to fabricate, compact, multifunctional, and mechanically robust. They represent a radically new actuation technology and may enable a number of unique applications. We have demonstrated a small walking robot, MERbot, with one 2-DOF spring roll as each of its six legs. The robot's speed is as high as 13.6 cm s-1 or two-thirds of its length per second. 'Sushi rolls' have also been fabricated: these consist of six 2-DOF springs connected in series and monolithic in structure. The sushi rolls can be driven so as to generate wavelike or serpentine motion.

  13. Multi-imager compatible actuation principles in surgical robotics

    PubMed Central

    Stoianovici, D

    2011-01-01

    Today’s most successful surgical robots are perhaps surgeon-driven systems, such as the daVinci (Intuitive Surgical Inc., USA, www.intuitivesurgical.com). These have already enabled surgery that was unattainable with classic instrumentation; however, at their present level of development, they have limited utility. The drawback of these systems is that they are independent self-contained units, and as such, they do not directly take advantage of patient data. The potential of these new surgical tools lies much further ahead. Integration with medical imaging and information are needed for these devices to achieve their true potential. Surgical robots and especially their subclass of image-guided systems require special design, construction and control compared to industrial types, due to the special requirements of the medical and imaging environments. Imager compatibility raises significant engineering challenges for the development of robotic manipulators with respect to imager access, safety, ergonomics, and above all the non-interference with the functionality of the imager. These apply to all known medical imaging types, but are especially challenging for achieving compatibility with the class of MRI systems. Even though a large majority of robotic components may be redesigned to be constructed of MRI compatible materials, for other components such as the motors used in actuation, prescribing MRI compatible materials alone is not sufficient. The electromagnetic motors most commonly used in robotic actuation, for example, are incompatible by principle. As such, alternate actuation principles using “intervention friendly” energy should be adopted and/or devised for these special surgical and radiological interventions. This paper defines the new concept of Multi-imager Compatibility of surgical manipulators and describes its requirements. Subsequently, the paper gives several recommendations and proposes new actuation principles for this concept. Several

  14. Plasma actuators for bluff body flow control

    NASA Astrophysics Data System (ADS)

    Kozlov, Alexey V.

    The aerodynamic plasma actuators have shown to be efficient flow control devices in various applications. In this study the results of flow control experiments utilizing single dielectric barrier discharge plasma actuators to control flow separation and unsteady vortex shedding from a circular cylinder in cross-flow are reported. This work is motivated by the need to reduce landing gear noise for commercial transport aircraft via an effective streamlining created by the actuators. The experiments are performed at Re D = 20,000...164,000. Circular cylinders in cross-flow are chosen for study since they represent a generic flow geometry that is similar in all essential aspects to a landing gear oleo or strut. The minimization of the unsteady flow separation from the models and associated large-scale wake vorticity by using actuators reduces the radiated aerodynamic noise. Using either steady or unsteady actuation at ReD = 25,000, Karman shedding is totally eliminated, turbulence levels in the wake decrease significantly and near-field sound pressure levels are reduced by 13.3 dB. Unsteady actuation at an excitation frequency of St D = 1 is found to be most effective. The unsteady actuation also has the advantage that total suppression of shedding is achieved for a duty cycle of only 25%. However, since unsteady actuation is associated with an unsteady body force and produces a tone at the actuation frequency, steady actuation is more suitable for noise control applications. Two actuation strategies are used at ReD = 82,000: spanwise and streamwise oriented actuators. Near field microphone measurements in an anechoic wind tunnel and detailed study of the near wake using LDA are presented in the study. Both spanwise and streamwise actuators give nearly the same noise reduction level of 11.2 dB and 14.2 dB, respectively, and similar changes in the wake velocity profiles. The contribution of the actuator induced noise is found to be small compared to the natural shedding

  15. Silkworm protein: its possibility as an actuator

    NASA Astrophysics Data System (ADS)

    Jin, Hyoung-Joon; Myung, Seung Jun; Kim, Heung Soo; Jung, Woochul; Kim, Jaehwan

    2006-03-01

    The possibility of silkworm (Bombyx mori) protein as a base material of biomimetic actuator was investigated in this paper. Silkworm films were prepared from high concentrations of regenerated fibroin in aqueous solution. Films with thickness of about 100 μm were prepared for coating electrodes. The cast silk films were coated by very thin gold electrode on both sides of the film. Tensile test of cast film showed bi-modal trend, which is typical stress-strain relation of polymeric film. As the test of a possible biomimetic actuator, silkworm film actuator provides bending deformations according to the magnitude and frequency of the applied electric filed. Although the present bending deformation of silkworm film actuator is smaller than that of Electro-Active Paper actuator, it provides the possibility of biomimetic actuator.

  16. What we learn from surveillance testing of standby turbine driven and motor driven pumps

    SciTech Connect

    Christie, B.

    1996-12-01

    This paper describes a comparison of the performance information collected by the author and the respective system engineers from five standby turbine driven pumps at four commercial nuclear electric generating units in the United States and from two standby motor driven pumps at two of these generating units. Information was collected from surveillance testing and from Non-Test actuations. Most of the performance information (97%) came from surveillance testing. {open_quotes}Conditional Probabilities{close_quotes} of the pumps ability to respond to a random demand were calculated for each of the seven standby pumps and compared to the historical record of the Non-Test actuations. It appears that the Conditional Probabilities are comparable to the rate of success for Non-Test actuations. The Conditional Probabilities of the standby motor driven pumps (approximately 99%) are better than the Conditional Probabilities of the standby turbine driven pumps (82%-96% range). Recommendations were made to improve the Conditional Probabilities of the standby turbine driven pumps.

  17. Actuation fluid adapter for hydraulically-actuated electronically-controlled fuel injector and engine using same

    DOEpatents

    Keyster, Eric S.; Merchant, Jack A.

    2002-01-01

    A fuel injector adapter consists of a block defining a pressure communication passage therethrough and an actuation fluid passage. The actuation fluid passage includes three separate branches that open through an outer surface of the block at three separate locations.

  18. MRI-powered Actuators for Robotic Interventions

    PubMed Central

    Vartholomeos, Panagiotis; Qin, Lei; Dupont, Pierre E.

    2012-01-01

    This paper presents a novel actuation technology for robotically assisted MRI-guided interventional procedures. Compact and wireless, the actuators are both powered and controlled by the MRI scanner. The design concept and performance limits are described and derived analytically. Simulation and experiments in a clinical MR scanner are used to validate the analysis and to demonstrate the capability of the approach for needle biopsies. The concepts of actuator locking mechanisms and multi-axis control are also introduced. PMID:22287082

  19. Fluidic self-actuating control assembly

    DOEpatents

    Grantz, Alan L.

    1979-01-01

    A fluidic self-actuating control assembly for use in a reactor wherein no external control inputs are required to actuate (scram) the system. The assembly is constructed to scram upon sensing either a sudden depressurization of reactor inlet flow or a sudden increase in core neutron flux. A fluidic control system senses abnormal flow or neutron flux transients and actuates the system, whereupon assembly coolant flow reverses, forcing absorber balls into the reactor core region.

  20. Direct-drive field actuator motors

    DOEpatents

    Grahn, Allen R.

    1995-01-01

    A high-torque, low speed, positive-drive field actuator motor including a stator carrying at least one field actuator which changes in dimension responsive to application of an energy field, and at least one drive shoe movable by the dimensional changes of the field actuator to contact and move a rotor element with respect to the stator. Various embodiments of the motor are disclosed, and the rotor element may be moved linearly or arcuately.

  1. Direct-drive field actuator motors

    DOEpatents

    Grahn, A.R.

    1995-07-11

    A high-torque, low speed, positive-drive field actuator motor is disclosed including a stator carrying at least one field actuator which changes in dimension responsive to application of an energy field, and at least one drive shoe movable by the dimensional changes of the field actuator to contact and move a rotor element with respect to the stator. Various embodiments of the motor are disclosed, and the rotor element may be moved linearly or arcuately. 37 figs.

  2. Pulsatile blood pump with a linear drive actuator.

    PubMed

    Fukunaga, Kazuyoshi; Homma, Akihiko; Funakubo, Akio; Tatsumi, Eisuke; Taenaka, Yoshiyuki; Kitamura, Soichiro; Fukui, Yasuhiro

    2007-01-01

    The main purpose of this study was to develop an implantable direct-electromagnetic left ventricular assist system driven by a linear actuator (linear LVAS). The linear LVAS is a pulsatile pump with a pusher plate that is driven directly by a linear oscillatory actuator (LOA) without any movement converters. This prototype pump unit with a LOA was 100 mm in diameter, 50 mm in thickness, and weighed 740 g. The full-fill/full-eject driving method was applied to the control algorithm. In addition, a mechanism to detect and release sucking was realized to overcome this problem that accompanies the active-filling type of VAS. The performance of the linear LVAS was evaluated in a long-term animal experiment using a goat (56 kg). The goat survived for 42 days. The reason why we terminated this experiment was that thrombus was found in the pump. There was no frictional debris found around the LOA. The linear LVAS did not exhibit electrical or mechanical problems during the first animal experiment. PMID:17574509

  3. Practical design of the optical lever intracavity topology of gravitational-wave detectors

    SciTech Connect

    Danilishin, S. L.; Khalili, F. Ya.

    2006-01-15

    The quantum nondemolition (QND) intracavity topologies of gravitational-wave detectors proposed several years ago allow us, in principle, to obtain sensitivity significantly better than the standard quantum limit using relatively small amount of optical pumping power. In this article we consider an improved more practical version of the optical lever intracavity scheme. It differs from the original version by the symmetry which allows to suppress influence of the input light amplitude fluctuation. In addition, it provides the means to inject optical pumping inside the scheme without increase of optical losses. We consider also sensitivity limitations imposed by the local meter which is the key element of the intracavity topologies. Two variants of the local meter are analyzed, which are based on the spectral variation measurement and on the discrete sampling variation measurement, correspondingly. The former one, while can not be considered as a candidate for a practical implementation, allows, in principle, to obtain the best sensitivity and thus can be considered as an ideal 'asymptotic case' for all other schemes. The DSVM-based local meter can be considered as a realistic scheme but its sensitivity, unfortunately, is by far not so good just due to a couple of peculiar numeric factors specific for this scheme. From our point of view search of new methods of mechanical QND measurements probably based on improved DSVM scheme or which combine the local meter with the pondermotive squeezing technique, is necessary.

  4. Experimental Investigation of Liquid-propellant Laser Propulsion with a Horizontal Momentum Measuring Lever

    SciTech Connect

    Wang Bin; Li Long; Tang Zhiping; Cai Jian

    2010-05-06

    Thrust performance of Liquid-propellant laser propulsion (LLP) is seriously influenced by factors like laser parameters, choice of propellants and ablation materials. For the purpose of studying these influences, series of impulse measuring experiments for various propellants and ablation materials were conducted. The key device is a Horizontal Momentum Measuring Lever, which covers a C{sub m} measuring range from 10{sup 3} Ns/MJ to about 1.6x10{sup 4} Ns/MJ. A Nd:YAG laser was used as the laser source. From the result, it is found that laser energy density plays an important role on LLP efficiency, higher energy density leads to higher C{sub m} and I{sub sp}. Highest C{sub m} of about 10{sup 4} Ns/MJ with the I{sub sp} of 3.57s was achieved by focusing the laser to the average energy density of 8.83x10{sup 8} W/cm{sup 2}. Besides of that, it is also found that when the energy density is certainly high, C{sub m} of LLP increases stably with the increase of the propellant thickness, which gives a potential way to further improve the thrust performance in LLP.

