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1

Thrust-Vector-Control System  

NASA Technical Reports Server (NTRS)

Control gains computed via matrix Riccati equation. Software-based system controlling aim of gimbaled rocket motor on spacecraft adaptive and optimal in sense it adjusts control gains in response to feedback, according to optimizing algorithm based on cost function. Underlying control concept also applicable, with modifications, to thrust-vector control on vertical-takeoff-and-landing airplanes, control of orientations of scientific instruments, and robotic control systems.

Murray, Jonathan

1992-01-01

2

Thrust Vector Control System Study for a Large Liquid Booster.  

National Technical Information Service (NTIS)

This effort consisted of evaluating six thrust vector control systems for application on a Large Liquid Booster. The thrust vector control systems evaluated were liquid injection thrust vector control, hot gas secondary injection thrust vector control and...

D. Stump, V. Olivier

1968-01-01

3

Ascent thrust vector control system test  

NASA Technical Reports Server (NTRS)

Testing of the Ascent Thrust Vector Control System in support of the Ares 1-X program at the Marshall Space Flight Center in Huntsville, Alabama. This image is extracted from a high definition video file and is the highest resolution available

2008-01-01

4

Three axis velocity probe system  

DOEpatents

A three-axis velocity probe system for determining three-axis positional velocities of small particles in fluidized bed systems and similar applications. This system has a sensor head containing four closely-spaced sensing electrodes of small wires that have flat ends to establish a two axis plane, e.g. a X-Y plane. Two of the sensing electrodes are positioned along one of the axes and the other two are along the second axis. These four sensing electrodes are surrounded by a guard electrode, and the outer surface is a ground electrode and support member for the sensing head. The electrodes are excited by, for example, sinusoidal voltage having a peak-to-peak voltage of up to 500 volts at a frequency of 2 MHz. Capacitive currents flowing between the four sensing electrodes and the ground electrode are influenced by the presence and position of a particle passing the sensing head. Any changes in these currents due to the particle are amplified and synchronously detected to produce positional signal values that are converted to digital form. Using these digital forms and two values of time permit generation of values of the three components of the particle vector and thus the total velocity vector.

Fasching, George E. (Morgantown, WV); Smith, Jr., Nelson S. (Morgantown, WV); Utt, Carroll E. (Morgantown, WV)

1992-01-01

5

Omni-axis secondary injection thrust vector control system  

NASA Technical Reports Server (NTRS)

The concept, development, design study and preliminary analysis and layout of the required digital logic scheme to be used for injection valve control are presented. An application and optimization study of an Omni-Axis Secondary Injection Control System applicable to the proposed Space Shuttle Pressure Fed Engine is reported. Technical definition and analysis control procedures and test routines, as well as a supporting set of drawing sketches and reference manual, are enclosed.

Kirkley, D. J.

1973-01-01

6

The development of H-II rocket solid rocket booster thrust vector control system  

NASA Astrophysics Data System (ADS)

The development of the thrust-vector-control (TVC) system for the two solid rocket boosters (SRBs) of the H-II rocket, which was started in 1984 and completed in 1989, is described. Special attention is given to the system's design, the trade-off studies, and the evaluation of the SRB-TVC system performance, as well as to problems that occurred in the course of the system's development and to the countermeasures that were taken. Schematic diagrams are presented for the H-II rocket, the SRB, and the SRB-TVC system configurations.

Nagai, Hirokazu; Fukushima, Yukio; Kazama, Hiroo; Asai, Tatsuro; Okaya, Shunichi; Watanabe, Yasushi; Muramatsu, Shoji

7

Fluidic thrust vector control  

NASA Astrophysics Data System (ADS)

The design and testing of a fluidic control nozzle for tactical missile thrust vector control (TVC) are discussed. Attention is given to a nozzle with a circular cross section up to the point of flow separation, two control ports that alternately open and close, and a nozzle extension downstream of the control ports being a two-dimensional rectangular slot. Design of the TVC system involved characterizing the flow and the sensitivity parameters, the dynamic response, and the performance of hot-gas firings. The test firings verified the feasibility of a nozzle that could withstand 5000 F, the use of thrust vector angles of over 20 deg. A dynamic model test demonstrated a repeatable performance with pressures up to 2000 psia, driving frequencies up to 50 Hz, and a response of 10-15 msec. Adjustment of the chamber pressures permitted equivalent performance using with different heat ratios during cold dynamic tests with CH4.

Haloulakos, V. E.

8

Noise generated by a flight weight, air flow control valve in a vertical takeoff and landing aircraft thrust vectoring system  

Microsoft Academic Search

Tests were conducted in the NASA Lewis Research Center's Powered Lift Facility to experimentally evaluate the noise generated by a flight weight, 12 in. butterfly valve installed in a proposed vertical takeoff and landing thrust vectoring system. Fluctuating pressure measurements were made in the circular duct upstream and downstream of the valve. This data report presents the results of these

Ronald G. Huff

1989-01-01

9

Results of solar electric thrust vector control system design, development and tests  

NASA Technical Reports Server (NTRS)

Efforts to develop and test a thrust vector control system TVCS for a solar-energy-powered ion engine array are described. The results of solar electric propulsion system technology (SEPST) III real-time tests of present versions of TVCS hardware in combination with computer-simulated attitude dynamics of a solar electric multi-mission spacecraft (SEMMS) Phase A-type spacecraft configuration are summarized. Work on an improved solar electric TVCS, based on the use of a state estimator, is described. SEPST III tests of TVCS hardware have generally proved successful and dynamic response of the system is close to predictions. It appears that, if TVCS electronic hardware can be effectively replaced by control computer software, a significant advantage in control capability and flexibility can be gained in future developmental testing, with practical implications for flight systems as well. Finally, it is concluded from computer simulations that TVCS stabilization using rate estimation promises a substantial performance improvement over the present design.

Fleischer, G. E.

1973-01-01

10

Application of Diagnostic Analysis Tools to the Ares I Thrust Vector Control System  

NASA Technical Reports Server (NTRS)

The NASA Ares I Crew Launch Vehicle is being designed to support missions to the International Space Station (ISS), to the Moon, and beyond. The Ares I is undergoing design and development utilizing commercial-off-the-shelf tools and hardware when applicable, along with cutting edge launch technologies and state-of-the-art design and development. In support of the vehicle s design and development, the Ares Functional Fault Analysis group was tasked to develop an Ares Vehicle Diagnostic Model (AVDM) and to demonstrate the capability of that model to support failure-related analyses and design integration. One important component of the AVDM is the Upper Stage (US) Thrust Vector Control (TVC) diagnostic model-a representation of the failure space of the US TVC subsystem. This paper first presents an overview of the AVDM, its development approach, and the software used to implement the model and conduct diagnostic analysis. It then uses the US TVC diagnostic model to illustrate details of the development, implementation, analysis, and verification processes. Finally, the paper describes how the AVDM model can impact both design and ground operations, and how some of these impacts are being realized during discussions of US TVC diagnostic analyses with US TVC designers.

Maul, William A.; Melcher, Kevin J.; Chicatelli, Amy K.; Johnson, Stephen B.

2010-01-01

11

Noise generated by a flight weight, air flow control valve in a vertical takeoff and landing aircraft thrust vectoring system  

NASA Technical Reports Server (NTRS)

Tests were conducted in the NASA Lewis Research Center's Powered Lift Facility to experimentally evaluate the noise generated by a flight weight, 12 in. butterfly valve installed in a proposed vertical takeoff and landing thrust vectoring system. Fluctuating pressure measurements were made in the circular duct upstream and downstream of the valve. This data report presents the results of these tests. The maximum overall sound pressure level is generated in the duct downstream of the valve and reached a value of 180 dB at a valve pressure ratio of 2.8. At the higher valve pressure ratios the spectra downstream of the valve is broad banded with its maximum at 1000 Hz.

Huff, Ronald G.

1989-01-01

12

Haptic controlled three-axis MEMS gripper system.  

PubMed

In this work, we describe the development and testing of a three degree of freedom meso/micromanipulation system for handling micro-objects, including biological cells and microbeads. Three-axis control is obtained using stepper motors coupled to micromanipulators. The test specimen is placed on a linear X-stage, which is coupled to one stepper motor. The remaining two stepper motors are coupled to the Y and Z axes of a micromanipulator. The stepper motor-micromanipulator arrangement in the Y and Z axes has a minimum step resolution of ?0.4??m with a total travel of 12 mm and the stepper motor-X stage arrangement has a minimum resolution of ?0.3??m with a total travel of 10 mm. Mechanical backlash error is ?0.8??m for ?750??m of travel. A MEMS microgripper from Femtotools™ acts as an end-effector in the shaft end of the micromanipulator. The gripping ranges of the grippers used are 0-100??m (for FT-G100) and 0-60??m (for FT-G60). As the gripping action is performed, the force sense circuit of FT-G100 measures the handling force. This force feedback is integrated to a commercially available three degree of freedom haptic device (Novint Falcon) allowing the user to receive tactile feedback during the microscale handling. Both mesoscale and microscale controls are important, as mesoscale control is required for the travel motion of the test object whereas microscale control is required for the gripping action. The haptic device is used to control the position of the microgripper, control the actuation of the microgripper, and provide force feedback. A LABVIEW program was developed to interlink communication and control among hardware used in the system. Micro-objects such as SF-9 cells and polystyrene beads (?45??m) are handled and handling forces of ?50??N were experienced. PMID:21034126

Vijayasai, Ashwin P; Sivakumar, Ganapathy; Mulsow, Matthew; Lacouture, Shelby; Holness, Alex; Dallas, Tim E

2010-10-01

13

A Change of Inertia-Supporting the Thrust Vector Control of the Space Launch System  

NASA Technical Reports Server (NTRS)

The Space Launch System (SLS) is America's next launch vehicle. To utilize the vehicle more economically, heritage hardware from the Space Transportation System (STS) will be used when possible. The Solid Rocket Booster (SRB) actuators could possibly be used in the core stage of the SLS. The dynamic characteristics of the SRB actuator will need to be tested on an Inertia Load Stand (ILS) that has been converted to Space Shuttle Main Engine (SSME). The inertia on the pendulum of the ILS will need to be changed to match the SSME inertia. In this testing environment an SRB actuator can be tested with the equivalent resistence of an SSME.

Dziubanek, Adam J.

2012-01-01

14

Conceptual design of a thrust-vectoring tailcone for underwater robotics  

E-print Network

Thrust-vectoring on Autonomous Underwater Vehicles is an appealing directional-control solution because it improves turning radius capabilities. Unfortunately, thrust-vectoring requires the entire propulsion system be ...

Nawrot, Michael T

2012-01-01

15

Thrust vectoring for lateral-directional stability  

NASA Technical Reports Server (NTRS)

The advantages and disadvantages of using thrust vectoring for lateral-directional control and the effects of reducing the tail size of a single-engine aircraft were investigated. The aerodynamic characteristics of the F-16 aircraft were generated by using the Aerodynamic Preliminary Analysis System II panel code. The resulting lateral-directional linear perturbation analysis of a modified F-16 aircraft with various tail sizes and yaw vectoring was performed at several speeds and altitudes to determine the stability and control trends for the aircraft compared to these trends for a baseline aircraft. A study of the paddle-type turning vane thrust vectoring control system as used on the National Aeronautics and Space Administration F/A-18 High Alpha Research Vehicle is also presented.

Peron, Lee R.; Carpenter, Thomas

1992-01-01

16

Computational Investigation of Fluidic Counterflow Thrust Vectoring  

NASA Technical Reports Server (NTRS)

A computational study of fluidic counterflow thrust vectoring has been conducted. Two-dimensional numerical simulations were run using the computational fluid dynamics code PAB3D with two-equation turbulence closure and linear Reynolds stress modeling. For validation, computational results were compared to experimental data obtained at the NASA Langley Jet Exit Test Facility. In general, computational results were in good agreement with experimental performance data, indicating that efficient thrust vectoring can be obtained with low secondary flow requirements (less than 1% of the primary flow). An examination of the computational flowfield has revealed new details about the generation of a countercurrent shear layer, its relation to secondary suction, and its role in thrust vectoring. In addition to providing new information about the physics of counterflow thrust vectoring, this work appears to be the first documented attempt to simulate the counterflow thrust vectoring problem using computational fluid dynamics.

Hunter, Craig A.; Deere, Karen A.

1999-01-01

17

Solid rocket booster thrust vector control subsystem description  

NASA Technical Reports Server (NTRS)

Major Solid Rocket Booster-Thrust Vector Control (SRB-TVC) subsystem components and subcomponents used in the Space Transportation System (STS) are identified. Simplified schematics, detailed schematics, figures, photographs, and data are included to acquaint the reader with the operation, performance, and physical layout as well as the materials and instrumentation used.

Redmon, J., Jr. (compiler)

1983-01-01

18

Tandem Cascade Thrust Vectoring Research Program.  

National Technical Information Service (NTIS)

Continuous thrust vectoring from horizontal through vertical, to reversed thrust can be accomplished by the use of one or two cascades in series, each employing variable camber airfoils. An experimental wind tunnel evaluation of three types of variable ca...

J. R. Erwin, D. E. Clark, R. G. Giffin, J. G. Kirkpatrick

1964-01-01

19

A multimission three-axis stabilized spacecraft flight dynamics ground support system  

NASA Technical Reports Server (NTRS)

The Multimission Three-Axis Stabilized Spacecraft (MTASS) Flight Dynamics Support System (FDSS) has been developed in an effort to minimize the costs of ground support systems. Unlike single-purpose ground support systems, which attempt to reduce costs by reusing software specifically developed for previous missions, the multimission support system is an intermediate step in the progression to a fully generalized mission support system in which numerous missions may be served by one general system. The benefits of multimission attitude ground support systems extend not only to the software design and coding process, but to the entire system environment, from specification through testing, simulation, operations, and maintenance. This paper reports the application of an MTASS FDSS to multiple scientific satellite missions. The satellites are the Upper Atmosphere Research Satellite (UARS), the Extreme Ultraviolet Explorer (EUVE), and the Solar Anomalous Magnetospheric Particle Explorer (SAMPEX). Both UARS and EUVE use the multimission modular spacecraft (MMS) concept. SAMPEX is part of the Small Explorer (SMEX) series and uses a much simpler set of attitude sensors. This paper centers on algorithm and design concepts for a multimission system and discusses flight experience from UARS.

Langston, J.; Krack, K.; Reupke, W.

1993-01-01

20

Thrust Vector Control for Nuclear Thermal Rockets  

NASA Technical Reports Server (NTRS)

Future space missions may use Nuclear Thermal Rocket (NTR) stages for human and cargo missions to Mars and other destinations. The vehicles are likely to require engine thrust vector control (TVC) to maintain desired flight trajectories. This paper explores requirements and concepts for TVC systems for representative NTR missions. Requirements for TVC systems were derived using 6 degree-of-freedom models of NTR vehicles. Various flight scenarios were evaluated to determine vehicle attitude control needs and to determine the applicability of TVC. Outputs from the models yielded key characteristics including engine gimbal angles, gimbal rates and gimbal actuator power. Additional factors such as engine thrust variability and engine thrust alignment errors were examined for impacts to gimbal requirements. Various technologies are surveyed for TVC systems for the NTR applications. A key factor in technology selection is the unique radiation environment present in NTR stages. Other considerations including mission duration and thermal environments influence the selection of optimal TVC technologies. Candidate technologies are compared to see which technologies, or combinations of technologies best fit the requirements for selected NTR missions. Representative TVC systems are proposed and key properties such as mass and power requirements are defined. The outputs from this effort can be used to refine NTR system sizing models, providing higher fidelity definition for TVC systems for future studies.

Ensworth, Clinton B. F.

2013-01-01

21

Ground test of the D shaped vented thrust vectoring nozzle  

NASA Technical Reports Server (NTRS)

Static ground tests of a large scale lift/cruise thrust vectoring nozzle were conducted to establish: (1) vectoring performance 'in' and 'out' of ground effect; (2) thrust spoilage capability; (3) compatibility of the nozzle with a turbotip fan; and (4) the nozzle structural temperature distribution. Vectoring performance of a short coupled, vented nozzle design on a large scale, (60%) basis was compared with small scale (4.5%) test nozzle results. The test nozzle was a "boilerplate" model of the MCAIR "D" vented nozzle configured for operation with the LF336/J85 turbotip lift fan system. Calibration of the LF336/J85 test fan with a simple convergent nozzle was performed with four different nozzle exit areas to establish reference thrust, nozzle pressure ratio, and nozzle corrected flow characteristics for comparison with the thrust vectoring nozzle data. Thrust vectoring tests with the 'D' vented nozzle were conducted over the range of vector angles between 0 and 117 deg for several different nozzle exit areas.

Esker, D. W.

1976-01-01

22

Summary of Fluidic Thrust Vectoring Research Conducted at NASA Langley Research Center  

NASA Technical Reports Server (NTRS)

Interest in low-observable aircraft and in lowering an aircraft's exhaust system weight sparked decades of research for fixed geometry exhaust nozzles. The desire for such integrated exhaust nozzles was the catalyst for new fluidic control techniques; including throat area control, expansion control, and thrust-vector angle control. This paper summarizes a variety of fluidic thrust vectoring concepts that have been tested both experimentally and computationally at NASA Langley Research Center. The nozzle concepts are divided into three categories according to the method used for fluidic thrust vectoring: the shock vector control method, the throat shifting method, and the counterflow method. This paper explains the thrust vectoring mechanism for each fluidic method, provides examples of configurations tested for each method, and discusses the advantages and disadvantages of each method.

Deere, Karen A.

2003-01-01

23

Electromechanical actuation for thrust vector control applications  

NASA Astrophysics Data System (ADS)

At present, actuation systems for the Thrust Vector Control (TVC) for launch vehicles are hydraulic systems. The Advanced Launch System (ALS), a joint initiative between NASA and the Air Force, is a launch vehicle that is designed to be cost effective, highly reliable and operationally efficient with a goal of reducing the cost per pound to orbit. As part of this initiative, an electromechanical actuation system is being developed as an attractive alternative to the hydraulic systems used today. NASA-Lewis is developing and demonstrating an Induction Motor Controller Actuation System with a 40 hp peak rating. The controller will integrate 20 kHz resonant link Power Management and Distribution (PMAD) technology and Pulse Population Modulation (PPM) techniques to implement Field Oriented Vector Control (FOVC) of a new advanced induction motor. Through PPM, multiphase variable frequency, variable voltage waveforms can be synthesized from the 20 kHz source. FOVC shows that varying both the voltage and frequency and their ratio (V/F), permits independent control of both torque and speed while operating at maximum efficiency at any point on the torque-speed curve. The driver and the FOVC will be microprocessor controlled. For increased system reliability, a Built-in Test (BITE) capability will be included. This involves introducing testability into the design of a system such that testing is calibrated and exercised during the design, manufacturing, maintenance and prelaunch activities. An actuator will be integrated with the motor controller for performance testing of the EMA TVC system. The design and fabrication of the motor controller is being done by General Dynamics Space Systems Division. The University of Wisconsin-Madison will assist in the design of the advanced induction motor and in the implementation of the FOVC theory. A 75 hp electronically controlled dynamometer will be used to test the motor controller in all four quadrants of operation using flight type control algorithms. Integrated testing of the controller and actuator will be conducted at a facility yet to be named. The EMA system described above is discussed in detail.

Roth, Mary Ellen

24

Electromechanical actuation for thrust vector control applications  

NASA Technical Reports Server (NTRS)

At present, actuation systems for the Thrust Vector Control (TVC) for launch vehicles are hydraulic systems. The Advanced Launch System (ALS), a joint initiative between NASA and the Air Force, is a launch vehicle that is designed to be cost effective, highly reliable and operationally efficient with a goal of reducing the cost per pound to orbit. As part of this initiative, an electromechanical actuation system is being developed as an attractive alternative to the hydraulic systems used today. NASA-Lewis is developing and demonstrating an Induction Motor Controller Actuation System with a 40 hp peak rating. The controller will integrate 20 kHz resonant link Power Management and Distribution (PMAD) technology and Pulse Population Modulation (PPM) techniques to implement Field Oriented Vector Control (FOVC) of a new advanced induction motor. Through PPM, multiphase variable frequency, variable voltage waveforms can be synthesized from the 20 kHz source. FOVC shows that varying both the voltage and frequency and their ratio (V/F), permits independent control of both torque and speed while operating at maximum efficiency at any point on the torque-speed curve. The driver and the FOVC will be microprocessor controlled. For increased system reliability, a Built-in Test (BITE) capability will be included. This involves introducing testability into the design of a system such that testing is calibrated and exercised during the design, manufacturing, maintenance and prelaunch activities. An actuator will be integrated with the motor controller for performance testing of the EMA TVC system. The design and fabrication of the motor controller is being done by General Dynamics Space Systems Division. The University of Wisconsin-Madison will assist in the design of the advanced induction motor and in the implementation of the FOVC theory. A 75 hp electronically controlled dynamometer will be used to test the motor controller in all four quadrants of operation using flight type control algorithms. Integrated testing of the controller and actuator will be conducted at a facility yet to be named. The EMA system described above is discussed in detail.

Roth, Mary Ellen

1990-01-01

25

An integrated micro HTS system for energy storage and attitude control for three-axis stabilized nanosatellites  

Microsoft Academic Search

This paper presents the development of an integrated micro high-temperature superconductor system for energy storage and attitude control of three-axis stabilized nano satellites. The micro HTS system consists of a flywheel\\/rotor, motor\\/generator, motor electronics, and a cooling system. The flywheel\\/rotor has been fabricated by using sintered NdFeB and the stator for motor\\/generator has been fabricated by micro fabrication technology. An

Eunjeong Lee; Bongsu Kim; Junseok Ko; Chi Young Song; Seong-Jin Kim; Sangkwon Jeong; Seung S. Lee

2005-01-01

26

Experimental Study of an Axisymmetric Dual Throat Fluidic Thrust Vectoring Nozzle for Supersonic Aircraft Application  

NASA Technical Reports Server (NTRS)

An axisymmetric version of the Dual Throat Nozzle concept with a variable expansion ratio has been studied to determine the impacts on thrust vectoring and nozzle performance. The nozzle design, applicable to a supersonic aircraft, was guided using the unsteady Reynolds-averaged Navier-Stokes computational fluid dynamics code, PAB3D. The axisymmetric Dual Throat Nozzle concept was tested statically in the Jet Exit Test Facility at the NASA Langley Research Center. The nozzle geometric design variables included circumferential span of injection, cavity length, cavity convergence angle, and nozzle expansion ratio for conditions corresponding to take-off and landing, mid climb and cruise. Internal nozzle performance and thrust vectoring performance was determined for nozzle pressure ratios up to 10 with secondary injection rates up to 10 percent of the primary flow rate. The 60 degree span of injection generally performed better than the 90 degree span of injection using an equivalent injection area and number of holes, in agreement with computational results. For injection rates less than 7 percent, thrust vector angle for the 60 degree span of injection was 1.5 to 2 degrees higher than the 90 degree span of injection. Decreasing cavity length improved thrust ratio and discharge coefficient, but decreased thrust vector angle and thrust vectoring efficiency. Increasing cavity convergence angle from 20 to 30 degrees increased thrust vector angle by 1 degree over the range of injection rates tested, but adversely affected system thrust ratio and discharge coefficient. The dual throat nozzle concept generated the best thrust vectoring performance with an expansion ratio of 1.0 (a cavity in between two equal minimum areas). The variable expansion ratio geometry did not provide the expected improvements in discharge coefficient and system thrust ratio throughout the flight envelope of typical a supersonic aircraft. At mid-climb and cruise conditions, the variable geometry design compromised thrust vector angle achieved, but some thrust vector control would be available, potentially for aircraft trim. The fixed area, expansion ratio of 1.0, Dual Throat Nozzle provided the best overall compromise for thrust vectoring and nozzle internal performance over the range of NPR tested compared to the variable geometry Dual Throat Nozzle.

Flamm, Jeffrey D.; Deere, Karen A.; Mason, Mary L.; Berrier, Bobby L.; Johnson, Stuart K.

2007-01-01

27

Flexible joints for thrust vector control  

NASA Technical Reports Server (NTRS)

Flexible joints have been used to achieve thrust vector control over a wide range of sizes of nozzles and have been demonstrated successfully in bench tests and static firings, and are operational on two motors. From these many joints the problems of flexible joints have been defined as establishment of the movable nozzle envelope, definition of the actuation power requirements, definition of the mechanical properties of joint materials, adhesive bonding, test methods, and quality control. These data and problem solutions are contained in a large number of reports. Data relating to joint configuration, design requirements, materials selection, joint design, structural analysis, manufacture, and testing are summarized.

Woodberry, R. F. H.

1975-01-01

28

Design and test of electromechanical actuators for thrust vector control  

NASA Technical Reports Server (NTRS)

New control mechanisms technologies are currently being explored to provide alternatives to hydraulic thrust vector control (TVC) actuation systems. For many years engineers have been encouraging the investigation of electromechanical actuators (EMA) to take the place of hydraulics for spacecraft control/gimballing systems. The rationale is to deliver a lighter, cleaner, safer, more easily maintained, as well as energy efficient space vehicle. In light of this continued concern to improve the TVC system, the Propulsion Laboratory at the NASA George C. Marshall Space Flight Center (MSFC) is involved in a program to develop electromechanical actuators for the purpose of testing and TVC system implementation. Through this effort, an electromechanical thrust vector control actuator has been designed and assembled. The design consists of the following major components: Two three-phase brushless dc motors, a two pass gear reduction system, and a roller screw, which converts rotational input into linear output. System control is provided by a solid-state electronic controller and power supply. A pair of resolvers and associated electronics deliver position feedback to the controller such that precise positioning is achieved. Testing and evaluation is currently in progress. Goals focus on performance comparisons between EMA's and similar hydraulic systems.

Cowan, J. R.; Weir, Rae Ann

1993-01-01

29

Design and test of electromechanical actuators for thrust vector control  

NASA Astrophysics Data System (ADS)

New control mechanisms technologies are currently being explored to provide alternatives to hydraulic thrust vector control (TVC) actuation systems. For many years engineers have been encouraging the investigation of electromechanical actuators (EMA) to take the place of hydraulics for spacecraft control/gimballing systems. The rationale is to deliver a lighter, cleaner, safer, more easily maintained, as well as energy efficient space vehicle. In light of this continued concern to improve the TVC system, the Propulsion Laboratory at the NASA George C. Marshall Space Flight Center (MSFC) is involved in a program to develop electromechanical actuators for the purpose of testing and TVC system implementation. Through this effort, an electromechanical thrust vector control actuator has been designed and assembled. The design consists of the following major components: Two three-phase brushless dc motors, a two pass gear reduction system, and a roller screw, which converts rotational input into linear output. System control is provided by a solid-state electronic controller and power supply. A pair of resolvers and associated electronics deliver position feedback to the controller such that precise positioning is achieved. Testing and evaluation is currently in progress. Goals focus on performance comparisons between EMA's and similar hydraulic systems.

Cowan, J. R.; Weir, Rae Ann

1993-05-01

30

Design and evaluation of thrust vectored nozzles using a multicomponent thrust stand  

NASA Technical Reports Server (NTRS)

Future aircraft with the capability of short takeoff and landing, and improved maneuverability especially in the post-stall flight regime will incorporate exhaust nozzles which can be thrust vectored. In order to conduct thrust vector research in the Mechanical Engineering Department at Cal Poly, a program was planned with two objectives; design and construct a multicomponent thrust stand for the specific purpose of measuring nozzle thrust vectors; and to provide quality low moisture air to the thrust stand for cold flow nozzle tests. The design and fabrication of the six-component thrust stand was completed. Detailed evaluation tests of the thrust stand will continue upon the receipt of one signal conditioning option (-702) for the Fluke Data Acquisition System. Preliminary design of thrust nozzles with air supply plenums were completed. The air supply was analyzed with regard to head loss. Initial flow visualization tests were conducted using dual water jets.

Carpenter, Thomas W.; Blattner, Ernest W.; Stagner, Robert E.; Contreras, Juanita; Lencioni, Dennis; Mcintosh, Greg

1990-01-01

31

Development and qualification of a STAR 48 rocket motor with thrust vector control  

NASA Astrophysics Data System (ADS)

A thrust vector control (TVC) nozzle for use on the STAR 48 rocket motor (STAR 48V) has been developed for use on the COMET program aboard the Conestoga launch vehicle. The first stages of qualification testing have been completed. The first STAR 48V has been successfully static-tested. The flexseal TVC nozzle design is based upon the qualified and flight-proven fixed nozzle design used on spin-stabilized spacecraft. The flexseal design and fabrication approach benefit from flight-proven and man-rated Thiokol Corporation flexseal designs. The thrust vector control system provides vectoring capability to 4 deg for use on nonspinning spacecraft. Electromechanical actuators coupled with a closed-loop controller provide thrust vector positioning and spacecraft attitude control.

Hamke, R.; Rade, J.; Weldin, R.

1992-07-01

32

Three axis Attitude Determination and Control System for a picosatellite: Design and implementation  

E-print Network

the payload, ADCS with actuators and sensors, deployable antennas, communication systems, OBDH and power picosatellite is presented. The satellite, named Ncube, is based on the CubeSat concept. This means that its will be presented. Simulations of both detumbling, boom deployment and stabilization are presented. The Ncube

Gravdahl, Jan Tommy

33

Gyroless yaw control system for a three axis stabilized, zero-momentum spacecraft  

NASA Technical Reports Server (NTRS)

A satellite attitude control system is usable in the absence of any inertial yaw attitude reference, such as a gyroscope, and in the absence of a pitch bias momentum. Both the roll-yaw rigid body dynamics and the roll-yaw orbit kinematics are modelled. Pitch and roll attitude control are conventional. The model receives inputs from a roll sensor, and roll and yaw torques from reaction wheel monitors. The model produces estimated yaw which controls the spacecraft yaw attitude.

Stetson, Jr., John B. (Inventor)

1993-01-01

34

High efficiency thrust vector control allocation  

NASA Astrophysics Data System (ADS)

The design of control mixing algorithms for launch vehicles with multiple vectoring engines yields competing objectives for which no straightforward solution approach exists. The designer seeks to optimally allocate the effector degrees of freedom such that maneuvering capability is maximized subject to constraints on available control authority. In the present application, such algorithms are generally restricted to linear transformations so as to minimize adverse control-structure interaction and maintain compatibility with industry-standard methods for control gain design and stability analysis. Based on the application of the theory of ellipsoids, a complete, scalable, and extensible framework is developed to effect rapid analysis of launch vehicle capability. Furthermore, a control allocation scheme is proposed that simultaneously balances attainment of the maximum maneuvering capability with rejection of internal loads and performance losses resulting from thrust vectoring in the null region of the admissible controls. This novel approach leverages an optimal parametrization of the weighted least squares generalized inverse and exploits the analytic properties of the constraint geometry so as to enable recovery of more than ninety percent of the theoretical capability while maintaining linearity over the majority of the attainable set.

Orr, Jeb S.

35

Thrust Vectoring on the NASA F-18 High Alpha Research Vehicle  

NASA Technical Reports Server (NTRS)

Investigations into a multiaxis thrust-vectoring system have been conducted on an F-18 configuration. These investigations include ground-based scale-model tests, ground-based full-scale testing, and flight testing. This thrust-vectoring system has been tested on the NASA F-18 High Alpha Research Vehicle (HARV). The system provides thrust vectoring in pitch and yaw axes. Ground-based subscale test data have been gathered as background to the flight phase of the program. Tests investigated aerodynamic interaction and vane control effectiveness. The ground-based full-scale data were gathered from static engine runs with image analysis to determine relative thrust-vectoring effectiveness. Flight tests have been conducted at the NASA Dryden Flight Research Center. Parameter identification input techniques have been developed. Individual vanes were not directly controlled because of a mixer-predictor function built into the flight control laws. Combined effects of the vanes have been measured in flight and compared to combined effects of the vanes as predicted by the cold-jet test data. Very good agreement has been found in the linearized effectiveness derivatives.

Bowers, Albion H.; Pahle, Joseph W.

1996-01-01

36

Aerodynamics of thrust vectoring by Navier-Stokes solutions  

NASA Technical Reports Server (NTRS)

Induced aerodynamics from thrust vectoring are investigated by a computational fluid dynamic method. A thin-layer Reynolds-averaged Navier-Stokes code with multiblock capability is used. Jet properties are specified on the nozzle exit plane to simulate the jet momentum. Results for a rectangular jet in a cross flow are compared with data to verify the code. Further verification of the calculation is made by comparing the numerical results with transonic data for a wing-body combination. Additional calculations were performed to elucidate the following thrust vectoring effects: the thrust vectoring effect on shock and expansion waves, induced effects on nearby surfaces, and the thrust vectoring effect on the leading edge vortex.

Tseng, Jing-Biau; Lan, C. Edward

1991-01-01

37

Design of thrust vectoring exhaust nozzles for real-time applications using neural networks  

NASA Technical Reports Server (NTRS)

Thrust vectoring continues to be an important issue in military aircraft system designs. A recently developed concept of vectoring aircraft thrust makes use of flexible exhaust nozzles. Subtle modifications in the nozzle wall contours produce a non-uniform flow field containing a complex pattern of shock and expansion waves. The end result, due to the asymmetric velocity and pressure distributions, is vectored thrust. Specification of the nozzle contours required for a desired thrust vector angle (an inverse design problem) has been achieved with genetic algorithms. This approach is computationally intensive and prevents the nozzles from being designed in real-time, which is necessary for an operational aircraft system. An investigation was conducted into using genetic algorithms to train a neural network in an attempt to obtain, in real-time, two-dimensional nozzle contours. Results show that genetic algorithm trained neural networks provide a viable, real-time alternative for designing thrust vectoring nozzles contours. Thrust vector angles up to 20 deg were obtained within an average error of 0.0914 deg. The error surfaces encountered were highly degenerate and thus the robustness of genetic algorithms was well suited for minimizing global errors.

Prasanth, Ravi K.; Markin, Robert E.; Whitaker, Kevin W.

1991-01-01

38

Design and test of a high power electromechanical actuator for thrust vector control  

NASA Astrophysics Data System (ADS)

NASA-Marshall is involved in the development of electromechanical actuators (EMA) for thrust-vector control (TVC) system testing and implementation in spacecraft control/gimballing systems, with a view to the replacement of hydraulic hardware. TVC system control is furnished by solid state controllers and power supplies; a pair of resolvers supply position feedback to the controller for precise positioning. Performance comparisons between EMA and hydraulic TVC systems are performed.

Cowan, J. R.; Myers, W. N.

1992-07-01

39

Internal performance characteristics of thrust-vectored axisymmetric ejector nozzles  

NASA Technical Reports Server (NTRS)

A series of thrust-vectored axisymmetric ejector nozzles were designed and experimentally tested for internal performance and pumping characteristics at the Langley research center. This study indicated that discontinuities in the performance occurred at low primary nozzle pressure ratios and that these discontinuities were mitigated by decreasing expansion area ratio. The addition of secondary flow increased the performance of the nozzles. The mid-to-high range of secondary flow provided the most overall improvements, and the greatest improvements were seen for the largest ejector area ratio. Thrust vectoring the ejector nozzles caused a reduction in performance and discharge coefficient. With or without secondary flow, the vectored ejector nozzles produced thrust vector angles that were equivalent to or greater than the geometric turning angle. With or without secondary flow, spacing ratio (ejector passage symmetry) had little effect on performance (gross thrust ratio), discharge coefficient, or thrust vector angle. For the unvectored ejectors, a small amount of secondary flow was sufficient to reduce the pressure levels on the shroud to provide cooling, but for the vectored ejector nozzles, a larger amount of secondary air was required to reduce the pressure levels to provide cooling.

Lamb, Milton

1995-01-01

40

Three-axis cryogenic Hall sensor  

Microsoft Academic Search

Magnetic field measurements are very important for magnetic and superconducting material research. Hall sensors have many advantages for these measurements. They can also be used for magnetic field profile measurements, which provide information about material homogeneity. We have developed a three-axis Hall system which consists of three perpendicular InSb Hall sensors for operation at room as well as cryogenic temperatures.

J. Kvitkovic; M. Majoros

1996-01-01

41

Numerical simulation of STOL operations using thrust-vectoring  

NASA Technical Reports Server (NTRS)

The flow field about a delta wing equipped with thrust reverser jets in slow speed flight near the ground has been computed. Results include the prediction of the flow about the delta wing at four fixed heights above the ground, and a simulated landing, in which the delta wing descends towards the ground. Comparison of computed and experimental lift coefficients indicates that the simulations can capture at least the qualitative trends in lift-loss encountered by thrust-vectoring aircraft operating in ground effect.

Chawla, Kalpana; Van Dalsem, W. R.

1992-01-01

42

Thrust vector control algorithm design for the Cassini spacecraft  

NASA Technical Reports Server (NTRS)

This paper describes a preliminary design of the thrust vector control algorithm for the interplanetary spacecraft, Cassini. Topics of discussion include flight software architecture, modeling of sensors, actuators, and vehicle dynamics, and controller design and analysis via classical methods. Special attention is paid to potential interactions with structural flexibilities and propellant dynamics. Controller performance is evaluated in a simulation environment built around a multi-body dynamics model, which contains nonlinear models of the relevant hardware and preliminary versions of supporting attitude determination and control functions.

Enright, Paul J.