  5. Five Policy Levers To Meet The Value Challenge In Cancer Care.

    PubMed

    Callahan, Ryan; Darzi, Ara

    2015-09-01

    The burden of cancer on public finances is a serious concern for policy makers. More people are developing cancer, and as standards of care have risen, more are surviving and requiring longer-term care. Precision medicine promises better outcomes but demands commensurately higher payments for care. As both incidence and per case costs rise, we suggest that the task of expanding access to high-quality cancer care poses a "value challenge" that policies in many countries are inadequate to meet. Policy makers should respond with a new approach. We explore questions that policy makers will need to consider regarding objectives, barriers, and levers for policy development. We use transparency and accountability as cornerstones of a new approach to promote value-based decision making. Although barriers to advancing this agenda are formidable, we recommend that governments define common standards for value-based accounting; serve as information brokers for evidence development; pioneer value-based procurement of goods and services; engage in deliberative democracy in cancer care; and educate communities to facilitate knowledge sharing between communities of patients, their caretakers, and researchers. PMID:26355059

  6. The neck region of the myosin motor domain acts as a lever arm to generate movement.

    PubMed Central

    Uyeda, T Q; Abramson, P D; Spudich, J A

    1996-01-01

    The myosin head consists of a globular catalytic domain that binds actin and hydrolyzes ATP and a neck domain that consists of essential and regulatory light chains bound to a long alpha-helical portion of the heavy chain. The swinging neck-level model assumes that a swinging motion of the neck relative to the catalytic domain is the origin of movement. This model predicts that the step size, and consequently the sliding velocity, are linearly related to the length of the neck. We have tested this point by characterizing a series of mutant Dictyostelium myosins that have different neck lengths. The 2xELCBS mutant has an extra binding site for essential light chain. The delta RLCBS mutant myosin has an internal deletion that removes the regulatory light chain binding site. The delta BLCBS mutant lacks both light chain binding sites. Wild-type myosin and these mutant myosins were subjected to the sliding filament in vitro motility assay. As expected, mutants with shorter necks move slower than wild-type myosin in vitro. Most significantly, a mutant with a longer neck moves faster than the wild type, and the sliding velocities of these myosins are linearly related to the neck length, as predicted by the swinging neck-lever model. A simple extrapolation to zero speed predicts that the fulcrum point is in the vicinity of the SH1-SH2 region in the catalytic domain. Images Fig. 1 Fig. 2 Fig. 3 PMID:8633089

  7. Actuator selection for variable camber foils

    NASA Astrophysics Data System (ADS)

    Madden, John D.

    2004-07-01

    A number of polymer based actuator technologies have emerged over the past decade. How do these compare with traditional actuators and are there applications for which they are appropriate? Some of the answers to these questions are provided by outlining the rationale for employing an electroactive polymer to control hydrodynamic surfaces. The surfaces are sections of propeller blades whose trailing edges are deflected in order to change camber. The objective is to insert the actuators into the blades. High work per unit volume is required of the actuators. The ideal actuator technologies also feature relatively large strains in order to deflect the trailing edges with minimal mechanical amplification. It is argued that the high work densities, flexibility in shaping and the ability to hold a force without expending energy (catch state) provide electroactive polymers with advantages over electromagnetic actuators, which also lack the torque to directly drive the blade deflection. Candidate actuators are compared, including electroactive polymers, shape memory alloys, magnetostrictives and traditional piezoceramics. Selections are made on the bases of work density, strain, existence of a catch state, drive voltage and cost. It is suggested that conducting polymer actuators are best suited for the variable camber application. It is also argued that in general electroactive polymers are well-suited for applications in which actuator volume or mass are very limited, catch states are desired, cycle life is moderate to low, or noise cannot be tolerated. Some electroactive polymers also feature low voltage operation, and may be biocompatible.

  8. Bucky gel actuators optimization towards haptic applications

    NASA Astrophysics Data System (ADS)

    Bubak, Grzegorz; Ansaldo, Alberto; Ceseracciu, Luca; Hata, Kenji; Ricci, Davide

    2014-03-01

    An ideal plastic actuator for haptic applications should generate a relatively large displacement (minimum 0.2-0.6 mm, force (~50 mN/cm2) and a fast actuation response to the applied voltage. Although many different types of flexible, plastic actuators based on electroactive polymers (EAP) are currently under investigation, the ionic EAPs are the only ones that can be operated at low voltage. This property makes them suitable for applications that require inherently safe actuators. Among the ionic EAPs, bucky gel based actuators are very promising. Bucky gel is a physical gel made by grounding imidazolium ionic liquids with carbon nanotubes, which can then be incorporated in a polymeric composite matrix to prepare the active electrode layers of linear and bending actuators. Anyhow, many conflicting factors have to be balanced to obtain required performance. In order to produce high force a large stiffness is preferable but this limits the displacement. Moreover, the bigger the active electrode the larger the force. However the thicker an actuator is, the slower the charging process becomes (it is diffusion limited). In order to increase the charging speed a thin electrolyte would be desirable, but this increases the probability of pinholes and device failure. In this paper we will present how different approaches in electrolyte and electrode preparation influence actuator performance and properties taking particularly into account the device ionic conductivity (which influences the charging speed) and the electrode surface resistance (which influences both the recruitment of the whole actuator length and its speed).

  9. The Mariner Mars 1971 gimbal actuator

    NASA Technical Reports Server (NTRS)

    Perkins, G. S.

    1971-01-01

    The actuator that will point the gimbaled engine, thus performing the autopilot actuation function for the Mariner Mars 1971 spacecraft, is described. The gimbaled engine has two axes of freedom, providing two-axis control to the spacecraft. Motion for the two axes is provided by identical and interchangeable actuators-gearless electromechanical linear servomechanisms. Each actuator is designed to have a long service life in the space environment and to be able to function at speeds ranging from hours per cycle to cycles per second.

  10. Two position optical element actuator device

    DOEpatents

    Holdener, Fred R.; Boyd, Robert D.

    2002-01-01

    The present invention is a two position optical element actuator device utilizing a powered means to hold an actuation arm, to which an optical element is attached, in a first position. A non-powered means drives the actuation arm to a second position, when the powered means ceases to receive power. The optical element may be a electromagnetic (EM) radiation or particle source, an instrument, or EM radiation or particle transmissive, reflective or absorptive elements. A bearing is used to transfer motion and smoothly transition the actuation arm from the first to second position.

  11. Bi-stable optical element actuator device

    DOEpatents

    Holdener, Fred R.; Boyd, Robert D.

    2002-01-01

    The present invention is a bistable optical element actuator device utilizing a powered means to move an actuation arm, to which an optical element is attached, between two stable positions. A non-powered means holds the actuation arm in either of the two stable positions. The optical element may be a electromagnetic (EM) radiation or particle source, an instrument, or EM radiation or particle transmissive reflective or absorptive elements. A bearing is used to transfer motion and smoothly transition the actuation arm between the two stable positions.

  12. Transparent actuators and robots based on single-layer superaligned carbon nanotube sheet and polymer composites

    NASA Astrophysics Data System (ADS)

    Chen, Luzhuo; Weng, Mingcen; Zhang, Wei; Zhou, Zhiwei; Zhou, Yi; Xia, Dan; Li, Jiaxin; Huang, Zhigao; Liu, Changhong; Fan, Shoushan

    2016-03-01

    Transparent actuators have been attracting emerging interest recently, as they demonstrate potential applications in the fields of invisible robots, tactical displays, variable-focus lenses, and flexible cellular phones. However, previous technologies did not simultaneously realize macroscopic transparent actuators with advantages of large-shape deformation, low-voltage-driven actuation and fast fabrication. Here, we develop a fast approach to fabricate a high-performance transparent actuator based on single-layer superaligned carbon nanotube sheet and polymer composites. Various advantages of single-layer nanotube sheets including high transparency, considerable conductivity, and ultra-thin dimensions together with selected polymer materials completely realize all the above required advantages. Also, this is the first time that a single-layer nanotube sheet has been used to fabricate actuators with high transparency, avoiding the structural damage to the single-layer nanotube sheet. The transparent actuator shows a transmittance of 72% at the wavelength of 550 nm and bends remarkably with a curvature of 0.41 cm-1 under a DC voltage for 5 s, demonstrating a significant advance in technological performances compared to previous conventional actuators. To illustrate their great potential usage, a transparent wiper and a humanoid robot ``hand'' were elaborately designed and fabricated, which initiate a new direction in the development of high-performance invisible robotics and other intelligent applications with transparency.Transparent actuators have been attracting emerging interest recently, as they demonstrate potential applications in the fields of invisible robots, tactical displays, variable-focus lenses, and flexible cellular phones. However, previous technologies did not simultaneously realize macroscopic transparent actuators with advantages of large-shape deformation, low-voltage-driven actuation and fast fabrication. Here, we develop a fast approach to

  13. Surface micromachined sensors and actuators

    SciTech Connect

    Sniegowski, J.J.

    1995-08-01

    A description of a three-level mechanical polysilicon surface-micromachining technology including a discussion of the advantages of this level of process complexity is presented. This technology is capable of forming mechanical elements ranging from simple cantilevered beams to complex, interconnected, interactive, microactuated micromechanisms. The inclusion of a third deposited layer of mechanical polysilicon greatly extends the degree of complexity available for micromechanism design. Additional features of the Sandia three-level process include the use of Chemical-Mechanical Polishing (CMP) for planarization, and the integration of micromechanics with the Sandia CMOS circuit process. The latter effort includes a CMOS-first, tungsten metallization process to allow the CMOS electronics to withstand high-temperature micromechanical processing. Alternatively, a novel micromechanics-first approach wherein the micromechanical devices are processed first in a well below the surface of the CMOS starting material followed by the standard, aluminum metallization CMOS process is also being pursued. Following the description of the polysilicon surface micromachining are examples of the major sensor and actuator projects based on this technology at the Microelectronics Development Laboratory (MDL) at Sandia National Laboratories. Efforts at the MDL are concentrated in the technology of surface micromachining due to the availability of and compatibility with standard CMOS processes. The primary sensors discussed are a silicon nitride membrane pressure sensor, hot polysilicon filaments for calorimetric gas sensing, and a smart hydrogen sensor. Examples of actuation mechanisms coupled to external devices are also presented. These actuators utilize the three-level process (plus an additional passive level) and employ either surface tension or electrostatic forces.

  14. Four-plate piezoelectric actuator driving a large-diameter special optical fiber for nonlinear optical microendoscopy.

    PubMed

    Wang, Ying; Li, Zhi; Liang, Xiaobao; Fu, Ling

    2016-08-22

    In nonlinear optical microendoscope (NOME), a fiber with excellent optical characteristics and a miniature scanning mechanism at the distal end are two key components. Double-clad fibers (DCFs) and double-clad photonic crystal fibers (DCPCFs) have shown great optical characteristics but limited vibration amplitude due to large diameter. Besides reducing the damping of fiber cantilever, optimizing the structural of the actuator for lower energy dissipation also contributes to better driving capability. This paper presented an optimized actuator for driving a particular fiber cantilever in the view point of energy. Firstly, deformation energy of a bending fiber cantilever operating in resonant mode is investigated. Secondly, strain and stress analyses revealed that the four-plate actuator achieved lower energy dissipation. Then, finite-element simulations showed that the large-diameter fiber yielded an adequate vibration amplitude driven by a four-plate actuator, which was confirmed by experiments of our home-made four-plate actuator prototypes. Additionally, a NOME based on a DCPCF with a diameter of 350 μm driven by four-plate piezoelectric actuator has been developed. The NOME can excite and collect intrinsic second-harmonic and two-photon fluorescence signals with the excitation power of 10-30 mW and an adequate field of view of 200 μm, which suggest great potential applications in neuroscience and clinical diagnoses. PMID:27557270

  15. A within-subject between-apparatus comparison of impulsive choice: T-maze and two-lever chamber.

    PubMed

    Cunningham, Paul J; Kuhn, Robin; Reilly, Mark P

    2015-07-01

    Whereas intertemporal choice procedures are a common method for examining impulsive choice in nonhuman subjects, the apparatus used to implement this procedure varies across studies. The purpose of the present study was to compare impulsive choice between a two-lever chamber and a T-maze. In Experiment 1, rats chose between a smaller, immediate reinforcer and a larger, delayed reinforcer, first in a two-lever chamber and then in a T-maze. Delay to the larger reinforcer changed in an ascending and descending order (0-32 s) across sessions. Experiment 2 examined the same between-apparatus comparison but under steady-state conditions with the delay fixed at 32 s. In Experiment 1, choice for the larger, delayed reinforcer was generally higher in the T-maze than in the two-lever chamber. Similarly in Experiment 2, steady-state choice for the larger, delayed reinforcer was higher in the T-maze. Choice for the 32-s delayed reinforcer was also greater in Experiment 2 than in Experiment 1, suggesting that extended exposure to the delay is required for the T-maze to yield reliable impulsive choice data. While the reasons for the between-apparatus discrepancies are at present unknown, results from both experiments clearly demonstrate that the apparatus matters when assessing overall level and reliability of impulsive choice data. PMID:26080901

  16. Excessive lever pressing following post-training signal attenuation in rats: a possible animal model of obsessive compulsive disorder?

    PubMed

    Joel, D; Avisar, A

    2001-08-27

    This study aimed at developing a rat model of obsessive compulsive disorder based on the hypothesis that a deficient response feedback mechanism underlies obsessions and compulsions. Rats were trained to lever press for food, whose delivery was signaled by the presentation of a compound stimulus (light+tone). Subsequently, the classical contingency between the stimulus and food was extinguished (signal attenuation). Experiment 1 showed that this manipulation resulted in increased lever pressing during a subsequent extinction test, which was highly correlated with an increase in the number of trials on which the rat did not attempt to collect the food reward. This behavioral pattern was not evident in an extinction test not preceded by signal attenuation (Experiment 2), suggesting that the latter is a crucial factor in the development of this behavioral pattern. Excessive lever pressing was attenuated by the selective serotonin re-uptake inhibitor, fluoxetine (10 mg/kg; Experiment 3), but not by the anxiolytic drug, diazepam (2 mg/kg; Experiment 4). Based on these results we propose that post-training signal attenuation may provide a rat model of obsessive compulsive disorder. PMID:11377731

  17. Lever-arm and mini-implant system for anterior torque control during retraction in lingual orthodontic treatment.

    PubMed

    Hong, Ryoon-Ki; Heo, Jung-Min; Ha, Young-Ki

    2005-01-01

    Anterior torque control during retraction is difficult to achieve with lingual orthodontic treatment. This article describes the use of a lever-arm and mini-implant system as absolute anchorage for controlled retraction of the anterior teeth during lingual orthodontic treatment and evaluates 2 protrusion cases treated with this system. Various clinical situations are discussed and analyzed from a biomechanical standpoint. Mini-implants are needed to control the point of force application in the posterior area and produce en masse retraction with no anchorage loss. When the length of the lever-arm is adjusted to the position of the mini-implant, the desired line of action of the retraction force with respect to the center of resistance of the anterior segment is selected. Controlled retraction of the anterior teeth was achieved with no loss of anchorage. The mini-implant, in conjunction with the lever-arm, is useful not only for absolute anchorage but also for anterior torque control during retraction in lingual orthodontic treatment. PMID:15747828

  18. Effect of cantilever geometry on the optical lever sensitivities and thermal noise method of the atomic force microscope

    SciTech Connect

    Sader, John E.; Lu, Jianing; Mulvaney, Paul

    2014-11-15

    Calibration of the optical lever sensitivities of atomic force microscope (AFM) cantilevers is especially important for determining the force in AFM measurements. These sensitivities depend critically on the cantilever mode used and are known to differ for static and dynamic measurements. Here, we calculate the ratio of the dynamic and static sensitivities for several common AFM cantilevers, whose shapes vary considerably, and experimentally verify these results. The dynamic-to-static optical lever sensitivity ratio is found to range from 1.09 to 1.41 for the cantilevers studied – in stark contrast to the constant value of 1.09 used widely in current calibration studies. This analysis shows that accuracy of the thermal noise method for the static spring constant is strongly dependent on cantilever geometry – neglect of these dynamic-to-static factors can induce errors exceeding 100%. We also discuss a simple experimental approach to non-invasively and simultaneously determine the dynamic and static spring constants and optical lever sensitivities of cantilevers of arbitrary shape, which is applicable to all AFM platforms that have the thermal noise method for spring constant calibration.

  19. Dielectric elastomer actuators for adaptive photonic microsystems

    NASA Astrophysics Data System (ADS)

    Heimann, Marcus; Schröder, Henning; Marx, Sebastian; Lang, Klaus-Dieter

    2013-03-01

    Various applications in the field of photonic microsystems for Dielectric Elastomer Actuators (DEA) were shown with this research. DEA belong to the class of Electro Active Polymers (EAP) and have the potential to substitute common technologies like piezoelectric actuators. DEAs offers several advantages like compact and variable shapes, large actuation ranges and cost efficient production processes that have to be emphasized. For the market of adaptive photonic microsystems especially area actuators are very suitable. They can be used e.g. as tuneable lens, mirror or grating component and tool for optical fiber alignment. These area actuators have a similar structure like a capacitor. They consist of three layers, two electrode layers on top and bottom and one dielectric layer in the center. The dielectric layer is made of a deformable and prestretched elastomer film. When applying a voltage between both electrode layers the thickness of the dielectric film is compressed and the actuator is displaced in the plane. The use of material compositions like a polymer matrix with graphite, carbon nano particles or carbon nano tubes as well as thin metal films for the electrodes were studied. The paper presents results on suitable dielectric and electrode materials, actuator geometries and respective adaptive photonic components. The manufacturing process of area actuators is described in detail. As a basic size of the area actuators (20 × 20) mm2 were chosen. Onto the produced area actuators polymer lenses or mirrors were assembled. The deflection of the optical beam path is calculated with optical simulations and measured at the prepared adaptive optical components. Static actuations of about +/-15 μm are achieved when applying a voltage of 200 V. Also the function of a tuneable beam splitter is demonstrated to show further applications.

  20. Real-time open-loop control of a 1024-actuator MEMS deformable mirror

    NASA Astrophysics Data System (ADS)

    Blain, Célia; Conan, Rodolphe; Bradley, Colin; Guyon, Olivier; Gamroth, Darryl; Nash, Reston

    2010-07-01

    This article reports the progress made at the University of Victoria AO Lab, regarding the realtime open-loop control of a 1024-actuator MEMS deformable mirror (DM). The setup is an hybrid woofer-tweeter/open-loop bench. A tip-tilt mirror and a woofer DM (a 57-actuator CILAS DM) are driven in closed-loop while a 1024-actuator MEMS DM is utilized on a parallel open-loop path. Previous work shows that open-loop control providing low residual error (with frozen Kolmogorov turbulence) can be obtained without the need of DM modelling. A preliminary methodical calibration of the DM is employed instead. The MEMS electronics were upgraded to an update rate of 500 Hz and the experiment lays the groundwork for showing how these performances can also be achieved on the bench with dynamic turbulence (created with custom hot air turbulence generators). The current status of the experiment and the next milestones are presented.

  1. Two-dimensional analysis of temperature-gradient actuation of cantilever beam resonators

    NASA Astrophysics Data System (ADS)

    Mahameed, Rashed; Elata, David

    2005-08-01

    This work considers microresonators that are driven by a temperature-gradient actuator. The driving forces in the temperature-gradient actuation scheme are internal mechanical moments induced by temperature gradients. In this work, a model for analyzing the dynamic thermomechanical response of temperature-gradient actuators is presented. In this model, the two-dimensional nature of the temperature field is fully considered. Several test structures were fabricated and their dynamic thermomechanical response was found to be in agreement with the model predictions. Some examples of parametric analysis are presented that show how the two-dimensional model can be used to optimize the system parameters under specific constraints of the operation conditions.

  2. Design and experimental performances of a piezoelectric linear actuator by means of lateral motion

    NASA Astrophysics Data System (ADS)

    Li, Jianping; Zhou, Xiaoqin; Zhao, Hongwei; Shao, Mingkun; Hou, Pengliang; Xu, Xiuquan

    2015-06-01

    A piezoelectric-driven actuator based on the lateral motion principle is proposed in this paper, it can achieve large-stroke linear motion with high resolution. One parallelogram-type flexure hinge mechanism and one piezoelectric stack are used to generate the lateral motion. The mechanical structure and working principle are discussed. A prototype was fabricated and a series of experiments were carried out to investigate its working performance. The results indicate that the maximum moving speed is about 14.25 mm s-1, and the maximum output force is 3.43 N, the minimum stepping displacement is about 0.04 μm. The experiments confirm that the lateral motion can be used to design piezoelectric actuators with a large moving stroke and high accuracy with a compact size. This actuator can be used in fast tool servo systems for ultra-precision machining, precision motors for aerospace, focusing systems for optics, and so on.

  3. Dual Piezoelectric Actuation Bridge of In-Plane Polarized Lead Zirconate Titanate Film

    NASA Astrophysics Data System (ADS)

    Hwang, Hyun-Suk; Song, Joon-Tae

    2008-08-01

    A dual piezoelectric actuation bridge of in-plane polarized lead zirconate titanate (PZT) film is demonstrated. The in-plane polarized PZT film makes the development of a bending mechanism in the d33 mode, which exhibits a strain performance twice that of the d31 mode. Further, this design can provide deflection exceeding the structure thickness and individual driving mechanism for improving reliability of the devices. In order to simplify the fabrication process, a photoresist and Au are selected for the sacrificial and structural materials, respectively. The PZT thin film, which is deposited on the Au structural layer by the RF magnetron sputtering method, is poled and driven with interdigitated electrodes (IDEs) in order to exploit d33 mode actuation. The fabricated actuator exhibits good performance with a fast response time of <500 ms and low driving voltage of 5 V. This design can also be applied for a linearly tunable capacitor, depending on the magnitude of biasing voltage.

  4. Numerical Study of Control of Flow Separation Over a Ramp with Nanosecond Plasma Actuator

    NASA Astrophysics Data System (ADS)

    Zheng, J. G.; Khoo, B. C.; Cui, Y. D.; Zhao, Z. J.; Li, J.

    2016-06-01

    The nanosecond plasma discharge actuator driven by high voltage pulse with typical rise and decay time of several to tens of nanoseconds is emerging as a promising active flow control means in recent years and is being studied intensively. The characterization study reveals that the discharge induced shock wave propagates through ambient air and introduces highly transient perturbation to the flow. On the other hand, the residual heat remaining in the discharge volume may trigger the instability of external flow. In this study, this type of actuator is used to suppress flow separation over a ramp model. Numerical simulation is carried out to investigate the interaction of the discharge induced disturbance with the external flow. It is found that the flow separation region over the ramp can be reduced significantly. Our work may provide some insights into the understanding of the control mechanism of nanosecond pulse actuator.

  5. NASA pyrotechnically actuated systems program

    NASA Technical Reports Server (NTRS)

    Schulze, Norman R.

    1993-01-01

    The Office of Safety and Mission Quality initiated a Pyrotechnically Actuated Systems (PAS) Program in FY-92 to address problems experienced with pyrotechnically actuated systems and devices used both on the ground and in flight. The PAS Program will provide the technical basis for NASA's projects to incorporate new technological developments in operational systems. The program will accomplish that objective by developing/testing current and new hardware designs for flight applications and by providing a pyrotechnic data base. This marks the first applied pyrotechnic technology program funded by NASA to address pyrotechnic issues. The PAS Program has been structured to address the results of a survey of pyrotechnic device and system problems with the goal of alleviating or minimizing their risks. Major program initiatives include the development of a Laser Initiated Ordnance System, a pyrotechnic systems data base, NASA Standard Initiator model, a NASA Standard Linear Separation System and a NASA Standard Gas Generator. The PAS Program sponsors annual aerospace pyrotechnic systems workshops.

  6. A thermopneumatically actuated bistable microvalve

    NASA Astrophysics Data System (ADS)

    Yang, Bocong; Wang, Boxiong; Schomburg, Werner Karl

    2010-09-01

    A bistable polymer microvalve with a thermopneumatic actuator has been developed. The microvalve was fabricated by micro milling of a polymer combined with sputtering and photolithography. The valve comprises two 2/2-way valves which are alternately switched such that they can be connected to serve as a 3/2-way valve. Two permanent magnets work with a movable soft magnet to keep the valve in its current state, resulting in bistable switching with a minimum energy of 320 mJ. An air flow rate of 1.36 L min-1 is achieved at 20 °C with a pressure difference of 200 kPa. No leakage is observed up to a differential pressure of 350 kPa. Flowing and switching performances were also tested at different temperatures. Sealing the flow channels from the actuator chamber makes the valve less sensitive to the temperature and other properties of the fluid to be switched. An initial gap between the valve seat and the silicone sealing membrane at least reduces the sticking problem. Switching time is found to be significantly influenced by the thickness of the heating membrane. With an 8 µm thick heating membrane, a response time of 10 ms can be achieved.