1993-01-01

43

Design of a three-axis micro-scale metrology system for the characterization of cylindrical flexures  

E-print Network

The objective of this thesis was to develop a laser metrology system in order to measure the movement in two of the rotation axes of a cylindrical flexure. The building and characterization of this system was achieved in ...

Perez, Ron M

2012-01-01

44

Attitude control of a spinning rocket via thrust vectoring  

SciTech Connect

Two controllers are developed to provide attitude control of a spinning rocket that has a thrust vectoring capability. The first controller has a single-input/single-output design that ignores the gyroscopic coupling between the control channels. The second controller has a multi-input/multi-output structure that is specifically intended to account for the gyroscopic coupling effects. A performance comparison between the two approached is conducted for a range of roll rates. Each controller is tested for the ability to track step commands, and for the amount of coupling impurity. Both controllers are developed via a linear-quadratic-regulator synthesis procedure, which is motivated by the multi-input/multi-output nature of second controller. Time responses and a singular value analysis are used to evaluate controller performance. This paper describes the development and comparison of two controllers that are designed to provide attitude control of a spinning rocket that is equipped with thrust vector control. 12 refs., 13 figs., 2 tabs.

White, J.E.

1990-12-19

45

Linear Test Bed. Volume 2: Test Bed No. 2. [linear aerospike test bed for thrust vector control  

NASA Technical Reports Server (NTRS)

Test bed No. 2 consists of 10 combustors welded in banks of 5 to 2 symmetrical tubular nozzle assemblies, an upper stationary thrust frame, a lower thrust frame which can be hinged, a power package, a triaxial combustion wave ignition system, a pneumatic control system, pneumatically actuated propellant valves, a purge and drain system, and an electrical control system. The power package consists of the Mark 29-F fuel turbopump, the Mark 29-0 oxidizer turbopump, a gas generator assembly, and propellant ducting. The system, designated as a linear aerospike system, was designed to demonstrate the feasibility of the concept and to explore technology related to thrust vector control, thrust vector optimization, improved sequencing and control, and advanced ignition systems. The propellants are liquid oxygen/liquid hydrogen. The system was designed to operate at 1200-psia chamber pressure at an engine mixture ratio of 5.5. With 10 combustors, the sea level thrust is 95,000 pounds.

1974-01-01

46

Test stand for precise measurement of impulse and thrust vector of small attitude control jets  

NASA Technical Reports Server (NTRS)

A test stand which accurately measures the impulse bit and thrust vector of reaction jet thrusters used in the attitude control system of space vehicles has been developed. It can be used to measure, in a vacuum or ambient environment, both impulse and thrust vector of reaction jet thrusters using hydrazine or inert gas propellants. The ballistic pendulum configuration was selected because of its accuracy, simplicity, and versatility. The pendulum is mounted on flexure pivots rotating about a vertical axis at the center of its mass. The test stand has the following measurement capabilities: impulse of 0.00004 to 4.4 N-sec (0.00001 to 1.0 lb-sec) with a pulse duration of 0.5 msec to 1 sec; static thrust of 0.22 to 22 N (0.05 to 5 lb) with a 5 percent resolution; and thrust angle alinement of 0.22 to 22 N (0.05 to 5 lb) thrusters with 0.01 deg accuracy.

Woodruff, J. R.; Chisel, D. M.

1973-01-01

47

Preliminary Investigation on Battery Sizing Investigation for Thrust Vector Control on Ares I and Ares V Launch Vehicles  

NASA Technical Reports Server (NTRS)

An investigation into the merits of battery powered Electro Hydrostatic Actuation (EHA) for Thrust Vector Control (TVC) of the Ares I and Ares V launch vehicles is described. A top level trade study was conducted to ascertain the technical merits of lithium-ion (Li-ion) and thermal battery performance to determine the preferred choice of an energy storage system chemistry that provides high power discharge capability for a relatively short duration.

Miller, Thomas B.

2011-01-01

48

Numerical solution of 2-D thrust reversing and thrust vectoring nozzle  

Microsoft Academic Search

The flowfield within and around two dimensional thrust reversing and thrust vectoring nozzles has been calculated using a new unfactored implicit method with a multiple zone grid. Computations are done for fully deployed thrust reversing nozzles, partially deployed thrust reversing nozzles with thrust vectoring, and a nozzle transitioning from partially to fully deployed. Agreement with available experimental data is good.

S. Imlay

1986-01-01

49

Design and evaluation of single and dual flow thrust vector nozzles with post exit vanes  

NASA Technical Reports Server (NTRS)

This Thrust Vectored Research project required that a 1/24 scale model of the F/A-18 High Alpha Research Vehicle, (HARV), propulsion system be constructed on the university campus. This propulsion system was designed for cold flow testing on a multicomponent test rig. Forces and moments were measured to study nozzle performance parameters. The flow visualization technique of color Schlieren photography was performed to investigate the flow phenomena at the nozzle exit. The flow interactions that were identified consisted of vane nozzleing between the outer and lower vanes and vane tip interference. The thrust vectoring system consisted of three asymmetrically spaced vanes installed circumferentially on a maximum afterburner nozzle. The performance of the nozzle was investigated with the outer and lower vanes equally deflected, (-10 deg is less than delta(sub v) is less than 25 deg), and with the upper vane fully retracted, (delta(sub v) equals -10 deg). The nozzle pressure ratio ranged from 4 to 6. The results indicated that a vane nozzleing effect developed at nozzle pressure ratios of 4 and 6 when the outer and lower vanes were deflected far enough into the flow field such that the increase in vane area accelerated the flow past the vanes causing distorted shock waves. This accelerated flow was a result of a pressure differential existing between the inside surface of the vane and the ambient pressure. The stagnation pressure that developed along the inside surface of the vane accelerated the flow past the vanes causing it to equalize with ambient pressure, thus providing distorted shock waves. A tip interference was present at the trailing edge of the upper vane as a result of low nozzle pressure, NPR 4, with high vane deflection, delta(sub v) equals 25 degrees, and also with a high nozzle pressure, NPR 6, and low vane deflections, delta(sub v) equals 15 degrees.

Carpenter, Thomas W.; Vaccarezza, Stephen E.; Dobbins, Sean

1992-01-01

50

Static performance of an axisymmetric nozzle with post-exit vanes for multiaxis thrust vectoring  

NASA Technical Reports Server (NTRS)

An investigation was conducted in the static test facility of the Langley 16-Foot Transonic Tunnel to determine the flow-turning capability and the nozzle internal performance of an axisymmetric convergent-divergent nozzle with post-exit vanes installed for multiaxis thrust vectoring. The effects of vane curvature, vane location relative to the nozzle exit, number of vanes, and vane deflection angle were determined. A comparison of the post-exit-vane thrust-vectoring concept with other thrust-vectoring concepts is provided. All tests were conducted with no external flow, and nozzle pressure ratio was varied from 1.6 to 6.0.

Berrier, Bobby L.; Mason, Mary L.

1988-01-01

51

Flight-Determined Subsonic Longitudinal Stability and Control Derivatives of the F-18 High Angle of Attack Research Vehicle (HARV) with Thrust Vectoring  

NASA Technical Reports Server (NTRS)

The subsonic longitudinal stability and control derivatives of the F-18 High Angle of Attack Research Vehicle (HARV) are extracted from dynamic flight data using a maximum likelihood parameter identification technique. The technique uses the linearized aircraft equations of motion in their continuous/discrete form and accounts for state and measurement noise as well as thrust-vectoring effects. State noise is used to model the uncommanded forcing function caused by unsteady aerodynamics over the aircraft, particularly at high angles of attack. Thrust vectoring was implemented using electrohydraulically-actuated nozzle postexit vanes and a specialized research flight control system. During maneuvers, a control system feature provided independent aerodynamic control surface inputs and independent thrust-vectoring vane inputs, thereby eliminating correlations between the aircraft states and controls. Substantial variations in control excitation and dynamic response were exhibited for maneuvers conducted at different angles of attack. Opposing vane interactions caused most thrust-vectoring inputs to experience some exhaust plume interference and thus reduced effectiveness. The estimated stability and control derivatives are plotted, and a discussion relates them to predicted values and maneuver quality.

Iliff, Kenneth W.; Wang, Kon-Sheng Charles

1997-01-01

52

Static performance investigation of a skewed-throat multiaxis thrust-vectoring nozzle concept  

NASA Technical Reports Server (NTRS)

The static performance of a jet exhaust nozzle which achieves multiaxis thrust vectoring by physically skewing the geometric throat has been characterized in the static test facility of the 16-Foot Transonic Tunnel at NASA Langley Research Center. The nozzle has an asymmetric internal geometry defined by four surfaces: a convergent-divergent upper surface with its ridge perpendicular to the nozzle centerline, a convergent-divergent lower surface with its ridge skewed relative to the nozzle centerline, an outwardly deflected sidewall, and a straight sidewall. The primary goal of the concept is to provide efficient yaw thrust vectoring by forcing the sonic plane (nozzle throat) to form at a yaw angle defined by the skewed ridge of the lower surface contour. A secondary goal is to provide multiaxis thrust vectoring by combining the skewed-throat yaw-vectoring concept with upper and lower pitch flap deflections. The geometric parameters varied in this investigation included lower surface ridge skew angle, nozzle expansion ratio (divergence angle), aspect ratio, pitch flap deflection angle, and sidewall deflection angle. Nozzle pressure ratio was varied from 2 to a high of 11.5 for some configurations. The results of the investigation indicate that efficient, substantial multiaxis thrust vectoring was achieved by the skewed-throat nozzle concept. However, certain control surface deflections destabilized the internal flow field, which resulted in substantial shifts in the position and orientation of the sonic plane and had an adverse effect on thrust-vectoring and weight flow characteristics. By increasing the expansion ratio, the location of the sonic plane was stabilized. The asymmetric design resulted in interdependent pitch and yaw thrust vectoring as well as nonzero thrust-vector angles with undeflected control surfaces. By skewing the ridges of both the upper and lower surface contours, the interdependency between pitch and yaw thrust vectoring may be eliminated and the location of the sonic plane may be further stabilized.

Wing, David J.

1994-01-01

53

Computational Study of an Axisymmetric Dual Throat Fluidic Thrust Vectoring Nozzle for a Supersonic Aircraft Application  

NASA Technical Reports Server (NTRS)

A computational investigation of an axisymmetric Dual Throat Nozzle concept has been conducted. This fluidic thrust-vectoring nozzle was designed with a recessed cavity to enhance the throat shifting technique for improved thrust vectoring. The structured-grid, unsteady Reynolds- Averaged Navier-Stokes flow solver PAB3D was used to guide the nozzle design and analyze performance. Nozzle design variables included extent of circumferential injection, cavity divergence angle, cavity length, and cavity convergence angle. Internal nozzle performance (wind-off conditions) and thrust vector angles were computed for several configurations over a range of nozzle pressure ratios from 1.89 to 10, with the fluidic injection flow rate equal to zero and up to 4 percent of the primary flow rate. The effect of a variable expansion ratio on nozzle performance over a range of freestream Mach numbers up to 2 was investigated. Results indicated that a 60 circumferential injection was a good compromise between large thrust vector angles and efficient internal nozzle performance. A cavity divergence angle greater than 10 was detrimental to thrust vector angle. Shortening the cavity length improved internal nozzle performance with a small penalty to thrust vector angle. Contrary to expectations, a variable expansion ratio did not improve thrust efficiency at the flight conditions investigated.

Deere, Karen A.; Flamm, Jeffrey D.; Berrier, Bobby L.; Johnson, Stuart K.

2007-01-01

54

Pneumatic motor powered Thrust Vector Control (TVC) for liquid propelled launch vehicles  

NASA Astrophysics Data System (ADS)

Recent studies performed for the Titan 4 launch vehicle indicate significant potential advantages in replacing the current stage 1 and 2 recirculating hydraulic TVC (thrust vector control) system with a PMA (pneumatic mechanical actuation) system. Some of the advantages of a PMA system over the recirculating hydraulic system include reduced part count and weight, reduced maintenance and life-cycle cost, and improved mission reliability. PMA technology, used in aircraft applications since the 1960s, is well suited in launch vehicle TVC applications where an existing pneumatic pressure source is available. A typical pneumatic motor TVC consists of a pneumatic power source, a dual rotor pneumatic motor, a gear box, a ball screw actuator, and the associated closed-loop servo-control elements. One key issue with implementing this mechanical approach is designing a TVC system to withstand large load transient disturbances during liquid engine starting. Hydraulic actuator transient loads have exceeded 60,000 lb(sub f) for a 30,000 lb(sub f) stall design actuator during ground starts of the Titan 3B, Stage 1 engine. A PMA TVC system must also withstand these start transients without imparting excessive reaction loads to the engine nozzle and thrust structure. Work completed to date with Martin Marietta to examine pneumatic motor powered TVC options and technology benefits is presented. The load transient issue is discussed along with potential solutions and the associated trades. General background on PMA technology and experience base is also presented.

Malone, Mark C.; Evans, P. S.

1992-02-01

55

Static performance of a cruciform nozzle with multiaxis thrust-vectoring and reverse-thrust capabilities  

NASA Technical Reports Server (NTRS)

A multiaxis thrust vectoring nozzle designed to have equal flow turning capability in pitch and yaw was conceived and experimentally tested for internal, static performance. The cruciform-shaped convergent-divergent nozzle turned the flow for thrust vectoring by deflecting the divergent surfaces of the nozzle, called flaps. Methods for eliminating physical interference between pitch and yaw flaps at the larger multiaxis deflection angles was studied. These methods included restricting the pitch flaps from the path of the yaw flaps and shifting the flow path at the throat off the nozzle centerline to permit larger pitch-flap deflections without interfering with the operation of the yaw flaps. Two flap widths were tested at both dry and afterburning settings. Vertical and reverse thrust configurations at dry power were also tested. Comparison with two dimensional convergent-divergent nozzles showed lower but still competitive thrust performance and thrust vectoring capability.

Wing, David J.; Asbury, Scott C.

1992-01-01

56

Internal performance of two nozzles utilizing gimbal concepts for thrust vectoring  

NASA Technical Reports Server (NTRS)

The internal performance of an axisymmetric convergent-divergent nozzle and a nonaxisymmetric convergent-divergent nozzle, both of which utilized a gimbal type mechanism for thrust vectoring was evaluated in the Static Test Facility of the Langley 16-Foot Transonic Tunnel. The nonaxisymmetric nozzle used the gimbal concept for yaw thrust vectoring only; pitch thrust vectoring was accomplished by simultaneous deflection of the upper and lower divergent flaps. The model geometric parameters investigated were pitch vector angle for the axisymmetric nozzle and pitch vector angle, yaw vector angle, nozzle throat aspect ratio, and nozzle expansion ratio for the nonaxisymmetric nozzle. All tests were conducted with no external flow, and nozzle pressure ratio was varied from 2.0 to approximately 12.0.

Berrier, Bobby L.; Taylor, John G.

1990-01-01

57

An Experimental/Modeling Study of Jet Attachment during Counterflow Thrust Vectoring  

NASA Technical Reports Server (NTRS)

Recent studies have shown the applicability of vectoring rectangular jets using asymmetrically applied counterflow in the presence of a short collar. This novel concept has applications in the aerospace industry where counterflow can be used to vector the thrust of a jet's exhaust, shortening take-off and landing distances and enhancing in-flight maneuverability of the aircraft. Counterflow thrust vectoring, 'CFTV' is desirable due to its fast time response, low thrust loss, and absence of moving parts. However, implementation of a CFTV system is only possible if bistable jet attachment can be prevented. This can be achieved by properly designing the geometry of the collar. An analytical model is developed herein to predict the conditions under which a two-dimensional jet will attach to an offset curved wall. Results from this model are then compared with experiment; for various jet exit Mach numbers, collar offset distances, and radii of curvature. Their excellent correlation permits use of the model as a tool for designing a CFTV system.

Strykowski, Paul J.

1997-01-01

58

Robust vibration suppression of an adaptive circular composite plate for satellite thrust vector control  

NASA Astrophysics Data System (ADS)

In this paper, a novel application of adaptive composite structures, a University of Hawaii at Manoa (UHM) smart composite platform, is developed for the Thrust Vector Control (TVC) of satellites. The device top plate of the UHM platform is an adaptive circular composite plate (ACCP) that utilizes integrated sensors/actuators and controllers to suppress low frequency vibrations during the thruster firing as well as to potentially isolate dynamic responses from the satellite structure bus. Since the disturbance due to the satellite thruster firing can be estimated, a combined strategy of an adaptive disturbance observer (DOB) and feed-forward control is proposed for vibration suppression of the ACCP with multi-sensors and multi-actuators. Meanwhile, the effects of the DOB cut-off frequency and the relative degree of the low-pass filter on the DOB performance are investigated. Simulations and experimental results show that higher relative degree of the low-pass filter with the required cut-off frequency will enhance the DOB performance for a high-order system control. Further, although the increase of the filter cut-off frequency can guarantee a sufficient stability margin, it may cause an undesirable increase of the control bandwidth. The effectiveness of the proposed adaptive DOB with feed-forward control strategy is verified through simulations and experiments using the ACCP system.

Yan, Su; Ma, Kougen; Ghasemi-Nejhad, Mehrdad N.

2008-03-01

59

Multi-objective Optimal Design of a Fluidic Thrust Vectoring Nozzle  

E-print Network

Multi-objective Optimal Design of a Fluidic Thrust Vectoring Nozzle Andr´as S´obester , Andy J to the shape of the main jet nozzle and the present work focuses on these. First, unless carefully designed flapless aircraft. One of the core components of a Coanda FTV device is the main jet nozzle, featuring

Sóbester, András

60

Application of the DRBEM to model ablation characteristics of a thrust vector control vane  

Microsoft Academic Search

A dual reciprocity boundary element method (DRBEM) is implemented to predict ablation in model thrust vector control (TVC) vanes. A moving front algorithm is described. Experimental data are available from tests performed on scaled vanes. Numerical results for recession of quarter-scale and half-scale vanes compare well with experimental data. Future work includes full coupling of the flowfield and conduction solutions.

E. Divo; A. Kassab; R. Cavalleri

1999-01-01

61

American Institute of Aeronautics and Astronautics Characterization of a Counterflow Thrust Vectoring Scheme  

E-print Network

Vectoring Scheme on a Gas Turbine Engine Exhaust Jet Dores, D.* and Madruga Santos, M.. Academia da Força of the application of 2-D counterflow thrust vectoring to the exhaust of a gas turbine engine. The characterization vanes, nozzles or plates vectored the jet. The performance of this new flight control concept was tested

Collins, Emmanuel

62

Solid rocket booster thrust vector control subsystem verification test (V-2) report  

NASA Technical Reports Server (NTRS)

The results of the verification testing sequence V-2 performed on the space shuttle solid rocket booster thrust vector control subsystem are presented. A detailed history of the hot firings plus additional discussion of the auxiliary power unit and the hydraulic component performance is presented. The test objectives, data, and conclusions are included.

Pagan, B.

1979-01-01

63

Design Specification for a Thrust-Vectoring, Actuated-Nose-Strake Flight Control Law for the High-Alpha Research Vehicle  

NASA Technical Reports Server (NTRS)

Specifications for a flight control law are delineated in sufficient detail to support coding the control law in flight software. This control law was designed for implementation and flight test on the High-Alpha Research Vehicle (HARV), which is an F/A-18 aircraft modified to include an experimental multi-axis thrust-vectoring system and actuated nose strakes for enhanced rolling (ANSER). The control law, known as the HARV ANSER Control Law, was designed to utilize a blend of conventional aerodynamic control effectors, thrust vectoring, and actuated nose strakes to provide increased agility and good handling qualities throughout the HARV flight envelope, including angles of attack up to 70 degrees.

Bacon, Barton J.; Carzoo, Susan W.; Davidson, John B.; Hoffler, Keith D.; Lallman, Frederick J.; Messina, Michael D.; Murphy, Patrick C.; Ostroff, Aaron J.; Proffitt, Melissa S.; Yeager, Jessie C.; Foster, John V.; Bundick, W. Thomas; Connelly, Patrick J.; Kelly, John W.; Pahle, Joseph W.; Thomas, Michael; Wichman, Keith D.; Wilson, R. Joseph

1996-01-01

64

Design Enhancements of the Two-Dimensional, Dual Throat Fluidic Thrust Vectoring Nozzle Concept  

NASA Technical Reports Server (NTRS)

A Dual Throat Nozzle fluidic thrust vectoring technique that achieves higher thrust-vectoring efficiencies than other fluidic techniques, without sacrificing thrust efficiency has been developed at NASA Langley Research Center. The nozzle concept was designed with the aid of the structured-grid, Reynolds-averaged Navier-Stokes computational fluidic dynamics code PAB3D. This new concept combines the thrust efficiency of sonic-plane skewing with increased thrust-vectoring efficiencies obtained by maximizing pressure differentials in a separated cavity located downstream of the nozzle throat. By injecting secondary flow asymmetrically at the upstream minimum area, a new aerodynamic minimum area is formed downstream of the geometric minimum and the sonic line is skewed, thus vectoring the exhaust flow. The nozzle was tested in the NASA Langley Research Center Jet Exit Test Facility. Internal nozzle performance characteristics were defined for nozzle pressure ratios up to 10, with a range of secondary injection flow rates up to 10 percent of the primary flow rate. Most of the data included in this paper shows the effect of secondary injection rate at a nozzle pressure ratio of 4. The effects of modifying cavity divergence angle, convergence angle and cavity shape on internal nozzle performance were investigated, as were effects of injection geometry, hole or slot. In agreement with computationally predicted data, experimental data verified that decreasing cavity divergence angle had a negative impact and increasing cavity convergence angle had a positive impact on thrust vector angle and thrust efficiency. A curved cavity apex provided improved thrust ratios at some injection rates. However, overall nozzle performance suffered with no secondary injection. Injection holes were more efficient than the injection slot over the range of injection rates, but the slot generated larger thrust vector angles for injection rates less than 4 percent of the primary flow rate.

Flamm, Jeffrey D.; Deere, Karen A.; Mason, Mary L.; Berrier, Bobby L.; Johnson, Stuart K.

2006-01-01

65

Fluidic scale model multi-plane thrust vector control test results  

NASA Technical Reports Server (NTRS)

An experimental investigation has been conducted at the NASA Langley 16-Foot Transonic Tunnel Static Test Facility to determine the concept feasibility of using fluidics to achieve multiplane thrust vector control in a 2D convergent-divergent (2D-CD) fixed aperture nozzle. Pitch thrust vector control is achieved by injection of flow through a slot in the divergent flap into the primary nozzle flow stream. Yaw vector control results from secondary air delivered tangentially to vertical Coanda flaps. These flaps are offset laterally and aligned parallel to the primary nozzle side walls. All tests were conducted at static (no external flow) conditions. Flow visualization was conducted using a paint flow technique and Focus Schlieren. Significant levels of pitch deflection angles (19 deg) were achieved at low pressure ratios and practical levels (14 deg) resulted at typical intermediate power settings. The ability of the Coanda surface blowing concept to produce yaw deflection was limited to NPR not greater than 4.

Chiarelli, Charles; Johnsen, Raymond K.; Shieh, Chih F.; Wing, David J.

1993-01-01

66

Static investigation of two STOL nozzle concepts with pitch thrust-vectoring capability  

NASA Technical Reports Server (NTRS)

A static investigation of the internal performance of two short take-off and landing (STOL) nozzle concepts with pitch thrust-vectoring capability has been conducted. An axisymmetric nozzle concept and a nonaxisymmetric nozzle concept were tested at dry and afterburning power settings. The axisymmetric concept consisted of a circular approach duct with a convergent-divergent nozzle. Pitch thrust vectoring was accomplished by vectoring the approach duct without changing the nozzle geometry. The nonaxisymmetric concept consisted of a two dimensional convergent-divergent nozzle. Pitch thrust vectoring was implemented by blocking the nozzle exit and deflecting a door in the lower nozzle flap. The test nozzle pressure ratio was varied up to 10.0, depending on model geometry. Results indicate that both pitch vectoring concepts produced resultant pitch vector angles which were nearly equal to the geometric pitch deflection angles. The axisymmetric nozzle concept had only small thrust losses at the largest pitch deflection angle of 70 deg., but the two-dimensional convergent-divergent nozzle concept had large performance losses at both of the two pitch deflection angles tested, 60 deg. and 70 deg.

Mason, M. L.; Burley, J. R., II

1986-01-01

67

Effect of thrust vectoring and wing maneuver devices on transonic aeropropulsive characteristics of a supersonic fighter  

NASA Technical Reports Server (NTRS)

The aeropropulsive characteristics of an advanced fighter designed for supersonic cruise were determined in the Langley 16-Foot Transonic Tunnel. The objectives of this investigation were to evaluate the interactive effects of thrust vectoring and wing maneuver devices on lift and drag and to determine trim characteristics. The wing maneuver devices consisted of a drooped leading edge and a trailing-edge flap. Thrust vectoring was accomplished with two dimensional (nonaxisymmetric) convergent-divergent nozzles located below the wing in two single-engine podded nacelles. A canard was utilized for trim. Thrust vector angles of 0 deg, 15 deg, and 30 deg were tested in combination with a drooped wing leading edge and with wing trailing-edge flap deflections up to 30 deg. This investigation was conducted at Mach numbers from 0.60 to 1.20, at angles of attack from 0 deg to 20 deg, and at nozzle pressure ratios from about 1 (jet off) to 10. Reynolds number based on mean aerodynamic chord varied from 9.24 x 10 to the 6th to 10.56 x 10 to the 6th.

Capone, F. J.; Reubush, D. E.

1983-01-01

68

Static performance of nonaxisymmetric nozzles with yaw thrust-vectoring vanes  

NASA Technical Reports Server (NTRS)

A static test was conducted in the static test facility of the Langley 16 ft Transonic Tunnel to evaluate the effects of post exit vane vectoring on nonaxisymmetric nozzles. Three baseline nozzles were tested: an unvectored two dimensional convergent nozzle, an unvectored two dimensional convergent-divergent nozzle, and a pitch vectored two dimensional convergent-divergent nozzle. Each nozzle geometry was tested with 3 exit aspect ratios (exit width divided by exit height) of 1.5, 2.5 and 4.0. Two post exit yaw vanes were externally mounted on the nozzle sidewalls at the nozzle exit to generate yaw thrust vectoring. Vane deflection angle (0, -20 and -30 deg), vane planform and vane curvature were varied during the test. Results indicate that the post exit vane concept produced resultant yaw vector angles which were always smaller than the geometric yaw vector angle. Losses in resultant thrust ratio increased with the magnitude of resultant yaw vector angle. The widest post exit vane produced the largest degree of flow turning, but vane curvature had little effect on thrust vectoring. Pitch vectoring was independent of yaw vectoring, indicating that multiaxis thrust vectoring is feasible for the nozzle concepts tested.

Mason, Mary L.; Berrier, Bobby L.

1988-01-01

69

Vista/F-16 Multi-Axis Thrust Vectoring (MATV) control law design and evaluation  

NASA Technical Reports Server (NTRS)

For the Multi-Axis Thrust Vectoring (MATV) program, a new control law was developed using multi-axis thrust vectoring to augment the aircraft's aerodynamic control power to provide maneuverability above the normal F-16 angle of attack limit. The control law architecture was developed using Lockheed Fort Worth's offline and piloted simulation capabilities. The final flight control laws were used in flight test to demonstrate tactical benefits gained by using thrust vectoring in air-to-air combat. Differences between the simulator aerodynamics data base and the actual aircraft aerodynamics led to significantly different lateral-directional flying qualities during the flight test program than those identified during piloted simulation. A 'dial-a-gain' flight test control law update was performed in the middle of the flight test program. This approach allowed for inflight optimization of the aircraft's flying qualities. While this approach is not preferred over updating the simulator aerodynamic data base and then updating the control laws, the final selected gain set did provide adequate lateral-directional flying qualities over the MATV flight envelope. The resulting handling qualities and the departure resistance of the aircraft allowed the 422nd_squadron pilots to focus entirely on evaluating the aircraft's tactical utility.

Zwerneman, W. D.; Eller, B. G.

1994-01-01

70

Hybrid electrical power source for thrust vector control electromechanical actuation  

SciTech Connect

The next generation of launch vehicles propose to use electromechanical actuators (EMA`s) for engine gimbaling and aerosurface control to eliminate hydraulics and its associated systems and problems. The new actuation systems are not without their own challenges. An EMA`s duty cycle has two components: a high power pulse to initiate and perform the actuation, and a nominal load to maintain position. Conventional batteries must be sized to meet the pulse power requirement while maintaining a bus voltage in range to satisfy the needs of the EMA control electronics, and therein lies the problem. Restricting the voltage sag limits the discharge rate of the battery and therefore requires an increase in the Amp-hour rating, which relates directly to an increase in weight. An option to lower power source weight is a hybrid source consisting of a conventional battery and a capacitor bank. A hybrid source of this type would utilize the power density strengths of a capacitor bank to meet the high power pulse demands, and the energy density strengths of a battery to provide average power and capacitor recharging. Testing has been performed at NASA`s Marshall Space Flight Center (MSFC) with support from Auburn University`s Space Power Institute to investigate the validity of the hybrid power source concept. This proof-of-concept testing used chemical double layer (CDL) capacitor technology in the form of a {approx}5 farad-270 volt capacitor bank, standard deep cycle marine lead-acid batteries, and a 25 horse power EMA developed at MSFC. The test data was used to size a flight type Ag-Zn battery to perform the same task in a battery-only configuration, and also size a battery for a hybrid configuration. Test results and analysis show that a >50% weight savings can be realized with this type of hybrid power source with no negative effect on performance. These results support the need for further development in the area of CDL capacitors and hybrid configurations.

Hall, D.K. [NASA, Huntsville, AL (United States). Marshall Space Flight Center; Merryman, S.A. [Auburn Univ., AL (United States). Space Power Inst.

1995-12-31

71

Attitude Determination for NPS Three-Axis Spacecraft Simulator  

Microsoft Academic Search

This paper presents the attitude determination method for the Bifocal Relay Mirror Spacecraft Simulator. The simulator simulates three-axis motion of a spacecraft and has an optical system emulating a bifocal space telescope. The simulator consists of three control moment gyroscopes, rate gyros, two-axis analog sun sensor, and two inclinometers. The five-foot diameter platform is supported on a spherical air bearing

Jong-Woo Kim; Roberto Cristi; Brij N. Agrawal

2004-01-01

72

Static investigation of two fluidic thrust-vectoring concepts on a two-dimensional convergent-divergent nozzle  

NASA Technical Reports Server (NTRS)

A static investigation was conducted in the static test facility of the Langley 16-Foot Transonic Tunnel of two thrust-vectoring concepts which utilize fluidic mechanisms for deflecting the jet of a two-dimensional convergent-divergent nozzle. One concept involved using the Coanda effect to turn a sheet of injected secondary air along a curved sidewall flap and, through entrainment, draw the primary jet in the same direction to produce yaw thrust vectoring. The other concept involved deflecting the primary jet to produce pitch thrust vectoring by injecting secondary air through a transverse slot in the divergent flap, creating an oblique shock in the divergent channel. Utilizing the Coanda effect to produce yaw thrust vectoring was largely unsuccessful. Small vector angles were produced at low primary nozzle pressure ratios, probably because the momentum of the primary jet was low. Significant pitch thrust vector angles were produced by injecting secondary flow through a slot in the divergent flap. Thrust vector angle decreased with increasing nozzle pressure ratio but moderate levels were maintained at the highest nozzle pressure ratio tested. Thrust performance generally increased at low nozzle pressure ratios and decreased near the design pressure ratio with the addition of secondary flow.

Wing, David J.

1994-01-01

73

Experimental Study of a Nozzle Using Fluidic Counterflow for Thrust Vectoring  

NASA Technical Reports Server (NTRS)

A static experimental investigation of a counterflow thrust vectoring nozzle concept was performed. The study was conducted in the NASA Langley Research Center Jet Exit Test Facility. Internal performance characteristics were defined over a nozzle pressure ratio (jet total to ambient) range of 3.5 to 10.0. The effects of suction collar geometry and suction slot height on nozzle performance were examined. In the counterflow concept, thrust vectoring is achieved by applying a vacuum to a slot adjacent to a primary jet that is shrouded by a suction collar. Two flow phenomena work to vector the primary jet depending upon the test conditions and configuration. In one case, the vacuum source creates a secondary reverse flowing stream near the primary jet. The shear layers between the two counterflowing streams mix and entrain mass from the surrounding fluid. The presence of the collar inhibits mass entrainment and the flow near the collar accelerates, causing a drop in pressure on the collar. The second case works similarly except that the vacuum is not powerful enough to create a counterflowing stream and instead a coflowing stream is present. The primary jet is vectored if suction is applied asymmetrically on the top or bottom of the jet.

Flamm, Jeffrey D.

1998-01-01

74

Static investigation of a two-dimensional convergent-divergent exhaust nozzle with multiaxis thrust-vectoring capability  

NASA Technical Reports Server (NTRS)

An investigation was conducted in the Static Test Facility of the NASA Langley 16-Foot Transonic Tunnel to determine the internal performance of two-dimensional convergent-divergent nozzles designed to have simultaneous pitch and yaw thrust vectoring capability. This concept utilized divergent flap rotation of thrust vectoring in the pitch plane and deflection of flat yaw flaps hinged at the end of the sidewalls for yaw thrust vectoring. The hinge location of the yaw flaps was varied at four positions from the nozzle exit plane to the throat plane. The yaw flaps were designed to contain the flow laterally independent of power setting. In order to eliminate any physical interference between the yaw flap deflected into the exhaust stream and the divergent flaps, the downstream corners of both upper and lower divergent flaps were cut off to allow for up to 30 deg of yaw flap deflection. The impact of varying the nozzle pitch vector angle, throat area, yaw flap hinge location, yaw flap length, and yaw flap deflection angle on nozzle internal performance characteristics, was studied. High-pressure air was used to simulate jet exhaust at nozzle pressure ratios up to 7.0. Static results indicate that configurations with the yaw flap hinge located upstream of the exit plane provide relatively high levels of thrust vectoring efficiency without causing large losses in resultant thrust ratio. Therefore, these configurations represent a viable concept for providing simultaneous pitch and yaw thrust vectoring.

Taylor, John G.

1990-01-01

75

A simple dynamic engine model for use in a real-time aircraft simulation with thrust vectoring  

NASA Technical Reports Server (NTRS)

A simple dynamic engine model was developed for use in thrust vectoring control law development and real-time aircraft simulation. Engine dynamics were simulated using a throttle rate limiter and low-pass filter. This paper includes a description of a method to account for axial thrust loss resulting from thrust vectoring and the development of the simple dynamic engine model and its incorporation into the F-18 high alpha research vehicle (HARV) thrust vectoring simulation. The simple dynamic engine model was evaluated at Mach 0.2, 35,000-ft altitude and at Mach 0.7, 35,000-ft altitude. The simple dynamic engine model is within 3 percent of the steady state response, and within 25 percent of the transient response of the complete nonlinear dynamic engine model.

Johnson, Steven A.

1990-01-01

76

Static internal performance of a two-dimensional convergent nozzle with thrust-vectoring capability up to 60 deg  

NASA Technical Reports Server (NTRS)

An investigation was conducted at wind-off conditions in the static-test facility of the Langley 16-Foot Transonic Tunnel to determine the internal performance characteristics of a two-dimensional convergent nozzle with a thrust-vectoring capability up to 60 deg. Vectoring was accomplished by a downward rotation of a hinged upper convergent flap and a corresponding rotation of a center-pivoted lower convergent flap. The effects of geometric thrust-vector angle and upper-rotating-flap geometry on internal nozzle performance characteristics were investigated. Nozzle pressure ratio was varied from 1.0 (jet off) to approximately 5.0.

Leavitt, L. D.

1985-01-01

77

Static internal performance of single-expansion-ramp nozzles with thrust-vectoring capability up to 60 deg  

NASA Technical Reports Server (NTRS)

An investigation has been conducted at static conditions (wind off) in the static-test facility of the Langley 16-Foot Transonic Tunnel. The effects of geometric thrust-vector angle, sidewall containment, ramp curvature, lower-flap lip angle, and ramp length on the internal performance of nonaxisymmetric single-expansion-ramp nozzles were investigated. Geometric thrust-vector angle was varied from -20 deg. to 60 deg., and nozzle pressure ratio was varied from 1.0 (jet off) to approximately 10.0.

Berrier, B. L.; Leavitt, L. D.

1984-01-01

78

Three-Axis Acceleration Sensor Using Polyurea Films  

NASA Astrophysics Data System (ADS)

Focusing on the possibilities of polyurea as an acceleration sensor with characteristics such as flexibility, durability against large deformation, good linearity, and capability of deposition in dryprocess and insolubility in organic solvent, we first fabricated a cantilever acceleration sensor and a three-axis acceleration sensor. The output voltage in the large-strain region is measured using a polyurea cantilever sensor attached to a beryllium copper substrate. The results show that output voltages have good linearity for large strains up to 1%. This value is much larger than the breakdown limit of lead zirconate titanate. Second, we fabricated a polyurea three-axis acceleration sensor. The sensor consists of an insulation layer of polyurea on the cross beam substrate of phosphor bronze, a bottom aluminum electrode, a polyurea active layer, and four top aluminum electrodes. The experimental results for harmonic acceleration show that the sensor works as expected. The cross-axis sensitivity of the polyurea sensor was less than 8%, which is close to that of conventional microelectromechanical system sensors.