  7. Optimization of Actuating Origami Networks

    NASA Astrophysics Data System (ADS)

    Buskohl, Philip; Fuchi, Kazuko; Bazzan, Giorgio; Joo, James; Gregory, Reich; Vaia, Richard

    2015-03-01

    Origami structures morph between 2D and 3D conformations along predetermined fold lines that efficiently program the form, function and mobility of the structure. By leveraging design concepts from action origami, a subset of origami art focused on kinematic mechanisms, reversible folding patterns for applications such as solar array packaging, tunable antennae, and deployable sensing platforms may be designed. However, the enormity of the design space and the need to identify the requisite actuation forces within the structure places a severe limitation on design strategies based on intuition and geometry alone. The present work proposes a topology optimization method, using truss and frame element analysis, to distribute foldline mechanical properties within a reference crease pattern. Known actuating patterns are placed within a reference grid and the optimizer adjusts the fold stiffness of the network to optimally connect them. Design objectives may include a target motion, stress level, or mechanical energy distribution. Results include the validation of known action origami structures and their optimal connectivity within a larger network. This design suite offers an important step toward systematic incorporation of origami design concepts into new, novel and reconfigurable engineering devices. This research is supported under the Air Force Office of Scientific Research (AFOSR) funding, LRIR 13RQ02COR.

  8. Dynamic profile of a prototype pivoted proof-mass actuator. [damping the vibration of large space structures

    NASA Technical Reports Server (NTRS)

    Miller, D. W.

    1981-01-01

    A prototype of a linear inertial reaction actuation (damper) device employing a flexure-pivoted reaction (proof) mass is discussed. The mass is driven by an electromechanic motor using a dc electromagnetic field and an ac electromagnetic drive. During the damping process, the actuator dissipates structural kinetic energy as heat through electromagnetic damping. A model of the inertial, stiffness and damping properties is presented along with the characteristic differential equations describing the coupled response of the actuator and structure. The equations, employing the dynamic coefficients, are oriented in the form of a feedback control network in which distributed sensors are used to dictate actuator response leading to a specified amount of structural excitation or damping.

  9. Silicon Membrane Mirrors with Electrostatic Shape Actuators

    NASA Technical Reports Server (NTRS)

    Yang, Eui-Hyeok

    2003-01-01

    Efforts are under way to develop deformable mirrors equipped with microscopic electrostatic actuators that would be used to maintain their reflective surfaces in precise shapes required for their intended applications. Unlike actuators that depend on properties of materials (e.g., piezoelectric and electrostrictive actuators), electrostatic actuators are effective over a wide temperature range. A mirror of the present type would be denoted a MEMSDM (for microelectromechanical system deformable mirror). The reflective surface of such a mirror would be formed on a single-crystal silicon membrane that would be attached by posts to a silicon actuator membrane that would, in turn, be attached by posts to a rigid silicon base (see figure). The actuator membrane would serve as the upper electrode of a capacitor. Multiple lower electrodes, each occupying a conveniently small fraction of the total area, would be formed on an electrically insulating oxide layer on the base, thereby defining a multiplicity of actuator pixels. The actuator membrane would be corrugated in a pattern that would impart mechanical compliance needed for relaxation of operational and fabrication-induced stresses and to minimize the degree of nonlinearity of deformations. The compliance afforded by the corrugations would also help to minimize the undesired coupling of deformations between adjacent pixels (a practical goal being to keep the influence coefficient between adjacent pixels below 10 percent).

  10. Integrated piezoelectric actuators in deep drawing tools

    NASA Astrophysics Data System (ADS)

    Neugebauer, R.; Mainda, P.; Drossel, W.-G.; Kerschner, M.; Wolf, K.

    2011-04-01

    The production of car body panels are defective in succession of process fluctuations. Thus the produced car body panel can be precise or damaged. To reduce the error rate, an intelligent deep drawing tool was developed at the Fraunhofer Institute for Machine Tools and Forming Technology IWU in cooperation with Audi and Volkswagen. Mechatronic components in a closed-loop control is the main differentiating factor between an intelligent and a conventional deep drawing tool. In correlation with sensors for process monitoring, the intelligent tool consists of piezoelectric actuators to actuate the deep drawing process. By enabling the usage of sensors and actuators at the die, the forming tool transform to a smart structure. The interface between sensors and actuators will be realized with a closed-loop control. The content of this research will present the experimental results with the piezoelectric actuator. For the analysis a production-oriented forming tool with all automotive requirements were used. The disposed actuators are monolithic multilayer actuators of the piezo injector system. In order to achieve required force, the actuators are combined in a cluster. The cluster is redundant and economical. In addition to the detailed assembly structures, this research will highlight intensive analysis with the intelligent deep drawing tool.

  11. Development of a theory-based instrument to identify barriers and levers to best hand hygiene practice among healthcare practitioners

    PubMed Central

    2013-01-01

    Background A theoretical approach to assessing the barriers and levers to evidence-based practice (EBP) with subsequent tailoring of theoretically informed strategies to address these may go some way to positively influencing the delay in implementing research findings into practice. Hand hygiene is one such example of EBP, chosen for this study due to its importance in preventing death through healthcare associated infections (HCAI). The development of an instrument to assess barriers and levers to hand hygiene and to allow the subsequent tailoring of theoretically informed implementation strategies is reported here. Methods A comprehensive list of barriers and levers to hand hygiene were categorised to the Theoretical Domains Framework (TDF) in a Delphi survey. These items formed the basis of an instrument that was tested to establish validity and reliability. The relationship between self-reported compliance with hand hygiene and barriers and levers to hand hygiene was also examined along with compliance according to where the barriers and levers fit within the domains of the TDF framework. Results A 33-item instrument that tested well for internal consistency (α = 0.84) and construct validity (χ2/df = 1.9 [p < 0.01], RMSEA = 0.05 and CFA = 0.84) was developed. The relationship between self-reported compliance with hand hygiene moderately correlated with barriers identified by participants (total barrier score) (r = 0.41, n = 276, p <0.001). The greater the number of barriers reported, the lower the level of compliance. A one-way between groups multivariate analysis of variance was performed to investigate differences between those adopting high or low compliance with hand hygiene. Compliance was highest for this sample of participants among practitioners with high levels of motivation, strong beliefs about capabilities, when there were positive social influences, when hand hygiene was central to participants’ sense of

  12. Actuator lifetime predictions for Ni60Ti40 shape memory alloy plate actuators

    NASA Astrophysics Data System (ADS)

    Wheeler, Robert; Ottmers, Cade; Hewling, Brett; Lagoudas, Dimitris

    2016-04-01

    Shape memory alloys (SMAs), due to their ability to repeatedly recover substantial deformations under applied mechanical loading, have the potential to impact the aerospace, automotive, biomedical, and energy industries as weight and volume saving replacements for conventional actuators. While numerous applications of SMA actuators have been flight tested and can be found in industrial applications, these actuators are generally limited to non-critical components, are not widely implemented and frequently one-off designs, and are generally overdesigned due to a lack of understanding of the effect of the loading path on the fatigue life and the lack of an accurate method of predicting actuator lifetimes. Previous efforts have been effective at predicting actuator lifetimes for isobaric dogbone test specimens. This study builds on previous work and investigates the actuation fatigue response of plate actuators with various stress concentrations through the use of digital image correlation and finite element simulations.

  13. Levers for Language Growth: Characteristics and Predictors of Language Trajectories between 4 and 7 Years

    PubMed Central

    McKean, Cristina; Eadie, Patricia; Bavin, Edith L.; Bretherton, Lesley; Cini, Eileen

    2015-01-01

    Background Evidence is required as to when and where to focus resources to achieve the greatest gains for children’s language development. Key to these decisions is the understanding of individual differences in children’s language trajectories and the predictors of those differences. To determine optimal timing we must understand if and when children’s relative language abilities become fixed. To determine where to focus effort we must identify mutable factors, that is those with the potential to be changed through interventions, which are associated with significant differences in children’s language scores and rate of progress. Methods Uniquely this study examined individual differences in language growth trajectories in a population sample of children between 4 and 7 years using the multilevel model for change. The influence of predictors, grouped with respect to their mutability and their proximity to the child (least-mutable, mutable-distal, mutable-proximal), were estimated. Results A significant degree of variability in rate of progress between 4 and 7 years was evident, much of which was systematically associated with mutable-proximal factors, that is, those factors with evidence that they are modifiable through interventions with the child or family, such as shared book reading, TV viewing and number of books in the home. Mutable-distal factors, such as family income, family literacy and neighbourhood disadvantage, hypothesised to be modifiable through social policy, were important predictors of language abilities at 4 years. Conclusions Potential levers for language interventions lie in the child’s home learning environment from birth to age 4. However, the role of a family’s material and cultural capital must not be ignored, nor should the potential for growth into the school years. Early Years services should acknowledge the effects of multiple, cascading and cumulative risks and seek to promote child language development through the

  14. Electroactive Polymer (EAP) Actuation of Mechanisms and Robotic Devices

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Y.; Leary, S.; Harrison, J.; Smith, J.

    1999-01-01

    Actuators are responsible to the operative capability of manipulation systems and robots. In recent years, electroactive polymers (EAP) have emerged as potential alternative to conventional actuators.

  15. Conducting IPN actuators for biomimetic vision system

    NASA Astrophysics Data System (ADS)

    Festin, Nicolas; Plesse, Cedric; Chevrot, Claude; Teyssié, Dominique; Pirim, Patrick; Vidal, Frederic

    2011-04-01

    In recent years, many studies on electroactive polymer (EAP) actuators have been reported. One promising technology is the elaboration of electronic conducting polymers based actuators with Interpenetrating Polymer Networks (IPNs) architecture. Their many advantageous properties as low working voltage, light weight and high lifetime (several million cycles) make them very attractive for various applications including robotics. Our laboratory recently synthesized new conducting IPN actuators based on high molecular Nitrile Butadiene Rubber, poly(ethylene oxide) derivative and poly(3,4-ethylenedioxithiophene). The presence of the elastomer greatly improves the actuator performances such as mechanical resistance and output force. In this article we present the IPN and actuator synthesis, characterizations and design allowing their integration in a biomimetic vision system.

  16. Lead magnesium niobate actuator for micropositioning

    DOEpatents

    Swift, C.D.; Bergum, J.W.

    1994-10-25

    An improved lead magnesium niobate actuator is disclosed comprising a cylindrical lead magnesium niobate crystal stack mounted in a cylindrical casing wherein a bias means, such as one or more belleville washers, is located between one end of the crystal stack and a partially closed end of the casing; and adjustment means are provided which bear against the opposite end of the crystal stack, whereby an adjustable compressive force is constantly applied against the crystal stack, whether the crystal stack is actuated in an extended position, or is in an unactuated contracted position. In a preferred embodiment, cooling ports are provided for the circulation of coolant in the actuator to cool the crystal stack, and provision is made for removal and replacement of the crystal stack without disconnecting the actuator from the external device being actuated. 3 figs.

  17. Lead magnesium niobate actuator for micropositioning

    DOEpatents

    Swift, Charles D.; Bergum, John W.

    1994-01-01

    An improved lead magnesium niobate actuator is disclosed comprising a cylindrical lead magnesium niobate crystal stack mounted in a cylindrical casing wherein a bias means, such as one or more belleville washers, is located between one end of the crystal stack and a partially closed end of the casing; and adjustment means are provided which bear against the opposite end of the crystal stack, whereby an adjustable compressive force is constantly applied against the crystal stack, whether the crystal stack is actuated in an extended position, or is in an unactuated contracted position. In a preferred embodiment, cooling ports are provided for the circulation of coolant in the actuator to cool the crystal stack, and provision is made for removal and replacement of the crystal stack without disconnecting the actuator from the external device being actuated.

  18. Piezoelectric Actuator/Sensor Technology at Rockwell

    NASA Technical Reports Server (NTRS)

    Neurgaonkar, Ratnakar R.

    1996-01-01

    We describe the state-of-the art of piezoelectric materials based on perovskite and tungsten bronze families for sensor, actuator and smart structure applications. The microstructural defects in these materials have been eliminated to a large extent and the resulting materials exhibit exceedingly high performance for various applications. The performance of Rockwell actuators/sensors is at least 3 times better than commercially available products. These high performance actuators are being incorporated into various applications including, DOD, NASA and commercial. The multilayer actuator stacks fabricated from our piezoceramics are advantageous for sensing and high capacitance applications. In this presentation, we will describe the use of our high performance piezo-ceramics for actuators and sensors, including multilayer stacks and composite structures.

  19. MEMS Electrostatic Actuation in Conducting Biological Media

    PubMed Central

    Mukundan, Vikram; Pruitt, Beth L.

    2009-01-01

    We present design and experimental implementation of electrostatic comb-drive actuators in solutions of high conductivity relevant for biological cells. The actuators are operated in the frequency range 1–10 MHz in ionic and biological cell culture media, with ionic strengths up to 150 mMoles/L. Typical displacement is 3.5 μm at an applied peak-to-peak signal of 5V. Two different actuation schemes are presented and tested for performance at high frequency. A differential drive design is demonstrated to overcome the attenuation due to losses in parasitic impedances. The frequency dependence of the electrostatic force has been characterized in media of different ionic strengths. Circuit models for the electric double layer phenomena are used to understand and predict the actuator behavior. The actuator is integrated into a planar force sensing system to measure the stiffness of cells cultured on suspended structures. PMID:20161046

  20. Genetic Algorithm Approaches for Actuator Placement

    NASA Technical Reports Server (NTRS)

    Crossley, William A.

    2000-01-01

    This research investigated genetic algorithm approaches for smart actuator placement to provide aircraft maneuverability without requiring hinged flaps or other control surfaces. The effort supported goals of the Multidisciplinary Design Optimization focus efforts in NASA's Aircraft au program. This work helped to properly identify various aspects of the genetic algorithm operators and parameters that allow for placement of discrete control actuators/effectors. An improved problem definition, including better definition of the objective function and constraints, resulted from this research effort. The work conducted for this research used a geometrically simple wing model; however, an increasing number of potential actuator placement locations were incorporated to illustrate the ability of the GA to determine promising actuator placement arrangements. This effort's major result is a useful genetic algorithm-based approach to assist in the discrete actuator/effector placement problem.

  1. Electromechanically Actuated Valve for Controlling Flow Rate

    NASA Technical Reports Server (NTRS)

    Patterson, Paul

    2007-01-01

    A proposed valve for controlling the rate of flow of a fluid would include an electric-motor-driven ball-screw mechanism for adjusting the seating element of the valve to any position between fully closed and fully open. The motor would be of a type that can be electronically controlled to rotate to a specified angular position and to rotate at a specified rate, and the ball screw would enable accurate linear positioning of the seating element as a function of angular position of the motor. Hence, the proposed valve would enable fine electronic control of the rate of flow and the rate of change of flow. The uniqueness of this valve lies in a high degree of integration of the actuation mechanism with the flow-control components into a single, relatively compact unit. A notable feature of this integration is that in addition to being a major part of the actuation mechanism, the ball screw would also be a flow-control component: the ball screw would be hollow so as to contain part of the main flow passage, and one end of the ball screw would be the main seating valve element. The relationships among the components of the valve are best understood by reference to the figure, which presents meridional cross sections of the valve in the fully closed and fully open positions. The motor would be supported by a bracket bolted to the valve body. By means of gears or pulleys and a timing belt, motor drive would be transmitted to a sleeve that would rotate on bearings in the valve body. A ball nut inside the sleeve would be made to rotate with the sleeve by use of a key. The ball screw would pass through and engage the ball nut. A key would prevent rotation of the ball screw in the valve body while allowing the ball screw to translate axially when driven by the ball nut. The outer surface of the ball screw would be threaded only in a mid-length region: the end regions of the outer surface of the ball screw would be polished so that they could act as dynamic sealing surfaces

  2. Controller for Driving a Piezoelectric Actuator at Resonance

    NASA Technical Reports Server (NTRS)

    Aldrich, Jack; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Bao, Xiaoqi; Chang, Zensheu

    2008-01-01

    A digital control system based partly on an extremum-seeking control algorithm tracks the changing resonance frequency of a piezoelectric actuator or an electrically similar electromechanical device that is driven by a sinusoidal excitation signal and is required to be maintained at or near resonance in the presence of uncertain, changing external loads and disturbances. Somewhat more specifically, on the basis of measurements of the performance of the actuator, this system repeatedly estimates the resonance frequency and alters the excitation frequency as needed to keep it at or near the resonance frequency. In the original application for which this controller was developed, the piezoelectric actuator is part of an ultrasonic/sonic drill/corer. Going beyond this application, the underlying principles of design and operation are generally applicable to tracking changing resonance frequencies of heavily perturbed harmonic oscillators. Resonance-frequency-tracking analog electronic circuits are commercially available, but are not adequate for the present purpose for several reasons: The input/output characteristics of analog circuits tend to drift, often necessitating recalibration, especially whenever the same controller is used in driving a different resonator. In the case of an actuator in a system that has multiple modes characterized by different resonance frequencies, an analog controller can tune erroneously to one of the higher-frequency modes. The lack of programmability of analog controllers is problematic when faults occur, and is especially problematic for preventing tuning to a higher-frequency mode. In contrast, a digital controller can be programmed to restrict itself to a specified frequency range and to maintain stability even when the affected resonator is driven at high power and subjected to uncertain disturbances and variable loads. The present digital control system (see figure) is implemented by means of an algorithm that comprises three main

  3. Application of photothermal effect to manufacture ultrasonic actuators (abstract)

    NASA Astrophysics Data System (ADS)

    Zhang, Shu-yi; Cheng, Li-ping; Shui, Xiu-ji; Yu, Jiong; Dong, Shu-xiang

    2003-01-01

    Photothermal (PT) effect has been applied to manufacture disks [A. C. Tam, a lecture at the Institute of Acoustics, Nanjing University, People's Republic of China (1996)] and magnetic head sliders for disk drives [A. C. Tam, C. C. Poon, and L. Crawforth, Analyt. Sci. 17, s 419 (2001)]. Now we apply the PT effect to manufacture ultrasonic motors (actuators). Recently, the ultrasonic actuators with different ultrasonic modes, such as Rayleigh (surface acoustic) mode, Lamb (plate) mode, etc., have been developed. We have designed and fabricated two rotary motors driven by surface acoustic wave (SAW) with different frequencies, but lower than 30 MHz [L. P. Cheng, G. M. Zhang, S. Y. Zhang, J. Yu, and X. J. Shui, Ultrasonics 39, 591 (2002)]. On the SAW motors (actuators), two Rayleigh wave beams were generated and propagating along the surface of a 128° YK-LiNbO3 substrate in opposite directions with each other as a stator, and a plastic disk with balls distributed along the circle of the disk was as a rotor. For miniaturizing the rotary SAW motors, and increasing the rotation velocity, the SAW frequency must be increased. Then we improve the manufacturing technology of the mechanical structure by PT effect instead of the conventional mechanical processes of the stator and rotor of the motor. A new type of rotary SAW motor (actuator) has been fabricated, in which both SAW beams with opposite propagating directions are excited by two pairs of interdigital transducers with the frequency between 30-50 MHz. In the surface of the stator (128° YX-LiNbO3 substrate), a hole with the depth about 500 μm is impinged by a focused pulsed Nd:YAG laser beam (PT effect) between two SAW propagating ways on the 128° YX-LiNbO3 substrate for fixing the axis of the motor, with the frequency between 30-50 MHz. In the bottom of the rotor (plastic disk), a lot of crown (flange) blocks with the high of 20-30 μm and the diameter of also 20-30 μm can be made by the focused pulsed Nd

  4. Design principle of actuators based on ferromagnetic shape memory alloy

    NASA Astrophysics Data System (ADS)

    Liang, Yuanchang

    2002-09-01

    -strain relationships based on micromechanics has been proposed as well. Finally, several actuators based on polycrystalline Fe-Pd have been reported. These actuators are driven by the "hybrid mechanism". A compact electromagnet may be incorporated in the actuator system.

  5. A moving-actuator type electromechanical total artificial heart--Part I: Linear type and mock circulation experiments.

    PubMed

    Min, B G; Kim, H C; Lee, S H; Kim, J W; Kim, J T; Kim, I Y; Kim, S W; Diegel, P D; Olsen, D B

    1990-12-01

    A new type of motor-driven total artificial heart system with a moving-actuator mechanism has been developed. The prototype system consists of a brushless dc motor inside of a rolling-cylinder, two arc-shaped pusher-plates and two polyurethane sacs. The moving-actuator type electromechanical pump has structural advantages of small size and light weight, as compared to other reported motor-driven pumps with fixed-actuator mechanisms. The results of the mock circulation tests are reported in this paper with a cardiac output of 9 L/min at an aortic pressure of 120 mmHg and a heart rate of 120 bpm. The fulfillment of the basic control requirements of the artificial heart was also confirmed, i.e., preload sensitive and afterload insensitive cardiac output response and balanced right and left ventricular outputs. PMID:2289792

  6. Nonlinear dynamic modeling for smart material electro-hydraulic actuator development

    NASA Astrophysics Data System (ADS)

    Larson, John P.; Dapino, Marcelo J.

    2013-03-01

    Smart material electro-hydraulic actuators use hydraulic rectification by one-way check valves to amplify the motion of smart materials, such as magnetostrictives and piezoelectrics, in order to create compact, lightweight actuators. A piston pump driven by a smart material is combined with a hydraulic cylinder to form a self-contained, power-by-wire actuator that can be used in place of a conventional hydraulic system without the need for hydraulic lines and a centralized pump. The performance of an experimental actuator driven by a 12.7 mm diameter, 114 mm length Terfenol-D rod is evaluated over a range of applied input frequencies, loads, and currents. The peak performance achieved is 37 W, moving a 220 N load at a rate of 17 cm/s and producing a blocked pressure of 12.5 MPa. Additional tests are conducted to quantify the dynamic behavior of the one-way reed valves using a scanning laser vibrometer to identify the frequency response of the reeds and the effect of the valve seat and fluid mass loading. A lumped-parameter model is developed for the system that includes valve inertia and fluid response nonlinearities, and the model results are compared with the experimental data.

  7. Magnetic fish-robot based on multi-motion control of a flexible magnetic actuator.

    PubMed

    Kim, Sung Hoon; Shin, Kyoosik; Hashi, Shuichiro; Ishiyama, Kazushi

    2012-09-01

    This paper presents a biologically inspired fish-robot driven by a single flexible magnetic actuator with a rotating magnetic field in a three-axis Helmholtz coil. Generally, magnetic fish-robots are powered by alternating and gradient magnetic fields, which provide a single motion such as bending the fish-robot's fins. On the other hand, a flexible magnetic actuator driven by an external rotating magnetic field can create several gaits such as the bending vibration, the twisting vibration, and their combination. Most magnetic fish-like micro-robots do not have pectoral fins on the side and are simply propelled by the tail fin. The proposed robot can swim and perform a variety of maneuvers with the addition of pectoral fins and control of the magnetic torque direction. In this paper, we find that the robot's dynamic actuation correlates with the magnetic actuator and the rotating magnetic field. The proposed robot is also equipped with new features, such as a total of six degrees of freedom, a new control method that stabilizes posture, three-dimensional swimming, a new velocity control, and new turning abilities. PMID:22550128

  8. Characterization of linear plasma synthetic jet actuators in an initially quiescent medium

    SciTech Connect

    Santhanakrishnan, Arvind; Reasor, Daniel A. Jr.; LeBeau, Raymond P. Jr.

    2009-04-15

    The plasma synthetic jet actuator (PSJA) is a geometrical variant of the aerodynamic plasma actuator that can be used to produce zero-mass flux jets similar to those created by mechanical devices. This jet can be either three-dimensional using annular electrode arrays (annular PSJA) or nearly two dimensional using two rectangular-strip exposed electrodes and one embedded electrode (linear PSJA). Unsteady pulsing of the PSJA at time scales decoupled to the ac input frequency results in a flow field dominated by counter-rotating vortical structures similar to conventional synthetic jets, and the peak velocity and momentum of the jet is found to be affected by a combination of the pulsing frequency and input power. This paper investigates the fluid dynamic characteristics of linear plasma synthetic jet actuators in an initially quiescent medium. Two-dimensional particle image velocimetry measurements on the actuator are used to validate a previously developed numerical model wherein the plasma behavior is introduced into the Navier-Stokes equations as an electrohydrodynamic force term calculated from Maxwell's equations and solved for the fluid momentum. The numerical model was implemented in an incompressible, unstructured grid code. The results of the simulations are observed to reproduce some aspects of the qualitative and quantitative experimental behavior of the jet for steady and pulsed modes of actuator operation. The self-similarity behavior of plasma synthetic jets are examined and compared to mechanically driven continuous and synthetic jets.