Tabaru, Masaya; Nakazawa, Marie; Nakamura, Kentaro; Ueha, Sadayuki

2008-05-01

79

Implicit time-marching solution of the Navier-Stokes equations for thrust reversing and thrust vectoring nozzle flows  

Microsoft Academic Search

An implicit finite volume method is investigated for the solution of the compressible Navier-Stokes equations for flows within thrust reversing and thrust vectoring nozzles. Thrust reversing nozzles typically have sharp corners, and the rapid expansion and large turning angles near these corners are shown to cause unacceptable time step restrictions when conventional approximate factorization methods are used. In this investigation

S. T. Imlay

1986-01-01

80

Design and development of the quad redundant servoactuator for the space shuttle solid rocket booster thrust vector control  

NASA Technical Reports Server (NTRS)

The design and theory of operation of the servoactuator used for thrust vector control of the space shuttle solid rocket booster is described accompanied by highlights from the development and qualification test programs. Specific details are presented concerning major anomalies that occurred during the test programs and the corrective courses of action pursued.

Lominick, J. M.

1980-01-01

81

Fiber-optic three axis magnetometer prototype development  

NASA Technical Reports Server (NTRS)

The goal of this research program was to develop a high sensitivity, fiber optic, interferometric, three-axis magnetometer for interplanetary spacecraft applications. Dynamics Technology, Inc. (DTI) has successfully integrated a low noise, high bandwidth interferometer with high sensitivity metallic glass transducers. Also, DTI has developed sophisticated signal processing electronics and complete data acquisition, filtering, and display software. The sensor was packaged in a compact, low power and weight unit which facilitates deployment. The magnetic field sensor had subgamma sensitivity and a dynamic range of 10(exp 5) gamma in a 10 Hz bandwidth. Furthermore, the vector instrument exhibited the lowest noise level when only one axis was in operation. A system noise level of 1 gamma rms was observed in a 1 Hz bandwidth. However, with the other two channels operating, the noise level increased by about one order of magnitude. Higher system noise was attributed to cross-channel interference among the dither fields.

Wang, Thomas D.; Mccomb, David G.; Kingston, Bradley R.; Dube, C. Michael; Poehls, Kenneth A.; Wanser, Keith

1989-01-01

82

Independent Orbiter Assessment (IOA): Assessment of the ascent thrust vector control actuator subsystem FMEA/CIL  

NASA Technical Reports Server (NTRS)

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed an analysis of the Ascent Thrust Vector Control Actuator (ATVD) hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The IOA results were then compared to the NASA FMEA/CIL baseline with proposed Post 51-L updates included. A resolution of each discrepancy from the comparison is provided through additional analysis as required. This report documents the results of that comparison for the Orbiter ATVC hardware. The IOA product for the ATVC actuator analysis consisted of 25 failure mode worksheets that resulted in 16 potential critical items being identified. Comparison was made to the NASA baseline which consisted of 21 FMEAs and 13 CIL items. This comparison produced agreement on all CIL items. Based on the Pre 51-L baseline, all non-CIL FMEAs were also in agreement.

Wilson, R. E.

1988-01-01

83

Improved Controller for a Three-Axis Piezoelectric Stage  

NASA Technical Reports Server (NTRS)

An improved closed-loop controller has been built for a three-axis piezoelectric positioning stage. The stage can be any of a number of commercially available or custom-made units that are used for precise three-axis positioning of optics in astronomical instruments and could be used for precise positioning in diverse fields of endeavor that include adaptive optics, fabrication of semiconductors, and nanotechnology.

Rao, Shanti; Palmer, Dean

2009-01-01

84

A simple dynamic engine model for use in a real-time aircraft simulation with thrust vectoring  

NASA Technical Reports Server (NTRS)

A simple dynamic engine model was developed at the NASA Ames Research Center, Dryden Flight Research Facility, for use in thrust vectoring control law development and real-time aircraft simulation. The simple dynamic engine model of the F404-GE-400 engine (General Electric, Lynn, Massachusetts) operates within the aircraft simulator. It was developed using tabular data generated from a complete nonlinear dynamic engine model supplied by the manufacturer. Engine dynamics were simulated using a throttle rate limiter and low-pass filter. Included is a description of a method to account for axial thrust loss resulting from thrust vectoring. In addition, the development of the simple dynamic engine model and its incorporation into the F-18 high alpha research vehicle (HARV) thrust vectoring simulation. The simple dynamic engine model was evaluated at Mach 0.2, 35,000 ft altitude and at Mach 0.7, 35,000 ft altitude. The simple dynamic engine model is within 3 percent of the steady state response, and within 25 percent of the transient response of the complete nonlinear dynamic engine model.

Johnson, Steven A.

1990-01-01

85

Attitude determination of small spinning spacecraft using three axis magnetometer and solar panels data  

Microsoft Academic Search

An algorithm for attitude determination of a spinning spacecraft in Low Earth Orbit using three axis magnetometer and solar panels data is proposed. With this algorithm, the solar panels necessary for power generation are also used as a sensing system for attitude determination. The algorithm employs voltage, current and temperature measurements from all of the solar panels to reconstruct the

F. Santoni; F. Bolotti

2000-01-01

86

Stable Three-Axis Nuclear Spin Gyroscope in Diamond  

E-print Network

We propose a sensitive and stable three-axis gyroscope in diamond. We achieve high sensitivity by exploiting the long coherence time of the N14 nuclear spin associated with the Nitrogen-Vacancy center in diamond, and the efficient polarization and measurement of its electronic spin. While the gyroscope is based on a simple Ramsey interferometry scheme, we use coherent control of the quantum sensor to improve its coherence time as well as its robustness against long-time drifts, thus achieving a very robust device with a resolution of 0.5mdeg/s/(Hz mm^3)^(1/2). In addition, we exploit the four axes of delocalization of the Nitrogen-Vacancy center to measure not only the rate of rotation, but also its direction, thus obtaining a compact three-axis gyroscope.

Ajoy, Ashok

2012-01-01

87

Stable Three-Axis Nuclear Spin Gyroscope in Diamond  

E-print Network

We propose a sensitive and stable three-axis gyroscope in diamond. We achieve high sensitivity by exploiting the long coherence time of the N14 nuclear spin associated with the Nitrogen-Vacancy center in diamond, and the efficient polarization and measurement of its electronic spin. While the gyroscope is based on a simple Ramsey interferometry scheme, we use coherent control of the quantum sensor to improve its coherence time as well as its robustness against long-time drifts, thus achieving a very robust device with a resolution of 0.5mdeg/s/(Hz mm^3)^(1/2). In addition, we exploit the four axes of delocalization of the Nitrogen-Vacancy center to measure not only the rate of rotation, but also its direction, thus obtaining a compact three-axis gyroscope.

Ashok Ajoy; Paola Cappellaro

2012-05-07

88

Three-axis attitude determination via Kalman filtering of magnetometer data  

NASA Technical Reports Server (NTRS)

A three-axis Magnetometer/Kalman Filter attitude determination system for a spacecraft in low-altitude Earth orbit is developed, analyzed, and simulation tested. The motivation for developing this system is to achieve light weight and low cost for an attitude determination system. The extended Kalman filter estimates the attitude, attitude rates, and constant disturbance torques. Accuracy near that of the International Geomagnetic Reference Field model is achieved. Covariance computation and simulation testing demonstrate the filter's accuracy. One test case, a gravity-gradient stabilized spacecraft with a pitch momentum wheel and a magnetically-anchored damper, is a real satellite on which this attitude determination system will be used. The application to a nadir pointing satellite and the estimation of disturbance torques represent the significant extensions contributed by this paper. Beyond its usefulness purely for attitude determination, this system could be used as part of a low-cost three-axis attitude stabilization system.

Martel, Francois; Pal, Parimal K.; Psiaki, Mark L.

1988-01-01

89

An experimental investigation of thrust vectoring two-dimensional convergent-divergent nozzles installed in a twin-engine fighter model at high angles of attack  

NASA Technical Reports Server (NTRS)

An investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine thrust vectoring capability of subscale 2-D convergent-divergent exhaust nozzles installed on a twin engine general research fighter model. Pitch thrust vectoring was accomplished by downward rotation of nozzle upper and lower flaps. The effects of nozzle sidewall cutback were studied for both unvectored and pitch vectored nozzles. A single cutback sidewall was employed for yaw thrust vectoring. This investigation was conducted at Mach numbers ranging from 0 to 1.20 and at angles of attack from -2 to 35 deg. High pressure air was used to simulate jet exhaust and provide values of nozzle pressure ratio up to 9.

Capone, Francis J.; Mason, Mary L.; Leavitt, Laurence D.

1990-01-01

90

Design and Modeling of a Three-axis Piezoresistive Microelectronic Accelerometer  

NASA Astrophysics Data System (ADS)

Micro-electro-mechanical systems (MEMS) for automotive industry and biomedical applications (BioMEMS) have the fastest growth rate within the MEMS market. The Microsystems job market imposes to research laboratories and universities to respond by increasing the quality of MEMS engineering and informatics interdisciplinary training programs. In this fact, our work consists to study and develop a three-axis piezoresistive accelerometer having uniform sensitivities along to three axes. This sensor which is made of a heavy proof mass and four long beams, allow us to obtain high sensitivities, by reducing the resonant frequencies. Uniform axial sensitivities, with a transverse sensitivity, could be obtained using a three-axis sensor. The stress analysis of this sensor was performed in order to determine the positions of the piezoresistances, in the four flexure beams.

Benmoussa, N.; Benichou, A.; Ghaffour, K.; Benyoucef, B.

91

Real-Time Attitude-Independent Gyro Calibration from Three-Axis Magnetometer Measurements  

E-print Network

Real-Time Attitude-Independent Gyro Calibration from Three-Axis Magnetometer Measurements Kok bias calibration using three-axis magnetometer mea- surements without any attitude knowledge is derived. This approach relies on a con- version of the three-axis magnetometer measurement and its derivative

Crassidis, John L.

92

Novel Calibration Algorithm for a Three-Axis Strapdown Magnetometer  

PubMed Central

A complete error calibration model with 12 independent parameters is established by analyzing the three-axis magnetometer error mechanism. The said model conforms to an ellipsoid restriction, the parameters of the ellipsoid equation are estimated, and the ellipsoid coefficient matrix is derived. However, the calibration matrix cannot be determined completely, as there are fewer ellipsoid parameters than calibration model parameters. Mathematically, the calibration matrix derived from the ellipsoid coefficient matrix by a different matrix decomposition method is not unique, and there exists an unknown rotation matrix R between them. This paper puts forward a constant intersection angle method (angles between the geomagnetic field and gravitational field are fixed) to estimate R. The Tikhonov method is adopted to solve the problem that rounding errors or other errors may seriously affect the calculation results of R when the condition number of the matrix is very large. The geomagnetic field vector and heading error are further corrected by R. The constant intersection angle method is convenient and practical, as it is free from any additional calibration procedure or coordinate transformation. In addition, the simulation experiment indicates that the heading error declines from ±1° calibrated by classical ellipsoid fitting to ±0.2° calibrated by a constant intersection angle method, and the signal-to-noise ratio is 50 dB. The actual experiment exhibits that the heading error is further corrected from ±0.8° calibrated by the classical ellipsoid fitting to ±0.3° calibrated by a constant intersection angle method. PMID:24831110

Liu, Yan Xia; Li, Xi Sheng; Zhang, Xiao Juan; Feng, Yi Bo

2014-01-01

93

Novel calibration algorithm for a three-axis strapdown magnetometer.  

PubMed

A complete error calibration model with 12 independent parameters is established by analyzing the three-axis magnetometer error mechanism. The said model conforms to an ellipsoid restriction, the parameters of the ellipsoid equation are estimated, and the ellipsoid coefficient matrix is derived. However, the calibration matrix cannot be determined completely, as there are fewer ellipsoid parameters than calibration model parameters. Mathematically, the calibration matrix derived from the ellipsoid coefficient matrix by a different matrix decomposition method is not unique, and there exists an unknown rotation matrix R between them. This paper puts forward a constant intersection angle method (angles between the geomagnetic field and gravitational field are fixed) to estimate R. The Tikhonov method is adopted to solve the problem that rounding errors or other errors may seriously affect the calculation results of R when the condition number of the matrix is very large. The geomagnetic field vector and heading error are further corrected by R. The constant intersection angle method is convenient and practical, as it is free from any additional calibration procedure or coordinate transformation. In addition, the simulation experiment indicates that the heading error declines from ±1° calibrated by classical ellipsoid fitting to ±0.2° calibrated by a constant intersection angle method, and the signal-to-noise ratio is 50 dB. The actual experiment exhibits that the heading error is further corrected from ±0.8° calibrated by the classical ellipsoid fitting to ±0.3° calibrated by a constant intersection angle method. PMID:24831110

Liu, Yan Xia; Li, Xi Sheng; Zhang, Xiao Juan; Feng, Yi Bo

2014-01-01

94

Real-Time Attitude Independent Three Axis Magnetometer Calibration  

NASA Technical Reports Server (NTRS)

In this paper new real-time approaches for three-axis magnetometer sensor calibration are derived. These approaches rely on a conversion of the magnetometer-body and geomagnetic-reference vectors into an attitude independent observation by using scalar checking. The goal of the full calibration problem involves the determination of the magnetometer bias vector, scale factors and non-orthogonality corrections. Although the actual solution to this full calibration problem involves the minimization of a quartic loss function, the problem can be converted into a quadratic loss function by a centering approximation. This leads to a simple batch linear least squares solution. In this paper we develop alternative real-time algorithms based on both the extended Kalman filter and Unscented filter. With these real-time algorithms, a full magnetometer calibration can now be performed on-orbit during typical spacecraft mission-mode operations. Simulation results indicate that both algorithms provide accurate integer resolution in real time, but the Unscented filter is more robust to large initial condition errors than the extended Kalman filter. The algorithms are also tested using actual data from the Transition Region and Coronal Explorer (TRACE).

Crassidis, John L.; Lai, Kok-Lam; Harman, Richard R.

2003-01-01

95

A static investigation of a simultaneous pitch and yaw thrust vectoring 2-D C-D nozzle  

NASA Technical Reports Server (NTRS)

An investigation has been conducted in the static test facility of the Langley 16-Foot Transonic Tunnel to determine the internal performance and flow-turning capability of a two-dimensional convergent-divergent nozzle. Thrust vectoring in the pitch plane was provided by rotation of the divergent flaps. The exhaust stream was turned in the yaw direction by deflection of yaw flaps hinged at the end of the nozzle sidewalls. The yaw flap hinge location was varied along the divergent region of the nozzle at four locations including the exit plane and the throat plane. The three hinge locations upstream of the nozzle exit plane required the downstream corners of both upper and lower divergent flaps to be cut off to eliminate interference when the yaw flaps were deflected. Three different lengths of yaw flaps were tested at several angles of deflection. The nozzle simulated a dry power setting with an expansion ratio typical of subsonic cruise and was tested at nozzle pressure ratios from 2.0 to 7.0.

Taylor, John G.

1988-01-01

96

Multiaxis control power from thrust vectoring for a supersonic fighter aircraft model at Mach 0.20 to 2.47  

NASA Technical Reports Server (NTRS)

The aeropropulsive characteristics of an advanced twin-engine fighter aircraft designed for supersonic cruise have been studied in the Langley 16-Foot Tansonic Tunnel and the Lewis 10- by 10-Foot Supersonic Tunnel. The objective was to determine multiaxis control-power characteristics from thrust vectoring. A two-dimensional convergent-divergent nozzle was designed to provide yaw vector angles of 0, -10, and -20 deg combined with geometric pitch vector angles of 0 and 15 deg. Yaw thrust vectoring was provided by yaw flaps located in the nozzle sidewalls. Roll control was obtained from differential pitch vectoring. This investigation was conducted at Mach numbers from 0.20 to 2.47. Angle of attack was varied from 0 to about 19 deg, and nozzle pressure ratio was varied from about 1 (jet off) to 28, depending on Mach number. Increments in force or moment coefficient that result from pitch or yaw thrust vectoring remain essentially constant over the entire angle-of-attack range of all Mach numbers tested. There was no effect of pitch vectoring on the lateral aerodynamic forces and moments and only very small effects of yaw vectoring on the longitudinal aerodynamic forces and moments. This result indicates little cross-coupling of control forces and moments for combined pitch-yaw vectoring.

Capone, Francis J.; Bare, E. Ann

1987-01-01

97

Control theory analysis of a three-axis VTOL flight director. M.S. Thesis - Pennsylvania State Univ.  

NASA Technical Reports Server (NTRS)

A control theory analysis of a VTOL flight director and the results of a fixed-based simulator evaluation of the flight-director commands are discussed. The VTOL configuration selected for this study is a helicopter-type VTOL which controls the direction of the thrust vector by means of vehicle-attitude changes and, furthermore, employs high-gain attitude stabilization. This configuration is the same as one which was simulated in actual instrument flight tests with a variable stability helicopter. Stability analyses are made for each of the flight-director commands, assuming a single input-output, multi-loop system model for each control axis. The analyses proceed from the inner-loops to the outer-loops, using an analytical pilot model selected on the basis of the innermost-loop dynamics. The time response of the analytical model of the system is primarily used to adjust system gains, while root locus plots are used to identify dominant modes and mode interactions.

Niessen, F. R.

1971-01-01

98

Real-Time Attitude-Independent Three-Axis Magnetometer Calibration  

E-print Network

Real-Time Attitude-Independent Three-Axis Magnetometer Calibration John L. Crassidis Kok-Lam Lai Richard R. Harman Abstract In this paper new real-time approaches for three-axis magnetometer sensor calibration are derived. These approaches rely on a conversion of the magnetometer-body and geomagnetic

Crassidis, John L.

99

Effects of upper-surface blowing and thrust vectoring on low-speed aerodynamic characteristics of a large-scale supersonic transport model  

NASA Technical Reports Server (NTRS)

Tests were conducted in the Langley full-scale tunnel to determine the low-speed aerodynamic characteristics of a large-scale arrow-wing supersonic transport configured with engines mounted above the wing for upper surface blowing, and conventional lower surface engines with provisions for thrust vectoring. A limited number of tests were conducted for the upper surface engine configuration in the high lift condition for beta = 10 in order to evaluate lateral directional characteristics, and with the right engine inoperative to evaluate the engine out condition.

Coe, P. L., Jr.; Mclemore, H. C.; Shivers, J. P.

1975-01-01

100

Note: A compact three-axis optical force/torque sensor using photo-interrupters  

NASA Astrophysics Data System (ADS)

By integrating four photo-interrupters in a cross-shaped structure, we developed a compact three-axis optical force/torque (F/T) sensor. The developed sensor has a diameter of 28 mm and a thickness of 7 mm. Despite simplicity and compactness, the experiments with a prototype of the proposed sensor demonstrate notably high accuracy. The RMS errors are 0.5% ± 0.1% of the maximum vertical force in z-axis, 1.9% ± 0.2% of the maximum torque in x-axis, and 2.0% ± 0.3% of the maximum torque in y-axis. It is expected that the proposed sensor allows cost-effective integration of robot systems requiring compact and multi-axis F/T sensors such as a walking assist robot.

Kim, Ji-Chul; Kim, Kyung-Soo; Kim, Soohyun

2013-12-01

101

Stable three-axis nuclear-spin gyroscope in diamond  

E-print Network

Gyroscopes find wide applications in everyday life from navigation and inertial sensing to rotation sensors in hand-held devices and automobiles. Current devices, based on either atomic or solid-state systems, impose a ...

Ajoy, Ashok

102

Orbit geometry for calibration and launch operations of a three-axis controlled satellite with inertial reference  

Microsoft Academic Search

A method for determining the spacecraft, Sun, Earth geometry for a three-axis controlled satellite with inertial reference in transfer orbit is presented. Using the spacecraft as the origin of the reference system, two orientation modes are considered: the Sun-Earth plane mode, in which the X axis is pointed along the sunline, the Z axis lies in the Sun-Earth plane, and

D. R. Brown

1986-01-01

103

Development of an ultraprecision three axis micromilling machine  

NASA Astrophysics Data System (ADS)

To meet the requirement for high efficiency machining of the ultra-precision, ultra-smooth micro structured optical surface, an ultra-precision three axes micro milling machine was developed. The overall size of the machine is 600mm×500mm×700mm and all the strokes of three axes are 75mm. To overcome nonlinearity that always exists in conventional servo mechanism driven by ball screw, permanent-magnet linear motor is used to directly drive the aerostatic bearing slide. Linear encoder with 1.2 nm resolution was used as the feedback of position to buildup closed loop control system. The open architected CNC system is composed of the high performance embedded PMAC motion control card and standard industrial PC, and the control algorithm is based on "PID + velocity/acceleration feed forward + notch filter" strategy. Test results indicate that the positioning accuracy of all the three axes is less than +/-0.25?m, and the repetitive positioning accuracy is less than +/-0.2?m. The machine is proved to achieve nanometer scale through step response and sinusoidal signal track. The preparatory milling experiments with micro cemented carbide milling cutter further proves the processing capacity.

Zhang, Peng; Wang, Bo; Liang, Yingchun

2009-05-01

104

Development of an ion energy mass spectrometer for application on board three-axis stabilized spacecraft  

Microsoft Academic Search

We have developed an ion energy mass spectrometer for use aboard three-axis stabilized spacecraft. This spectrometer measures the three-dimensional distribution function of mass-discriminated ions with a high sampling rate using electrostatic energy analysis and time-of-flight mass analysis. Three-axis stabilized spacecraft make it difficult to obtain complete coverage of all possible plasma arrival directions. We have added angular scanning deflectors to

Shoichiro Yokota; Yoshifumi Saito; Kazushi Asamura; Toshifumi Mukai

2005-01-01

105

A monolithic silicon multi-sensor for measuring three-axis acceleration, pressure and temperature  

Microsoft Academic Search

A monolithic multi-sensor for small unmanned aerial vehicles is presented in the paper; it consists of a three-axis piezoresistive\\u000a accelerometer, a piezoresistive absolute pressure sensor and a silicon thermistor temperature sensor. The accelerometer is\\u000a designed with four silicon beams supporting the seismic mass and appropriate piezoresistors arrangement to detect three-axis\\u000a acceleration and greatly reduce cross-axis sensitivities. For minimizing the effect

Jingbo Xu; Yulong Zhao; Zhuangde Jiang; Jian Sun

2008-01-01

106

THREE-AXIS AIR-BEARING BASED PLATFORM FOR SMALL SATELLITE ATTITUDE DETERMINATION AND CONTROL SIMULATION  

Microsoft Academic Search

A frictionless environment simulation platform, utilized for accomplishing three-axis attitude control tests in small satellites, is introduced. It is employed to develop, improve, and carry out objective tests of sensors, actuators, and algorithms in the experimental framework. Different sensors (i.e. sun, earth, magnetometer, and an inertial measurement unit) are utilized to assess three-axis deviations. A set of three inertial wheels

J. Prado; G. Bisiacchi; L. Reyes; E. Vicente; F. Contreras; M. Mesinas

107

Three-dimensional plasma measurements from three-axis stabilized spacecraft  

SciTech Connect

Future planetary missions require that comprehensive three-dimensional measurements of electrons and mass-resolved ions be made from three-axis stabilized spacecraft. In order to make these measurements without requiring expensive and resource intensive platforms to scan space mechanically, we are developing various systems that are designed to scan space electrostatically. These systems also make it possible to circumvent the significant shadowing that would be present even with a scan platform, caused by necessary spacecraft appendages such as communications antennas and a power source (RTG or solar cell panels). The systems, which are axially symmetric, select particles arriving from 360/degree/ in azimuth along conical surfaces whose polar (or elevation) angles, referenced to the instrument symmetry axes, are determined by applying suitable deflection voltages to shapes deflectors. Particles thus selected in polar angle pass into spherically or toroidally-shaped electrostatic analyzers. After analysis, the 360/degree/ outputs of the analyzers are divided into discrete angular swaths to provide azimuthal angle resolution. In the case of electrons, the analyzed particles can be detected directly; in the case of ions, the particles in each swath can be counted directly, or further analyzed with time-of-flight or magnetic analyzers to obtain the velocity distributions of the separated major ion constituents. We present computer simulations of particle paths through the various analyzers of this type and show results from laboratory calibrations of prototypes.

Bame, S.J.; Martin, R.H.; McComas, D.J.; Burch, J.L.; Marshall, J.A.; Young, D.T.

1988-01-01

108

Performance of twin two-dimensional wedge nozzles including thrust vectoring and reversing effects at speeds up to Mach 2.20  

NASA Technical Reports Server (NTRS)

Transonic tunnel and supersonic pressure tunnel tests were reformed to determine the performance characteristics of twin nonaxisymmetric or two-dimensional nozzles with fixed shrouds and variable-geometry wedges. The effects of thrust vectoring, reversing, and installation of various tails were also studied. The investigation was conducted statically and at flight speeds up to a Mach number of 2.20. The total pressure ratio of the simulated jet exhaust was varied up to approximately 26 depending on Mach number. The Reynolds number per meter varied up to 13.20 x 1 million. An analytical study was made to determine the effect on calculated wave drag by varying the mathematical model used to simulate nozzle jet-exhaust plume.

Capone, F. J.; Maiden, D. L.

1977-01-01

109

Variable Reflectance/Transmittance Coatings for Solar Sail Altitude Control and Three Axis Stabilization  

NASA Astrophysics Data System (ADS)

Altitude control and three axis stabilization of the solar sail is critically important and may be accomplished either through a mechanical arrangement or through the use of variable solar reflectance/transmittance coatings (VSRCs/VSTCs). Electrochromic coatings that change reflectance or transmittance in response to the application of an electric potential may be used for this purpose. The primary objective of this work is to evaluate the effect of changes in the emittance of the front and rear surfaces of a solar sail on the thrust modulation efficiency. The results presented in this article demonstrate that the most efficient change in thrust for a solar sail panel with a VSRC is reached when the side shaded from the sun has the higher emittance than the side facing the sun. For a solar sail panel with a VSTC, the condition for the most efficient change in thrust occurs when the side facing the sun has the higher emittance than the side shaded from the sun. Also, it was highlighted that an opaque VSRC is more compatible with an opaque reflective solar sail thruster than a transparent VSTC. This design of a solar sail altitude control system with VSRC panels is recommended for further development.

Kislov, Nikolai

2004-02-01

110

Unshielded three-axis vector operation of a spin-exchange-relaxation-free atomic magnetometer  

E-print Network

Unshielded three-axis vector operation of a spin-exchange-relaxation-free atomic magnetometer S. J (Received 29 June 2004; accepted 20 September 2004) We describe a vector alkali­metal magnetometer, the total field at the location of the magnetometer is kept near zero, suppressing the broadening due

Romalis, Mike

111

Gait analyzer based on a cell phone with a single three-axis accelerometer  

Microsoft Academic Search

We propose a fuss-free gait analyzer based on a single three- axis accelerometer mounted on a cell phone for health care and presence services. It is not necessary for users not to wear sensors on any part of their bodies; all they need to do is to carry the cell phone. Our algorithm has two main functions; one is to

Toshiki Iso; Kenichi Yamazaki

2006-01-01

112

REAL-TIME ATTITUDE-INDEPENDENT THREE-AXIS MAGNETOMETER CALIBRATION  

E-print Network

REAL-TIME ATTITUDE-INDEPENDENT THREE-AXIS MAGNETOMETER CALIBRATION John L. Crassidis and Kok-axis magnetometer sensor calibration are de- rived. These approaches rely on a conversion of the magnetometer of the full cal- ibration problem involves the determination of the magnetometer bias vector, scale factors

Crassidis, John L.

113

Bias and linearity measurement of three axis fluxgate magnetometers using high precise electromagnetic devices  

Microsoft Academic Search

Bias error and linearity error influence the measurement precision of three axis fluxgate magnetometers. So, it is important to obtain and calibrate these errors. Bias error and linearity error of a German made DM-060 digital magnetometer are measured by precise electromagnetic devices. Firstly, bias of each axis is obtained by an alternating weak electromagnetic standard equipment. A method by comparing

Hong Feng Pang; Shi Tu Luo; Meng Chun Pan; Di Xiang Chen; Fei Lu Luo; Qi Zhang

2011-01-01

114

Three-axis magnetic flux leakage in-line inspection simulation based on finite-element analysis  

NASA Astrophysics Data System (ADS)

With the increase of pipelines, corrosion leakage accidents happen frequently. Therefore, nondestructive testing technology is important for ensuring the safe operation of the pipelines and energy mining. In this paper, the structure and principle of magnetic flux leakage (MFL) in-line inspection system is introduced first. Besides, a mathematic model of the system according to the ampere circuit rule, flux continuity theorem, and column coordinate transform is built, and the magnetic flux density in every point of space is calculated based on the theory of finite element analysis. Then we analyze and design the disposition of measurement section probes and sensors combining both three-axis MFL in-line inspection and multi-sensor fusion technology. Its advantage is that the three-axis changes of magnetic flux leakage field are measured by the multi-probes at the same time, so we can determine various defects accurately. Finally, the theory of finite element analysis is used to build a finite element simulation model, and the relationship between defects and MFL inspection signals is studied. Simulation and experiment results verify that the method not only enhances the detection ability to different types of defects but also improves the precision and reliability of the inspection system.

Feng, Jian; Zhang, Jun-Feng; Lu, Sen-Xiang; Wang, Hong-Yang; Ma, Rui-Ze

2013-01-01

115

Static thrust-vectoring performance of nonaxisymmetric convergent-divergent nozzles with post-exit yaw vanes. M.S. Thesis - George Washington Univ., Aug. 1988  

NASA Technical Reports Server (NTRS)

A static (wind-off) test was conducted in the Static Test Facility of the 16-ft transonic tunnel to determine the performance and turning effectiveness of post-exit yaw vanes installed on two-dimensional convergent-divergent nozzles. One nozzle design that was previously tested was used as a baseline, simulating dry power and afterburning power nozzles at both 0 and 20 degree pitch vectoring conditions. Vanes were installed on these four nozzle configurations to study the effects of vane deflection angle, longitudinal and lateral location, size, and camber. All vanes were hinged at the nozzle sidewall exit, and in addition, some were also hinged at the vane quarter chord (double-hinged). The vane concepts tested generally produced yaw thrust vectoring angles much less than the geometric vane angles, for (up to 8 percent) resultant thrust losses. When the nozzles were pitch vectored, yawing effectiveness decreased as the vanes were moved downstream. Thrust penalties and yawing effectiveness both decreased rapidly as the vanes were moved outboard (laterally). Vane length and height changes increased yawing effectiveness and thrust ratio losses, while using vane camber, and double-hinged vanes increased resultant yaw angles by 50 to 100 percent.

Foley, Robert J.; Pendergraft, Odis C., Jr.

1991-01-01

116

Integrated aerodynamic fin and stowable TVC vane system  

NASA Astrophysics Data System (ADS)

An aerodynamic fin and stowable jet vane system preferably for rocket motor missile applications to control roll, pitch, and yaw, in either the aerodynamic or thrust flight control conditions, has a retractable and stowable aerodynamic vane integrated with a stowable aerodynamic vane integrated with a stowable thrust vector reaction steering system on a common support. The integrated aerodynamic fins and thrust vector control reduce the overall missile mainframe dimensions and are mounted on a single, space saving support.

Danielson, Arnold O.

1994-06-01

117

Sensing characteristics of an optical three-axis tactile sensor mounted on a multi-fingered robotic hand  

Microsoft Academic Search

To develop a new three-axis tactile sensor for mounting on multi-fingered robotic hands, in this work we optimize sensing elements on the basis of our previous works concerning optical three-axis tactile sensors with a flat sensing surface. The present tactile sensor is based on the principle of an optical waveguide-type tactile sensor, which is composed of an acrylic hemispherical dome,

Masahiro Ohka; Hiroaki Kobayashi; Yasunaga Mitsuya

2005-01-01

118

Study on grinding of free-form optics surface in three-axis CNC machine  

NASA Astrophysics Data System (ADS)

Due to the glass is a type of brittle material, so the high-precision free-form optics of glass material is usually machined by the technical of grinding. In this paper, for the characteristics of the diamond grinding wheel, analyzing the grinding path of free-form optics and mathematical model of the path is established based on the three-axis CNC grinding device. Moreover, the cause of the interference in the process of grinding is analyzed and the methods of avoiding. Finally, based on the above analysis results, through the experiment, the free-form optics surface accuracy was reached to 3.6um, realize the machining of the free-form optics.

Yang, Haicheng; Zhang, Yun-long; Zhang, Feng; Wang, Zhibin; Bao, Long-xiang; Su, Ying; Guo, Rui; Liu, Xuan-min

2014-08-01

119

A Three-Axis Force Sensor for Dual Finger Haptic Interfaces  

PubMed Central

In this work we present the design process, the characterization and testing of a novel three-axis mechanical force sensor. This sensor is optimized for use in closed-loop force control of haptic devices with three degrees of freedom. In particular the sensor has been conceived for integration with a dual finger haptic interface that aims at simulating forces that occur during grasping and surface exploration. The sensing spring structure has been purposely designed in order to match force and layout specifications for the application. In this paper the design of the sensor is presented, starting from an analytic model that describes the characteristic matrix of the sensor. A procedure for designing an optimal overload protection mechanism is proposed. In the last part of the paper the authors describe the experimental characterization and the integrated test on a haptic hand exoskeleton showing the improvements in the controller performances provided by the inclusion of the force sensor. PMID:23202012

Fontana, Marco; Marcheschi, Simone; Salsedo, Fabio; Bergamasco, Massimo

2012-01-01

120

A Study on Aircraft Engine Control Systems for Integrated Flight and Propulsion Control  

NASA Astrophysics Data System (ADS)

The Integrated Flight and Propulsion Control (IFPC) for a highly maneuverable aircraft and a fighter-class engine with pitch/yaw thrust vectoring is described. Of the two IFPC functions the aircraft maneuver control utilizes the thrust vectoring based on aerodynamic control surfaces/thrust vectoring control allocation specified by the Integrated Control Unit (ICU) of a FADEC (Full Authority Digital Electronic Control) system. On the other hand in the Performance Seeking Control (PSC) the ICU identifies engine's various characteristic changes, optimizes manipulated variables and finally adjusts engine control parameters in cooperation with the Engine Control Unit (ECU). It is shown by hardware-in-the-loop simulation that the thrust vectoring can enhance aircraft maneuverability/agility and that the PSC can improve engine performance parameters such as SFC (specific fuel consumption), thrust and gas temperature.

Yamane, Hideaki; Matsunaga, Yasushi; Kusakawa, Takeshi; Yasui, Hisako

121

An accurate calibration method for accelerometer nonlinear scale factor on a low-cost three-axis turntable  

NASA Astrophysics Data System (ADS)

Strapdown inertial navigation system (SINS) requirements are very demanding on gyroscopes and accelerometers as well as on calibration. To improve the accuracy of SINS, high-accuracy calibration is needed. Adding the accelerometer nonlinear scale factor into the model and reducing estimation errors is essential for improving calibration methods. In this paper, the inertial navigation error model is simplified, including only velocity and tilt errors. Based on the simplified error model, the relationship between the navigation errors (the rates of change of velocity errors) and the inertial measurement unit (IMU) calibration parameters is presented. A tracking model is designed to estimate the rates of change of velocity errors. With a special calibration procedure consisting of six rotation sequences, the accelerometer nonlinear scale factor errors can be computed by the estimates of the rates of change of velocity errors. Simulation and laboratory test results show that the accelerometer nonlinear scale factor can be calibrated with satisfactory accuracy on a low-cost three-axis turntable in several minutes. The comparison with the traditional calibration method highlights the superior performance of the proposed calibration method without precise orientation control. In addition, the proposed calibration method saves a lot of time in comparison with the multi-position calibration method.

Pan, Jianye; Zhang, Chunxi; Cai, Qingzhong

2014-02-01

122

Simulation and experimental study of a three-axis fiber Bragg grating accelerometer based on the pull-push mechanism  

NASA Astrophysics Data System (ADS)

A three-axis fiber Bragg grating accelerometer, which has uniform sensitivities to three axes, has been developed for seismic application. This paper presents the design, simulation and calibration of the three-axis accelerometer. A series of experiments were performed to measure harmonic vibration and shock vibration. The precise acceleration was measured by a PZT accelerometer which provided high sensitivity. The fully described dynamic sensitivity of three-axis accelerometers represented by a 3-by-3 matrix is given. The results indicate that the accelerometer has a sensitivity of 0.068 V g-1 in a measured full scale of ±2.5 m s-2. The cross-axis sensitivity was measured as -75.5 dB, -75.5 dB and -78.2 dB, respectively.

Jiang, Qi; Yang, Meng

2013-11-01

123

THREE AXIS ATTITUDE DETERMINATION AND CONTROL SYSTEM FOR A PICO-SATELLITE  

E-print Network

. The complete cube includes the payload, ADCS with actuators and sensors, deployable antennas, commu- nication) for a Norwegian pico-satellite is presented. The satellite, named nCube, is based on the CubeSat concept. The gravity boom is realized using measurement tape. Simulations of both detumbling, boom deployment

Gravdahl, Jan Tommy

124

Two and three-dimensional microcoil fabrication process for three-axis magnetic sensors on flexible substrates  

Microsoft Academic Search

This work presents a fabrication process validation for planar and 3D microcoils (microsolenoids) as three-axis magnetic sensors. The devices are elaborated on flexible substrates (Kapton® and Peek®) to allow its location as close as possible to the surface to be characterized. The fabrication process is based on copper micromoulding. For planar microcoils, the process implements only one step of micromoulding:

M. Woytasik; J.-P. Grandchamp; E. Dufour-Gergam; J.-P. Gilles; S. Megherbi; E. Martincic; H. Mathias; P. Crozat

2006-01-01

125

Method for three-axis attitude determination by image-processed star constellation matching  

Microsoft Academic Search

An unmanned system for automatically 3-axis attitude determination by star constellation matching is a very useful tool for applications primary in the field of satellite technology, where stars are visible all the time. A special designed CCD-camera-system, which is sensitive enough to detect stars, points to the direction to be determinated and captures stars within the camera field of view.