  9. All inkjet-printed electroactive polymer actuators for microfluidic lab-on-chip systems

    NASA Astrophysics Data System (ADS)

    Pabst, Oliver; Beckert, Erik; Perelaer, Jolke; Schubert, Ulrich S.; Eberhardt, Ramona; Tünnermann, Andreas

    2013-04-01

    Piezoelectric electroactive polymers (EAP) are promising materials for applications in microfluidic lab-on-chip systems. In such systems, fluids can be analyzed by different chemical or physical methods. During the analysis the fluids need to be distributed through the channels of the chip, which requires a pumping function. We present here all inkjet-printed EAP actuators that can be configured as a membrane-based micropump suitable for direct integration into lab-on-chip systems. Drop-on-demand inkjet printing is a versatile digital deposition technique that is capable of depositing various functional materials onto a wide variety of substrates in an additive way. Compared to conventional lithography-based processing it is cost-efficient and flexible, as no masking is required. The actuators consist of a polymer foil substrate with an inkjet-printed EAP layer sandwiched between a set of two electrodes. The actuators are printed using a commercially available EAP solution and silver nanoparticle inks. When a voltage is applied across the polymer layer, piezoelectric strain leads to a bending deflection of the beam or membrane. Circular membrane actuators with 20 mm diameter and EAP thicknesses of 10 to 15 μm exhibit deflections of several μm when driven at their resonance frequency with voltages of 110 V. From the behavior of membrane actuators a pumping rate of several 100 μL/min can be estimated, which is promising for applications in lab-on-chip devices.

  10. Design of a series visco-elastic actuator for multi-purpose rehabilitation haptic device

    PubMed Central

    2011-01-01

    Background Variable structure parallel mechanisms, actuated with low-cost motors with serially added elasticity (series elastic actuator - SEA), has considerable potential in rehabilitation robotics. However, reflected masses of a SEA and variable structure parallel mechanism linked with a compliant actuator result in a potentially unstable coupled mechanical oscillator, which has not been addressed in previous studies. Methods The aim of this paper was to investigate through simulation, experimentation and theoretical analysis the necessary conditions that guarantee stability and passivity of a haptic device (based on a variable structure parallel mechanism driven by SEA actuators) when in contact with a human. We have analyzed an equivalent mechanical system where a dissipative element, a mechanical damper was placed in parallel to a spring in SEA. Results The theoretical analysis yielded necessary conditions relating the damping coefficient, spring stiffness, both reflected masses, controller's gain and desired virtual impedance that needs to be fulfilled in order to obtain stable and passive behavior of the device when in contact with a human. The validity of the derived passivity conditions were confirmed in simulations and experimentally. Conclusions These results show that by properly designing variable structure parallel mechanisms actuated with SEA, versatile and affordable rehabilitation robotic devices can be conceived, which may facilitate their wide spread use in clinical and home environments. PMID:21251299

  11. Corrugated paraffin nanocomposite films as large stroke thermal actuators and self-activating thermal interfaces.

    PubMed

    Copic, Davor; Hart, A John

    2015-04-22

    High performance active materials are of rapidly growing interest for applications including soft robotics, microfluidic systems, and morphing composites. In particular, paraffin wax has been used to actuate miniature pumps, solenoid valves, and composite fibers, yet its deployment is typically limited by the need for external volume constraint. We demonstrate that compact, high-performance paraffin actuators can be made by confining paraffin within vertically aligned carbon nanotube (CNT) films. This large-stroke vertical actuation is enabled by strong capillary interaction between paraffin and CNTs and by engineering the CNT morphology by mechanical compression before capillary-driven infiltration of the molten paraffin. The maximum actuation strain of the corrugated CNT-paraffin films (∼0.02-0.2) is comparable to natural muscle, yet the maximum stress is limited to ∼10 kPa by collapse of the CNT network. We also show how a CNT-paraffin film can serve as a self-activating thermal interface that closes a gap when it is heated. These new CNT-paraffin film actuators could be produced by large-area CNT growth, infiltration, and lamination methods, and are attractive for use in miniature systems due to their self-contained design. PMID:25822633

  12. Development of electro-mechanical actuator for TR-1A rocket

    NASA Astrophysics Data System (ADS)

    Mori, Hidehiko; Kochiyama, Jiro; Miwada, Makoto; Sato, Toshiaki; Fujiwara, Teruo; Watanabe, Yasushi; Ohtuka, Hirohito; Fujii, Hiroshi

    TR-1A, a microgravity experiment rocket of the National Space Development Agency of Japan (NASDA), is equiped with an attitude control system with four canards to make the summit of the trajectory high, lengthening the microgravity time period for the experiment and also to make dispersion of the splashdown area narrow for the convenience of the payload recovery. The canards are driven by electro-mechanical actuators. The canards and actuators are located in the interstage section, to be separated from the payload before the microgravity experiment is commenced. Lessons learned in various development tests using engineering and prototype models of the actuator were reflected in the design and fabrication of the flight model actuator. The first flight of TR-1A was conducted on September 16, 1991 at Tanegashima Space Center of NASDA with successful completion of planned microgravity experiments. The electro-mechanical actuators worked perfectly to control the rocket vehicle attitude as programmed throughout the time period of separation of the payload after liftoff.

  13. Spooled packaging of shape memory alloy actuators

    NASA Astrophysics Data System (ADS)

    Redmond, John A.

    A vast cross-section of transportation, manufacturing, consumer product, and medical technologies rely heavily on actuation. Accordingly, progress in these industries is often strongly coupled to the advancement of actuation technologies. As the field of actuation continues to evolve, smart materials show significant promise for satisfying the growing needs of industry. In particular, shape memory alloy (SMA) wire actuators present an opportunity for low-cost, high performance actuation, but until now, they have been limited or restricted from use in many otherwise suitable applications by the difficulty in packaging the SMA wires within tight or unusually shaped form constraints. To address this packaging problem, SMA wires can be spool-packaged by wrapping around mandrels to make the actuator more compact or by redirecting around multiple mandrels to customize SMA wire pathways to unusual form factors. The goal of this dissertation is to develop the scientific knowledge base for spooled packaging of low-cost SMA wire actuators that enables high, predictable performance within compact, customizable form factors. In developing the scientific knowledge base, this dissertation defines a systematic general representation of single and multiple mandrel spool-packaged SMA actuators and provides tools for their analysis, understanding, and synthesis. A quasi-static analytical model distills the underlying mechanics down to the three effects of friction, bending, and binding, which enables prediction of the behavior of generic spool-packaged SMA actuators with specifiable geometric, loading, frictional, and SMA material parameters. An extensive experimental and simulation-based parameter study establishes the necessary understanding of how primary design tradeoffs between performance, packaging, and cost are governed by the underlying mechanics of spooled actuators. A design methodology outlines a systematic approach to synthesizing high performance SMA wire actuators

  14. Lost-motion valve actuator

    SciTech Connect

    Burris, W.J. III; Ringgenberg, P.D.

    1987-04-07

    A lost-motion valve actuator is described for a bore closure valve employed in a well bore, comprising: operating connector means adapted to move the bore closure valve between open and closed positions through longitudinal movement of the operating connector means. The operating connector means comprises an operating connector and a connector insert defining a recess therebetween; locking dog means comprising at least one locking dog received in the recess and spring biasing means adapted to urge at least one locking dog radially inwardly; and mandrel means slidably received within the operating connector means and including dog slot means associated therewith. The dog slot means comprises an annular slot on the exterior of the mandrel means adapted to lockingly receive at least one inwardly biased locking dog when proximate thereto, whereby longitudinal movement of the mandrel means is transmitted to the operating connector means.

  15. Magnetic actuation of hair cells

    PubMed Central

    Rowland, David; Roongthumskul, Yuttana; Lee, Jae-Hyun; Cheon, Jinwoo; Bozovic, Dolores

    2011-01-01

    The bullfrog sacculus contains mechanically sensitive hair cells whose stereociliary bundles oscillate spontaneously when decoupled from the overlying membrane. Steady-state offsets on the resting position of a hair bundle can suppress or modulate this native motility. To probe the dynamics of spontaneous oscillation in the proximity of the critical point, we describe here a method for mechanical actuation that avoids loading the bundles or contributing to the viscous drag. Magnetite beads were attached to the tips of the stereocilia, and a magnetic probe was used to impose deflections. This technique allowed us to observe the transition from multi-mode to single-mode state in freely oscillating bundles, as well as the crossover from the oscillatory to the quiescent state. PMID:22163368

  16. Magnetic actuation of hair cells.

    PubMed

    Rowland, David; Roongthumskul, Yuttana; Lee, Jae-Hyun; Cheon, Jinwoo; Bozovic, Dolores

    2011-11-01

    The bullfrog sacculus contains mechanically sensitive hair cells whose stereociliary bundles oscillate spontaneously when decoupled from the overlying membrane. Steady-state offsets on the resting position of a hair bundle can suppress or modulate this native motility. To probe the dynamics of spontaneous oscillation in the proximity of the critical point, we describe here a method for mechanical actuation that avoids loading the bundles or contributing to the viscous drag. Magnetite beads were attached to the tips of the stereocilia, and a magnetic probe was used to impose deflections. This technique allowed us to observe the transition from multi-mode to single-mode state in freely oscillating bundles, as well as the crossover from the oscillatory to the quiescent state. PMID:22163368

  17. Droplet actuator analyzer with cartridge

    NASA Technical Reports Server (NTRS)

    Smith, Gregory F. (Inventor); Sturmer, Ryan A. (Inventor); Paik, Philip Y. (Inventor); Srinivasan, Vijay (Inventor); Pollack, Michael G. (Inventor); Pamula, Vamsee K. (Inventor); Brafford, Keith R. (Inventor); West, Richard M. (Inventor)

    2011-01-01

    A droplet actuator with cartridge is provided. According to one embodiment, a sample analyzer is provided and includes an analyzer unit comprising electronic or optical receiving means, a cartridge comprising self-contained droplet handling capabilities, and a wherein the cartridge is coupled to the analyzer unit by a means which aligns electronic and/or optical outputs from the cartridge with electronic or optical receiving means on the analyzer unit. According to another embodiment, a sample analyzer is provided and includes a sample analyzer comprising a cartridge coupled thereto and a means of electrical interface and/or optical interface between the cartridge and the analyzer, whereby electrical signals and/or optical signals may be transmitted from the cartridge to the analyzer.

  18. Pressure-actuated joint system

    NASA Technical Reports Server (NTRS)

    McGuire, John R. (Inventor)

    2004-01-01

    A pressure vessel is provided that includes first and second case segments mated with one another. First and second annular rubber layers are disposed inboard of the first and second case segments, respectively. The second annular rubber layer has a slot extending from the radial inner surface across a portion of its thickness to define a main body portion and a flexible portion. The flexible portion has an interfacing surface portion abutting against an interfacing surface portion of the first annular rubber layer to follow movement of the first annular rubber layer during operation of the pressure vessel. The slot receives pressurized gas and establishes a pressure-actuated joint between the interfacing surface portions. At least one of the interfacing surface portions has a plurality of enclosed and sealed recesses formed therein.

  19. Out-of-Plane Translational PZT Bimorph Actuator with Archimedes’ Spiral Actuating Tethers

    NASA Astrophysics Data System (ADS)

    Yang, Chenye; Liu, Sanwei; Livermore, Carol

    2015-12-01

    The design, finite element analysis (FEA), and experimental characterization of a MEMS out-of-plane (vertical) translational lead-zirconate-titanate (PZT) bimorph actuator supported on Archimedes’ spiral tethers are presented. Two types of bimorph actuators with different electrode patterns (with spiral tethers half actuated or fully actuated) are designed and fabricated. Both designs are fabricated by commercial processes and are compatible with integration into more complex MEMS systems. Finite element analysis (FEA) was used to analyze and predict the displacements of both types of actuators. The deflections of both fully- actuated and half-actuated devices were measured experimentally to validate the design. At an applied voltage of 110V, the out-of-plane deflections of the actuators with half-actuated and fully-actuated tethers were measured at about 17 μm and 29 μm respectively, in good agreement with FEA predictions of 17.1 μm and 25.8 μm. The corresponding blocking forces are predicted as 10 mN and 17 mN by FEA.

  20. Enhanced Actuation Performance and Reduced Heat Generation in Shear-Bending Mode Actuator at High Temperature.

    PubMed

    Chen, Jianguo; Liu, Guoxi; Cheng, Jinrong; Dong, Shuxiang

    2016-08-01

    The actuation performance, strain hysteresis, and heat generation of the shear-bending mode actuators based on soft and hard BiScO3-PbTiO3 (BS-PT) ceramics were investigated under different thermal (from room temperature to 300 °C) and electrical loadings (from 2 to 10 kV/cm and from 1 to 1000 Hz). The actuator based on both soft and hard BS-PT ceramics worked stably at the temperature as high as 300 °C. The maximum working temperature of this shear-bending actuators is 150 °C higher than those of the traditional piezoelectric actuators based on commercial Pb(Zr, Ti)O3 materials. Furthermore, although the piezoelectric properties of soft-type ceramics based on BS-PT ceramics were superior to those of hard ceramics, the maximum displacement of the actuator based on hard ceramics was larger than that fabricated by soft ceramics at high temperature. The maximum displacement of the actuator based on hard ceramics was [Formula: see text] under an applied electric field of 10 kV/cm at 300 °C. The strain hysteresis and heat generation of the actuator based on hard ceramics was smaller than those of the actuator based on soft ceramics in the wide temperature range. These results indicated that the shear-bending actuator based on hard piezoelectric ceramics was more suitable for high-temperature piezoelectric applications. PMID:27214895

  1. Bi-directional series-parallel elastic actuator and overlap of the actuation layers.

    PubMed

    Furnémont, Raphaël; Mathijssen, Glenn; Verstraten, Tom; Lefeber, Dirk; Vanderborght, Bram

    2016-02-01

    Several robotics applications require high torque-to-weight ratio and energy efficient actuators. Progress in that direction was made by introducing compliant elements into the actuation. A large variety of actuators were developed such as series elastic actuators (SEAs), variable stiffness actuators and parallel elastic actuators (PEAs). SEAs can reduce the peak power while PEAs can reduce the torque requirement on the motor. Nonetheless, these actuators still cannot meet performances close to humans. To combine both advantages, the series parallel elastic actuator (SPEA) was developed. The principle is inspired from biological muscles. Muscles are composed of motor units, placed in parallel, which are variably recruited as the required effort increases. This biological principle is exploited in the SPEA, where springs (layers), placed in parallel, can be recruited one by one. This recruitment is performed by an intermittent mechanism. This paper presents the development of a SPEA using the MACCEPA principle with a self-closing mechanism. This actuator can deliver a bi-directional output torque, variable stiffness and reduced friction. The load on the motor can also be reduced, leading to a lower power consumption. The variable recruitment of the parallel springs can also be tuned in order to further decrease the consumption of the actuator for a given task. First, an explanation of the concept and a brief description of the prior work done will be given. Next, the design and the model of one of the layers will be presented. The working principle of the full actuator will then be given. At the end of this paper, experiments showing the electric consumption of the actuator will display the advantage of the SPEA over an equivalent stiff actuator. PMID:26813145

  2. Design, characterization, and testing of macro-fiber composite actuators for integration on a fixed-wing UAV

    NASA Astrophysics Data System (ADS)

    Prazenica, Richard J.; Kim, Daewon; Moncayo, Hever; Azizi, Boutros; Chan, May

    2014-04-01

    Smart materials offer several potential advantages for UAV flight control applications compared to traditional servo actuators. One important benefit is that smart materials are lightweight and can be embedded directly into the structure of a wing or control surface. Therefore, they can reduce the overall weight of the vehicle and eliminate the need for mechanical appendages that may compromise the form factor of the wing, benefits that become more significant as the size of the vehicle decreases. In addition, smart materials can be used to realize continuous camber change of aerodynamic surfaces. Such designs offer improved aerodynamic efficiency compared to the discontinuous deflections of traditional hinged control surfaces driven by servo actuators. In the research discussed in this paper, macro-fiber composite (MFC) aileron actuators are designed for implementation on a medium-scale, fixed-wing UAV in order to achieve roll control. Macro-fiber composites, which consist of piezoceramic fibers and electrodes embedded in an epoxy matrix, are an attractive choice for UAV actuation because they are manufactured as lightweight, thin sheets and, when implemented as bending actuators, can provide both large structural deflections and high bandwidth. In this study, several MFC aileron actuator designs were evaluated through a combination of theoretical and experimental analysis. The current design consists of glass fiber composite ailerons with two unimorph MFC actuators embedded in each aileron to produce upward deflection. Wind tunnel test results are presented to assess the changes in lift and drag coefficients for different levels of MFC aileron actuation. Preparations for open-loop flight testing using a Skywalker UAV with MFC ailerons are also discussed. In addition, the development of a closed-loop, autonomous flight control system for the Skywalker is overviewed in preparation for conducting simulations and flight testing of an autonomous Skywalker with MFC

  3. Post-buckled precompressed (PBP) elements: a new class of flight control actuators enhancing high-speed autonomous VTOL MAVs

    NASA Astrophysics Data System (ADS)

    Barrett, Ronald; McMurtry, Ross; Vos, Roelof; Tiso, Paolo; Breuker, Roeland D.

    2005-05-01

    This paper describes a new class of flight control actuators using Post-Buckled Precompressed (PBP) piezoelectric elements. These actuators are designed to produce significantly higher deflection and force levels than conventional piezoelectric actuator elements. Classical laminate plate theory (CLPT) models are shown to work very well in capturing the behavior of the free, unloaded elements. A new high transverse deflection model which employs nonlinear structural relations is shown to successfully predict the performance of the PBP actuators as they are exposed to higher and higher levels of axial force, which induces post buckling deflections. A proof-of-concept empennage assembly and actuator were fabricated using the principles of PBP actuation. A single grid-fin flight control effector was driven by a 3.5" (88.9mm) long piezoceramic bimorph PBP actuator. By using the PBP configuration, deflections were controllably magnified 4.5 times with excellent correlation between theory and experiment. Quasi-static bench testing showed deflection levels in excess of +/-6° at rates exceeding 15 Hz. The new solid state PBP actuator was shown to reduce the part count with respect to conventional servoactuators by an order of magnitude. Power consumption dropped from 24W to 100mW, weight was cut from 108g to 14g, slop went from 1.6° to 0.02° and current draw went from 5A to 1.4mA. The result was that the XQ-138 subscale UAV family experienced nearly a 4% reduction in operating empty weight via the switch from conventional to PBP actuators while in every other measure, gross performance was significantly enhanced.

  4. Magnetic suspension characteristics of electromagnetic actuators

    NASA Technical Reports Server (NTRS)

    Rao, Dantam K.; Dill, J.; Zorzi, E.

    1993-01-01

    Electromagnetic actuators that use a current-carrying coil (which is placed in a magnetic field) to generate mechanical force are conceptually attractive components for active control of rotating shafts. In one concept that is being tested in the laboratory, the control forces from such actuators are applied on the flexibly supported bearing housings of the rotor. Development of this concept into a practical reality requires a clear and thorough understanding of the role of electromechanical parameters of these actuators in delivering the right amount of control force at the right phase into the rotor. The electromechanical parameters of the actuators investigated are the mass of the armature, stiffness of its suspension, electrical resistance, and inductance of the coils. Improper selection of these parameters can result in degradation in their performance, leading to mistuning between the actuator and the rotor. Through a simple analysis, it is shown that use of such mistuned actuators could result in sharp fluctuations in the phase of the control force delivered into the rotor around the critical speeds. These sharp fluctuations in phase, called 'Phase Glitches', are undesirable. Hence, future designs of controllers should take into account the undesirable mistuning effects between the actuator and the rotor caused by the phase glitches.

  5. Dielectric elastomer actuators with hydrostatic coupling

    NASA Astrophysics Data System (ADS)

    Carpi, Federico; Frediani, Gabriele; De Rossi, Danilo

    2009-03-01

    The rapidly growing adoption of dielectric elastomer (DE) actuators as a high performance EAP technology for many kinds of new applications continuously opens new technical challenges, in order to take always the most from each adopted device and actuating configuration. This paper presents a new type of DE actuators, which show attractive potentialities for specific application needs. The concept here proposed adopts an incompressible fluid to mechanically couple active and passive parts. The active parts work according to the DE actuation principle, while the passive parts represent the end effector, in contact with the load. The fluid is used to transfer actuation hydrostatically from an active to a passive part and, then, to the load. This can provide specific advantages, including improved safety and less stringent design constraints for the architecture of the actuator, especially for soft end effectors. Such a simple concept can be readily implemented according to different shapes and intended functionalities of the resulting actuators. The paper describes the structure and the performance of the first prototype devices developed so far.

  6. Thermostatic Valves Containing Silicone-Oil Actuators

    NASA Technical Reports Server (NTRS)

    Bhandari, Pradeep; Birur, Gajanana C.; Bame, David P.; Karlmann, Paul B.; Prina, Mauro; Young, William; Fisher, Richard

    2009-01-01

    Flow-splitting and flow-mixing thermally actuated spool valves have been developed for controlling flows of a heat-transfer fluid in a temperature-regulation system aboard the Mars Science Laboratory (MSL) rover. Valves like these could also be useful in terrestrial temperature-regulation systems, including automobile air-conditioning systems and general refrigeration systems. These valves are required to provide smoother actuation over a wider temperature range than the flow-splitting, thermally actuated spool valves used in the Mars Explorer Rover (MER). Also, whereas the MER valves are unstable (tending to oscillate) in certain transition temperature ranges, these valves are required not to oscillate. The MER valves are actuated by thermal expansion of a wax against spring-loaded piston rods (as in common automotive thermostats). The MSL valves contain similar actuators that utilize thermal expansion of a silicone oil, because silicone-oil actuators were found to afford greater and more nearly linear displacements, needed for smoother actuation, over the required wider temperature range. The MSL valves also feature improved spool designs that reflect greater understanding of fluid dynamics, consideration of pressure drops in valves, and a requirement for balancing of pressures in different flow branches.

  7. Active Damping Using Distributed Anisotropic Actuators

    NASA Technical Reports Server (NTRS)

    Schiller, Noah H.; Cabell, Randolph H.; Quinones, Juan D.; Wier, Nathan C.

    2010-01-01

    A helicopter structure experiences substantial high-frequency mechanical excitation from powertrain components such as gearboxes and drive shafts. The resulting structure-borne vibration excites the windows which then radiate sound into the passenger cabin. In many cases the radiated sound power can be reduced by adding damping. This can be accomplished using passive or active approaches. Passive treatments such as constrained layer damping tend to reduce window transparency. Therefore this paper focuses on an active approach utilizing compact decentralized control units distributed around the perimeter of the window. Each control unit consists of a triangularly shaped piezoelectric actuator, a miniature accelerometer, and analog electronics. Earlier work has shown that this type of system can increase damping up to approximately 1 kHz. However at higher frequencies the mismatch between the distributed actuator and the point sensor caused control spillover. This paper describes new anisotropic actuators that can be used to improve the bandwidth of the control system. The anisotropic actuators are composed of piezoelectric material sandwiched between interdigitated electrodes, which enables the application of the electric field in a preferred in-plane direction. When shaped correctly the anisotropic actuators outperform traditional isotropic actuators by reducing the mismatch between the distributed actuator and point sensor at high frequencies. Testing performed on a Plexiglas panel, representative of a helicopter window, shows that the control units can increase damping at low frequencies. However high frequency performance was still limited due to the flexible boundary conditions present on the test structure.

  8. Elastomeric actuator devices for magnetic resonance imaging

    NASA Technical Reports Server (NTRS)

    Dubowsky, Steven (Inventor); Hafez, Moustapha (Inventor); Jolesz, Ferenc A. (Inventor); Kacher, Daniel F. (Inventor); Lichter, Matthew (Inventor); Weiss, Peter (Inventor); Wingert, Andreas (Inventor)

    2008-01-01

    The present invention is directed to devices and systems used in magnetic imaging environments that include an actuator device having an elastomeric dielectric film with at least two electrodes, and a frame attached to the actuator device. The frame can have a plurality of configurations including, such as, for example, at least two members that can be, but not limited to, curved beams, rods, plates, or parallel beams. These rigid members can be coupled to flexible members such as, for example, links wherein the frame provides an elastic restoring force. The frame preferably provides a linear actuation force characteristic over a displacement range. The linear actuation force characteristic is defined as .+-.20% and preferably 10% over a displacement range. The actuator further includes a passive element disposed between the flexible members to tune a stiffness characteristic of the actuator. The passive element can be a bi-stable element. The preferred embodiment actuator includes one or more layers of the elastomeric film integrated into the frame. The elastomeric film can be made of many elastomeric materials such as, for example, but not limited to, acrylic, silicone and latex.