Hartmut Renken; Hans J. Rath

1997-01-01

126

exTAS: a new concept in three axis spectroscopy for small samples  

NASA Astrophysics Data System (ADS)

The progress in neutron delivery systems and in neutron focusing techniques has made possible neutron studies of excitations in sub-cm3-sized single crystals, which are still much larger than crystal sizes needed for standard laboratory characterization techniques. In an effort to further reduce this gap we are proposing the exTAS project, which intends to stimulate a paradigm shift towards the use of mm3-sized samples in neutron spectroscopy. The exTAS project aims to boost the TAS sensitivity limits by combining sharp mm-sized focal spots, minimizing penumbra effects in sample environment illumination, with a spectrometer layout downscaled to a tabletop size and enclosed in a shielding casemate. The reduced spectrometer dimensions will provide enhanced flexibility in adapting the momentum resolution to the problem being studied and will facilitate the sub-millimetre positioning accuracy of its components, matching the reduced focal spot size.

Piovano, A.; Roux, S.; Kulda, J.

2014-07-01

127

OPMILL - MICRO COMPUTER PROGRAMMING ENVIRONMENT FOR CNC MILLING MACHINES THREE AXIS EQUATION PLOTTING CAPABILITIES  

NASA Technical Reports Server (NTRS)

OPMILL is a computer operating system for a Kearney and Trecker milling machine that provides a fast and easy way to program machine part manufacture with an IBM compatible PC. The program gives the machinist an "equation plotter" feature which plots any set of equations that define axis moves (up to three axes simultaneously) and converts those equations to a machine milling program that will move a cutter along a defined path. Other supported functions include: drill with peck, bolt circle, tap, mill arc, quarter circle, circle, circle 2 pass, frame, frame 2 pass, rotary frame, pocket, loop and repeat, and copy blocks. The system includes a tool manager that can handle up to 25 tools and automatically adjusts tool length for each tool. It will display all tool information and stop the milling machine at the appropriate time. Information for the program is entered via a series of menus and compiled to the Kearney and Trecker format. The program can then be loaded into the milling machine, the tool path graphically displayed, and tool change information or the program in Kearney and Trecker format viewed. The program has a complete file handling utility that allows the user to load the program into memory from the hard disk, save the program to the disk with comments, view directories, merge a program on the disk with one in memory, save a portion of a program in memory, and change directories. OPMILL was developed on an IBM PS/2 running DOS 3.3 with 1 MB of RAM. OPMILL was written for an IBM PC or compatible 8088 or 80286 machine connected via an RS-232 port to a Kearney and Trecker Data Mill 700/C Control milling machine. It requires a "D:" drive (fixed-disk or virtual), a browse or text display utility, and an EGA or better display. Users wishing to modify and recompile the source code will also need Turbo BASIC, Turbo C, and Crescent Software's QuickPak for Turbo BASIC. IBM PC and IBM PS/2 are registered trademarks of International Business Machines. Turbo BASIC and Turbo C are trademarks of Borland International.

Ray, R. B.

1994-01-01

128

Attitude control study for a large flexible spacecraft using a Solar Electric Propulsion System (SEPS)  

NASA Technical Reports Server (NTRS)

The attitude control performance of the solar electric propulsion system (SEPS) was evaluated. A thrust vector control system for powered flight control was examined along with a gas jet reaction control system, and a reaction wheel system, both of which have been proposed for nonpowered flight control. Comprehensive computer simulations of each control system were made and evaluated using a 30 mode spacecraft model. Results obtained indicate that thrust vector control and reaction wheel systems offer acceptable smooth proportional control. The gas jet control system is shown to be risky for a flexible structure such as SEPS, and is therefore, not recommended as a primary control method.

Tolivar, A. F.; Key, R. W.

1980-01-01

129

Research flight-control system development for the F-18 high alpha research vehicle  

NASA Technical Reports Server (NTRS)

The F-18 high alpha research vehicle was recently modified by adding a thrust vectoring control system. A key element in the modification was the development of a research flight control system integrated with the basic F-18 flight control system. Discussed here are design requirements, system development, and research utility of the resulting configuration as an embedded system for flight research in the high angle of attack regime. Particular emphasis is given to control system modifications and control law features required for high angle of attack flight. Simulation results are used to illustrate some of the thrust vectoring control system capabilities and predicted maneuvering improvements.

Pahle, Joseph W.; Powers, Bruce; Regenie, Victoria; Chacon, Vince; Degroote, Steve; Murnyak, Steven

1991-01-01

130

A three-axis micromachined accelerometer with a CMOS position-sense interface and digital offset-trim electronics  

SciTech Connect

This paper describes a three-axis accelerometer implemented in a surface-micromachining technology with integrated CMOS. The accelerometer measures changes in a capacitive half-bridge to detect deflections of a proof mass, which result from acceleration input. The half-bridge is connected to a fully differential position-sense interface, the output of which is used for one-bit force feedback. By enclosing the proof mass in a one-bit feedback loop, simultaneous force balancing and analog-to-digital conversion are achieved. On-chip digital offset-trim electronics enable compensation of random offset in the electronic interface. Analytical performance calculations are shown to accurately model device behavior. The fabricated single-chip accelerometer measures 4 {times} 4 mm{sup 2}, draws 27 mA from a 5-V supply, and has a dynamic range of 84, 81, and 70 dB along the x-, y-, and z-axes, respectively.

Lemkin, M.; Boser, B.E. [Univ. of California, Berkeley, CA (United States)] [Univ. of California, Berkeley, CA (United States)

1999-04-01

131

Development of a flexible three-axis tactile sensor based on screen-printed carbon nanotube-polymer composite  

NASA Astrophysics Data System (ADS)

A flexible, three-axis carbon nanotube (CNT)-polymer composite-based tactile sensor is presented. The proposed sensor consists of a flexible substrate, four sensing cells, and a bump structure. A CNT-polydimethylsiloxane (PDMS) composite is produced by a solvent evaporation method, and thus, the CNTs are well-dispersed within the PDMS matrix. The composite is directly patterned onto a flexible substrate using a screen printing technique to fabricate a sensor with four sensing cells. When a force is applied on the bump, the magnitude and direction of force could be detected by comparing the changes in electrical resistance of each sensing cell caused by the piezoresistive effect of the composite. The experimentally verified sensing characteristics of the fabricated sensor exhibit a linear relationship between the resistance change and the applied force, and the measured sensitivities of the sensor for the normal and shear forces are 6.67 and 86.7%/N for forces up to 2.0 and 0.5?N, respectively. Experiments to verify the load-sensing repeatability show a maximum 2.00% deviation of the resistance change within the tested force range.

Pyo, Soonjae; Lee, Jae-Ik; Kim, Min-Ook; Chung, Taeyoung; Oh, Yongkeun; Lim, Soo-Chul; Park, Joonah; Kim, Jongbaeg

2014-07-01

132

Development of a three-axis hybrid mesh isolator using the pseudoelasticity of a shape memory alloy  

NASA Astrophysics Data System (ADS)

Launch vehicles and satellites experience severe vibration and pyroshock loads during flight phases. In particular, intense pyroshock, which is generated by the actuation of separation devices, can cause malfunctions in the electronic components in launch vehicles and satellites, potentially resulting in catastrophic failure during flight. This paper introduces a new three-axis hybrid mesh isolator using the pseudoelasticity of a shape memory alloy wire that was manufactured and tested to attenuate pyroshock and vibration transmitted to the electronic components. To characterize the isolation capability, quasi-static loading tests were performed; the test results showed that the pseudoelastic effect of the shape memory alloy wire significantly absorbs energy due to the stress-induced phase transformation. The ground pyroshock test results showed a remarkable pyroshock load attenuation of the hybrid mesh isolator in all frequency ranges. The dynamic characteristics and vibration isolation performances of the mesh isolators were also verified by random vibration tests. The healthiness of the hybrid mesh isolator was also studied under a harsh vibration loading level, and the results confirmed its wide applicability without degradation of the isolation capability.

Youn, Se-Hyun; Jang, Young-Soon; Han, Jae-Hung

2011-07-01

133

National Aeronautics and Space Administration SLS System Integration Lab and Thrust  

E-print Network

National Aeronautics and Space Administration NASAfacts SLS System Integration Lab and Thrust Vector Control Test Lab at Marshall Center's Propulsion Research Laboratory The MSFC System Integration Lab (SIL) supports development of NASA's Space Launch System--a new U.S. heavy-lift launch vehicle

Waliser, Duane E.

134

Transition of a technology base for advanced aircraft gas turbine control systems  

Microsoft Academic Search

Technology assessments during the 1980s projected the development of advanced military fighter aircraft that would require propulsion systems that could accommodate multimission capability with super maneuverability. These propulsion systems would be required to provide significantly improved thrust to weight, reduced thrust specific fuel consumption, and up and away thrust vectoring capabilities. Digital electronic control systems with significantly expanded capabilities would

M. E. McGlone

1998-01-01

135

Liquid Rocket Booster (LRB) for the Space Transportion System (STS) systems study. Appendix D: Trade study summary for the liquid rocket booster  

NASA Technical Reports Server (NTRS)

Trade studies plans for a number of elements in the Liquid Rocket Booster (LRB) component of the Space Transportation System (STS) are given in viewgraph form. Some of the elements covered include: avionics/flight control; avionics architecture; thrust vector control studies; engine control electronics; liquid rocket propellants; propellant pressurization systems; recoverable spacecraft; cryogenic tanks; and spacecraft construction materials.

1989-01-01

136

Design and fabrication of three-axis accelerometer sensor microsystem for wide temperature range applications using semi-custom process  

NASA Astrophysics Data System (ADS)

This paper describes an integrated CMOS-MEMS inertial sensor microsystem, consisting of a 3-axis accelerometer sensor device and its complementary readout circuit, which is designed to operate over a wide temperature range from - 55°C to 175°C. The accelerometer device is based on capacitive transduction and is fabricated using PolyMUMPS, which is a commercial process available from MEMSCAP. The fabricated accelerometer device is then post-processed by depositing a layer of amorphous silicon carbide to form a composite sensor structure to improve its performance over an extended wide temperature range. We designed and fabricated a CMOS readout circuit in IBM 0.13?m process that interfaces with the accelerometer device to serve as a capacitance to voltage converter. The accelerometer device is designed to operate over a measurement range of +/-20g. The described sensor system allows low power, low cost and mass-producible implementation well suited for a variety of applications with harsh or wide temperature operating conditions.

Merdassi, A.; Wang, Y.; Xereas, G.; Chodavarapu, V. P.

2014-03-01

137

Missile guidance system against a ballistic missile  

NASA Astrophysics Data System (ADS)

A new antiballistic missile guidance system is presented. The system consists of a reusable autonomous missile-launch vehicle (MLV) and two ABMs. The desired trajectory for the MLV and the algorithm to guide the MLV along the trajectory are discussed. The thrust vector control law for the AMB is given. Simulation results show that the proposed missile system can intercept a ballistic missile even if the hit point is far from the MLV location.

Baba, Yoriaki; Takano, Hiroyuki; Takao, Kichiro

138

A new three-axis vibrating sample magnetometer for continuous high-temperature magnetization measurements: Applications to paleo- and archeointensity determinations  

NASA Astrophysics Data System (ADS)

We have developed a new three-axis vibrating sample magnetometer (Triaxe) which allows continuous high-temperature magnetization measurements of individual cylindrical 0.75 cm3 samples up to 650°C, and the acquisition of thermoremanent magnetization (TRM) in any direction with a field of up to 200 microT. This equipment offers many possibilities for investigating rock magnetic properties at high temperature. As a first application, we propose a fast (2 hours) automated experimental procedure based on a modified version of the Thellier and Thellier (1959) method revised by Coe (1967) which provides continuous intensity determinations over a large (typically 300°C) temperature interval for each sample. This procedure takes into account both the cooling rate dependence of the TRM acquisition and the anisotropy of TRM. Analyses of numerous pottery and baked brick fragments from Mesopotamia demonstrate the quality and the reliability of the data, and illustrate the potential of this new instrument for paleo- and archeomagnetism.

Gallet, Y.; Le Goff, M.

2004-12-01

139

Taking low-temperature measurements of remanence beyond the state-of-the-art: new three-axis data from Umkondo Province sills  

NASA Astrophysics Data System (ADS)

Low-temperature cycling of paleomagnetic specimens across the Verwey transition is a common technique used to preferentially remove remanence associated with multi-domain magnetite grains. This low-temperature demagnetization (LTD) step is gaining increasing use in both paleodirectional and paleointensity protocols making it imperative to understand the mechanism, efficiency and possible limitations of LTD. A recently developed cryogenic probe used in conjunction with a superconducting rock magnetometer at the Institute for Rock Magnetism allows for three-axis measurements to be made during cycling to and from low-temperatures in a low-field environment. In this study, we targeted a suite of well-characterized samples from the Umkondo Large Igneous Province of Botswana that displayed large (~50%) demagnetization of the natural remanence after cooling to 77 K including some samples that underwent large directional changes. Three-axis data were continuously collected during low-temperature cycling experiments on both natural remanence and lab-induced anhysteretic remanent magnetization (pARM). Experiments were designed with orthogonal pARMs to observe the behavior and efficiency of demagnetization of remanence carried by low coercivity (multi-domain grains). These experiments revealed high efficiency of demagnetization (>95%) of a pARM imparted to low coercivity grains (AF fields of 0 to 5 mT) with a return to the direction of a pARM imparted to higher coercivity grains (AF fields of 5 to 200 mT). The data also demonstrate that low-temperature demagnetization of such a pARM upon cooling is dominated by changes prior to the Verwey transition or the isotropic point. These results suggests that it is changes in magnetocrystalline anisotropy (K1) at temperatures above the isotropic point that are responsible for the majority of low-temperature demagnetization of multidomain magnetite grains. The low-temperature probe is available for community use at the Institute for Rock Magnetism and we encourage fellowship applications to use it for experiments that continue to take low-temperature measurements of remanence beyond the state-of-the-art.

Swanson-Hysell, N.; Solheid, P.; Feinberg, J. M.

2013-12-01

140

Design, construction, and calibration of a three-axis, high-frequency magnetic probe (B-dot probe) as a diagnostic for exploding plasmas  

SciTech Connect

A three-axis, 2.5 mm overall diameter differential magnetic probe (also known as B-dot probe) is discussed in detail from its design and construction to its calibration and use as diagnostic of fast transient effects in exploding plasmas. A design and construction method is presented as a means to reduce stray pickup, eliminate electrostatic pickup, reduce physical size, and increase magnetic signals while maintaining a high bandwidth. The probe's frequency response is measured in detail from 10 kHz to 50 MHz using the presented calibration method and compared to theory. The effect of the probe's self-induction as a first order correction in frequency, O({omega}), on experimental signals and magnetic field calculations is discussed. The probe's viability as a diagnostic is demonstrated by measuring the magnetic field compression and diamagnetism of a sub-Alfvenic ({approx}500 km/s,M{sub A}{approx}0.36) flow created from the explosion of a high-density energetic laser plasma through a cooler, low-density, magnetized ambient plasma.

Everson, E. T.; Pribyl, P.; Constantin, C. G.; Zylstra, A.; Schaeffer, D.; Kugland, N. L.; Niemann, C. [Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095 (United States)

2009-11-15

141

Design, construction, and calibration of a three-axis, high-frequency magnetic probe (B-dot probe) as a diagnostic for exploding plasmas.  

PubMed

A three-axis, 2.5 mm overall diameter differential magnetic probe (also known as B-dot probe) is discussed in detail from its design and construction to its calibration and use as diagnostic of fast transient effects in exploding plasmas. A design and construction method is presented as a means to reduce stray pickup, eliminate electrostatic pickup, reduce physical size, and increase magnetic signals while maintaining a high bandwidth. The probe's frequency response is measured in detail from 10 kHz to 50 MHz using the presented calibration method and compared to theory. The effect of the probe's self-induction as a first order correction in frequency, O(omega), on experimental signals and magnetic field calculations is discussed. The probe's viability as a diagnostic is demonstrated by measuring the magnetic field compression and diamagnetism of a sub-Alfvenic (approximately 500 km/s, M(A) approximately 0.36) flow created from the explosion of a high-density energetic laser plasma through a cooler, low-density, magnetized ambient plasma. PMID:19947729

Everson, E T; Pribyl, P; Constantin, C G; Zylstra, A; Schaeffer, D; Kugland, N L; Niemann, C

2009-11-01

142

Actuator participation in a bending mode identification system  

NASA Technical Reports Server (NTRS)

A hydraulic actuator designed for a thrust vector control system used as a shaker for a vehicle to determine the bending mode frequencies is described. The actuator is used as the prime mover and the frequency sensor for the flexible vehicle in a test tower. Advantages in using the actuator piston position with respect to a commanded position to obtain the bending mode frequencies are shown.

Thompson, Z.; Davis, P.

1972-01-01

143

In-flight system identification for the CRAF\\/Cassini spacecraft  

Microsoft Academic Search

The feasibility and payoffs of conducting in-flight system dynamics identification for the CRAFT\\/Cassini\\/(C\\/C) spacecraft are studied. The primary control modes of: (a) the boom-mounted high precision scan platform articulation\\/pointing control; and (b) the main engine thrust vector control are analyzed. Identification of key transfer functions and models and subsequent design of modern robust controllers by recently developed advanced processing algorithms

Edward Mettler; David S. Bayard; Yeung Yam; Robert E. Scheid

1992-01-01

144

Global Positioning System Integer Ambiguity Resolution without Attitude Knowledge  

E-print Network

1 Global Positioning System Integer Ambiguity Resolution without Attitude Knowledge John L measurements from Global Positioning System (GPS) receivers provides a novel approach for three-axis attitude

Crassidis, John L.

145

SERT 2 gimbal system  

NASA Technical Reports Server (NTRS)

The gimbal system is described that was designed to mount the thruster and to reposition the thrust vector of a mercury ion bombardment thruster through the center of gravity of the SERT 2 assembly. The SERT 2 assembly was launched 3 February 1970. The gimbal ring, gimbal mounts, bearings, actuators, and environmental testing are described. Due to the accurate alinements provided, it was not necessary to use the gimbal for the intended function. However, the gimbals were operated successfully numerous times in space after 8 months of storage.

Zavesky, R. J.; Hurst, E. B.

1971-01-01

146

Three-axis fiber optic vector magnetometer  

NASA Astrophysics Data System (ADS)

This patent application discloses an optical fiber for magnetostrictive responsive detection of magnetic fields. The strength of the protective magnetic field is determined by standard interferometry techniques by comparing the phase or mode properties of the light from a light source exiting the fiber having a magnetostrictive jacket against the phase or mode properties of light from a light source exiting a reference fiber having pre-determined or identical light transmission properties. The sensitivity of magnetic effect upon the magnetostrictively affected fiber is enhanced by subjecting the magnetostrictive material to a quantitative low-level magnetic field.

Koo, K. P.; Sigel, G. H.; Bucholtz, Frank

1991-09-01

147

The Control System for the X-33 Linear Aerospike Engine  

NASA Technical Reports Server (NTRS)

The linear aerospike engine is being developed for single-stage -to-orbit (SSTO) applications. The primary advantages of a linear aerospike engine over a conventional bell nozzle engine include altitude compensation, which provides enhanced performance, and lower vehicle weight resulting from the integration of the engine into the vehicle structure. A feature of this integration is the ability to provide thrust vector control (TVC) by differential throttling of the engine combustion elements, rather than the more conventional approach of gimballing the entire engine. An analysis of the X-33 flight trajectories has shown that it is necessary to provide +/- 15% roll, pitch and yaw TVC authority with an optional capability of +/- 30% pitch at select times during the mission. The TVC performance requirements for X-33 engine became a major driver in the design of the engine control system. The thrust level of the X-33 engine as well as the amount of TVC are managed by a control system which consists of electronic, instrumentation, propellant valves, electro-mechanical actuators, spark igniters, and harnesses. The engine control system is responsible for the thrust control, mixture ratio control, thrust vector control, engine health monitoring, and communication to the vehicle during all operational modes of the engine (checkout, pre-start, start, main-stage, shutdown and post shutdown). The methodology for thrust vector control, the health monitoring approach which includes failure detection, isolation, and response, and the basic control system design are the topic of this paper. As an additional point of interest a brief description of the X-33 engine system will be included in this paper.

Jackson, Jerry E.; Espenschied, Erich; Klop, Jeffrey

1998-01-01

148

The development of a pseudo-nyquist analysis technique for hybrid sampled-data control systems  

NASA Technical Reports Server (NTRS)

The stability characteristics of a launch vehicle, as a function of gain and phase variations at the thrust vector controller, cannot be obtained using classical sampled-data control theory if the launch vehicle attitude control system contains both sampled-data and continuous feedback control loops. A method was developed which can be used to generate a sampled-data pseudo-Nyquist plot for gain and phase variations at the controller. This method was developed and used to determine the stability characteristics of the Saturn 1B launch vehicle in the backup guidance mode.

Burnitt, M. G.; Davis, C. W.

1973-01-01

149

Development of a unified guidance system for geocentric transfer. [solar electric propulsion spacecraft  

NASA Technical Reports Server (NTRS)

A method is presented for open loop guidance of a solar electric propulsion spacecraft to geosynchronsus orbit. The method consists of determining the thrust vector profiles on the ground with an optimization computer program, and performing updates based on the difference between the actual trajectory and that predicted with a precision simulation computer program. The motivation for performing the guidance analysis during the mission planning phase is discussed, and a spacecraft design option that employs attitude orientation constraints is presented. The improvements required in both the optimization program and simulation program are set forth, together with the efforts to integrate the programs into the ground support software for the guidance system.

Cake, J. E.; Regetz, J. D., Jr.

1975-01-01

150

VSTOL Systems Research Aircraft (VSRA) Harrier  

NASA Technical Reports Server (NTRS)

NASA's Ames Research Center has developed and is testing a new integrated flight and propulsion control system that will help pilots land aircraft in adverse weather conditions and in small confined ares (such as, on a small ship or flight deck). The system is being tested in the V/STOL (Vertical/Short Takeoff and Landing) Systems research Aircraft (VSRA), which is a modified version of the U.S. Marine Corps's AV-8B Harrier jet fighter, which can take off and land vertically. The new automated flight control system features both head-up and panel-mounted computer displays and also automatically integrates control of the aircraft's thrust and thrust vector control, thereby reducing the pilot's workload and help stabilize the aircraft for landing. Visiting pilots will be encouraged to test the new system and provide formal evaluation flights data and feedback. An actual flight test and the display panel of control system are shown in this video.

1994-01-01

151

Static internal performance of single expansion-ramp nozzles with thrust vectoring and reversing  

NASA Technical Reports Server (NTRS)

The effects of geometric design parameters on the internal performance of nonaxisymmetric single expansion-ramp nozzles were investigated at nozzle pressure ratios up to approximately 10. Forward-flight (cruise), vectored-thrust, and reversed-thrust nozzle operating modes were investigated.

Re, R. J.; Berrier, B. L.

1982-01-01

152

F-15B ACTIVE with thrust vectoring nozzles on test stand at sunrise  

NASA Technical Reports Server (NTRS)

This November 13, 1995, photograph of the F-15 Advanced Controls Technology for Integrated Vehicles (ACTIVE) at NASA's Dryden Flight Research Center, Edwards, California, shows the aircraft on a test stand at sunrise. Not shown in this photograph are the aircraft's two new Pratt & Whitney nozzles that can turn up to 20 degrees in any direction. These nozzles give the aircraft thrust control in the pitch (up and down) and yaw (left and right) directions. This will reduce drag and increase fuel economy or range as compared with conventional aerodynamic controls, which increase the retarding forces (drag) acting upon the aircraft. These tests could result in significant performance increases for military and commercial aircraft. The research program is the product of a collaborative effort by NASA, the Air Force's Wright Laboratory, Pratt & Whitney, and McDonnell Douglas Aerospace. The aircraft was originally built as an F-15B (Serial #71-0290).

1995-01-01

153

An electromechanical actuation system for an expendable launch vehicle  

NASA Technical Reports Server (NTRS)

A major effort at NASA-Lewis in recent years has been to develop electro-mechanical actuators (EMA's) to replace the hydraulic systems used for thrust vector control (TVC) on launch vehicles. This is an attempt to overcome the inherent inefficiencies and costs associated with the existing hydraulic structures. General Dynamics Space Systems Division, under contract to NASA Lewis, is developing 18.6 kW (25 hp), 29.8 kW (40 hp), and 52.2 kW (70 hp) peak EMA systems to meet the power demands for TVC on a family of vehicles developed for the National Launch System. These systems utilize a pulse population modulated converter and field-oriented control scheme to obtain independent control of both the voltage and frequency. These techniques allow an induction motor to be operated at its maximum torque at all times.

Burrows, Linda M.; Roth, Mary E.

1992-01-01

154

An electromechanical actuation system for an expendable launch vehicle  

NASA Astrophysics Data System (ADS)

A major effort at NASA-Lewis in recent years has been to develop electro-mechanical actuators (EMA's) to replace the hydraulic systems used for thrust vector control (TVC) on launch vehicles. This is an attempt to overcome the inherent inefficiencies and costs associated with the existing hydraulic structures. General Dynamics Space Systems Division, under contract to NASA Lewis, is developing 18.6 kW (25 hp), 29.8 kW (40 hp), and 52.2 kW (70 hp) peak EMA systems to meet the power demands for TVC on a family of vehicles developed for the National Launch System. These systems utilize a pulse population modulated converter and field-oriented control scheme to obtain independent control of both the voltage and frequency. These techniques allow an induction motor to be operated at its maximum torque at all times.

Burrows, Linda M.; Roth, Mary E.

155

Performance optimized, small structurally integrated ion thruster system  

NASA Technical Reports Server (NTRS)

A 5-cm structurally integrated ion thruster has been developed for attitude control and stationkeeping of synchronous satellites. As optimized with a conventional ion extraction system, the system demonstrates a thrust T = 0.47 mlb at a beam voltage of 1600 V, total mass efficiency of 76%, and electrical efficiency of 56%. Under the subject contract effort, no significant performance change was noted for operation with two dimensional electrostatic thrust-vectoring grids. Structural integrity with the vectoring grids was demonstrated for shock (+ or - 30 G), sinusoidal (9 G), and random (19.9 G rms) accelerations. System envelope is 31.2 cm long by 13.4 cm flange bolt circle, with a mass of 9.0 Kg, including 6.8 Kg mercury propellant.

Hyman, J., Jr.

1973-01-01

156

Flight-determined benefits of integrated flight-propulsion control systems  

NASA Technical Reports Server (NTRS)

Over the last two decades, NASA has conducted several experiments in integrated flight-propulsion control. Benefits have included improved maneuverability; increased thrust, range, and survivability; reduced fuel consumption; and reduced maintenance. This paper presents the basic concepts for control integration, examples of implementation, and benefits. The F-111E experiment integrated the engine and inlet control systems. The YF-12C incorporated an integral control system involving the inlet, autopilot, autothrottle, airdata, navigation, and stability augmentation systems. The F-15 research involved integration of the engine, flight, and inlet control systems. Further extension of the integration included real-time, onboard optimization of engine, inlet, and flight control variables; a self-repairing flight control system; and an engines-only control concept for emergency control. The F-18A aircraft incorporated thrust vectoring integrated with the flight control system to provide enhanced maneuvering at high angles of attack. The flight research programs and the resulting benefits of each program are described.

Stewart, James F.; Burcham, Frank W., Jr.; Gatlin, Donald H.

1992-01-01

157

On the M-V attitude control system, Part 2: Hardware design  

NASA Astrophysics Data System (ADS)

The hardware design of the attitude control systems of the Institute of Space and Astronomical Science's (ISAS's) newest version of launch vehicle M-V will be reviewed in this paper with a special emphasis on the technologically newly developed items. The third stage rocket, which has been simply spin-stabilized through the launches of the scientific satellites of the ISAS, will be now controlled by a movable nozzle thrust vector control (MNTVC) system together with the side jet (SJ) engines for more maneuverability of the upper stage. To improve the control characteristics, the first stage rocket will be stabilized by another version of MNTVC system. A liquid injection TVC (LITVC) system, of the newly developed chamber bleed hot gas blow down type, is also expected to have enhanced control capability.

Mortia, Yasuhiro; Kohno, Masahiro; Matsuo, Hiroki; Okaya, Shunichi; Maruizumi, Haruki

158

Development of three-axis actuator for HD-DVD  

Microsoft Academic Search

There is much research being conducted on developing information storage devices based on formats of Blu-ray Disc (BD) and HD-DVD with requirements for high-density storage devices. This trend is set toward the use of a short-wave length laser and objective lens (OL) with high numerical aperture in optical storage devices. However, it causes the rapid decrease of tilt margin. Therefore,

Dong-Ju Lee; Kang-Nyung Lee; No-Cheol Park; Young-Pil Park

2005-01-01

159

Analysis of a Linear System for Variable-Thrust Control in the Terminal Phase of Rendezvous  

NASA Technical Reports Server (NTRS)

A linear system for applying thrust to a ferry vehicle in the 3 terminal phase of rendezvous with a satellite is analyzed. This system requires that the ferry thrust vector per unit mass be variable and equal to a suitable linear combination of the measured position and velocity vectors of the ferry relative to the satellite. The variations of the ferry position, speed, acceleration, and mass ratio are examined for several combinations of the initial conditions and two basic control parameters analogous to the undamped natural frequency and the fraction of critical damping. Upon making a desirable selection of one control parameter and requiring minimum fuel expenditure for given terminal-phase initial conditions, a simplified analysis in one dimension practically fixes the choice of the remaining control parameter. The system can be implemented by an automatic controller or by a pilot.

Hord, Richard A.; Durling, Barbara J.

1961-01-01

160

NASA Marshall Space Flight Center Controls Systems Design and Analysis Branch  

NASA Technical Reports Server (NTRS)

Marshall Space Flight Center maintains a critical national capability in the analysis of launch vehicle flight dynamics and flight certification of GN&C algorithms. MSFC analysts are domain experts in the areas of flexible-body dynamics and control-structure interaction, thrust vector control, sloshing propellant dynamics, and advanced statistical methods. Marshall's modeling and simulation expertise has supported manned spaceflight for over 50 years. Marshall's unparalleled capability in launch vehicle guidance, navigation, and control technology stems from its rich heritage in developing, integrating, and testing launch vehicle GN&C systems dating to the early Mercury-Redstone and Saturn vehicles. The Marshall team is continuously developing novel methods for design, including advanced techniques for large-scale optimization and analysis.

Gilligan, Eric

2014-01-01

161

Solar electric propulsion thrust subsystem development  

NASA Technical Reports Server (NTRS)

The Solar Electric Propulsion System developed under this program was designed to demonstrate all the thrust subsystem functions needed on an unmanned planetary vehicle. The demonstration included operation of the basic elements, power matching input and output voltage regulation, three-axis thrust vector control, subsystem automatic control including failure detection and correction capability (using a PDP-11 computer), operation of critical elements in thermal-vacuum-, zero-gravity-type propellant storage, and data outputs from all subsystem elements. The subsystem elements, functions, unique features, and test setup are described. General features and capabilities of the test-support data system are also presented. The test program culminated in a 1500-h computer-controlled, system-functional demonstration. This included simultaneous operation of two thruster/power conditioner sets. The results of this testing phase satisfied all the program goals.

Masek, T. D.

1973-01-01

162

Study of vortex valve for medium temperature solid propellants  

NASA Technical Reports Server (NTRS)

Fluid state vortex valve secondary injection control system shows considerable promise for future application to solid propellant rocket engine thrust vector control. The single axis injection system tested would be capable of providing secondary injection thrust vector control using 2000 deg F gas.

Holt, W. D.; Rivard, J. G.

1966-01-01

163

Adaptive nonlinear contour coupling control for a machine tool system  

Microsoft Academic Search

The quality of products from a machine tool system is largely determined by the tolerances maintained, which is a function of how well the desired contour is tracked. To mitigate contour errors in a three axis machine tool feed drive system, the control development in this paper is based on an error system that is transformed into tangential, normal and

J.-H. Lee; W. E. Dixon; J. C. Ziegert; C. Makkar

2005-01-01

164

Flywheel energy storage for electromechanical actuation systems  

NASA Astrophysics Data System (ADS)

The authors describe a flywheel energy storage system designed specifically to provide load-leveling for a thrust vector control (TVC) system using electromechanical actuators (EMAs). One of the major advantages of an EMA system over a hydraulic system is the significant reduction in total energy consumed during the launch profile. Realization of this energy reduction will, however, require localized energy storage capable of delivering the peak power required by the EMAs. A combined flywheel-motor/generator unit which interfaces directly to the 20-kHz power bus represents an ideal candidate for this load leveling. The overall objective is the definition of a flywheel energy storage system for this application. The authors discuss progress on four technical objectives: (1) definition of the specifications for the flywheel-motor/generator system, including system-level trade-off analysis; (2) design of the flywheel rotor; (3) design of the motor/generator; and (4) determination of the configuration for the power management system.

Hockney, Richard L.; Goldie, James H.; Kirtley, James L.

165

Evaluation of dual flow thrust vectored nozzles with exhaust stream impingement. MS Thesis Final Technical Report, Oct. 1990 - Jul. 1991  

NASA Technical Reports Server (NTRS)

The main objective of this project was to predict the expansion wave/oblique shock wave structure in an under-expanded jet expanding from a convergent nozzle. The shock structure was predicted by combining the calculated curvature of the free pressure boundary with principles and governing equations relating to oblique shock wave and expansion wave interaction. The procedure was then continued until the shock pattern repeated itself. A mathematical model was then formulated and written in FORTRAN to calculate the oblique shock/expansion wave structure within the jet. In order to study shock waves in expanding jets, Schlieren photography, a form of flow visualization, was employed. Thirty-six Schlieren photographs of jets from both a straight and 15 degree nozzle were taken. An iterative procedure was developed to calculate the shock structure within the jet and predict the non-dimensional values of Prandtl primary wavelength (w/rn), distance to Mach Disc (Ld) and Mach Disc radius (rd). These values were then compared to measurements taken from Schlieren photographs and experimental results. The results agreed closely to measurements from Schlieren photographs and previously obtained data. This method provides excellent results for pressure ratios below that at which a Mach Disc first forms. Calculated values of non-dimensional distance to the Mach Disc (Ld) agreed closely to values measured from Schlieren photographs and published data. The calculated values of non-dimensional Mach Disc radius (rd), however, deviated from published data by as much as 25 percent at certain pressure ratios.

Carpenter, Thomas W.

1991-01-01

166

Aircraft ground test and subscale model results of axial thrust loss caused by thrust vectoring using turning vanes  

NASA Technical Reports Server (NTRS)

The NASA-Dryden F/A-18 high alpha research vehicle was modified to incorporate three independently controlled turning vanes located aft of the primary nozzle of each engine to vector thrust for pitch and yaw control. Ground measured axial thrust losses were compared with the results from a 14.25 pct. cold jet model for single and dual vanes inserted up to 25 degs into the engine exhaust. Data are presented for nozzle pressure ratios of 2.0 and 3.0 and nozzle exit areas of 253 and 348 sq in. The results indicate that subscale nozzle test results properly predict trends but underpredict the full scale results by approx. 1 to 4.5 pct. in thrust loss.

Johnson, Steven A.

1992-01-01

167

Solid Rocket Booster (SRB) Flight System Integration at Its Best  

NASA Technical Reports Server (NTRS)

The Solid Rocket Booster (SRB) element integrates all the subsystems needed for ascent flight, entry, and recovery of the combined Booster and Motor system. These include the structures, avionics, thrust vector control, pyrotechnic, range safety, deceleration, thermal protection, and retrieval systems. This represents the only human-rated, recoverable and refurbishable solid rocket ever developed and flown. Challenges included subsystem integration, thermal environments and severe loads (including water impact), sometimes resulting in hardware attrition. Several of the subsystems evolved during the program through design changes. These included the thermal protection system, range safety system, parachute/recovery system, and others. Because the system was recovered, the SRB was ideal for data and imagery acquisition, which proved essential for understanding loads, environments and system response. The three main parachutes that lower the SRBs to the ocean are the largest parachutes ever designed, and the SRBs are the largest structures ever to be lowered by parachutes. SRB recovery from the ocean was a unique process and represented a significant operational challenge; requiring personnel, facilities, transportation, and ground support equipment. The SRB element achieved reliability via extensive system testing and checkout, redundancy management, and a thorough postflight assessment process. However, the in-flight data and postflight assessment process revealed the hardware was affected much more strongly than originally anticipated. Assembly and integration of the booster subsystems required acceptance testing of reused hardware components for each build. Extensive testing was done to assure hardware functionality at each level of stage integration. Because the booster element is recoverable, subsystems were available for inspection and testing postflight, unique to the Shuttle launch vehicle. Problems were noted and corrective actions were implemented as needed. The postflight assessment process was quite detailed and a significant portion of flight operations. The SRBs provided fully redundant critical systems including thrust vector control, mission critical pyrotechnics, avionics, and parachute recovery system. The design intent was to lift off with full redundancy. On occasion, the redundancy management scheme was needed during flight operations. This paper describes some of the design challenges and technical issues, how the design evolved with time, and key areas where hardware reusability contributed to improved system level understanding.