  9. Characterization of piezoelectric macrofiber composite actuated winglets

    NASA Astrophysics Data System (ADS)

    Guha, T. K.; Oates, W. S.; Kumar, R.

    2015-06-01

    The present study primarily focuses on the design, development, and structural characterization of an oscillating winglet actuated using a piezoelectric macrofiber composite (MFC). The primary objective is to study the effect of controlled wingtip oscillations on the evolution of wingtip vortices, with a goal of weakening these potentially harmful tip vortices by introducing controlled instabilities through both spatial and temporal perturbations producible through winglet oscillations. MFC-actuated winglets have been characterized under different input excitation and pressure-loading conditions. The winglet oscillations show bimodal behavior for both structural and actuation modes of resonance. The oscillatory amplitude at these actuation modes increases linearly with the magnitude of excitation. During wind-tunnel tests, fluid-structure interactions led to structural vibrations of the wing. The effect of these vibrations on the overall winglet oscillations decreased when the strength of actuation increased. At high input excitation, the actuated winglet was capable of generating controlled oscillations. As a proof of concept, the current study has demonstrated that microfiber composite-actuated winglets produce sufficient displacements to alter the development of the wingtip vortex.

  10. V2O5 nanofibre sheet actuators

    NASA Astrophysics Data System (ADS)

    Gu, Gang; Schmid, Michael; Chiu, Po-Wen; Minett, Andrew; Fraysse, Jerôme; Kim, Gyu-Tae; Roth, Siegmar; Kozlov, Mikhail; Muñoz, Edgar; Baughman, Ray H.

    2003-05-01

    Vanadium oxides, such as V2O5, are promising for lithium-ion batteries, catalysis, electrochromic devices and sensors. Vanadium oxides were proposed more than a decade ago for another redox-dependent application: the direct conversion of electrical energy to mechanical energy in actuators (artificial muscles). Although related conducting polymer and carbon nanotube actuators have been demonstrated, electromechanical actuators based on vanadium oxides have not be realized. V2O5 nanofibres and nanotubes provide the potential advantages of low-cost synthesis by sol-gel routes and high charging capacity and long cycle life. Here, we demonstrate electromechanical actuation for obtained high modulus V2O5 sheets comprising entangled V2O5 nanofibres. The high surface area of these V2O5 sheets facilitates electrochemical charge injection and intercalation that causes the electromechanical actuation. We show that the V2O5 sheets provide high Young's modulus, high actuator-generated stress, and high actuator stroke at low applied voltage.

  11. A new concept for actuating space mechanisms. [for the Mariner Jupiter-Saturn spacecraft magnetometer

    NASA Technical Reports Server (NTRS)

    Stange, W. C.

    1975-01-01

    A two position (0 and 180 deg) actuating mechanism driven by two alternately heated opposing flat NITINOL springs is proposed for rotating the low field triaxial fluxgate magnetometer experiment on the 1977 Mariner Jupiter-Saturn spacecraft to its 0 deg and 180 deg positions. The magnetic field, power requirements, weight, and volume of this device are very restrictive. The problems encountered in design and development are presented.

  12. Advanced piezoelectric single crystal based actuators

    NASA Astrophysics Data System (ADS)

    Jiang, Xiaoning; Rehrig, Paul W.; Hackenberger, Wesley S.; Smith, Edward; Dong, Shuxiang; Viehland, Dwight; Moore, Jim, Jr.; Patrick, Brian

    2005-05-01

    TRS is developing new actuators based on single crystal piezoelectric materials such as Pb(Zn1/3Nb2/3)1-xTixO3 (PZN-PT) and Pb(Mg1/3Nb2/3)x-1TixO3 (PMN-PT) which exhibit very high piezoelectric coefficients (d33 = 1800-2200 pC/N) and electromechanical coupling factors (k33 > 0.9), respectively, for a variety of applications, including active vibration damping, active flow control, high precision positioning, ultrasonic motors, deformable mirrors, and adaptive optics. The d32 cut crystal plate actuators showed d32 ~ -1600 pC/N, inter-digital electroded (IDE) plate actuators showed effective d33 ~ 1100 pC/N. Single crystal stack actuators with stroke of 10 μm-100 μm were developed and tested at both room temperature and cryogenic temperatures. Flextensional single crystal piezoelectric actuators with either stack driver or plate driver were developed with stroke 70 μm - > 250 μm. For large stroke cryogenic actuation (> 1mm), a single crystal piezomotor was developed and tested at temperature of 77 K-300K and stroke of > 10mm and step resolution of 20 nm were achieved. In order to demonstrate the significance of developed single crystal actuators, modeling on single crystal piezoelectric deformable mirrors and helicopter flap control using single crystal actuators were conducted and the modeling results show that more than 20 wavelength wavefront error could be corrected by using the single crystal deformable mirrors and +/- 5.8 ° flap deflection will be obtained for a 36" flap using single crystal stack actuators.

  13. The emphasis given to evolution in state science standards: A lever for change in evolution education?

    NASA Astrophysics Data System (ADS)

    Skoog, Gerald; Bilica, Kimberly

    2002-07-01

    This study analyzed the science frameworks of 49 states and the District of Colombia to determine the emphasis given to evolution in these documents at the middle and secondary levels. These concepts were species evolve over time, speciation, diversity of life, descent with modification from common ancestry, evidence of evolution, natural selection, pace and direction of evolution, and human evolution. Collectively, the 50 science frameworks emphasized evolution in a manner that suggests that if the public's support for standards-based curricula is a reality, the study of evolution will be emphasized in an unprecedented manner in the nation's schools in the near future. However, all concepts were not emphasized equally in these documents. For example, human evolution was included in only seven documents. The word evolution is absent from some standards. Despite these negatives, recent actions to improve existing standards or to adopt new standards that emphasize evolution have occurred. The metaphor lever of change is often used in the context of school reform. This metaphor suggests a simple system where one change can result in a desired outcome. However, in classrooms where curriculum decisions evolve constantly, multiple factors interact and reinforce one another in response to both internal and external contingencies that emerge. Educational change can not be reduced to a simple linear cause/effect situation. The change process involved is nonlinear where what goes in is not proportional to what comes out because of feedback loops and other factors that complicate results. This nonlinearity is reflected in the varied responses of teachers to specific contingencies. Yet, systems can be changed and nudged towards a structure where desired outcomes will emerge. Judicial rulings indicating that the teaching of evolution cannot be prohibited or equal time for creationism mandated, improved coverage of evolution in secondary school biology textbooks, the negative

  14. Membrane Mirrors With Bimorph Shape Actuators

    NASA Technical Reports Server (NTRS)

    Yang, Eui-Hyeok

    2003-01-01

    Deformable mirrors of a proposed type would be equipped with relatively-large-stroke microscopic piezoelectric actuators that would be used to maintain their reflective surfaces in precise shapes. These mirrors would be members of the class of MEMS-DM (for microelectromechanical system deformable mirror) devices, which offer potential for a precise optical control in adaptive-optics applications in such diverse fields as astronomy and vision science. The proposed mirror would be fabricated, in part, by use of a membrane-transfer technique. The actuator design would contain bimorph-type piezoelectric actuators.

  15. Diagnostics for characterisation of plasma actuators

    NASA Astrophysics Data System (ADS)

    Kotsonis, Marios

    2015-09-01

    The popularity of plasma actuators as flow control devices has sparked a flurry of diagnostic efforts towards their characterisation. This review article presents an overview of experimental investigations employing diagnostic techniques specifically aimed at AC dielectric barrier discharge, DC corona and nanosecond pulse plasma actuators. Mechanical, thermal and electrical characterisation techniques are treated. Various techniques for the measurement of induced velocity, body force, heating effects, voltage, current, power and discharge morphology are presented and common issues and challenges are described. The final part of this report addresses the effect of ambient conditions on the performance of plasma actuators.

  16. Optimization Strategies for Sensor and Actuator Placement

    NASA Technical Reports Server (NTRS)

    Padula, Sharon L.; Kincaid, Rex K.

    1999-01-01

    This paper provides a survey of actuator and sensor placement problems from a wide range of engineering disciplines and a variety of applications. Combinatorial optimization methods are recommended as a means for identifying sets of actuators and sensors that maximize performance. Several sample applications from NASA Langley Research Center, such as active structural acoustic control, are covered in detail. Laboratory and flight tests of these applications indicate that actuator and sensor placement methods are effective and important. Lessons learned in solving these optimization problems can guide future research.

  17. Microcantilever actuation via periodic internal heating

    SciTech Connect

    Lee, Jungchul; King, William P.

    2007-12-15

    This paper reports electrothermal actuation of silicon microcantilevers having integrated resistive heaters. Periodic electrical excitation induced periodic resistive heating in the cantilever, while the cantilever deflection was monitored with a photodetector. Excitation was either at the cantilever resonant frequency, f{sub 0}, f{sub 0}/2, or f{sub 0}/3. When the time averaged maximum cantilever temperature was 174 deg. C, the cantilever out-of-plane actuation amplitude was 484 nm near the cantilever resonance frequency of 24.9 kHz. This actuation was sufficiently large to operate the cantilever in intermittent contact mode and scan a calibration grating of height of 20 nm.

  18. Refreshable Braille Displays Using EAP Actuators

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph

    2010-01-01

    Refreshable Braille can help visually impaired persons benefit from the growing advances in computer technology. The development of such displays in a full screen form is a great challenge due to the need to pack many actuators in small area without interferences. In recent years, various displays using actuators such as piezoelectric stacks have become available in commercial form but most of them are limited to one line Braille code. Researchers in the field of electroactive polymers (EAP) investigated methods of using these materials to form full screen displays. This manuscript reviews the state of the art of producing refreshable Braille displays using EAP-based actuators..

  19. Misfire tolerant combustion-powered actuation

    DOEpatents

    Spletzer, Barry L.; Fischer, Gary J.; Marron, Lisa C.; Kuehl, Michael A.

    2001-01-01

    The present invention provides a combustion-powered actuator that is suitable for intermittent actuation, that is suitable for use with atmospheric pressure carburetion, and that requires little electrical energy input. The present invention uses energy from expansion of pressurized fuel to effectively purge a combustion chamber, and to achieve atmospheric pressure carburetion. Each purge-fill-power cycle can be independent, allowing the actuator to readily tolerate misfires. The present invention is suitable for use with linear and rotary operation combustion chambers, and is suitable for use in a wide variety of applications.

  20. A Model of the THUNDER Actuator

    NASA Technical Reports Server (NTRS)

    Curtis, Alan R. D.

    1997-01-01

    A THUNDER actuator is a composite of three thin layers, a metal base, a piezoelectric wafer and a metal top cover, bonded together under pressure and at high temperature with the LaRC SI polyimid adhesive. When a voltage is applied between the metal layers across the PZT the actuator will bend and can generate a force. This document develops and describes an analytical model the transduction properties of THUNDER actuators. The model development is divided into three sections. First, a static model is described that relates internal stresses and strains and external displacements to the thermal pre-stress and applied voltage. Second, a dynamic energy based model is described that allows calculation of the resonance frequencies, developed force and electrical input impedance. Finally, a fully coupled electro-mechanical transducer model is described. The model development proceeds by assuming that both the thermal pre-stress and the piezoelectric actuation cause the actuator to deform in a pure bend in a single plane. It is useful to think of this as a two step process, the actuator is held flat, differential stresses induce a bending moment, the actuator is released and it bends. The thermal pre-stress is caused by the different amounts that the constituent layers shrink due to their different coefficients of thermal expansion. The adhesive between layers sets at a high temperature and as the actuator cools, the metal layers shrink more than the PZT. The PZT layer is put into compression while the metal layers are in tension. The piezoelectric actuation has a similar effect. An applied voltage causes the PZT layer to strain, which in turn strains the two metal layers. If the PZT layer expands it will put the metal layers into tension and PZT layer into compression. In both cases, if shear force effects are neglected, the actuator assembly will experience a uniform in-plane strain. As the materials each have a different elastic modulus, different stresses will