Wood, T. David; Kanner, Howard S.; Freeland, Donna M.; Olson, Derek T.

2011-01-01

168

Dynamic interactions between hypersonic vehicle aerodynamics and propulsion system performance  

NASA Technical Reports Server (NTRS)

Described here is the development of a flexible simulation model for scramjet hypersonic propulsion systems. The primary goal is determination of sensitivity of the thrust vector and other system parameters to angle of attack changes of the vehicle. Such information is crucial in design and analysis of control system performance for hypersonic vehicles. The code is also intended to be a key element in carrying out dynamic interaction studies involving the influence of vehicle vibrations on propulsion system/control system coupling and flight stability. Simple models are employed to represent the various processes comprising the propulsion system. A method of characteristics (MOC) approach is used to solve the forebody and external nozzle flow fields. This results in a very fast computational algorithm capable of carrying out the vast number of simulation computations needed in guidance, stability, and control studies. The three-dimensional fore- and aft body (nozzle) geometry is characterized by the centerline profiles as represented by a series of coordinate points and body cross-section curvature. The engine module geometry is represented by an adjustable vertical grid to accommodate variations of the field parameters throughout the inlet and combustor. The scramjet inlet is modeled as a two-dimensional supersonic flow containing adjustable sidewall wedges and multiple fuel injection struts. The inlet geometry including the sidewall wedge angles, the number of injection struts, their sweepback relative to the vehicle reference line, and strut cross-section are user selectable. Combustion is currently represented by a Rayleigh line calculation including corrections for variable gas properties; improved models are being developed for this important element of the propulsion flow field. The program generates (1) variation of thrust magnitude and direction with angle of attack, (2) pitching moment and line of action of the thrust vector, (3) pressure and temperature distributions throughout the system, and (4) performance parameters such as thrust coefficient, specific impulse, mass flow rates, and equivalence ratio. Preliminary results are in good agreement with available performance data for systems resembling the NASP vehicle configuration.

Flandro, G. A.; Roach, R. L.; Buschek, H.

1992-01-01

169

Design and development issues for a control actuation system for the AdKEM  

Microsoft Academic Search

The paper addresses three issues critical to the design and development of the control actuation system (CAS) for the Advanced Kinetic Energy Missile (AdKEM), a hypersonic, kinetic energy weapon system. First of all, the small missile diameter requires that a high performance, three-axis control system be packaged within a limited amount of space. The second critical issue is the need

Stephen C. Cayson

1992-01-01

170

A New Algorithm for Attitude Determination Using Global Positioning System Signals  

E-print Network

A New Algorithm for Attitude Determination Using Global Positioning System Signals John L-by-point (deterministic) attitude solution of a vehicle using Global Positioning System phase difference measurements Global Positioning System (GPS) receivers provides a novel approach for three-axis attitude determination

Crassidis, John L.

171

The 3-axis Dynamic Motion Simulator (DMS) system  

NASA Technical Reports Server (NTRS)

A three-axis dynamic motion simulator (DMS) consisting of a test table with three degrees of freedom and an electronics control system was designed, constructed, delivered, and tested. Documentation, as required in the Data Requirements List (DRL), was also provided.

1975-01-01

172

A system for autonomous navigation and attitude determination in geostationary orbit  

Microsoft Academic Search

The results of a joint CNES-Aerospatiale study leading to an autonomous navigation and three-axis attitude determination system are presented. The principles, software architecture, preprocessing, navigator, orbit control, and hardware configuration of the system are described. The optimization process is described as well with attention given to sensor architecture and operational modes. It is found that the presence of an additional

P. Maute; O. Defonte

1990-01-01

173

Design of power electronics for TVC EMA systems  

NASA Astrophysics Data System (ADS)

The Composite Development Division of the Propulsion Laboratory at Marshall Space Flight Center (MSFC) is currently developing a class of electromechanical actuators (EMA's) for use in space transportation applications such as thrust vector control (TVC) and propellant control valves (PCV). These high power servomechanisms will require rugged, reliable, and compact power electronic modules capable of modulating several hundred amperes of current at up to 270 volts. MSFC has selected the brushless dc motor for implementation in EMA's. This report presents the results of an investigation into the applicability of two new technologies, MOS-controlled thyristors (MCT's) and pulse density modulation (PDM), to the control of brushless dc motors in EMA systems. MCT's are new power semiconductor devices, which combine the high voltage and current capabilities of conventional thyristors and the low gate drive requirements of metal oxide semiconductor field effect transistors (MOSFET's). The commanded signals in a PDM system are synthesized using a series of sinusoidal pulses instead of a series of square pulses as in a pulse width modulation (PWM) system. A resonant dc link inverter is employed to generate the sinusoidal pulses in the PDM system. This inverter permits zero-voltage switching of all semiconductors which reduces switching losses and switching stresses. The objectives of this project are to develop and validate an analytical model of the MCT device when used in high power motor control applications and to design, fabricate, and test a prototype electronic circuit employing both MCT and PDM technology for controlling a brushless dc motor.

Nelms, R. Mark

1993-08-01

174

Design of power electronics for TVC EMA systems  

NASA Technical Reports Server (NTRS)

The Composite Development Division of the Propulsion Laboratory at Marshall Space Flight Center (MSFC) is currently developing a class of electromechanical actuators (EMA's) for use in space transportation applications such as thrust vector control (TVC) and propellant control valves (PCV). These high power servomechanisms will require rugged, reliable, and compact power electronic modules capable of modulating several hundred amperes of current at up to 270 volts. MSFC has selected the brushless dc motor for implementation in EMA's. This report presents the results of an investigation into the applicability of two new technologies, MOS-controlled thyristors (MCT's) and pulse density modulation (PDM), to the control of brushless dc motors in EMA systems. MCT's are new power semiconductor devices, which combine the high voltage and current capabilities of conventional thyristors and the low gate drive requirements of metal oxide semiconductor field effect transistors (MOSFET's). The commanded signals in a PDM system are synthesized using a series of sinusoidal pulses instead of a series of square pulses as in a pulse width modulation (PWM) system. A resonant dc link inverter is employed to generate the sinusoidal pulses in the PDM system. This inverter permits zero-voltage switching of all semiconductors which reduces switching losses and switching stresses. The objectives of this project are to develop and validate an analytical model of the MCT device when used in high power motor control applications and to design, fabricate, and test a prototype electronic circuit employing both MCT and PDM technology for controlling a brushless dc motor.

Nelms, R. Mark

1993-01-01

175

Spin free analytic platform type guidance and control system  

NASA Astrophysics Data System (ADS)

The components of the spin free analytic satellite guidance and control system (SFAP) used for attitude reference on the M-3S Japanese launch vehicles are described. SFAP consists of attitude reference, control electronics, and actuators for each of three rocket stages. The attitude reference is performed with a single axis stabilized platform and three rate integrating gyroscopes mounted orthogonally to each other on the table. One gyro, aligned with the table axis, serves as the torque signal source. The gyros have a pulse output, each corresponding to a 2 x 10 to the -16th radian pitch/yaw attitude change. The electronic compare pitch, roll, and yaw angles with preset values, that are amenable to changes through ground control signals. The actuators include linear thrust vector controls (TVC) on the side of the first stage nozzle and an on/off system on the side of the second stage nozzle, together with hydrogen peroxide jets. Separate programs control each stage, and performance has been nominal in flight testing.

Higashiguchi, M.; Ishitani, H.

176

A micro high-temperature superconductor system: fabrication and operation  

Microsoft Academic Search

This paper presents the development of an integrated micro high-temperature superconductor system for energy storage and attitude control of three-axis stabilized nano satellites. The micro high-temperature superconductor system consists of a flywheel\\/rotor, motor\\/generator, motor electronics, and a cooling system. The flywheel\\/rotor has been fabricated by using sintered NdFeB and the stator for motor\\/generator has been fabricated by micro fabrication technology.

Eunjeong Lee; Bongsu Kim; Junseok Ko; Chi Young Song; Seong-Jin Kim; Sangkwon Jeong; Seung S. Lee

2006-01-01

177

Attitude Determination Error Analysis System (ADEAS) mathematical specifications document  

NASA Technical Reports Server (NTRS)

The mathematical specifications of Release 4.0 of the Attitude Determination Error Analysis System (ADEAS), which provides a general-purpose linear error analysis capability for various spacecraft attitude geometries and determination processes, are presented. The analytical basis of the system is presented. The analytical basis of the system is presented, and detailed equations are provided for both three-axis-stabilized and spin-stabilized attitude sensor models.

Nicholson, Mark; Markley, F.; Seidewitz, E.

1988-01-01

178

Auxiliary lift propulsion system with oversized front fan  

SciTech Connect

A propulsion system for use primarily in V/STOL aircraft is provided with a variable cycle, double bypass gas turbofan engine and a remote augmenter to produce auxiliary lift. The fan is oversized in air-pumping capability with respect to the cruise flight requirements of the remainder of the engine and a variable area, low pressure turbine is capable of supplying varying amounts of rotational energy to the oversized fan, thereby modulating its speed and pumping capability. During powered lift flight, the variable cycle engine is operated in the single bypass mode with the oversized fan at its maximum pumping capability. In this mode, substantially all of the bypass flow is routed as an auxiliary airstream to the remote augmenter where it is mixed with fuel, burned and exhausted through a vectorable nozzle to produce thrust for lifting. Additional lift is generated by the high energy products of combustion of the variable cycle engine which are further energized in an afterburner and exhausted through a thrust vectorable nozzle at the rear of the engine.

Castells, O.T.; Johnson, J.E.; Rundell, D.J.

1980-09-16

179

X-31 Post Stall Maneuver  

NASA Video Gallery

The X-31 program demonstrated the value of thrust vectoring (directing engine exhaust flow) coupled with advanced flight control systems, to provide controlled flight during close-in air combat at ...

180

X-31 Herbst Turn  

NASA Video Gallery

The X-31 program demonstrated the value of thrust vectoring (directing engine exhaust flow) coupled with advanced flight control systems, to provide controlled flight during close-in air combat at ...

181

Aristoteles magnetometer system  

NASA Technical Reports Server (NTRS)

A magnetometer system capable of meeting the stringent requirements of the Aristoteles mission is described. The system will comprise a three axis or Vector Flux gas Magnetometer (VFM) and a highly accurate resonance magnetometer, the Scalar Helium Magnetometer (SHM). Basic operational features of these instruments are described and their performance is related to the scientific objectives of the mission appropriate to the geomagnetic field measurements. The major requirements imposed on the spacecraft are summarized. Photographs and diagrams of both instruments are presented along with graphs of the sensitivity of the SHM to magnetic field orientation.

Smith, Edward J.; Marquedant, Roy J.; Langel, Robert; Acuna, Mario

1991-01-01

182

A system for spacecraft attitude control and energy storage  

NASA Technical Reports Server (NTRS)

A conceptual design for a double-gimbal reaction-wheel energy-wheel device which has three-axis attitude control and electrical energy storage capability is given. A mathematical model for the three-axis gyroscope (TAG) was developed, and a system of multiple units is proposed for attitude control and energy storage for a class of spacecraft. Control laws were derived to provide the required attitude-control torques and energy transfer while minimizing functions of TAG gimbal angles, gimbal rates, reaction-wheel speeds, and energy-wheel speed differences. A control law is also presented for a magnetic torquer desaturation system. A computer simulation of a three-TAG system for an orbiting telescope was used to evaluate the concept. The results of the study indicate that all control and power requirements can be satisfied by using the TAG concept.

Shaughnessy, J. D.

1974-01-01

183

Design and on-orbit performance of the attitude determination and control system for the ZDPS-1A pico-satellite  

NASA Astrophysics Data System (ADS)

The ZDPS-1A pico-satellite, developed by the Zhejiang University, is featured with a three-axis stabilizing capability. It is 15×15×15 cm3 cube-shaped satellite with a total mass of 3.5 kg. ZDPS-1A is the first pico-satellite that has been launched successfully in China. The mission of ZDPS-1A is on-orbit system verification of student-build pico-satellite and wide range earth observation with a micro panoramic camera. A miniature momentum wheel is employed to offer gyro stiffness stability in the pitch (orbit normal) axis. Magnetic coils are employed to generate control torques to achieve the three-axis stabilization of nadir-pointing. The attitude sensors employed in the design include two three-axis magnetometers (TAMs), a three-axis gyro, and two sun sensors. Both ground simulations and on-orbit testing are conducted to verify the feasibility of the given attitude determination and control system (ADCS).

Xiang, Tian; Meng, Tao; Wang, Hao; Han, Ke; Jin, Zhong-He

2012-08-01

184

Operations with the new FUSE observatory: three-axis control with one reaction wheel  

E-print Network

coverage capability or modifications to pointing performance. The CalFUSE data pipeline has also undergone Spectroscopic Explorer (FUSE), is a NASA astrophysics mission designed to collect spectra of astronomical the spectrograph entrance apertures and to obtain high quality spectra, the satellite must maintain stable pointing

185

A three-axis flight simulator. [for testing and evaluating inertial measuring units, and flight platforms  

NASA Technical Reports Server (NTRS)

A simulator is described, which was designed for testing and evaluating inertial measuring units, and flight platforms. Mechanical and electrical specifications for the outer, middle, and inner axis are presented. Test results are included.

Mason, M. G.

1975-01-01

186

Three-axis digital holographic microscopy for high speed volumetric imaging.  

PubMed

Digital Holographic Microscopy allows to numerically retrieve three dimensional information encoded in a single 2D snapshot of the coherent superposition of a reference and a scattered beam. Since no mechanical scans are involved, holographic techniques have a superior performance in terms of achievable frame rates. Unfortunately, numerical reconstructions of scattered field by back-propagation leads to a poor axial resolution. Here we show that overlapping the three numerical reconstructions obtained by tilted red, green and blue beams results in a great improvement over the axial resolution and sectioning capabilities of holographic microscopy. A strong reduction in the coherent background noise is also observed when combining the volumetric reconstructions of the light fields at the three different wavelengths. We discuss the performance of our technique with two test objects: an array of four glass beads that are stacked along the optical axis and a freely diffusing rod shaped E.coli bacterium. PMID:24921564

Saglimbeni, F; Bianchi, S; Lepore, A; Di Leonardo, R

2014-06-01

187

Pointing control system of SOFIA  

NASA Astrophysics Data System (ADS)

The challenging pointing stability requirement for the SOFIA telescope requires the application of sophisticated control concepts and high performance sensors and actuators. The pointing control concept involves a tracking system with optical cameras, a three-axis inertial stabilization loop, and the compensation of telescope deflections taking the secondary mirror control system into account. Special algorithms and techniques based on finite element calculations are applied for the online identification of telescope deflections and the design of the position control loop algorithm. New developments have been performed with regard to low noise fiber optic gyroscopes and spherical torquers for three degrees of freedom. The paper explains the control concept of the SOFIA telescope.

Wandner, Karl; Kaercher, Hans J.

2000-06-01

188

Space Launch System Implementation of Adaptive Augmenting Control  

NASA Technical Reports Server (NTRS)

Given the complex structural dynamics, challenging ascent performance requirements, and rigorous flight certification constraints owing to its manned capability, the NASA Space Launch System (SLS) launch vehicle requires a proven thrust vector control algorithm design with highly optimized parameters to robustly demonstrate stable and high performance flight. On its development path to preliminary design review (PDR), the stability of the SLS flight control system has been challenged by significant vehicle flexibility, aerodynamics, and sloshing propellant dynamics. While the design has been able to meet all robust stability criteria, it has done so with little excess margin. Through significant development work, an adaptive augmenting control (AAC) algorithm previously presented by Orr and VanZwieten, has been shown to extend the envelope of failures and flight anomalies for which the SLS control system can accommodate while maintaining a direct link to flight control stability criteria (e.g. gain & phase margin). In this paper, the work performed to mature the AAC algorithm as a baseline component of the SLS flight control system is presented. The progress to date has brought the algorithm design to the PDR level of maturity. The algorithm has been extended to augment the SLS digital 3-axis autopilot, including existing load-relief elements, and necessary steps for integration with the production flight software prototype have been implemented. Several updates to the adaptive algorithm to increase its performance, decrease its sensitivity to expected external commands, and safeguard against limitations in the digital implementation are discussed with illustrating results. Monte Carlo simulations and selected stressing case results are shown to demonstrate the algorithm's ability to increase the robustness of the integrated SLS flight control system.

VanZwieten, Tannen S.; Wall, John H.; Orr, Jeb S.

2014-01-01

189

Space Launch System Implementation of Adaptive Augmenting Control  

NASA Technical Reports Server (NTRS)

Given the complex structural dynamics, challenging ascent performance requirements, and rigorous flight certification constraints owing to its manned capability, the NASA Space Launch System (SLS) launch vehicle requires a proven thrust vector control algorithm design with highly optimized parameters to provide stable and high-performance flight. On its development path to Preliminary Design Review (PDR), the SLS flight control system has been challenged by significant vehicle flexibility, aerodynamics, and sloshing propellant. While the design has been able to meet all robust stability criteria, it has done so with little excess margin. Through significant development work, an Adaptive Augmenting Control (AAC) algorithm has been shown to extend the envelope of failures and flight anomalies the SLS control system can accommodate while maintaining a direct link to flight control stability criteria such as classical gain and phase margin. In this paper, the work performed to mature the AAC algorithm as a baseline component of the SLS flight control system is presented. The progress to date has brought the algorithm design to the PDR level of maturity. The algorithm has been extended to augment the full SLS digital 3-axis autopilot, including existing load-relief elements, and the necessary steps for integration with the production flight software prototype have been implemented. Several updates which have been made to the adaptive algorithm to increase its performance, decrease its sensitivity to expected external commands, and safeguard against limitations in the digital implementation are discussed with illustrating results. Monte Carlo simulations and selected stressing case results are also shown to demonstrate the algorithm's ability to increase the robustness of the integrated SLS flight control system.

Wall, John H.; Orr, Jeb S.; VanZwieten, Tannen S.

2014-01-01

190

Structure and properties of nano-hydroxypatite scaffolds for bone tissue engineering with a selective laser sintering system  

Microsoft Academic Search

In this study, nano-hydroxypatite (n-HAP) bone scaffolds are prepared by a homemade selective laser sintering (SLS) system based on rapid prototyping (RP) technology. The SLS system consists of a precise three-axis motion platform and a laser with its optical focusing device. The implementation of arbitrary complex movements based on the non-uniform rational B-Spline (NURBS) theory is realized in this system.

Cijun Shuai; Chengde Gao; Yi Nie; Huanlong Hu; Ying Zhou; Shuping Peng

2011-01-01

191

A PC-based magnetometer-only attitude and rate determination system for gyroless spacecraft  

NASA Technical Reports Server (NTRS)

This paper describes a prototype PC-based system that uses measurements from a three-axis magnetometer (TAM) to estimate the state (three-axis attitude and rates) of a spacecraft given no a priori information other than the mass properties. The system uses two algorithms that estimate the spacecraft's state - a deterministic magnetic-field only algorithm and a Kalman filter for gyroless spacecraft. The algorithms are combined by invoking the deterministic algorithm to generate the spacecraft state at epoch using a small batch of data and then using this deterministic epoch solution as the initial condition for the Kalman filter during the production run. System input comprises processed data that includes TAM and reference magnetic field data. Additional information, such as control system data and measurements from line-of-sight sensors, can be input to the system if available. Test results are presented using in-flight data from two three-axis stabilized spacecraft: Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) (gyroless, Sun-pointing) and Earth Radiation Budget Satellite (ERBS) (gyro-based, Earth-pointing). The results show that, using as little as 700 s of data, the system is capable of accuracies of 1.5 deg in attitude and 0.01 deg/s in rates; i.e., within SAMPEX mission requirements.

Challa, M.; Natanson, G.; Deutschmann, J.; Galal, K.

1995-01-01

192

Space construction base control system  

NASA Technical Reports Server (NTRS)

Several approaches for an attitude control system are studied and developed for a large space construction base that is structurally flexible. Digital simulations were obtained using the following techniques: (1) the multivariable Nyquist array method combined with closed loop pole allocation, (2) the linear quadratic regulator method. Equations for the three-axis simulation using the multilevel control method were generated and are presented. Several alternate control approaches are also described. A technique is demonstrated for obtaining the dynamic structural properties of a vehicle which is constructed of two or more submodules of known dynamic characteristics.

Kaczynski, R. F.

1979-01-01

193

V/STOL Systems Research Aircraft: A Tool for Cockpit Integration  

NASA Technical Reports Server (NTRS)

The next generation ASTOVL aircraft will have a complicated propulsion System. The configuration choices include Direct Lift, Lift-Fan and Lift+Lift /Cruise but the aircraft must also have supersonic performance and low-observable characteristics. The propulsion system may have features such as flow blockers, vectoring nozzles and flow transfer schemes. The flight control system will necessarily fully integrate the aerodynamic surfaces and the propulsive elements. With a fully integrated, fly-by-wire flight/propulsion control system, the options for cockpit integration are interesting and varied. It is possible to decouple longitudinal and vertical responses allowing the pilot to close the loop on flight path and flight path acceleration directly. In the hover, the pilot can control the translational rate directly without having to stabilize the inner rate and attitude loops. The benefit of this approach, reduced workload and increased precision. has previously been demonstrated through several motion-based simulations. In order to prove the results in flight, the V/STOL System Research Aircraft (VSRA) was developed at the NASA Ames Research Center. The VSRA is the YAV-8B Prototype modified with a research flight control system using a series-parallel servo configuration in all the longitudinal degrees of freedom (including thrust and thrust vector angle) to provide an integrated flight and propulsion control system in a limited envelope. Development of the system has been completed and flight evaluations of the response types have been performed. In this paper we will discuss the development of the VSRA, the evolution of the flight path command and translational rate command response types and the Guest Pilot evaluations of the system. Pilot evaluation results will be used to draw conclusions regarding the suitability of the system to satisfy V/STOL requirements.

Stortz, Michael W.; ODonoghue, Dennis P.; Tiffany, Geary (Technical Monitor)

1995-01-01

194

V/STOL systems research aircraft: A tool for cockpit integration  

NASA Technical Reports Server (NTRS)

The next generation ASTOVL aircraft will have a complicated propulsion system. The configuration choices include Direct Lift, Lift-Fan and Lift + Lift/Cruise but the aircraft must also have supersonic performance and low-observable characteristics. The propulsion system may have features such as flow blockers, vectoring nozzles and flow transfer schemes. The flight control system will necessarily fully integrate the aerodynamic surfaces and the propulsive elements. With a fully integrated, fly-by-wire flight/propulsion control system, the options for cockpit integration are interesting and varied. It is possible to de-couple longitudinal and vertical responses allowing the pilot to close the loop on flightpath and flightpath acceleration directly. In the hover, the pilot can control the translational rate directly without having to stabilize the inner rate and attitude loops. The benefit of this approach, reduced workload and increased precision, has previously been demonstrated through several motion-based simulations. In order to prove the results in flight, the V/STOL System Research Aircraft (VSRA) was developed at the NASA Ames Research Center. The VSRA is the YAV-8B Prototype modified with a research flight control system using a series-parallel servo configuration in all the longitudinal degrees of freedom (including thrust and thrust vector angle) to provide an integrated flight and propulsion control system in a limited envelope. Development of the system has been completed and flight evaluations of the response types have been performed. In this paper we will discuss the development of the VSRA, the evolution of the flightpath command and translational rate command response types and the Guest Pilot evaluations of the system. Pilot evaluation results are used to draw conclusions regarding the suitability of the system to satisfy V/STOL requirements.

Stortz, Michael W.; ODonoghue, Dennis P.

1995-01-01

195

Design of power electronics for TVC and EMA systems  

NASA Astrophysics Data System (ADS)

The Component Development Division of the Propulsion Laboratory at Marshall Space Flight Center (MSFC) is currently developing a class of electromechanical actuators (EMA's) for use in space transportation applications such as thrust vector control (TVC) and propellant control valves (PCV). These high power servomechanisms will require rugged, reliable, and compact power electronic modules capable of modulating several hundred amperes of current at up to 270 volts. MSFC has selected the brushless dc motor for implementation in EMA's. A previous project performed by Auburn University examined the use of the resonant dc link (RDCL) inverter, pulse density modulation (PDM), and mos-controlled thyristors (MCT's) for speed control of a brushless dc motor. The speed of the brushless dc motor is proportional to the applied stator voltage. In a PDM system, the control system determines the number of resonant voltage pulses which must be applied to the stator to achieve a desired speed. The addition of a waveshaping circuit to the front end of a standard three-phase inverter yields a RDCL inverter; the resonant voltage pulses are produced through the action of this wave shaping circuit and the inverter. This project has focused on the implementation of a system which permits zero-voltage switching with the bus voltage clamped at the input voltage level. In the same manner as the RDCL inverter, the inverter selected for this implementation is a combination of waveshaping circuit and a standard three-phase inverter. In addition, this inverter allows a pulse-width modulated (PWM)-like control scheme instead of a PDM scheme. The operation of waveshaping circuit will be described through analysis and waveforms. Design relationships will also be presented.

Nelms, R. Mark; Bell, J. Brett; Shepherd, Michael T.

1994-11-01

196

Enhancement of the inertial navigation system for the Morpheus autonomous underwater vehicles  

Microsoft Academic Search

This paper presents the design and development of an enhanced inertial navigation system that is to be integrated into the Morpheus autonomous underwater vehicle at Florida Atlantic University. The inertial measurement unit is based on the off-the-shelf Honeywell HG1700-AG25 3-axis ring-laser gyros and three-axis accelerometers and is aided with ground speed measurements obtained using an RDI Doppler-velocity-log sonar. An extended

Gabriel Grenon; P. Edgar An; Samuel M. Smith; Anthony J. Healey

2001-01-01

197

Development of a GPS-aided motion measurement, pointing, and stabilization system for a Synthetic Aperture Radar. [Global Positioning System (GPS)  

SciTech Connect

An advanced Synthetic Aperture Radar Motion Compensation System has been developed by Sandia National Laboratories (SNL). The system includes a miniaturized high accuracy ring laser gyro inertial measurement unit, a three axis gimbal pointing and stabilization assembly, a differential Global Positioning System (GPS) navigation aiding system, and a pilot guidance system. The system provides several improvements over previous SNL motion compensation systems and is capable of antenna stabilization to less than 0.01 degrees RMS and absolute position measurement to less than 5.0 meters RMS. These accuracies have been demonstrated in recent flight testing aboard a DHC-6-300 Twin Otter'' aircraft.

Fellerhoff, J.R.; Kohler, S.M.

1991-01-01

198

A measuring system for well logging attitude and a method of sensor calibration.  

PubMed

This paper proposes an approach for measuring the azimuth angle and tilt angle of underground drilling tools with a MEMS three-axis accelerometer and a three-axis fluxgate sensor. A mathematical model of well logging attitude angle is deduced based on combining space coordinate transformations and algebraic equations. In addition, a system implementation plan of the inclinometer is given in this paper, which features low cost, small volume and integration. Aiming at the sensor and assembly errors, this paper analyses the sources of errors, and establishes two mathematical models of errors and calculates related parameters to achieve sensor calibration. The results show that this scheme can obtain a stable and high precision azimuth angle and tilt angle of drilling tools, with the deviation of the former less than ±1.4° and the deviation of the latter less than ±0.1°. PMID:24859028

Ren, Yong; Wang, Yangdong; Wang, Mijian; Wu, Sheng; Wei, Biao

2014-01-01

199

Space Launch System Development Status  

NASA Technical Reports Server (NTRS)

Development of NASA's Space Launch System (SLS) heavy lift rocket is shifting from the formulation phase into the implementation phase in 2014, a little more than three years after formal program approval. Current development is focused on delivering a vehicle capable of launching 70 metric tons (t) into low Earth orbit. This "Block 1" configuration will launch the Orion Multi-Purpose Crew Vehicle (MPCV) on its first autonomous flight beyond the Moon and back in December 2017, followed by its first crewed flight in 2021. SLS can evolve to a130-t lift capability and serve as a baseline for numerous robotic and human missions ranging from a Mars sample return to delivering the first astronauts to explore another planet. Benefits associated with its unprecedented mass and volume include reduced trip times and simplified payload design. Every SLS element achieved significant, tangible progress over the past year. Among the Program's many accomplishments are: manufacture of Core Stage test panels; testing of Solid Rocket Booster development hardware including thrust vector controls and avionics; planning for testing the RS-25 Core Stage engine; and more than 4,000 wind tunnel runs to refine vehicle configuration, trajectory, and guidance. The Program shipped its first flight hardware - the Multi-Purpose Crew Vehicle Stage Adapter (MSA) - to the United Launch Alliance for integration with the Delta IV heavy rocket that will launch an Orion test article in 2014 from NASA's Kennedy Space Center. Objectives of this Earth-orbit flight include validating the performance of Orion's heat shield and the MSA design, which will be manufactured again for SLS missions to deep space. The Program successfully completed Preliminary Design Review in 2013 and Key Decision Point C in early 2014. NASA has authorized the Program to move forward to Critical Design Review, scheduled for 2015 and a December 2017 first launch. The Program's success to date is due to prudent use of proven technology, infrastructure, and workforce from the Saturn and Space Shuttle programs, a streamlined management approach, and judicious use of new technologies. The result is a safe, affordable, sustainable, and evolutionary path to development of an unprecedented capability for future missions across the solar system. In an environment of economic challenges, the nationwide SLS team continues to meet ambitious budget and schedule targets. This paper will discuss SLS program and technical accomplishments over the past year and provide a look at the milestones and challenges ahead.

Lyles, Garry

2014-01-01

200

America's Next Great Ship: Space Launch System Core Stage Transitioning from Design to Manufacturing  

NASA Technical Reports Server (NTRS)

The Space Launch System (SLS) Program is essential to achieving the Nation's and NASA's goal of human exploration and scientific investigation of the solar system. As a multi-element program with emphasis on safety, affordability, and sustainability, SLS is becoming America's next great ship of exploration. The SLS Core Stage includes avionics, main propulsion system, pressure vessels, thrust vector control, and structures. Boeing manufactures and assembles the SLS core stage at the Michoud Assembly Facility (MAF) in New Orleans, LA, a historical production center for Saturn V and Space Shuttle programs. As the transition from design to manufacturing progresses, the importance of a well-executed manufacturing, assembly, and operation (MA&O) plan is crucial to meeting performance objectives. Boeing employs classic techniques such as critical path analysis and facility requirements definition as well as innovative approaches such as Constraint Based Scheduling (CBS) and Cirtical Chain Project Management (CCPM) theory to provide a comprehensive suite of project management tools to manage the health of the baseline plan on both a macro (overall project) and micro level (factory areas). These tools coordinate data from multiple business systems and provide a robust network to support Material & Capacity Requirements Planning (MRP/CRP) and priorities. Coupled with these tools and a highly skilled workforce, Boeing is orchestrating the parallel buildup of five major sub assemblies throughout the factory. Boeing and NASA are transforming MAF to host state of the art processes, equipment and tooling, the most prominent of which is the Vertical Assembly Center (VAC), the largest weld tool in the world. In concert, a global supply chain is delivering a range of structural elements and component parts necessary to enable an on-time delivery of the integrated Core Stage. SLS is on plan to launch humanity into the next phase of space exploration.

Birkenstock, Benjamin; Kauer, Roy

2014-01-01

201

Closed-Loop System Identification Experience for Flight Control Law and Flying Qualities Evaluation of a High Performance Fighter Aircraft  

NASA Technical Reports Server (NTRS)

This paper highlights some of the results and issues associated with estimating models to evaluate control law design methods and design criteria for advanced high performance aircraft. Experimental fighter aircraft such as the NASA High Alpha Research Vehicle (HARV) have the capability to maneuver at very high angles of attack where nonlinear aerodynamics often predominate. HARV is an experimental F/A-18, configured with thrust vectoring and conformal actuated nose strakes. Identifying closed-loop models for this type of aircraft can be made difficult by nonlinearities and high-order characteristics of the system. In this paper only lateral-directional axes are considered since the lateral-directional control law was specifically designed to produce classical airplane responses normally expected with low-order, rigid-body systems. Evaluation of the control design methodology was made using low-order equivalent systems determined from flight and simulation. This allowed comparison of the closed-loop rigid-body dynamics achieved in flight with that designed in simulation. In flight, the On Board Excitation System was used to apply optimal inputs to lateral stick and pedals at five angles of attack: 5, 20, 30, 45, and 60 degrees. Data analysis and closed-loop model identification were done using frequency domain maximum likelihood. The structure of the identified models was a linear state-space model reflecting classical 4th-order airplane dynamics. Input time delays associated with the high-order controller and aircraft system were accounted for in data preprocessing. A comparison of flight estimated models with small perturbation linear design models highlighted nonlinearities in the system and indicated that the estimated closed-loop rigid-body dynamics were sensitive to input amplitudes at 20 and 30 degrees angle of attack.

Murphy, Patrick C.

1999-01-01

202

Closed-Loop System Identification Experience for Flight Control Law and Flying Qualities Evaluation of a High Performance Fighter Aircraft  

NASA Technical Reports Server (NTRS)

This paper highlights some of the results and issues associated with estimating models to evaluate control law design methods and design criteria for advanced high performance aircraft. Experimental fighter aircraft such as the NASA-High Alpha Research Vehicle (HARV) have the capability to maneuver at very high angles of attack where nonlinear aerodynamics often predominate. HARV is an experimental F/A-18, configured with thrust vectoring and conformal actuated nose strakes. Identifying closed-loop models for this type of aircraft can be made difficult by nonlinearities and high order characteristics of the system. In this paper, only lateral-directional axes are considered since the lateral-directional control law was specifically designed to produce classical airplane responses normally expected with low-order, rigid-body systems. Evaluation of the control design methodology was made using low-order equivalent systems determined from flight and simulation. This allowed comparison of the closed-loop rigid-body dynamics achieved in flight with that designed in simulation. In flight, the On Board Excitation System was used to apply optimal inputs to lateral stick and pedals at five angles at attack : 5, 20, 30, 45, and 60 degrees. Data analysis and closed-loop model identification were done using frequency domain maximum likelihood. The structure of identified models was a linear state-space model reflecting classical 4th-order airplane dynamics. Input time delays associated with the high-order controller and aircraft system were accounted for in data preprocessing. A comparison of flight estimated models with small perturbation linear design models highlighted nonlinearities in the system and indicated that the closed-loop rigid-body dynamics were sensitive to input amplitudes at 20 and 30 degrees angle of attack.

Murphy, Patrick C.

1996-01-01

203

Characterization of in-flight performance of ion propulsion systems  

NASA Technical Reports Server (NTRS)

In-flight measurements of ion propulsion performance, ground test calibrations, and diagnostic performance measurements were reviewed. It was found that accelerometers provided the most accurate in-flight thrust measurements compared with four other methods that were surveyed. An experiment has also demonstrated that pre-flight alignment of the thrust vector was sufficiently accurate so that gimbal adjustments and use of attitude control thrusters were not required to counter disturbance torques caused by thrust vector misalignment. The effects of facility background pressure, facility enhanced charge-exchange reactions, and contamination on ground-based performance measurements are also discussed. Vacuum facility pressures for inert-gas ion thruster life tests and flight qualification tests will have to be less than 2 mPa to ensure accurate performance measurements.

Sovey, James S.; Rawlin, Vincent K.

1993-01-01

204

Design and development issues for a control actuation system for the AdKEM  

NASA Astrophysics Data System (ADS)

The paper addresses three issues critical to the design and development of the control actuation system (CAS) for the Advanced Kinetic Energy Missile (AdKEM), a hypersonic, kinetic energy weapon system. First of all, the small missile diameter requires that a high performance, three-axis control system be packaged within a limited amount of space. The second critical issue is the need for a high speed solenoid so that the system performance requirements may be met. Experimental data are presented to quantify the solenoid performance. Finally, the issue of control fin flutter, a phenomenon that could cause control system failure, is addressed.

Cayson, Stephen C.

1992-05-01

205

CMG-Augmented Control of a Hovering VTOL Platform  

NASA Technical Reports Server (NTRS)

This paper describes how Control Moment Gyroscopes (CMGs) can be used for stability augmentation to a thrust vectoring system for a generic Vertical Take-Off and Landing platform. The response characteristics of the platform which uses only thrust vectoring and a second configuration which includes a single-gimbal CMG array are simulated and compared for hovering flight while subject to severe air turbulence. Simulation results demonstrate the effectiveness of a CMG array in its ability to significantly reduce the agility requirement on the thrust vectoring system. Albeit simplifying physical assumptions on a generic CMG configuration, the numerical results also suggest that reasonably sized CMGs will likely be sufficient for a small hovering vehicle.

Lim, K. B.; Moerder, D. D.

2007-01-01

206

NASA's Space Launch System Development Status  

NASA Technical Reports Server (NTRS)

Development of the National Aeronautics and Space Administration's (NASA's) Space Launch System (SLS) heavy lift rocket is shifting from the formulation phase into the implementation phase in 2014, a little more than 3 years after formal program establishment. Current development is focused on delivering a vehicle capable of launching 70 metric tons (t) into low Earth orbit. This "Block 1" configuration will launch the Orion Multi-Purpose Crew Vehicle (MPCV) on its first autonomous flight beyond the Moon and back in December 2017, followed by its first crewed flight in 2021. SLS can evolve to a130t lift capability and serve as a baseline for numerous robotic and human missions ranging from a Mars sample return to delivering the first astronauts to explore another planet. Benefits associated with its unprecedented mass and volume include reduced trip times and simplified payload design. Every SLS element achieved significant, tangible progress over the past year. Among the Program's many accomplishments are: manufacture of core stage test barrels and domes; testing of Solid Rocket Booster development hardware including thrust vector controls and avionics; planning for RS- 25 core stage engine testing; and more than 4,000 wind tunnel runs to refine vehicle configuration, trajectory, and guidance. The Program shipped its first flight hardware - the Multi-Purpose Crew Vehicle Stage Adapter (MSA) - to the United Launch Alliance for integration with the Delta IV heavy rocket that will launch an Orion test article in 2014 from NASA's Kennedy Space Center. The Program successfully completed Preliminary Design Review in 2013 and will complete Key Decision Point C in 2014. NASA has authorized the Program to move forward to Critical Design Review, scheduled for 2015 and a December 2017 first launch. The Program's success to date is due to prudent use of proven technology, infrastructure, and workforce from the Saturn and Space Shuttle programs, a streamlined management approach, and judicious use of new technologies. The result is a safe, affordable, sustainable, and evolutionary path to development of an unprecedented capability for future missions across the solar system. In an environment of economic challenges, the nationwide SLS team continues to meet ambitious budget and schedule targets. This paper will discuss SLS Program and technical accomplishments over the past year and provide a look at the milestones and challenges ahead.

Lyles, Garry

2014-01-01

207

An electromechanical actuation system for an expendable launch vehicle  

NASA Astrophysics Data System (ADS)

A major effort at the NASA Lewis Research Center in recent years has been to develop electro-mechanical actuators (EMA's) to replace the hydraulic systems used for thrust vector control (TVC) on launch vehicles. This is an attempt ot overcome the inherent inefficiencies and costs associated with the existing hydraulic structures. General Dynamics Space Systems Division, under contract to NASA Lewis, is developing 18.6 kW (25 hp), 29.8 kW (40 hp), and 52.2 kW (70 hp) peak EMA systems to meet the power demands for TVC on a family of vehicles developed for the National Launch System. These systems utilize a pulse population modulated converter and field-oriented control scheme to obtain independent control of both the voltage and frequency. These techniques allow an induction motor to be operated at its maximum torque at all times. At NASA Lewis, we are building on this technology to develop our own in-house system capable of meeting the peak power requirements for an expendable launch vehicle (ELV) such as the Atlas. Our EMA will be capable of delivering 22.4 kW (30 hp) peak power with a nominal of 6.0 kW (8 hp). This system differs from the previous ones in two areas: (1) the use of advanced control methods, and (2) the incorporation of built-in-test. The advanced controls are essential for minimizing the controller size, while the built-in-test is necessary to enhance the system reliability and vehicle health monitoring. The ultimate goal of this program is to demonstrate an EMA which will be capable of self-test and easy integration into other projects. This paper will describe the effort underway at NASA Lewis to develop an EMA for an Atlas class ELV. An explanation will be given for each major technology block, and the status of each major technology block and the status of the overall program will be reported.

Burrows, Linda M.; Roth, Mary Ellen

1992-08-01

208

An electromechanical actuation system for an expendable launch vehicle  

NASA Technical Reports Server (NTRS)

A major effort at the NASA Lewis Research Center in recent years has been to develop electro-mechanical actuators (EMA's) to replace the hydraulic systems used for thrust vector control (TVC) on launch vehicles. This is an attempt ot overcome the inherent inefficiencies and costs associated with the existing hydraulic structures. General Dynamics Space Systems Division, under contract to NASA Lewis, is developing 18.6 kW (25 hp), 29.8 kW (40 hp), and 52.2 kW (70 hp) peak EMA systems to meet the power demands for TVC on a family of vehicles developed for the National Launch System. These systems utilize a pulse population modulated converter and field-oriented control scheme to obtain independent control of both the voltage and frequency. These techniques allow an induction motor to be operated at its maximum torque at all times. At NASA Lewis, we are building on this technology to develop our own in-house system capable of meeting the peak power requirements for an expendable launch vehicle (ELV) such as the Atlas. Our EMA will be capable of delivering 22.4 kW (30 hp) peak power with a nominal of 6.0 kW (8 hp). This system differs from the previous ones in two areas: (1) the use of advanced control methods, and (2) the incorporation of built-in-test. The advanced controls are essential for minimizing the controller size, while the built-in-test is necessary to enhance the system reliability and vehicle health monitoring. The ultimate goal of this program is to demonstrate an EMA which will be capable of self-test and easy integration into other projects. This paper will describe the effort underway at NASA Lewis to develop an EMA for an Atlas class ELV. An explanation will be given for each major technology block, and the status of each major technology block and the status of the overall program will be reported.

Burrows, Linda M.; Roth, Mary Ellen

1992-01-01

209

SCI Hazard Report Methodology  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the methodology in creating a Source Control Item (SCI) Hazard Report (HR). The SCI HR provides a system safety risk assessment for the following Ares I Upper Stage Production Contract (USPC) components (1) Pyro Separation Systems (2) Main Propulsion System (3) Reaction and Roll Control Systems (4) Thrust Vector Control System and (5) Ullage Settling Motor System components.

Mitchell, Michael S.

2010-01-01

210

Six-degree-of-freedom simulation of an astronaut detumble system  

NASA Technical Reports Server (NTRS)

The problem of stabilizing the attitude of an untethered astronaut in a three-axis tumble is addressed. A simple six thruster detumbling system mounted on the astronaut's Portable Life Support System backpack is analyzed as a possible solution. A six-degree-of-freedom dynamical model is constructed using the Clohessy-Wiltshire equations, Euler's moment equations, and quaternions. The six thruster system produces both moments and forces when activated. However, it is shown that the thrust forces acting on the body during detumbling do not significantly affect the translational motion.

Fowler, W. T.; Neff, J. M.

1991-01-01

211

New image-stabilizing system  

NASA Astrophysics Data System (ADS)

In this paper, a new method for image stabilization with a three-axis image- stabilizing reflecting prism assembly is presented, and the principle of image stabilization in this prism assembly, formulae for image stabilization and working formulae with an approximation up to the third power are given in detail. In this image-stabilizing system, a single chip microcomputer is used to calculate value of compensating angles and thus to control the prism assembly. Two gyroscopes act as sensors from which information of angular perturbation is obtained, three stepping motors drive the prism assembly to compensate for the movement of image produced by angular perturbation. The image-stabilizing device so established is a multifold system which involves optics, mechanics, electronics and computer.

Zhao, Yuejin

1996-06-01

212

Testing the three axis magnetometer and gradiometer MOURA and data comparison on San Pablo de los Montes Observatory.  

NASA Astrophysics Data System (ADS)

A magnetometer and gradiometer named MOURA has been developed with the objective to measure the magnetic field on Mars in the frame of Mars MetNet Precursor Mission (MMPM) [1]. MOURA is a compact, miniaturized, intelligent and low cost instrument, based on two sets of triaxial magnetometers separated one centimeter from each other to do gradiometry studies. It has a resolution of 2.2 nT, and a field range of + 65?T, which can be extended to +130 ?T when sensors are saturated. [2] These sensor heads are Anisotropic MagnetoResistances (AMR) Commercial-Off-The-Shelf (COTS) by Honeywell, specifically HMC1043, which has been selected due to their relative low consumption, weight and size, factors very important for the mission with very limited mass and power budget (shared 150 g for three full payloads). Also, this technology has been previously successfully employed on board Unmanned Aerial Vehicles (UAV) to perform geomagnetic surveys in extreme conditions areas [3], and in several space missions for different applications. [4] After the development of the MOURA Engineering Qualification Model (EQM) in November 2011, an exhaustive set of tests have been performed to validate and fully characterize the instrument. Compensation equations have been derived for the temperature corrections in the operation range (between -135 °C and 30 °C) in controlled environments. These compensation equations have been applied to field data, which have shown to follow the daily Earth's magnetic field variations as registered by San Pablo Geomagnetic Observatory (IAGA code: SPT) (available at www.ign.es and www.intermagnet.org) with deviations lower than 40 nT. These deviations were attributed to several error factors as the different locations between MOURA and SPT and other possible different geomagnetic conditions. Due to the above, a measurement campaign on SPT installations are been done. The main objective is to compare MOURA measurements on a relevant environment, with data obtained by SPT magnetometers. This is considered the last step prior to Mars in situ measurements. SPT employs for geomagnetic observations a fluxgate magnetometer FGE-Danish Meteorological Institute and a fluxgate vector magnetometer Geomag M390, both equipped with Overhauser effect magnetometers GSM90. The conditions into the rooms that contain these instruments are controlled. The equipments are situated on several pillars fixed strategically at Earth surface avoiding vibrations and other Earth movement that could affect measurement due to changes on the sensor position, the region is magnetically clean and the temperature variation is very low. Magnetic measurements are performed by MOURA for several days located on one of these pillars. These measurements are compared with SPT reference instrumentation with the aim to obtain a direct and very accurate evaluation of MOURA facing reference instrumentation. http://metnet.fmi.fi/index.php Development of miniaturized instrumentation for Planetary Exploration and its application to the Mars MetNet Precursor Mission. H. Guerrero et al. EGU General Assembly 2010, held 2-7 May, 2010 in Vienna, Austria, p.13330 Funaki, M.; Hirasawa, N.; and the Ant-Plane Group. Outline of a small unmanned aerial vehicle (Ant-Plane) designed for Antartic research. Polar Science 2008, 2, 129-142. M. Diaz-Michelena Sensors 2009, 9(4), 2271-2288

Belen Fernandez, Ana; Sanz, Ruy; Covisa, Pablo; Tordesillas, Jose Manuel; Diaz-Michelena, Marina

2013-04-01

213

3-Axis Magnetic Sensor Hybrid The Honeywell HMC2003 is a high sensitivity, three-axis magnetic sensor hybrid  

E-print Network

. With the sensitivity and linearity of this hybrid, changes can be detected in the earth's magnetic field to provide-axis magnetic sensor hybrid assembly used to measure low magnetic field strengths. Honeywell's most sensitive Magnetic Field Sensitivity 0.98 1 1.02 V/gauss Null Field Output 2.3 2.5 2.7 V Resolution 40 gauss Field

Kleinfeld, David

214

Space Shuttle 1976 into mainstream development - Program commitments on schedule to insure careful progress  

NASA Technical Reports Server (NTRS)

A progress report is given on various systems, noting conformity to schedule or changes in design. The Orbiter thermal protection system, the Space Shuttle main engine, the intertank for the structural test article (STA), thrust vector control systems, the Kennedy Space Center launch processing system, and Orbiters No. 1 and No. 2 are discussed.

Malkin, M. S.

1976-01-01

215

Reusable Reentry Satellite (RRS) system design study. Phase B, appendix E: Attitude control system study  

NASA Technical Reports Server (NTRS)

A study which consisted of a series of design analyses for an Attitude Control System (ACS) to be incorporated into the Re-usable Re-entry Satellite (RRS) was performed. The main thrust of the study was associated with defining the control laws and estimating the mass and power requirements of the ACS needed to meet the specified performance goals. The analyses concentrated on the different on-orbit control modes which start immediately after the separation of the RRS from the launch vehicle. The three distinct on-orbit modes considered for these analyses are as follows: (1) Mode 1 - A Gravity Gradient (GG) three-axis stabilized spacecraft with active magnetic control; (2) Mode 2 - A GG stabilized mode with a controlled yaw rotation rate ('rotisserie') using three-axis magnetic control and also incorporating a 10 N-m-s momentum wheel along the (Z) yaw axis; and (3) Mode 3 - A spin stabilized mode of operation with the spin about the pitch (Y) axis, incorporating a 20 N-m-s momentum wheel along the pitch (Y) axis and attitude control via thrusters. To investigate the capabilities of the different controllers in these various operational modes, a series of computer simulations and trade-off analyses have been made to evaluate the achievable performance levels, and the necessary mass and power requirements.

1991-01-01

216

Precision Pointing Control System (PPCS) system design and analysis. [for gimbaled experiment platforms  

NASA Technical Reports Server (NTRS)

The precision pointing control system (PPCS) is an integrated system for precision attitude determination and orientation of gimbaled experiment platforms. The PPCS concept configures the system to perform orientation of up to six independent gimbaled experiment platforms to design goal accuracy of 0.001 degrees, and to operate in conjunction with a three-axis stabilized earth-oriented spacecraft in orbits ranging from low altitude (200-2500 n.m., sun synchronous) to 24 hour geosynchronous, with a design goal life of 3 to 5 years. The system comprises two complementary functions: (1) attitude determination where the attitude of a defined set of body-fixed reference axes is determined relative to a known set of reference axes fixed in inertial space; and (2) pointing control where gimbal orientation is controlled, open-loop (without use of payload error/feedback) with respect to a defined set of body-fixed reference axes to produce pointing to a desired target.

Frew, A. M.; Eisenhut, D. F.; Farrenkopf, R. L.; Gates, R. F.; Iwens, R. P.; Kirby, D. K.; Mann, R. J.; Spencer, D. J.; Tsou, H. S.; Zaremba, J. G.

1972-01-01

217

Tracking and data relay satellite system configuration and tradeoff study. Volume 1: Study summary  

NASA Technical Reports Server (NTRS)

A study was conducted to determine the configuration and tradeoffs of a tracking and data relay satellite. The study emphasized the design of a three axis stabilized satellite and a telecommunications system optimized for support of low and medium data rate user spacecraft. Telecommunications support to low and high, or low medium, and high data rate users, considering launches with the Delta 2914, the Atlas/Centaur, and the space shuttle was also considered. The following subjects are presented: (1) launch and deployment profile, (2) spacecraft mechanical and structural design, (3) attitude stabilization and control subsystem, and (4) reliability analysis.

Hill, T. E.

1973-01-01

218

A computer-aided telescope pointing system utilizing a video star tracker  

NASA Technical Reports Server (NTRS)

The Video Inertial Pointing (VIP) System developed to satisfy the acquisition and pointing requirements of astronomical telescopes is described. A unique feature of the system is the use of a single sensor to provide information for the generation of three axis pointing error signals and for a cathode ray tube (CRT) display of the star field. The pointing error signals are used to update the telescope's gyro stabilization and the CRT display is used by an operator to facilitate target acquisition and to aid in manual positioning of the telescope optical axis. A model of the system using a low light level vidicon built and flown on a balloon-borne infrared telescope is briefly described from a state of the art charge coupled device (CCD) sensor. The advanced system hardware is described and an analysis of the multi-star tracking and three axis error signal generation, along with an analysis and design of the gyro update filter, are presented. Results of a hybrid simulation are described in which the advanced VIP system hardware is driven by a digital simulation of the star field/CCD sensor and an analog simulation of the telescope and gyro stabilization dynamics.

Murphy, J. P.; Lorell, K. R.; Swift, C. D.

1975-01-01

219

Flight Control of a Rotary wing UAV using Adaptive Backstepping Bilal Ahmed and Hemanshu R. Pota  

E-print Network

thrust vector, while the outer loop controller (position control) tracks the reference position research conducted in the area of system identification modeling and design of controllers for RUAVs. Major of the rigid body, resulting in a two-level hierarchical control scheme. The inner loop controller (attitude

Pota, Himanshu Roy

220

Model-reference attitude control and reaction control jet engine placement for space shuttle  

NASA Technical Reports Server (NTRS)

Analytical studies on the theoretical aspects of thrust vector control of large space vehicles were conducted. A system for attitude control of the space shuttle vehicle was developed. Major accomplishments of the project are: (1) investigation of a model-reference adaptive control scheme for controlling the space shuttle attitude and (2) determination of optimum placement of reaction control jet engines on space shuttles.

Boland, J. S., III

1973-01-01

221

Communications satellite systems operations with the space station, volume 2  

NASA Technical Reports Server (NTRS)

A financial model was developed which described quantitatively the economics of the space segment of communication satellite systems. The model describes the economics of the space system throughout the lifetime of the satellite. The expected state-of-the-art status of communications satellite systems and operations beginning service in 1995 were assessed and described. New or enhanced space-based activities and associated satellite system designs that have the potential to achieve future communications satellite operations in geostationary orbit with improved economic performance were postulated and defined. Three scenarios using combinations of space-based activities were analyzed: a spin stabilized satellite, a three axis satellite, and assembly at the Space Station and GEO servicing. Functional and technical requirements placed on the Space Station by the scenarios were detailed. Requirements on the satellite were also listed.

Price, K.; Dixon, J.; Weyandt, C.

1987-01-01

222

Construction of a patient observation system using KINECTTM  

NASA Astrophysics Data System (ADS)

Improvement in the positional accuracy of irradiation is expected by capturing patient motion (intra-fractional error) during irradiation. The present study reports the construction of a patient observation system using Microsoft® KINECTTM. By tracking movement, we made it possible to add a depth component to the acquired position coordinates and to display three-axis (X, Y, and Z) movement. Moreover, the developed system can be displayed in a graph which is constructed from the coordinate position at each time interval. Using the developed system, an observer can easily visualize patient movement. When the body phantom was moved a known distance in the X, Y, and Z directions, good coincidence was shown with each axis. We built a patient observation system which captures a patient's motion using KINECTTM.

Miyaura, Kazunori; Kumazaki, Yu; Fukushima, Chika; Kato, Shingo; Saitoh, Hidetoshi

2014-03-01

223

A New Approach to Attitude Stability and Control for Low Airspeed Vehicles  

NASA Technical Reports Server (NTRS)

This paper describes an approach for controlling the attitude of statically unstable thrust-levitated vehicles in hover or slow translation. The large thrust vector that characterizes such vehicles can be modulated to provide control forces and moments to the airframe, but such modulation is accompanied by significant unsteady flow effects. These effects are difficult to model, and can compromise the practical value of thrust vectoring in closed-loop attitude stability, even if the thrust vectoring machinery has sufficient bandwidth for stabilization. The stabilization approach described in this paper is based on using internal angular momentum transfer devices for stability, augmented by thrust vectoring for trim and other "outer loop" control functions. The three main components of this approach are: (1) a z-body axis angular momentum bias enhances static attitude stability, reducing the amount of control activity needed for stabilization, (2) optionally, gimbaled reaction wheels provide high-bandwidth control torques for additional stabilization, or agility, and (3) the resulting strongly coupled system dynamics are controlled by a multivariable controller. A flight test vehicle is described, and nonlinear simulation results are provided that demonstrate the efficiency of the approach.

Lim, K. B.; Shin, Y-Y.; Moerder, D. D.; Cooper, E. G.

2004-01-01

224

Image change detection using a SWIR active imaging system  

NASA Astrophysics Data System (ADS)

We are currently developing a system consisting of a GPS receiver, a three-axis magnetic compass as well as a digital video camera in order to visualize changes occuring along a regularily used itinerary. This is done by comparing actual images with images from the same scene, which have been acquired during a previous measurement. The luminosity of images from two different passages however can be quite different (due to different meteorological conditions). Whereas the global luminosity can be adjusted using non-linear luminosity correction, the treatment of shadows is more di cult. Since meteorological conditions cannot be controlled, we are investigating the possibility of using a Laser Gated Viewing system in the SWIR domain to illuminate the scene. Using appropriate filters for the camera, we are completely independent of natural illumination and in addition, the system can also be used at night.

Schneider, Armin L.; Monnin, David; Laurenzis, Martin; Christnacher, Frank

2013-10-01

225

A study of variable thrust, variable specific impulse trajectories for solar system exploration  

NASA Astrophysics Data System (ADS)

A study has been performed to determine the advantages and disadvantages of variable thrust and variable Isp (specific impulse) trajectories for solar system exploration. There have been several numerical research efforts for variable thrust, variable Isp, power-limited trajectory optimization problems. All of these results conclude that variable thrust, variable Isp (variable specific impulse, or VSI) engines are superior to constant thrust, constant Isp (constant specific impulse; or CSI) engines. However, most of these research efforts assume a mission from Earth to Mars, and some of them further assume that these planets are circular and coplanar. Hence they still lack the generality. This research has been conducted to answer the following questions: (1) Is a VSI engine always better than a CSI engine or a high thrust engine for any mission to any planet with any time of flight considering lower propellant mass as the sole criterion? (2) If a planetary swing-by is used for a VSI trajectory, is the fuel savings of a VSI swing-by trajectory better than that of a CSI swing-by or high thrust swing-by trajectory? To support this research, an unique, new computer-based interplanetary trajectory calculation program has been created. This program utilizes a calculus of variations algorithm to perform overall optimization of thrust, Isp, and thrust vector direction along a trajectory that minimizes fuel consumption for interplanetary travel. It is assumed that the propulsion system is power-limited, and thus the compromise between thrust and Isp is a variable to be optimized along the flight path. This program is capable of optimizing not only variable thrust trajectories but also constant thrust trajectories in 3-D space using a planetary ephemeris database. It is also capable of conducting planetary swing-bys. Using this program, various Earth-originating trajectories have been investigated and the optimized results have been compared to traditional CSI and high thrust trajectory solutions. Results show that VSI rocket engines reduce fuel requirements for any mission compared to CSI rocket engines. Fuel can be saved by applying swing-by maneuvers for VSI engines; but the effects of swing-bys due to VSI engines are smaller than that of CSI or high thrust engines.

Sakai, Tadashi

226

Cosmic non-TEM radiation and synthetic feed array sensor system in ASIC mixed signal technology  

NASA Astrophysics Data System (ADS)

The paper deals with the opportunity to introduce "Not strictly TEM waves" Synthetic detection Method (NTSM), consisting in a Three Axis Digital Beam Processing (3ADBP), to enhance the performances of radio telescope and sensor systems. Current Radio Telescopes generally use the classic 3D "TEM waves" approximation Detection Method, which consists in a linear tomography process (Single or Dual axis beam forming processing) neglecting the small z component. The Synthetic FEED ARRAY three axis Sensor SYSTEM is an innovative technique using a synthetic detection of the generic "NOT strictly TEM Waves radiation coming from the Cosmo, which processes longitudinal component of Angular Momentum too. Than the simultaneous extraction from radiation of both the linear and quadratic information component, may reduce the complexity to reconstruct the Early Universe in the different requested scales. This next order approximation detection of the observed cosmologic processes, may improve the efficacy of the statistical numerical model used to elaborate the same information acquired. The present work focuses on detection of such waves at carrier frequencies in the bands ranging from LF to MMW. The work shows in further detail the new generation of on line programmable and reconfigurable Mixed Signal ASIC technology that made possible the innovative Synthetic Sensor. Furthermore the paper shows the ability of such technique to increase the Radio Telescope Array Antenna performances.

Centureli, F.; Scotti, G.; Tommasino, P.; Trifiletti, A.; Romano, F.; Cimmino, R.; Saitto, A.

2014-08-01

227

Vector magnetometry and lightwave defect imaging sensor technologies for internal pipe inspection systems. Phase 1 and 2 feasibility study, conceptual design, and prototype development. Final report, March 1991-July 1993  

SciTech Connect

The Gas Research Institute (GRI) has been sponsoring the development of a vehicle and sensors for an integrated nondestructive internal inspection system for natural gas distribution pipes. Arthur D. Little has developed two sensor technologies, Vector Magnetometry (VM) and Lightwave Defect Imaging (LDI) for the system. The Vector Magnetometry sensor utilizes multiple arrays of miniature detection coils (fluxgate magnetometer elements); a three-axis array measures both the amplitude and phase of the magnetic leakage field that occurs in the vicinity of pipe wall defects. This technology is applicable to both cast iron and steel pipe.

Carroll, S.; Fowler, T.; Peters, E.; Power, W.; Reed, M.

1994-01-05

228

Waterhammer modeling for the Ares I Upper Stage Reaction Control System cold flow development test article  

NASA Astrophysics Data System (ADS)

The Upper Stage Reaction Control System provides in-flight three-axis attitude control for the Ares I Upper Stage. The system design must accommodate rapid thruster firing to maintain proper launch trajectory and thus allow for the possibility to pulse multiple thrusters simultaneously. Rapid thruster valve closure creates an increase in static pressure, known as waterhammer, which propagates throughout the propellant system at pressures exceeding nominal design values. A series of development tests conducted at Marshall Space Flight Center in 2009 were performed using a water-flow test article to better understand fluid characteristics of the Upper Stage Reaction Control System. A subset of the tests examined the waterhammer pressure and frequency response in the flight-representative system and provided data to anchor numerical models. This thesis presents a comparison of waterhammer test results with numerical model and analytical results. An overview of the flight system, test article, modeling and analysis are also provided.

Williams, Jonathan Hunter

229

Wellborne inertial navigation system  

SciTech Connect

A phototype wireline tool which includes a downhole inertial platform and a surface computer to spatially map a well is described. The hardware consists of a single-gimbaled inertial platform with accelerometers and gyros to obtain three-axis motion information. The gyroscope and accelerometer outputs are transmitted to a computer at the surface which calculates probe attitude relative to north, east, and vertical. Double integration of the accelerometer data provides the position information. A conventional 7-conductor wireline is used for the system data transmission. System accuracy is enhanced by advances made in the computer software which processes the data received from the tool. The software uses statistical sampling estimation to obtain optimal estimates of the system errors. Measurement errors are determined by periodically stopping the tool during the logging procedure and observing the indicated velocity measurements. This procedure, known as Kalman filtering, results in increased accuracy of the data. Present mapping systems have an X-Y-Z location accuracy of +- 100 to +- 200 feet for a typical well depth of 10,000 feet. Test results show that the new system is accurate to about +- 1 foot per 1000 feet of well depth. Unlike conventional systems, the inertial navigator does not require any sort of projection of the cable length (which may not be accurately known). Also this system provides continuous data throughout the wellbore and logging speeds on the order of 10 ft/sec appear possible. The hardware and software associated with this mapping system are described and the recent field test results are reported.

Kelsey, J.R.

1983-01-01

230

Controlling Attitude of a Solar-Sail Spacecraft Using Vanes  

NASA Technical Reports Server (NTRS)

A paper discusses a concept for controlling the attitude and thrust vector of a three-axis stabilized Solar Sail spacecraft using only four single degree-of-freedom articulated spar-tip vanes. The vanes, at the corners of the sail, would be turned to commanded angles about the diagonals of the square sail. Commands would be generated by an adaptive controller that would track a given trajectory while rejecting effects of such disturbance torques as those attributable to offsets between the center of pressure on the sail and the center of mass. The controller would include a standard proportional + derivative part, a feedforward part, and a dynamic component that would act like a generalized integrator. The controller would globally track reference signals, and in the presence of such control-actuator constraints as saturation and delay, the controller would utilize strategies to cancel or reduce their effects. The control scheme would be embodied in a robust, nonlinear algorithm that would allocate torques among the vanes, always finding a stable solution arbitrarily close to the global optimum solution of the control effort allocation problem. The solution would include an acceptably small angle, slow limit-cycle oscillation of the vanes, while providing overall thrust vector pointing stability and performance.

Mettler, Edward; Acikmese, Ahmet; Ploen, Scott

2006-01-01

231

Spacecraft flight control system design selection process for a geostationary communication satellite  

NASA Astrophysics Data System (ADS)

The Earth's first artificial satellite, Sputnik 1, slowly tumbled in orbit. The first U.S. satellite, Explorer 1, also tumbled out of control. Now, as we launch the Mars observer and the Cassini spacecraft, stability and control have become higher priorities. The flight control system design selection process is reviewed using as an example a geostationary communication satellite which is to have a life expectancy of 10 to 14 years. Disturbance torques including aerodynamic, magnetic, gravity gradient, solar, micrometeorite, debris, collision, and internal torques are assessed to quantify the disturbance environment so that the required compensating torque can be determined. Then control torque options, including passive versus active, momentum control, bias momentum, spin stabilization, dual spin, gravity gradient, magnetic, reaction wheels, control moment gyros, nutation dampers, inertia augmentation techniques, three-axis control, reactions control system (RCS), and RCS sizing, are considered. A flight control system design is then selected and preliminary stability criteria are met by the control gains selection.

Barret, C.

1992-09-01

232

Finite element based electric motor design optimization  

NASA Technical Reports Server (NTRS)

The purpose of this effort was to develop a finite element code for the analysis and design of permanent magnet electric motors. These motors would drive electromechanical actuators in advanced rocket engines. The actuators would control fuel valves and thrust vector control systems. Refurbishing the hydraulic systems of the Space Shuttle after each flight is costly and time consuming. Electromechanical actuators could replace hydraulics, improve system reliability, and reduce down time.

Campbell, C. Warren

1993-01-01

233

A wellbore inertial navigation system  

SciTech Connect

A prototype wireline tool which includes a downhole inertial platform and a surface computer to spatially map a well is described. The hardware consists of a single-gimballed inertial platform with accelerometers and gyros to obtain three-axis motion information. The gyroscope and accelerometer outputs are transmitted to a computer at the surface which calculates probe attitude relative to north, east, and vertical. Double integration of the accelerometer data provides the position information. A conventional 7-conductor wireline is used for the system data transmission. System accuracy is enhanced by advances made in the computer software which processes the data received from the tool. The software uses statistical sampling estimation to obtain optimal estimates of the system errors. Measurement errors are determined by periodically stopping the tool during the logging procedure and observing the indicated velocity measurements. This procedure, known as Kalman filtering, results in increased accuracy of the data. Present mapping systems have an X-Y-Z location accuracy of 100 to 200 feet for a typical well depth of 10,000 feet. Test results show that the new system is accurate to about 1 foot per 1000 feet of well depth. Unlike conventional systems, the inertial navigator does not require any sort of projection of the cable length (which may not be accurately known). Also, this system provides continuous data throughout the wellbore and logging speeds on the order of 10 ft/sec appear possible. The hardware and software associated with this mapping system are described and the recent field test results are reported.

Kelsey, J.R.

1983-02-01

234

The control of satellites with microgravity constraints: The COMET Control System  

NASA Technical Reports Server (NTRS)

The COMET attitude determination and control system, using inverse dynamics and a novel torque distribution/momentum management technique, has shown great flexibility, performance, and robustness. Three-axis control with two wheels is an inherent consequence of inverse dynamics control which allows for reduction in spacecraft weight and cost, or alternatively, provides a simple means of failure-redundancy for three-wheel spacecraft. The control system, without modification, has continued to perform well in spite of large changes in spacecraft mass properties and mission orbit altitude that have occurred during development. This flexibility has obviated imposition of early stringent ADACS design constraints and has greatly reduced commonly incurred ADACS modification costs and delay associated with program maturation.

Grossman, Walter; Freesland, Douglas

1994-01-01

235

Attitude control system conceptual design for the GOES-N spacecraft series  

NASA Technical Reports Server (NTRS)

The attitude determination sensing and processing of the system are considered, and inertial reference units, star trackers, and beacons and landmarks are discussed as well as an extended Kalman filter and expected attitude-determination performance. The baseline controller is overviewed, and a spacecraft motion compensation (SMC) algorithm, disturbance environment, and SMC performance expectations are covered. Detailed simulation results are presented, and emphasis is placed on dynamic models, attitude estimation and control, and SMC disturbance accommmodation. It is shown that the attitude control system employing gyro/star tracker sensing and active three-axis control with reaction wheels is capable of maintaining attitude errors of 1.7 microrad or less on all axes in the absence of attitude disturbances, and that the sensor line-of-sight pointing errors can be reduced to 0.1 microrad by SMC.

Markley, F. L.; Bauer, F. H.; Deily, J. J.; Femiano, M. D.

1991-01-01

236

Linear-Parameter-Varying Antiwindup Compensation for Enhanced Flight Control Performance  

NASA Technical Reports Server (NTRS)

Actuator saturation is one of the major issues of flight control in the high angle-of-attack region. This paper presents a saturation control scheme for linear parameter varyjing (LPV) systems from an antiwindup control perspective. The proposed control approach is advantageous from the implementation standpoint because it can be thought of as an augmented control algorithm to the existing control system. Moreover, the synthesis condition for an antiwindup compensator is formulated as a linear matrix inequality (LMI) optimization problem and can be solved efficiently. We have applied te LPV antiwindup controller to an F-16 longitudinal autopilot control system design and compared it with the thrust vectoring control scheme. The nonlinear simulations show that an LPV antiwindup controller improves flight quality and offers advantages over thrust vectoring in a high angle-of-attack region.

Lu, Bei; Wu, Fen; Kim, Sung Wan

2005-01-01

237

Variable structure-based nonlinear missile guidance\\/autopilot design with highly maneuverable actuators  

Microsoft Academic Search

In this brief, we propose a variable structure based nonlinear missile guidance\\/autopilot system with highly maneuverable actuators, mainly consisting of thrust vector control and divert control system, for the task of intercepting of a theater ballistic missile. The aim of the present work is to achieve bounded target interception under the mentioned 5 degree-of-freedom (DOF) control such that the distance

Fu-Kuang Yeh; Kai-Yuan Cheng; Li-Chen Fu

2004-01-01

238

International Symposium on Air Breathing Engines, 8th, Cincinnati, OH, June 14-19, 1987, Proceedings  

Microsoft Academic Search

The present conference on air-breathing aircraft engine technology considers topics in inlet design, radial-flow turbomachinery, fuel injection and combustion systems, axial flow compressor design and performance, ramjet configurations, turbine flow phenomena, engine control and service life, fluid flow-related problems, engine diagnostic methods, propfan design, combustor performance and pollutant chemistry, combustion dynamics, and engine system analysis. Attention is given to thrust-vectoring

Billig

1987-01-01

239

The F-18 high alpha research vehicle: A high-angle-of-attack testbed aircraft  

NASA Technical Reports Server (NTRS)

The F-18 High Alpha Research Vehicle is the first thrust-vectoring testbed aircraft used to study the aerodynamics and maneuvering available in the poststall flight regime and to provide the data for validating ground prediction techniques. The aircraft includes a flexible research flight control system and full research instrumentation. The capability to control the vehicle at angles of attack up to 70 degrees is also included. This aircraft was modified by adding a pitch and yaw thrust-vectoring system. No significant problems occurred during the envelope expansion phase of the program. This aircraft has demonstrated excellent control in the wing rock region and increased rolling performance at high angles of attack. Initial pilot reports indicate that the increased capability is desirable although some difficulty in judging the size and timing of control inputs was observed. The aircraft, preflight ground testing and envelope expansion flight tests are described.

Regenie, Victoria; Gatlin, Donald; Kempel, Robert; Matheny, Neil

1992-01-01

240

TALON and CRADLE: Systems for the rescue of tumbling spacecraft and astronauts  

NASA Technical Reports Server (NTRS)

Advanced pressure suit and tool designs are beginning to allow extravehicular astronauts to repair space vehicles and so increase mission life and system reliability. A common spacecraft failure that is a severe challenge to the rescue mission planner is loss of attitude control resulting in tumbling motion. If an extravehicular astronaut flying the Manned Maneuvering Unit (MMU) 'falls' into a tumble, the result could be loss of life. TALON (Tumble Arresting Large Oscillation Nullifier) is a device capable of capturing a target in an uncontrolled three-axis tumble. CRADLE (Concentric Rotating Astronaut Detumble Lifesaving Equipment) is a similar device sized to rescue a suited astronaut. The two rescue vehicles work on the same basic principle. They are structural shells with articulated limbs which can surround a tumbling target and thus align both the chaser and target centers of mass (CM).

Idle, Dunning, V

1991-01-01

241

An analysis of cross-coupling of a multicomponent jet engine test stand using finite element modeling techniques  

NASA Technical Reports Server (NTRS)

A two axis thrust measuring system was analyzed by using a finite a element computer program to determine the sensitivities of the thrust vectoring nozzle system to misalignment of the load cells and applied loads, and the stiffness of the structural members. Three models were evaluated: (1) the basic measuring element and its internal calibration load cells; (2) the basic measuring element and its external load calibration equipment; and (3) the basic measuring element, external calibration load frame and the altitude facility support structure. Alignment of calibration loads was the greatest source of error for multiaxis thrust measuring systems. Uniform increases or decreases in stiffness of the members, which might be caused by the selection of the materials, have little effect on the accuracy of the measurements. It is found that the POLO-FINITE program is a viable tool for designing and analyzing multiaxis thrust measurement systems. The response of the test stand to step inputs that might be encountered with thrust vectoring tests was determined. The dynamic analysis show a potential problem for measuring the dynamic response characteristics of thrust vectoring systems because of the inherently light damping of the test stand.

Schweikhard, W. G.; Singnoi, W. N.

1985-01-01

242

Explicit Finite Element Techniques Used to Characterize Splashdown of the Space Shuttle Solid Rocket Booster Aft Skirt  

NASA Technical Reports Server (NTRS)

NASA Glenn Research Center s Structural Mechanics Branch has years of expertise in using explicit finite element methods to predict the outcome of ballistic impact events. Shuttle engineers from the NASA Marshall Space Flight Center and NASA Kennedy Space Flight Center required assistance in assessing the structural loads that a newly proposed thrust vector control system for the space shuttle solid rocket booster (SRB) aft skirt would expect to see during its recovery splashdown.

Melis, Matthew E.

2003-01-01

243

High fidelity ground effect model based on DGPS data  

Microsoft Academic Search

A global model approach developed on the X-31 EFM data was recently improved during the experimental aircraft program X-31 VECTOR. The VECTOR program is briefly presented, focusing on extremely precise ESTOL (Extremely Short Take-Off and Landing) manoeuvre following a slow, thrust-vectored approach at high angle of attack. High accuracy navigation and inertial sensor systems enable onboard calculation of the height

Detlef Rohlf; Holger Friehmelt

2005-01-01

244

Low-speed wind-tunnel test of a STOL supersonic-cruise fighter concept  

NASA Technical Reports Server (NTRS)

A wind-tunnel investigation was conducted to examine the low-speed static stability and control characteristics of a 0.10 scale model of a STOL supersonic cruise fighter concept. The concept, referred to as a twin boom fighter, was designed as a STOL aircraft capable of efficient long range supersonic cruise. The configuration name is derived from the long twin booms extending aft of the engine to the twin vertical tails which support a high center horizontal tail. The propulsion system features a two dimensional thrust vectoring exhaust nozzle which is located so that the nozzle hinge line is near the aircraft center of gravity. This arrangement is intended to allow large thrust vector angles to be used to obtain significant values of powered lift, while minimizing pitching moment trim changes. Low speed stability and control information was obtained over an angle of attack range including the stall. A study of jet induced power effects was included.

Coe, Paul L., Jr.; Riley, Donald R.

1988-01-01

245

systems  

Microsoft Academic Search

Empirical observations often indicate that complexity enhances stability, while most theoretical studies, such as May's (1972) classic paper, point to the opposite. Despite the wide generality of these latter theoretical analyses, our examination of the well-known competitive Lotka-Volterra system reveals that increasing complexity (measured in terms of connectance) can enhance species coexistence and persistence in model communities (measured in terms

Ian D. Rozdilsky; Lewi Stone

246

Low Gravity Guidance System for Airborne Microgravity Research  

NASA Technical Reports Server (NTRS)

Microgravity research techniques have been established to achieve a greater understanding of the role of gravity in the fundamentals of a variety of physical phenomena and material processing. One technique in use at the NASA Lewis Research Center involves flying Keplarian trajectories with a modified Lear Jet and DC-9 aircraft to achieve a highly accurate Microgravity environment by neutralizing accelerations in all three axis of the aircraft. The Low Gravity Guidance System (LGGS) assists the pilot and copilot in flying the trajectories by displaying the aircraft acceleration data in a graphical display format. The Low Gravity Guidance System is a microprocessor based system that acquires and displays the aircraft acceleration information. This information is presented using an electroluminescent display mounted over the pilot's instrument panel. The pilot can select the Microgravity range that is required for a given research event. This paper describes the characteristics, design, calibration and testing of the Low Gravity Guidance System Phase 3, significant lessons from earlier systems and the developmental work on future systems.

Rieke, W. J.; Emery, E. F.; Boyer, E. O.; Hegedus, C.; ODonoghue, D. P.

1996-01-01

247

Static, noise, and transition tests of a combined-surface-blowing V/STOL lift/propulsion system  

NASA Technical Reports Server (NTRS)

Efficient thrust vectoring and high levels of circulatory lift were obtained in tests of a half model V/STOL airplane by using a type of externally blown jet flap in which the jet exhaust from wing-mounted cruise fans is directed over both upper and lower surfaces of a flapped wing. Approximately 90% thrust recovery with 87 deg of thrust vectoring was achieved under static conditions using 89 deg of trailing edge flap deflection. The approximately 10% loss appears to be associated primarily with pressure losses due to the flap brackets or slot entries. The jet induced lift was shown to be 55% of the theoretical value for a fullspan jet-flapped wing, even though only 27.5% of the wingspan was immersed in the jet. Steady rate of descent capability in excess of 1,000 feet per minute is predicted. The possibility of significant aerodynamic-noise cancelling when blowing over both surfaces at high velocities is indicated.

Schoen, A. H.; Kolesar, C. E.; Schaeffer, E. G.

1977-01-01

248

Payload carrier systems for conducting sortie mode science  

NASA Technical Reports Server (NTRS)

The capabilities and characteristics of the payload carriers developed to provide structural and operational interfaces between the Space Shuttle and the various types of experiments designed to operate in the sortie mode are discussed. The Spacelab is a flexible laboratory system composed of interchangeable elements that can be put together in eight different combinations of pallets and pressurized modules, and provides considerable standard services to users in such areas as equipment installation, power distribution, thermal control, command and data management, software, pointing systems and crew participation. A modular three-axis pointing control system designated the Annular Suspension and Pointing System, is being developed to provide additional pointing capabilities to those payloads that require capabilities not provided by the Spacelab instrument pointing system. Two engineering models of the Spacelab pallet have been designated Orbital Flight Test Pallets which, together with a special experiment support structure, are intended for initial and operational payloads that do not constitute a complete Spacelab mission. The simplest and smallest payload carriers are the Getaway Special cans, intended for small, self-contained, self-sufficient payloads, and the orbiter middeck lockers. In this way, most of the user requirements for Shuttle sortie missions identified to date can be fulfilled.

Jean, O. C.; Allen, L. B.

1981-01-01

249

Space Launch System Ascent Flight Control Design  

NASA Technical Reports Server (NTRS)

A robust and flexible autopilot architecture for NASA's Space Launch System (SLS) family of launch vehicles is presented. As the SLS configurations represent a potentially significant increase in complexity and performance capability of the integrated flight vehicle, it was recognized early in the program that a new, generalized autopilot design should be formulated to fulfill the needs of this new space launch architecture. The present design concept is intended to leverage existing NASA and industry launch vehicle design experience and maintain the extensibility and modularity necessary to accommodate multiple vehicle configurations while relying on proven and flight-tested control design principles for large boost vehicles. The SLS flight control architecture combines a digital three-axis autopilot with traditional bending filters to support robust active or passive stabilization of the vehicle's bending and sloshing dynamics using optimally blended measurements from multiple rate gyros on the vehicle structure. The algorithm also relies on a pseudo-optimal control allocation scheme to maximize the performance capability of multiple vectored engines while accommodating throttling and engine failure contingencies in real time with negligible impact to stability characteristics. The architecture supports active in-flight load relief through the use of a nonlinear observer driven by acceleration measurements, and envelope expansion and robustness enhancement is obtained through the use of a multiplicative forward gain modulation law based upon a simple model reference adaptive control scheme.

VanZwieten, Tannen S.; Orr, Jeb S.; Wall, John H.; Hall, Charles E.

2014-01-01

250

Space Launch System Ascent Flight Control Design  

NASA Technical Reports Server (NTRS)

A robust and flexible autopilot architecture for NASA's Space Launch System (SLS) family of launch vehicles is presented. The SLS configurations represent a potentially significant increase in complexity and performance capability when compared with other manned launch vehicles. It was recognized early in the program that a new, generalized autopilot design should be formulated to fulfill the needs of this new space launch architecture. The present design concept is intended to leverage existing NASA and industry launch vehicle design experience and maintain the extensibility and modularity necessary to accommodate multiple vehicle configurations while relying on proven and flight-tested control design principles for large boost vehicles. The SLS flight control architecture combines a digital three-axis autopilot with traditional bending filters to support robust active or passive stabilization of the vehicle's bending and sloshing dynamics using optimally blended measurements from multiple rate gyros on the vehicle structure. The algorithm also relies on a pseudo-optimal control allocation scheme to maximize the performance capability of multiple vectored engines while accommodating throttling and engine failure contingencies in real time with negligible impact to stability characteristics. The architecture supports active in-flight disturbance compensation through the use of nonlinear observers driven by acceleration measurements. Envelope expansion and robustness enhancement is obtained through the use of a multiplicative forward gain modulation law based upon a simple model reference adaptive control scheme.

Orr, Jeb S.; Wall, John H.; VanZwieten, Tannen S.; Hall, Charles E.

2014-01-01

251

TRMM On Orbit Attitude Control System Performance  

NASA Technical Reports Server (NTRS)

This paper presents an overview of the Tropical Rainfall Measuring Mission (TRMM) Attitude Control System (ACS) along with detailed in-flight performance results for each operational mode. The TRMM spacecraft is an Earth-pointed, zero momentum bias satellite launched on November 27, 1997 from Tanegashima Space Center, Japan. TRMM is a joint mission between NASA and the National Space Development Agency (NASDA) of Japan designed to monitor and study tropical rainfall and the associated release of energy. Launched to provide a validation for poorly known rainfall data sets generated by global climate models, TRMM has demonstrated its utility by reducing uncertainties in global rainfall measurements by a factor of two. The ACS is comprised of Attitude Control Electronics (ACE), an Earth Sensor Assembly (ESA), Digital Sun Sensors (DSS), Inertial Reference Units (IRU), Three Axis Magnetometers (TAM), Coarse Sun Sensors (CSS), Magnetic Torquer Bars (MTB), Reaction Wheel Assemblies (RWA), Engine Valve Drivers (EVD) and thrusters. While in Mission Mode, the ESA provides roll and pitch axis attitude error measurements and the DSS provide yaw updates twice per orbit. In addition, the TAM in combination with the IRU and DSS can be used to provide pointing in a contingency attitude determination mode which does not rely on the ESA. Although the ACS performance to date has been highly successful, lessons were learned during checkout and initial on-orbit operation. This paper describes the design, on-orbit checkout, performance and lessons learned for the TRMM ACS.

Robertson, Brent; Placanica, Sam; Morgenstern, Wendy

1999-01-01

252

System  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations were carried out to investigate the anionic structures of the molten CaO-SiO2-P2O5 system. The results show that the average first nearest-neighbor distances for Si-O and P-O pairs are 1.61 and 1.53 Å, respectively. As expected, above 98 pct P and 95 pct Si show fourfold coordination and form tetrahedral structures. Due to the high basicity, nonbridging oxygen occupies a predominant position in Si and P tetrahedron. Based on the oxygen number of different types, the structures of both Si and P tetrahedron were classified as Q 0, Q 1, Q 2, Q 3, and Q 4, where the superscript referred to the number of bridging oxygen atoms. With the substitution of P2O5 for SiO2, Q 0 decreased and other type of Q i units increased. For Si tetrahedron, Q 2 and Q 3 show most notable change, for P tetrahedron, Q 1and Q 2 show the most notable change. The change of Q i units for Si tetrahedron is larger than that for P tetrahedron. The concentration of free oxygen decreases remarkably with the increase of P2O5 content. The Si-O-P linkage is energetically more favorable than Si-O-Si and P-O-P linkages. P ion has a tendency to promote the polymerization of phosphosilicate melts.

Diao, Jiang; Fan, Guozheng; Liu, Xuan; Xie, Bing

2014-10-01

253

Testing a satellite automatic nutation control system. [on synchronous meteorological satellite  

NASA Technical Reports Server (NTRS)

Testing of a particular nutation control system for the synchronous meteorological satellite (SMS) is described. The test method and principles are applicable to nutation angle control for other satellites with similar requirements. During its ascent to synchronous orbit, a spacecraft like the SMS spins about its minimum-moment-of-inertia axis. An uncontrolled spacecraft in this state is unstable because torques due to fuel motion increase the nutation angle. However, the SMS is equipped with an automatic nutation control (ANC) system which will keep the nutation angle close to zero. Because correct operation of this system is critical to mission success, it was tested on an air-bearing table. The ANC system was mounted on the three-axis air-bearing table which was scaled to the SMS and equipped with appropriate sensors and thrusters. The table was spun up in an altitude chamber and nutation induced so that table motion simulated spacecraft motion. The ANC system was used to reduce the nutation angle. This dynamic test of the ANC system met all its objectives and provided confidence that the ANC system will control the SMS nutation angle.

Hrasiar, J. A.

1974-01-01

254

An integrated GPS attitude determination system for small satellites  

NASA Astrophysics Data System (ADS)

This dissertation develops attitude determination methods based on the Global Positioning System (GPS) for small satellites. A GPS attitude receiver is used in combination with other sensors planned for a small, three-axis stabilized satellite called JAWS AT. The other attitude sensors include fiber optic gyros and digital sun sensors. The development of integrated attitude determination systems contributes to critical national technological objectives identified for small spacecraft. A recent study by the National Research Council addresses key technologies for small satellite programs. One of their principal recommendations was that, 'GPS in various combinations with other guidance components can determine position and attitude very accurately, probably at significantly reduced weight and cost.' The report also identifies specific potential benefits of integrating OPS with other sensors on small spacecraft. 'Combining GPS and an inertial measurement unit (with gyroscopes, accelerometers, or trackers) offers major advantages by bounding errors of the inertial set, providing exceptionally good long-term references and thereby ensuring precise, on-board navigation and, with appropriate complimentary techniques, providing a higher level of redundancy and/or accuracy for position, velocity, and attitude.' This dissertation develops algorithms that result in improved accuracy and redundancy through the development of complimentary techniques for combining GPS measurements with gyroscopes and sun sensors.

Chesley, Bruce Carl

1995-07-01

255

Design, analysis, and testing of a precision guidance, navigation, and control system for a dual-spinning Cubesat  

E-print Network

The Microsized Microwave Atmospheric Satellite (MicroMAS) combines two traditional control approaches: a dual spinner and a three-axis gyrostat. Unlike typical dual spinners, the purpose of MicroMAS 's 2U bus and spinner ...

Wise, Evan Dale

2013-01-01

256

Development of Microelectromechanical Systems (MEMS) forceps for intraocular surgery  

PubMed Central

Aim: To develop silicon microforceps for intraocular surgery using Microelectromechanical Systems (MEMS) technology, the application of microchip fabrication techniques for the production of controllable three dimensional devices on the micrometre scale. Methods: Prototype MEMS forceps were designed and manufactured for intraocular surgery. Scanning electron microscopy was used to evaluate device tip construction. Designs using both thermal expansion actuators and conventional mechanical activation were tested in human cadaver eyes and in vivo rabbit eyes to assess functionality in standard vitreoretinal surgery. Results: MEMS forceps were constructed with various tip designs ranging from 100 ?m to 2 mm in length. Scanning electron microscopy confirmed accurate construction of micro features such as forceps teeth as small as tens of micrometres. In surgical testing, the silicon forceps tips were effective in surgical manoeuvres, including grasping retinal membranes and excising tissue. The mechanical actuator design on a 20 gauge handle was more operational in the intraocular environment than the thermal expansion actuator design. While handheld operation was possible, the precision of the forceps was best exploited when mounted on a three axis micromanipulator. Conclusion: MEMS microforceps are feasible for conventional vitreoretinal surgery, and offer advances in terms of small scale, operating precision, and construction tolerance. PMID:16299136

Bhisitkul, R B; Keller, C G

2005-01-01

257

A vector fetal magnetocardiogram system with high sensitivity  

NASA Astrophysics Data System (ADS)

The vector fetal magnetocardiogram (V-FMCG) system that measures the three orthogonal components of the magnetic field from a fetal heart has been developed to clearly observe fetal cardiac activity during pregnancy by using the superconducting quantum interference device. To detect a clear V-FMCG signal, the bottom of the cryostat was made of thin glass-fiber-reinforced plastic and the total length between the pickup coil to the outer surface is 12 mm. Because the cryostat bottom was made thinner, the area of the cryostat's top and bottom could be made smaller, thus a low evaporation loss (<1.2 l per day) and a long refilling interval (>10 days) were obtained. The gantry was able to tilt the cryostat and the bed could move in three axis directions, which made it possible to easily locate the vector pickup coil at an optimum position to obtain the maximum magnetic field from a fetal heart. We obtained V-FMCGs from 21 normal fetuses with gestation periods of 27-38 weeks. Using these vector signals, the dipoles were estimated and the relationship between the strength of the dipole moments and the number of gestation weeks could be obtained. Thus, V-FMCG seems to represent a new noninvasive tool for clearly detecting the electrophysiological activity of a fetal heart.

Kandori, Akihiko; Miyashita, Tsuyoshi; Tsukada, Keiji; Horigome, Hitoshi; Asaka, Mitsuhiro; Shigemitsu, Sadahiko; Takahashi, Miho; Terada, Yasushi; Mitsui, Toshio; Chiba, Yoshihide

1999-12-01

258

Real-time in-flight engine performance and health monitoring techniques for flight research application  

NASA Technical Reports Server (NTRS)

Procedures for real time evaluation of the inflight health and performance of gas turbine engines and related systems were developed to enhance flight test safety and productivity. These techniques include the monitoring of the engine, the engine control system, thrust vectoring control system health, and the detection of engine stalls. Real time performance techniques were developed for the determination and display of inflight thrust and for aeroperformance drag polars. These new methods were successfully shown on various research aircraft at NASA-Dryden. The capability of NASA's Western Aeronautical Test Range and the advanced data acquisition systems were key factors for implementation and real time display of these methods.

Ray, Ronald J.; Hicks, John W.; Wichman, Keith D.

1991-01-01

259

Multi-star processing and gyro filtering for the video inertial pointing system  

NASA Technical Reports Server (NTRS)

The video inertial pointing (VIP) system is being developed to satisfy the acquisition and pointing requirements of astronomical telescopes. The VIP system uses a single video sensor to provide star position information that can be used to generate three-axis pointing error signals (multi-star processing) and for input to a cathode ray tube (CRT) display of the star field. The pointing error signals are used to update the telescope's gyro stabilization system (gyro filtering). The CRT display facilitates target acquisition and positioning of the telescope by a remote operator. Linearized small angle equations are used for the multistar processing and a consideration of error performance and singularities lead to star pair location restrictions and equation selection criteria. A discrete steady-state Kalman filter which uses the integration of the gyros is developed and analyzed. The filter includes unit time delays representing asynchronous operations of the VIP microprocessor and video sensor. A digital simulation of a typical gyro stabilized gimbal is developed and used to validate the approach to the gyro filtering.

Murphy, J. P.

1976-01-01

260

A Smartphone-Based Driver Safety Monitoring System Using Data Fusion  

PubMed Central

This paper proposes a method for monitoring driver safety levels using a data fusion approach based on several discrete data types: eye features, bio-signal variation, in-vehicle temperature, and vehicle speed. The driver safety monitoring system was developed in practice in the form of an application for an Android-based smartphone device, where measuring safety-related data requires no extra monetary expenditure or equipment. Moreover, the system provides high resolution and flexibility. The safety monitoring process involves the fusion of attributes gathered from different sensors, including video, electrocardiography, photoplethysmography, temperature, and a three-axis accelerometer, that are assigned as input variables to an inference analysis framework. A Fuzzy Bayesian framework is designed to indicate the driver’s capability level and is updated continuously in real-time. The sensory data are transmitted via Bluetooth communication to the smartphone device. A fake incoming call warning service alerts the driver if his or her safety level is suspiciously compromised. Realistic testing of the system demonstrates the practical benefits of multiple features and their fusion in providing a more authentic and effective driver safety monitoring. PMID:23247416

Lee, Boon-Giin; Chung, Wan-Young

2012-01-01

261

Damping Control by One Axis Magnetic Torquer and Gravity Gradient Attitude Stabilization System for Small Satellite  

NASA Astrophysics Data System (ADS)

A Whale Ecology Observation Satellite (WEOS) was successfully launched on 14th December 2002. We adopted gravity gradient attitude control technique for the attitude stabilization of the WEOS as the first trial in Japan for pointing the communications antennas toward the earth, and the GPS antenna toward the zenith. The attitude control system of the WEOS consists of a three axis magnetometer, a magnetic torquer coil, and a deployable mast with a mass fixed at the tip, and attitude control software. This system carries out rate damping control of the principal axis of maximum moment of inertia and earth pointing attitude control. Immediately after the separation from the H2A-4 rocket, WEOS tumbled due to the imbalance force of three separation springs. The tumbling was reduced by the closed loop damping control and then the mast was extended. After one week, we confirmed the establishment of the gravity gradient attitude stabilization. This paper describes the attitude control system, operation procedure, and control results.

Hosokawa, Shigeru; Masumoto, Yoshinari; Takezawa, Susumu; Haneji, Kazuhiko

262

Space applications of microelectromechanical systems: Southwest Research Institute® vacuum microprobe facility and initial vacuum test results  

NASA Astrophysics Data System (ADS)

We have designed and built the first fully functional vacuum microprobe test facility specifically intended to optimize the development of microelectromechanical systems (MEMS) devices for space applications. This facility includes an ion-pumped, ultraclean vacuum system outfitted with four three-axis precision microprobe stages. The testing is monitored with a long focal length microscope through a thin sapphire window. Testing of several initial MEMS designs shows extremely promising results for using such devices in space applications. In particular, we show that significantly reduced voltages are adequate to resonantly drive some MEMS devices in vacuum owing to significantly reduced damping and the consequent much higher Q of the systems (˜1000×) in the absence of air. We also show the results of a many cycle (>1010) test of a comb-driven, force-distance multiplied sliding aperture door and demonstrate that potential show-stopper issues such as stiction and vacuum welding can be overcome in MEMS devices properly designed for the vacuum environment.

McComas, D. J.; Miller, G. P.; Mitchell, J. N.; Pope, S. E.; Valek, P. W.

2003-08-01

263

Effects of sensor orientation on AC electromagnetic tracking system accuracy in a CT scanner environment  

NASA Astrophysics Data System (ADS)

The purpose of this study was to examine the effects of different sensor orientation on the positional accuracy of an AC electromagnetic tracking system, the second generation NDI Aurora, within a CT scanner environment. A three-axis positioning robot was used to move three electromagnetically tracked needles above the CT table throughout a 30cm by 30cm by 30cm volume sampled in 2.5cm steps. All three needle tips were held within 2mm of each other, with the needle axes orthogonally located in the +x, +y, and +z directions of the Aurora coordinate system. The corresponding position data was captured from the Aurora for each needle and was registered to the positioning system data using a rigid body transformation minimizing the least squares L2-norm. For all three needle orientations the largest errors were observed farthest from the field generator and closest to the CT table. However, the 3D distortion error patterns were different for each needle, demonstrating that the sensor orientation has an effect on the positional measurement of the sensor. This suggests that the effectiveness of using arrays of reference sensors to model and correct for metal distortions may depend strongly on the orientation of the reference sensors in relation to the orientation of the tracked device. In an ideal situation, the reference sensors should be oriented in the same direction as the tracked needle.

Shen, Eric; Shechter, Guy; Kruecker, Jochen; Stanton, Douglas

2008-03-01

264

Helicopters and VTOL. I  

NASA Technical Reports Server (NTRS)

Performance projections into the next half-century of VTOL aircraft design are presently made on the basis of recent design trends. Attention is given to the technology-development and commercial prospects for tilt-rotor, thrust-vectoring hover, lighter-than-air, and speculative electromagnetic-propulsion, remotely-beamed power systems. Highly automated air traffic control systems are envisioned which will incorporate AI, satellite positioning, synthetic vision, obstacle detection/avoidance and fiber-optic transmission to safely manage giant airborne mass-transit commuter systems. It is expected that tilt-rotor aircraft will become the dominant VTOL configuration as time passes.

Burks, John S.

1989-01-01

265

Electrical actuation technology bridging, volume 1  

NASA Astrophysics Data System (ADS)

This document contains the proceedings from the conference. 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.

Hammond, Monica S.; Doane, George B., III

1993-01-01

266

Dynamical Modeling and Control Simulation of a Large Flexible Launch Vehicle  

NASA Technical Reports Server (NTRS)

This paper presents dynamical models of a large flexible launch vehicle. A complete set of coupled dynamical models of propulsion, aerodynamics, guidance and control, structural dynamics, fuel sloshing, and thrust vector control dynamics are described. Such dynamical models are used to validate NASA s SAVANT Simulink-based program which is being used for the preliminary flight control systems analysis and design of NASA s Ares-1 Crew Launch Vehicle. SAVANT simulation results for validating the performance and stability of an ascent phase autopilot system of Ares-1 are also presented.

Du, Wei; Wie, Bong; Whorton, Mark

2008-01-01

267

Earth Observing System (EOS) Aqua Launch and Early Mission Attitude Support Experiences  

NASA Technical Reports Server (NTRS)

The Earth Observing System (EOS) Aqua satellite was successfully launched on May 4,2002. Aqua is the second in the series of EOS satellites. EOS is part of NASA s Earth Science Enterprise Program, whose goals are to advance the scientific understanding of the Earth system. Aqua is a three-axis stabilized, Earth-pointing spacecraft in a nearly circular, sun-synchronous orbit at an altitude of 705 km. The Goddard Space Flight Center (GSFC) Flight Dynamics attitude team supported all phases of the launch and early mission. This paper presents the main results and lessons learned during this period, including: real-time attitude mode transition support, sensor calibration, onboard computer attitude validation, response to spacecraft emergencies, postlaunch attitude analyses, and anomaly resolution. In particular, Flight Dynamics support proved to be invaluable for successful Earth acquisition, fine-point mode transition, and recognition and correction of several anomalies, including support for the resolution of problems observed with the MODIS instrument.

Tracewell, D.; Glickman, J.; Hashmall, J.; Natanson, G.; Sedlak, J.

2003-01-01

268

Development of measuring system to measure standing pose of the foot using distributed triaxial force sensor.  

PubMed

The bottom of a person's foot grips the floor for balance, and the action force and action moment work at the foot bottom when he maintains posture and when he moves. They are important indices in the evaluation and the medical attention of standing pose balance and gait disturbances. A lot of equipments to measure the floor reaction force have been researched. However, no floor reaction force meter exists that can measure distribution information force in three directions. This paper aims at the development of a system that can measure the standing pose of the foot that exists from a measuring instrument and that can measure the standing pose of foot distributed 6times4 three axis force sensors and software that displays and preserves the output of the sensor element. A time change of force that worked at the foot bottom is sought as a vector by outputting each sensor element. Moreover, an action vector is three dimensionally displayed whose data can be intuitively understood. The results of experiments show that the measuring system can measure the action force of the foot bottom as distribution information on force in three directions. PMID:17945646

Nishi, Akimi; Tanaka, Noriko; Tsujiuchi, Nobutaka; Koizumi, Takayuki; Oshima, Hiroko; Minato, Kotaro; Yoshida, Masaki; Tsuchiya, Yotaro

2006-01-01

269

Flow visualization of transient phenomena in wind tunnels  

NASA Astrophysics Data System (ADS)

Axial and vectored flow from a 2D thrust-vector control nozzle are examined with schlieren photography in two wind tunnels to evaluate the usefulness of the technique in monitoring flow behavior. Observations of both the steady state and transient behaviors of the flow types are attempted with a video recorder in conjunction with the schlieren technique. Input variations in the 2D jet nozzle are recorded with the video/schlieren system, and the technique is found to be effective for monitoring transient flow conditions.

Caton, J. L.; Franke, M. E.

270

Erosion effects on TVC vane heat transfer characteristics  

NASA Astrophysics Data System (ADS)

This work describes the effects of erosion on the heat transfer characteristics on thrust vector control vanes exposed to aluminized propellant exhaust flows. This was accomplished using an inverse heat transfer parameter identification of quarter scale models. The model is based on a four node lumped parameter system with two heat energy inputs. The erosion is modeled as decreasing the geometric dimensions linearly as function of time and percentage of aluminum in the propellant. Excellent agreement was found between experimental and model temperature profiles. The heat transfer coefficients of the vanes were found to decrease with increasing erosion rates.

Gardner, Steven R.

1994-03-01

271

U.S. Space Shuttle Solid Rocket Booster - Return to flight  

NASA Technical Reports Server (NTRS)

The Space Shuttle Solid Rocket Booster (SRB) redesign program instituted in the wake of the Challenger accident encompassed a design requirements review, a failure modes effect analysis/critical items list determination, a hazards analysis, an operational maintenance and requirements specification study, the definition of operational maintenance instructions and launch commit criteria, and design certification and flight readiness reviews. Attention is presently given to the SRB's thrust vector control, separation, and recovery functions, as well as its electrical and instrumentation systems and its case assembly and hardware interfaces.

Coates, K. D.; Smith, J. D.; Aldridge, L. L.; Heidemann, W. B.; Langhenry, M. T.

1987-01-01

272

Parameter Identification Flight Test Maneuvers for Closed Loop Modeling of the F-18 High Alpha Research Vehicle (HARV)  

NASA Technical Reports Server (NTRS)

Flight test maneuvers are specified for the F-18 High Alpha Research Vehicle (HARV). The maneuvers were designed for closed loop parameter identification purposes, specifically for longitudinal and lateral linear model parameter estimation at 5,20,30,45, and 60 degrees angle of attack, using the Actuated Nose Strakes for Enhanced Rolling (ANSER) control law in Thrust Vectoring (TV) mode. Each maneuver is to be realized by applying square wave inputs to specific pilot station controls using the On-Board Excitation System (OBES). Maneuver descriptions and complete specifications of the time / amplitude points defining each input are included, along with plots of the input time histories.

Batterson, James G. (Technical Monitor); Morelli, E. A.

1996-01-01

273

Spacecraft attitude control system performance using pulse-width pulse-frequency modulated thrusters  

NASA Astrophysics Data System (ADS)

Many current satellites employ on-off thrusters to accomplish attitude control tasks which may include initial acquisition, rotational maneuvers, and on-orbit stabilization. This work shows that the use of pulse-width pulse-frequency (PWPF)-modulated thrusters provides several important advantages over conventional bang- bang thruster control methods, including less thruster activity and closer-to-linear actuation. The PWPF modulator is implemented in simulations using the Matrix/System build software package. Simulations assuming a rigid spacecraft are first performed to compare the performance of the PWPF-modulated thrust controller with that of conventional bang-bang and time-optimal bang-bang controllers. The discussion is then extended to the case of a spacecraft with structural flexibility, as is encountered quite often in three-axis stabilized vehicles with large fold-out solar arrays. Simulations for comparison of the controllers are performed using the flexible spacecraft dynamics model. The control loop design in the presence of flexibility and possible interaction with the PWPF modulator nonlinearity are addressed. Using a describing function model of the modulator, stability margin with respect to the structural mode limit cycle is predicted. Simulations are then conducted to verify the predicted stability margin.

McClelland, Robert S.

1994-03-01

274

A simple 5-DoF MR-compatible motion signal measurement system.  

PubMed

The purpose of this study was to develop a simple motion measurement system with magnetic resonance (MR) compatibility and safety. The motion measurement system proposed here can measure 5-DoF motion signals without deteriorating the MR images, and it has no effect on the intense and homogeneous main magnetic field, the temporal-gradient magnetic field (which varies rapidly with time), the transceiver radio frequency (RF) coil, and the RF pulse during MR data acquisition. A three-axis accelerometer and a two-axis gyroscope were used to measure 5-DoF motion signals, and Velcro was used to attach a sensor module to a finger or wrist. To minimize the interference between the MR imaging system and the motion measurement system, nonmagnetic materials were used for all electric circuit components in an MR shield room. To remove the effect of RF pulse, an amplifier, modulation circuit, and power supply were located in a shielded case, which was made of copper and aluminum. The motion signal was modulated to an optic signal using pulse width modulation, and the modulated optic signal was transmitted outside the MR shield room using a high-intensity light-emitting diode and an optic cable. The motion signal was recorded on a PC by demodulating the transmitted optic signal into an electric signal. Various kinematic variables, such as angle, acceleration, velocity, and jerk, can be measured or calculated by using the motion measurement system developed here. This system also enables motion tracking by extracting the position information from the motion signals. It was verified that MR images and motion signals could reliably be measured simultaneously. PMID:21487903

Chung, Soon-Cheol; Kim, Hyung-Sik; Yang, Jae-Woong; Lee, Su-Jeong; Choi, Mi-Hyun; Kim, Ji-Hye; Yeon, Hong-Won; Park, Jang-Yeon; Yi, Jeong-Han; Tack, Gye-Rae

2011-09-01

275

Full moment tensor inversion of mining induced seismic events recorded at the Legnica-Glogow Underground Mining Induced Earthquale Observing System (LUMINEOS), Poland  

NASA Astrophysics Data System (ADS)

Since January 2013 a new surface seismic network LUMINEOS (Legnica-Glogow Underground Mining INduced Earthquake Observing System) is in operation to monitor induced seismicity around the mining district of Legnica Glogow Copper District (LGCP), Poland. The network belongs to the Institute of Geophysics of the Polish Academy of Sciences. The network is located above the deep copper mine "Rudna". It consists of nine three-axis short period seismometers and continuously records seismic events connected with intensive copper ore excavation at close by mines. In parallel, the mining company operates an in-mine underground seismic network, consisting of 32 short period vertical sensors. During 2013 several strong induced seismic events with M > 2.5 were recorded on both networks. The collected data set provides an opportunity to analyze their focal mechanisms. In this work we present the first results of full moment tensor inversion for mining induced seismic events, using both recording systems. LUMINEOS results were obtained with waveforms inversion using the Kiwi tool package (http://kinherd.org), while for the in-mine network, we used a first amplitude P-wave inversions. Our results suggest that both systems can be used complementary in cases of strong mining events, providing a well constrained focal mechanism and information on the rupture processes in the mine.

Rudzinski, Lukasz; Cesca, Simone; Lizurek, Grzegorz

2014-05-01

276

Cape Canaveral Air Force Station, Launch Complex 39, Solid Rocket ...  

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

Cape Canaveral Air Force Station, Launch Complex 39, Solid Rocket Booster Disassembly & Refurbishment Complex, Thrust Vector Control Deservicing Facility, Hangar Road, Cape Canaveral, Brevard County, FL

277

Accuracy Studies of a Magnetometer-Only Attitude-and-Rate-Determination System  

NASA Technical Reports Server (NTRS)

A personal computer based system was recently prototyped that uses measurements from a three axis magnetometer (TAM) to estimate the attitude and rates of a spacecraft using no a priori knowledge of the spacecraft's state. Past studies using in-flight data from the Solar, Anomalous, and Magnetospheric Particles Explorer focused on the robustness of the system and demonstrated that attitude and rate estimates could be obtained accurately to 1.5 degrees (deg) and 0.01 deg per second (deg/sec), respectively, despite limitations in the data and in the accuracies of te truth models. This paper studies the accuracy of the Kalman filter in the system using several orbits of in-flight Earth Radiation Budget Satellite (ERBS) data and attitude and rate truth models obtained from high precision sensors to demonstrate the practical capabilities. This paper shows the following: Using telemetered TAM data, attitude accuracies of 0.2 to 0.4 deg and rate accuracies of 0.002 to 0.005 deg/sec (within ERBS attitude control requirements of 1 deg and 0.0005 deg/sec) can be obtained with minimal tuning of the filter; Replacing the TAM data in the telemetry with simulated TAM data yields corresponding accuracies of 0.1 to 0.2 deg and 0.002 to 0.005 deg/sec, thus demonstrating that the filter's accuracy can be significantly enhanced by further calibrating the TAM. Factors affecting the fillter's accuracy and techniques for tuning the system's Kalman filter are also presented.

Challa, M. (Editor); Wheeler, C. (Editor)

1996-01-01

278

Quantification of AC electromagnetic tracking system accuracy in a CT scanner environment  

NASA Astrophysics Data System (ADS)

The purpose of this study was to quantify the effects of a computed tomography (CT) scanner environment on the positional accuracy of an AC electromagnetic tracking system, the second generation NDI Aurora. A three-axis positioning robot was used to move an electromagnetically tracked needle above the CT table throughout a 30cm by 30cm axial plane sampled in 2.5cm steps. The corresponding position data was captured from the Aurora and was registered to the positioning system data using a rigid body transformation minimizing the least squares L2-norm. Data was sampled at varying distances from the CT gantry (three feet, two feet, and one foot) and with the CT table in a nominal position and lowered by 10cm. A coordinate system was defined with the x axis normal to the CT table and the origin at the center of the CT table, and the z axis spanning the table in the lateral direction with the origin at the center of the CT table. In this coordinate system, the positional relationships of each sampled point, the CT table, and the Aurora field generator are clearly defined. This allows error maps to be displayed in accurate spatial relationship to the CT scanner as well as to a representative patient anatomy. By quantifying the distortions in relation to the position of CT scanner components and the Aurora field generator, the optimal working field of view and recommended guidelines for operation can be determined such that targeting inside human anatomy can be done with reasonable expectations of desired performance.

Shen, Eric; Shechter, Guy; Kruecker, Jochen; Stanton, Douglas

2007-03-01

279

Maintaining Aura's Orbit Requirements While Performing Orbit Maintenance Maneuvers Containing an Orbit Normal Delta-V Component  

NASA Technical Reports Server (NTRS)

The Earth Observing System (EOS) Afternoon Constellation consists of five member missions (GCOM-W1, Aqua, CALIPSO, CloudSat, and Aura), each of which maintain a frozen, sun-synchronous orbit with a 16-day repeating ground track that follows the Worldwide Reference System-2 (WRS-2). Under nominal science operations for Aura, the propulsion system is oriented such that the resultant thrust vector is aligned 13.493 degrees away from the velocity vector along the yaw axis. When performing orbit maintenance maneuvers, the spacecraft performs a yaw slew to align the thrust vector in the appropriate direction. A new Drag Make Up (DMU) maneuver operations scheme has been implemented for Aura alleviating the need for the 13.493 degree yaw slew. The focus of this investigation is to assess the impact that no-slew DMU maneuver operations will have on Aura's Mean Local Time (MLT) which drives the required along track separation between Aura and the constellation members, as well as Aura's frozen orbit properties, eccentricity and argument of perigee. Seven maneuver strategies were analyzed to determine the best operational approach. A mirror pole strategy, with maneuvers alternating at the North and South poles, was implemented operationally to minimize impact to the MLT. Additional analysis determined that the mirror pole strategy could be further modified to include frozen orbit maneuvers and thus maintain both MLT and the frozen orbit properties under noslew operations.

Johnson, Megan R.; Petersen, Jeremy D.

2014-01-01

280

Maintaining Aura's Orbit Requirements Under New Maneuver Operations  

NASA Technical Reports Server (NTRS)

The Earth Observing System (EOS) Afternoon Constellation consists of five member missions (GCOM-W1, Aqua, CALIPSO, CloudSat, and Aura), each of which maintain a frozen, sun-synchronous orbit with a 16-day repeating ground track that follows the Worldwide Reference System-2 (WRS-2). Under nominal science operations for Aura, the propulsion system is oriented such that the resultant thrust vector is aligned 13.493 degrees away from the velocity vector along the yaw axis. When performing orbit maintenance maneuvers, the spacecraft performs a yaw slew to align the thrust vector in the appropriate direction. A new Drag Make Up (DMU) maneuver operations scheme has been implemented for Aura alleviating the need for the 13.493 degree yaw slew. The focus of this investigation is to assess the impact that no-slew DMU maneuver operations will have on Auras Mean Local Time (MLT) which drives the required along track separation between Aura and the constellation members, as well as Auras frozen orbit properties, eccentricity and argument of perigee. Seven maneuver strategies were analyzed to determine the best operational approach. A mirror pole strategy, with maneuvers alternating at the North and South poles, was implemented operationally to minimize impact to the MLT. Additional analysis determined that the mirror pole strategy could be further modified to include frozen orbit maneuvers and thus maintain both MLT and the frozen orbit properties under no-slew operations

Johnson, Megan; Petersen, Jeremy D.

2014-01-01

281

Cloud Absorption Radiometer Autonomous Navigation System - CANS  

NASA Technical Reports Server (NTRS)

CAR (cloud absorption radiometer) acquires spatial reference data from host aircraft navigation systems. This poses various problems during CAR data reduction, including navigation data format, accuracy of position data, accuracy of airframe inertial data, and navigation data rate. Incorporating its own navigation system, which included GPS (Global Positioning System), roll axis inertia and rates, and three axis acceleration, CANS expedites data reduction and increases the accuracy of the CAR end data product. CANS provides a self-contained navigation system for the CAR, using inertial reference and GPS positional information. The intent of the software application was to correct the sensor with respect to aircraft roll in real time based upon inputs from a precision navigation sensor. In addition, the navigation information (including GPS position), attitude data, and sensor position details are all streamed to a remote system for recording and later analysis. CANS comprises a commercially available inertial navigation system with integral GPS capability (Attitude Heading Reference System AHRS) integrated into the CAR support structure and data system. The unit is attached to the bottom of the tripod support structure. The related GPS antenna is located on the P-3 radome immediately above the CAR. The AHRS unit provides a RS-232 data stream containing global position and inertial attitude and velocity data to the CAR, which is recorded concurrently with the CAR data. This independence from aircraft navigation input provides for position and inertial state data that accounts for very small changes in aircraft attitude and position, sensed at the CAR location as opposed to aircraft state sensors typically installed close to the aircraft center of gravity. More accurate positional data enables quicker CAR data reduction with better resolution. The CANS software operates in two modes: initialization/calibration and operational. In the initialization/calibration mode, the software aligns the precision navigation sensors and initializes the communications interfaces with the sensor and the remote computing system. It also monitors the navigation data state for quality and ensures that the system maintains the required fidelity for attitude and positional information. In the operational mode, the software runs at 12.5 Hz and gathers the required navigation/attitude data, computes the required sensor correction values, and then commands the sensor to the required roll correction. In this manner, the sensor will stay very near to vertical at all times, greatly improving the resulting collected data and imagery. CANS greatly improves quality of resulting imagery and data collected. In addition, the software component of the system outputs a concisely formatted, high-speed data stream that can be used for further science data processing. This precision, time-stamped data also can benefit other instruments on the same aircraft platform by providing extra information from the mission flight.

Kahle, Duncan; Gatebe, Charles; McCune, Bill; Hellwig, Dustan

2013-01-01

282

Magnetic and electric field testing of the Amtrak Northeast Corridor and New Jersey Transit/North Jersey coast line rail systems. Volume 1. Analysis. Final report, May 1992-March 1992  

SciTech Connect

The safety of magnetically levitated (maglev) and high speed rail (HSR) trains proposed for application in the United States is the responsibility of the Federal Railroad Administration (FRA). The characterization of electric and magnetic fields (EMF) produced by both steady (dc) and alternating currents (ac) at power frequency (50 Hz in Europe and 60 Hz in the U.S.) and above, in the Extreme Low Frequency (ELF) range (3-3000 Hz), is of interest with respect to any potential health effects these fields may have on the public and on transportation workers. An EMF survey of National Rail Passengers Corporation trains operating on the Northeast Corridor (NEC) was performed, as part of a comprehensive comparative safety assessment of the German Transrapid (TR-07) maglev system, and of existing (NEC and transit trains) and advanced rail systems (the French TGV). The report is Volume 1 of two volumes. A portable magnetic field monitoring system (augmented to include an electric fields probe) was used to sample, record and store three-axis static and ac magnetic fields waveforms simultaneously, at multiple locations. A real time Digital Audio Tape (DAT) recorder able to capture EMF transients, and two personal power-frequency magnetic field monitors were used to collect complementary data.

Dietrich, F.M.; Feero, W.E.; Papas, P.N.; Steiner, G.A.

1993-04-01

283

Magnetic and electric field testing of the Amtrak Northeast Corridor and New Jersey transit/North Jersey coast line rail systems. Volume 2. Appendices. Final report, May 1993-March 1993  

SciTech Connect

The safety of magnetically levitated (maglev) and high speed rail (HSR) trains proposed for application in the United States is the responsibility of the Federal Railroad Administration (FRA). The characterization of electric and magnetic fields (EMF) produced by both steady (dc) and alternating currents (ac) at power frequency (50 Hz in Europe and 60 Hz in the U.S.) and above, in the Extreme Low Frequency (ELF) range (3-3000 Hz), is of interest with respect to any potential health effects these fields may have on the public and on transportation workers. An EMF survey of National Rail Passengers Corporation trains operating on the Northeast Corridor (NEC) was performed, as part of a comprehensive comparative safety assessment of the German Transrapid (TR-07) maglev system and of existing (NEC and transit trains) and advanced rail systems (the French TGV). The report is Volume 2 of two volumes. A portable magnetic field monitoring system (augmented to include an electric fields probe) was used to sample, record and store three-axis static and ac magnetic fields waveforms simultaneously, at multiple locations. A real time Digital Audio Tape (DAT) recorder able to capture EMF transients, and two personal power-frequency magnetic field monitors were used to collect complementary data.

Dietrich, F.M.; Robertson, D.C.; Steiner, G.A.

1993-04-01

284

Warm gas TVC design study  

NASA Technical Reports Server (NTRS)

A warm gas thrust vector control system was studied to optimize the injection geometry for a specific engine configuration, and an injection valve was designed capable of meeting the base line requirements. To optimize injection geometry, studies were made to determine the performance effects of varying injection location, angle, port size, and port configuration. Having minimized the injection flow rate required, a warm gas valve was designed to handle the required flow. A direct drive hydraulic servovalve capable of operating with highly contaminated hydraulic fluid was designed. The valve is sized to flow 15 gpm at 3000 psia and the direct drive feature is capable of applying a spool force of 200 pounds. The baseline requirements are the development of 6 deg of thrust vector control utilizing 2000 F (total temperature) gas for 180 seconds on a 1.37 million pound thrust engine burning LOX and RP-1 at a chamber pressure of 250 psia with a 155 inch long conical nozzle having a 68 inch diameter throat and a 153 inch diameter exit.

Moorhead, S. B., Jr.

1973-01-01

285

Development of a two-dimensional dual pendulum thrust stand for Hall thrusters  

NASA Astrophysics Data System (ADS)

A two-dimensional dual pendulum thrust stand was developed to measure thrust vectors [axial and horizontal (transverse) direction thrusts] of a Hall thruster. A thruster with a steering mechanism is mounted on the inner pendulum, and thrust is measured from the displacement between inner and outer pendulums, by which a thermal drift effect is canceled out. Two crossover knife-edges support each pendulum arm: one is set on the other at a right angle. They enable the pendulums to swing in two directions. Thrust calibration using a pulley and weight system showed that the measurement errors were less than 0.25mN (1.4%) in the main thrust direction and 0.09mN (1.4%) in its transverse direction. The thrust angle of the thrust vector was measured with the stand using the thruster. Consequently, a vector deviation from the main thrust direction of ±2.3° was measured with the error of ±0.2° under the typical operating conditions for the thruster.

Nagao, N.; Yokota, S.; Komurasaki, K.; Arakawa, Y.

2007-11-01

286

Propulsion Flight Research at NASA Dryden From 1967 to 1997  

NASA Technical Reports Server (NTRS)

From 1967 to 1997, pioneering propulsion flight research activities have been conceived and conducted at the NASA Dryden Flight Research Center. Many of these programs have been flown jointly with the United States Department of Defense, industry, or the Federal Aviation Administration. Propulsion research has been conducted on the XB-70, F-111 A, F-111E, YF-12, JetStar, B-720, MD-11, F-15, F- 104, Highly Maneuverable Aircraft Technology, F-14, F/A-18, SR-71, and the hypersonic X-15 airplanes. Research studies have included inlet dynamics and control, in-flight thrust computation, integrated propulsion controls, inlet and boattail drag, wind tunnel-to-flight comparisons, digital engine controls, advanced engine control optimization algorithms, acoustics, antimisting kerosene, in-flight lift and drag, throttle response criteria, and thrust-vectoring vanes. A computer-controlled thrust system has been developed to land the F-15 and MD-11 airplanes without using any of the normal flight controls. An F-15 airplane has flown tests of axisymmetric thrust-vectoring nozzles. A linear aerospike rocket experiment has been developed and tested on the SR-71 airplane. This paper discusses some of the more unique flight programs, the results, lessons learned, and their impact on current technology.

Burcham, Frank W., Jr.; Ray, Ronald J.; Conners, Timothy R.; Walsh, Kevin R.

1997-01-01

287

Development of a two-dimensional dual pendulum thrust stand for Hall thrusters  

SciTech Connect

A two-dimensional dual pendulum thrust stand was developed to measure thrust vectors (axial and horizontal (transverse) direction thrusts) of a Hall thruster. A thruster with a steering mechanism is mounted on the inner pendulum, and thrust is measured from the displacement between inner and outer pendulums, by which a thermal drift effect is canceled out. Two crossover knife-edges support each pendulum arm: one is set on the other at a right angle. They enable the pendulums to swing in two directions. Thrust calibration using a pulley and weight system showed that the measurement errors were less than 0.25 mN (1.4%) in the main thrust direction and 0.09 mN (1.4%) in its transverse direction. The thrust angle of the thrust vector was measured with the stand using the thruster. Consequently, a vector deviation from the main thrust direction of {+-}2.3 deg. was measured with the error of {+-}0.2 deg. under the typical operating conditions for the thruster.

Nagao, N.; Yokota, S.; Komurasaki, K.; Arakawa, Y. [Department of Aeronautics and Astronautics, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Advanced Energy, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Aeronautics and Astronautics, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2007-11-15

288

Bias Momentum Sizing for Hovering Dual-Spin Platforms  

NASA Technical Reports Server (NTRS)

An atmospheric flight vehicle in hover is typically controlled by varying its thrust vector. Achieving both levitation and attitude control with the propulsion system places considerable demands on it for agility and precision, particularly if the vehicle is statically unstable, or nearly so. These demands can be relaxed by introducing an appropriately sized angular momentum bias aligned with the vehicle's yaw axis, thus providing an additional margin of attitude stability about the roll and pitch axes. This paper describes a methodical approach for trading off angular momentum bias level needed with desired levels of vehicle response due to the design disturbance environment given a vehicle's physical parameters. It also describes several simplifications that provide a more physical and intuitive understanding of dual-spin dynamics for hovering atmospheric vehicles. This approach also mitigates the need for control torques and inadvertent actuator saturation difficulties in trying to stabilize a vehicle via control torques produced by unsteady aerodynamics, thrust vectoring, and unsteady throttling. Simulation results, based on a subscale laboratory test flying platform, demonstrate significant improvements in the attitude control robustness of the vehicle with respect to both wind disturbances and off-center of gravity payload changes during flight.

Lim, Kyong B.; Shin, Jong-Yeob; Moerder, Daniel D.

2006-01-01

289

Estimating Thruster Impulses From IMU and Doppler Data  

NASA Technical Reports Server (NTRS)

A computer program implements a thrust impulse measurement (TIM) filter, which processes data on changes in velocity and attitude of a spacecraft to estimate the small impulsive forces and torques exerted by the thrusters of the spacecraft reaction control system (RCS). The velocity-change data are obtained from line-of-sight-velocity data from Doppler measurements made from the Earth. The attitude-change data are the telemetered from an inertial measurement unit (IMU) aboard the spacecraft. The TIM filter estimates the threeaxis thrust vector for each RCS thruster, thereby enabling reduction of cumulative navigation error attributable to inaccurate prediction of thrust vectors. The filter has been augmented with a simple mathematical model to compensate for large temperature fluctuations in the spacecraft thruster catalyst bed in order to estimate thrust more accurately at deadbanding cold-firing levels. Also, rigorous consider-covariance estimation is applied in the TIM to account for the expected uncertainty in the moment of inertia and the location of the center of gravity of the spacecraft. The TIM filter was built with, and depends upon, a sigma-point consider-filter algorithm implemented in a Python-language computer program.

Lisano, Michael E.; Kruizinga, Gerhard L.

2009-01-01

290

Design Challenges of Power Systems for Instrumented Spacecraft with Very Low Perigees in the Earth's Ionosphere  

NASA Technical Reports Server (NTRS)

Designing a solar array to power a spacecraft bus supporting a set of instruments making in situ plasma and neutral atmosphere measurements in the ionosphere at altitudes of 120km or lower poses several challenges. The driving scientific requirements are the field-of-view constraints of the instruments resulting in a three-axis stabilized spacecraft, the need for an electromagnetically unperturbed environment accomplished by designing an electrostatically conducting solar array surface to avoid large potentials, making the spacecraft body as small and as symmetric as possible, and body-mounting the solar array. Furthermore, the life and thermal constraints, in the midst of the effects of the dense atmosphere at low altitude, drive the cross-sectional area of the spacecraft to be small particularly normal to the ram direction. Widely varying sun angles and eclipse durations add further complications, as does the growing desire for multiple spacecraft to resolve spatial and temporal variations packaged into a single launch vehicle. Novel approaches to insure adequate orbit-averaged power levels of approximately 250W include an oval-shaped cross section to increase the solar array collecting area during noon-midnight orbits and the use of a flywheel energy storage system. The flywheel could also be used to help maintain the spacecraft's attitude, particularly during excursions to the lowest perigee altitudes. This paper discusses the approaches used in conceptual power designs for both the proposed Dipper and the Global Electrodynamics Connections (GEC) Mission currently being studied at the NASA/Goddard Space Flight Center.

Moran, Vickie Eakin; Manzer, Dominic D.; Pfaff, Robert E.; Grebowsky, Joseph M.; Gervin, Jan C.

1999-01-01

291

Flight Control of a Rotary wing UAV -A Practical Approach Bilal Ahmed, Hemanshu R. Pota and Matt Garratt  

E-print Network

control) tracks the attitude commands and sets the main rotor thrust vector, while the outer loop rotor thrust vector. High fidelity RUAV simulation results are used to demonstrate the control of the blades are ignored [2]; flapping angles are considered as control inputs resulting in impractical RUAV

Pota, Himanshu Roy

292

Accommodating electric propulsion on SMART-1  

NASA Astrophysics Data System (ADS)

This paper focuses on the technical challenges that arise when electric propulsion is used on a small spacecraft such as SMART-1. The choice of electric propulsion influences not only the attitude control system and the power system, but also the thermal control as well as the spacecraft structure. A description is given on how the design of the attitude control system uses the possibility to control the alignment of the thrust vector in order to reduce the momentum build-up. An outline is made of the philosophy of power generation and distribution and shows how the thermal interfaces to highly dissipating units have been solved. Areas unique for electric propulsion are the added value of a thrust vector orientation mechanism and the special consideration given to the electromagnetic compatibility. SMART-1 is equipped with a thruster gimbal mechanism providing a 10° cone in which the thrust vector can be pointed. Concerning the electromagnetic compatibility, a discussion on how to evaluate the available test results is given keeping in mind that one of the main objectives of the SMART-1 mission is to assess the impact of electric propulsion on the scientific instruments and on other spacecraft systems. Finally, the assembly, integration and test of the spacecraft is described. Compared to traditional propulsion systems, electric propulsion puts different requirements on the integration sequence and limits the possibilities to verify the correct function of the thruster since it needs high quality vacuum in order to operate. Prime contractor for SMART-1 is the Swedish Space Corporation (SSC). The electric propulsion subsystem is procured directly by ESA from SNECMA, France and is delivered to SSC as a customer furnished item. The conclusion of this paper is that electric propulsion is possible on a small spacecraft, which opens up possibilities for a new range of missions for which a large velocity increment is needed. The paper will also present SMART-1 and show how the problems related to the accommodation of electric propulsion have been solved during design and planning of the project.

Kugelberg, Joakim; Bodin, Per; Persson, Staffan; Rathsman, Peter

2004-07-01

293

Space Shuttle Propulsion Safety Upgrades  

NASA Technical Reports Server (NTRS)

This document is a viewgraph presentation which reviews the proposed upgrades to the Space Shuttle Propulsion system, to improve safety, and reduce significant hazards. The goals of the program are to reduce the risk of a catastrophe in ascent, to achieve significant reduction in orbital and entry systems, and to improve the crew cockpit situational awareness for managing the critical operational situations. The document reviews the upgrades to the propulsion system which are planned to improve the safety. These include modifications to the Advanced Thrust Vector Control, modifications to the Space Shuttle Main Engine Block III, improvement in the Advanced Health Management System, the use of Friction Stir welding on the external tank, which is expected to improve mechanical properties, and reduce defect rate, and the modification of the propellant grains geometry.

Humphries, William Randy, Jr.; McCool, Alex (Technical Monitor)

2000-01-01

294

International Symposium on Air Breathing Engines, 8th, Cincinnati, OH, June 14-19, 1987, Proceedings  

SciTech Connect

The present conference on air-breathing aircraft engine technology considers topics in inlet design, radial-flow turbomachinery, fuel injection and combustion systems, axial flow compressor design and performance, ramjet configurations, turbine flow phenomena, engine control and service life, fluid flow-related problems, engine diagnostic methods, propfan design, combustor performance and pollutant chemistry, combustion dynamics, and engine system analysis. Attention is given to thrust-vectoring systems, supersonic missile air intakes, three-dimensional centrifugal compressors, airblast atomizers, secondary flows in axial flow compressors, axial compressor blade tip clearance flows, hydrogen scramjets with sidewall injection, the performance of a variable-geometry turbine, advanced tip clearance control systems, rotary jet mixing, fan blade aeroelastic behavior, flow dynamics in combustion processes, and the technology of low cost turbomachinery.

Billig, F.S.

1987-01-01

295

Development of the command data system and ground software for the SEDSAT-1 microsatellite  

NASA Technical Reports Server (NTRS)

SEDSAT-1 is designed to be a low cost scientific satellite which is to be used to perform a minimum of five tasks which include: (1) the acquisition of a number of important parameters associated with the tethering processes from the payloads perspective (such as accelerations incurred and imaging data of the tether during deployment), (2) to act as a remote sensing platform for making measurements of the Earth's Atmosphere (allowing research to be performed in such areas as vertical lightning observation, visible light spectrography, and cloud cover studies, (3) to act as a general purpose amateur radio communication satellite relaying information back to earth, (4) to demonstrate the feasibility of the deployment in low earth orbit of advanced technology such as the Gallium Arsenide Solar Cells, Nickel Metal Hydride batteries, and multi-chip module technology and, (5) to support student's active participation in applying the disciplines of engineering and science to space-based hardware platforms. The project includes the Three-axis Accelerometer System, TAS, Experiment which is designed to report the accelerations that the satellite undergoes during the tethering operations and during the second phase of the mission when the free floating satellite comes in contact with orbit debris. The SEASIS (SEDS Earth, Atmosphere, and Space Imaging System) is another SEDSAT experiment designed to provide images of the tether during its deployment and the earth during the second phase of the mission. To control these experiments and virtually all other satellite operations the Command Data System, CDS is employed. This system utilizes a moderate complexity micro-controller controlled by tasks operating under a real-time operating system to dynamically monitor and control the satellite. The scope of this researchers efforts has been in the general area of coordinating and assisting the student researchers with the development of the CDS and ground station interfaces. This included the low level CDS hardware design and the formulization of a general software plan and schedule for both the CDS and ground station portions of the project.

Wells, B. Earl

1996-01-01

296

Visual Servo Control Achieving Nanometer Resolution in X - Y - Z  

Microsoft Academic Search

This paper presents a three-axis vision motion sensor and its applications to visual servo control. The vision sensor is integrated with a three-axis piezo stage to form a visual servo control system that achieves nanometer resolution in all three x- y-z motion axes. Motion measurement is achieved using a single interferometer-equipped optical microscope. A real-time image-processing algorithm that processes interference

Jung H. Kim; Chia-Hsiang Menq

2009-01-01

297

Electrical Actuation Technology Bridging  

NASA Astrophysics Data System (ADS)

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.

Hammond, Monica; Sharkey, John

1993-05-01

298

Impulsive control for hypervelocity missiles  

NASA Astrophysics Data System (ADS)

A hypervelocity agile interceptor/quickshot is being developed for defense of ballistic missile launch sites. A guidance and control system is required to achieve the missile guidance accuracy necessary for direct target impact. Attitude control systems evaluated for the agile interceptor included aerodynamic controls, thrust vector controls and impulsive motor controls. The solid squib impulsive control motion was selected because of high response rate, low weight and low volume. A baseline motor configuration was designed and a solid propellant squib was developed for use in the control system. Ballistic pendulum and bench tests were conducted with a test impulsive control motor to measure nominal performance, establish the standard deviation of performance, and define requirements to prevent sympathetic ignition. A dynamic control wind tunnel test was also conducted to determine the impulse augmentation due to the impulsive motor jet interaction with the missile boundary layer. The degree and direction of augmentation was measured for variations in Mach number and angle of attack.

Magness, R. W.

1981-05-01

299

Library System Library System  

E-print Network

Library System #12;Library System 5150 Anthony Wayne Drive David Adamany Undergraduate Library that for the current fiscal year, we've been given an additional $600,000 for our library materials budget. We're very subscriptions. The Wayne State University Libraries are deeply committed to providing our faculty and students

Cinabro, David

300

Technical Progress on the Ares I-X Flight Test  

NASA Technical Reports Server (NTRS)

Ares I-X will be NASA's first test flight for a new human-rated launch vehicle since 1981, and the team is well on its way toward completing the vehicle's design and hardware fabrication for an April 2009 launch. This uncrewed suborbital development test flight gives NASA its first opportunities to: gather critical data about the flight dynamics of the integrated launch vehicle; understand how to control its roll during flight; better characterize the stage separation environments during future flight; and demonstrate the first stage recovery system. The Ares I-X Flight Test Vehicle (FTV) incorporates a mix of flight and mockup hardware. It is powered by a four-segment solid rocket booster, and will be modified to include a fifth, spacer segment; the upper stage, Orion crew exploration vehicle, and launch abort system are simulator hardware to make the FTV aerodynamically similar to the same size, shape, and weight of Ares I. The Ares IX first stage includes an existing Shuttle solid rocket motor and thrust vector control system controlled by an Ascent Thrust Vector Controller (ATVC) designed and built by Honeywell International. The avionics system will be tested in a dedicated System Integration Laboratory located at Lockheed Martin Space Systems (LMSS) in Denver, Colorado. The Upper Stage Simulator (USS) is made up of cylindrical segments that will be stacked and integrated at Kennedy Space Center (KSC) for launch. Glenn Research Center is already building these segments, along with their internal access structures. The active Roll Control System (RoCS) includes two thruster units harvested from Peacekeeper missiles. Duty cycle testing for RoCS was conducted, and fuel tanking and detanking tests will occur at KSC in early 2008. This important flight will provide valuable experience for the ground operations team in integrating, stacking, and launching Ares I. Data from Ares I-X will ensure the safety and reliability of America's newest launch vehicle.

Davis, S.R.; Robinson, K.F.; Flynn, K.C.

2008-01-01

301

Solar system positioning system  

NASA Technical Reports Server (NTRS)

Power-rich spacecraft envisioned in Prometheus initiative open up possibilities for long-range high-rate communication. A constellation of spacecraft on orbits several A.U. from the Sun, equipped with laser transponders and precise clocks can be configured to measure their mutual distances to within few cm. High on-board power can create substantial non-inertial contribution to the spacecraft trajectory. We propose to alleviate this contribution by employing secondary ranging to a passive daughter spacecraft. Such constellation can form the basis of it navigation system capable of providing position information anywhere in the soIar system with similar accuracy. Apart from obvious Solar System exploration implications, this system can provide robust reference for GPS and its successors.

Penanen, Konstantin I.; Chui, Talso

2006-01-01

302

SYSTEMS BIOM BIOMEDICAL SYSTEMS,  

E-print Network

exercise studies under normal and diseased conditions. Cellular metabolic changes are quantitatively of heart disease. Therapeutic strategies are developed related to biomechanical, vascular, muscular control systems, human locomotion, and exercise to reduce loss of musculoskeletal function

Rollins, Andrew M.

303

Advanced electric motor technology: Flux mapping  

NASA Technical Reports Server (NTRS)

This report contains the assumptions, mathematical models, design methodology, and design points involved with the design of an electromechanical actuator (EMA) suitable for directing the thrust vector of a large MSFC/NASA launch vehicle. Specifically the design of such an actuator for use on the upcoming liquid fueled National Launch System (NLS) is considered culminating in a point design of both the servo system and the electric motor needed. A major thrust of the work is in selecting spur gear and roller screw reduction ratios to achieve simultaneously wide bandwidth, maximum power transfer, and disturbance rejection while meeting specified horsepower requirements at a given stroking speed as well as a specified maximum stall force. An innovative feedback signal is utilized in meeting these diverse objectives.

Doane, George B., III; Campbell, Warren; Brantley, Larry W.; Dean, Garvin

1992-01-01

304

Xenon ion propulsion for orbit transfer  

NASA Technical Reports Server (NTRS)

The status of critical ion propulsion system elements is reviewed. Electron bombardment ion thrusters for primary propulsion have evolved to operate on xenon in the 5-10 kW power range. Thruster efficiencies of 0.7 and specific impulse values of 4000 s have been documented. The baseline thruster currently under development by NASA LeRC includes ring-cusp magnetic field plasma containment and dished two-grid ion optics. Based on past experience and demonstrated simplifications, power processors for these thrusters should have approximately 500 parts, a mass of 40 kg, and an efficiency near 0.94. Thrust vector control, via individual thruster gimbals, is a mature technology. High pressure, gaseous xenon propellant storage and control schemes, using flight qualified hardware, result in propellant tankage fractions between 0.1 and 0.2. In-space and ground integration testing has demonstrated that ion propulsion systems can be successfully integrated with their host spacecraft.

Rawlin, V. K.; Patterson, M. J.; Gruber, R. P.

1990-01-01

305

F-18 high alpha research vehicle: Lessons learned  

NASA Technical Reports Server (NTRS)

The F-18 High Alpha Research Vehicle has proven to be a useful research tool with many unique capabilities. Many of these capabilities are to assist in characterizing flight at high angles of attack, while some provide significant research in their own right. Of these, the thrust vectoring system, the unique ability to rapidly reprogram flight controls, the reprogrammable mission computer, and a reprogrammable onboard excitation system have allowed an increased utility and versatility of the research being conducted. Because of this multifaceted approach to research in the high angle of attack regime, the capabilities of the F-18 High Alpha Research Vehicle were designed to cover as many high alpha technology bases as the program would allow. These areas include aerodynamics, controls, handling qualities, and propulsion.

Bowers, Albion H.; Regenie, Victoria A.; Flick, Bradley C.

1994-01-01

306

Attitude determination and control system simulation and analysis for low-cost micro-satellites  

Microsoft Academic Search

The Air Force Academy's latest satellite endeavor, FalconSAT-3, is a 50 kg microsatellite being developed by faculty and cadets, and is the Air Force Academy's first attempt at achieving three axis attitude determination and control (ADCS). FalconSAT-3 carries three payloads to conduct DoD research. The attitude requirements for FalconSAT-3 include pointing the satellite within +\\/- five degrees of ram direction,

Andrew D. Anderson; Jerry J. Sellers; Yoshi Hashida

2004-01-01

307

Integrated attitude determination and control system via magnetic measurements and actuation  

Microsoft Academic Search

A nonlinear control scheme using a Modified State-Dependent Riccati Equation (MSDRE) is developed through a pseudo-linearization of spacecraft augmented nonlinear dynamics and kinematics. The full-state knowledge required for the control loop is provided through a generalized algorithm for spacecraft three-axis attitude and rate estimation based on the utilization of magnetometer measurements and their time derivatives, while the control torque is

Mohammad Abdelrahman; Sang-Young Park

2011-01-01

308

Attitude determination and control system simulation and analysis for low-cost micro-satellites  

Microsoft Academic Search

The Air Force Academy's latest satellite endeavor, FalconSAT-3, is a 50 kg microsatellite being developed by faculty and cadets, and is the Air Force Academy's first attempt at achieving three axis attitude determination and control (ADCS). FalconSAT-3 will carry three payloads to conduct DoD research. The attitude requirements for FalconSAT-3 include pointing the satellite within +\\/- five degrees of ram

Andrew D. Anderson; Jerry I. Sellers; Yoshi Hashida

2004-01-01

309

The Software Design for the Wide-Field Infrared Explorer Attitude Control System  

NASA Technical Reports Server (NTRS)

The Wide-Field Infrared Explorer (WIRE), currently scheduled for launch in September 1998, is the fifth of five spacecraft in the NASA/Goddard Small Explorer (SMEX) series. This paper presents the design of WIRE's Attitude Control System flight software (ACS FSW). WIRE is a momentum-biased, three-axis stabilized stellar pointer which provides high-accuracy pointing and autonomous acquisition for eight to ten stellar targets per orbit. WIRE's short mission life and limited cryogen supply motivate requirements for Sun and Earth avoidance constraints which are designed to prevent catastrophic instrument damage and to minimize the heat load on the cryostat. The FSW implements autonomous fault detection and handling (FDH) to enforce these instrument constraints and to perform several other checks which insure the safety of the spacecraft. The ACS FSW implements modules for sensor data processing, attitude determination, attitude control, guide star acquisition, actuator command generation, command/telemetry processing, and FDH. These software components are integrated with a hierarchical control mode managing module that dictates which software components are currently active. The lowest mode in the hierarchy is the 'safest' one, in the sense that it utilizes a minimal complement of sensors and actuators to keep the spacecraft in a stable configuration (power and pointing constraints are maintained). As higher modes in the hierarchy are achieved, the various software functions are activated by the mode manager, and an increasing level of attitude control accuracy is provided. If FDH detects a constraint violation or other anomaly, it triggers a safing transition to a lower control mode. The WIRE ACS FSW satisfies all target acquisition and pointing accuracy requirements, enforces all pointing constraints, provides the ground with a simple means for reconfiguring the system via table load, and meets all the demands of its real-time embedded environment (16 MHz Intel 80386 processor with 80387 coprocessor running under the VRTX operating system). The mode manager organizes and controls all the software modules used to accomplish these goals, and in particular, the FDH module is tightly coupled with the mode manager.

Anderson, Mark O.; Barnes, Kenneth C.; Melhorn, Charles M.; Phillips, Tom

1998-01-01

310

Systems autonomy  

NASA Technical Reports Server (NTRS)

Information on systems autonomy is given in viewgraph form. Information is given on space systems integration, intelligent autonomous systems, automated systems for in-flight mission operations, the Systems Autonomy Demonstration Project on the Space Station Thermal Control System, the architecture of an autonomous intelligent system, artificial intelligence research issues, machine learning, and real-time image processing.

Lum, Henry, Jr.

1988-01-01

311

Effects of internal yaw-vectoring devices on the static performance of a pitch-vectoring nonaxisymmetric convergent-divergent nozzle  

NASA Technical Reports Server (NTRS)

An investigation was conducted in the static test facility of the Langley 16-Foot Transonic Tunnel to evaluate the internal performance of a nonaxisymmetric convergent divergent nozzle designed to have simultaneous pitch and yaw thrust vectoring capability. This concept utilized divergent flap deflection for thrust vectoring in the pitch plane and flow-turning deflectors installed within the divergent flaps for yaw thrust vectoring. Modifications consisting of reducing the sidewall length and deflecting the sidewall outboard were investigated as means to increase yaw-vectoring performance. This investigation studied the effects of multiaxis (pitch and yaw) thrust vectoring on nozzle internal performance characteristics. All tests were conducted with no external flow, and nozzle pressure ratio was varied from 2.0 to approximately 13.0. The results indicate that this nozzle concept can successfully generate multiaxis thrust vectoring. Deflection of the divergent flaps produced resultant pitch vector angles that, although dependent on nozzle pressure ratio, were nearly equal to the geometric pitch vector angle. Losses in resultant thrust due to pitch vectoring were small or negligible. The yaw deflectors produced resultant yaw vector angles up to 21 degrees that were controllable by varying yaw deflector rotation. However, yaw deflector rotation resulted in significant losses in thrust ratios and, in some cases, nozzle discharge coefficient. Either of the sidewall modifications generally reduced these losses and increased maximum resultant yaw vector angle. During multiaxis (simultaneous pitch and yaw) thrust vectoring, little or no cross coupling between the thrust vectoring processes was observed.

Asbury, Scott C.

1993-01-01

312

Systems Analysis Systems Integration  

E-print Network

to H2 not straightforward Exploratory research is essential Extensive R&D needed Issues: Economic any previously undertaken by DOE in civilian energy Systems Analysis essential guidance / perspective include coal liquids, shale oil & biomass. #12;7 OPTIONS FOR FUTURE U.S. ENERGY - MY VIEW Coal

313

Development of the Multiple Use Plug Hybrid for Nanosats (MUPHyN) miniature thruster  

NASA Astrophysics Data System (ADS)

The Multiple Use Plug Hybrid for Nanosats (MUPHyN) prototype thruster incorporates solutions to several major challenges that have traditionally limited the deployment of chemical propulsion systems on small spacecraft. The MUPHyN thruster offers several features that are uniquely suited for small satellite applications. These features include 1) a non-explosive ignition system, 2) non-mechanical thrust vectoring using secondary fluid injection on an aerospike nozzle cooled with the oxidizer flow, 3) a non-toxic, chemically-stable combination of liquid and inert solid propellants, 4) a compact form factor enabled by the direct digital manufacture of the inert solid fuel grain. Hybrid rocket motors provide significant safety and reliability advantages over both solid composite and liquid propulsion systems; however, hybrid motors have found only limited use on operational vehicles due to 1) difficulty in modeling the fuel flow rate 2) poor volumetric efficiency and/or form factor 3) significantly lower fuel flow rates than solid rocket motors 4) difficulty in obtaining high combustion efficiencies. The features of the MUPHyN thruster are designed to offset and/or overcome these shortcomings. The MUPHyN motor design represents a convergence of technologies, including hybrid rocket regression rate modeling, aerospike secondary injection thrust vectoring, multiphase injector modeling, non-pyrotechnic ignition, and nitrous oxide regenerative cooling that address the traditional challenges that limit the use of hybrid rocket motors and aerospike nozzles. This synthesis of technologies is unique to the MUPHyN thruster design and no comparable work has been published in the open literature.

Eilers, Shannon

314

Pulsed Plasma Thruster Plume Study: Symmetry and Impact on Spacecraft Surfaces  

NASA Technical Reports Server (NTRS)

Twenty-four witness plates were positioned on perpendicular arrays near a breadboard Pulsed Plasma Thruster (PPT) to collect plume constituents for analysis. Over one million shots were fired during the experiment at 43 J using fluorocarbon polymer propellant. The asymmetry of the film deposition on the witness plates was investigated with mass and thickness measurements and correlated with off-axis thrust vector measurements. The composition of the films was determined. The transmittance and reflectance of the films were measured and the absorption coefficients were calculated in the wavelength range from 350 to 1200 mn. These data were applied to calculate the loss in signal intensity through the films, which will impact the visibility of spaceborne interferometer systems positioned by these thrusters.

Arrington, Lynn A.; Marrese, Colleen M.; Blandino, John J.

2000-01-01

315

Nozzle Side Load Testing and Analysis at Marshall Space Flight Center  

NASA Technical Reports Server (NTRS)

Realistic estimates of nozzle side loads, the off-axis forces that develop during engine start and shutdown, are important in the design cycle of a rocket engine. The estimated magnitude of the nozzle side loads has a large impact on the design of the nozzle shell and the engine s thrust vector control system. In 2004 Marshall Space Flight Center (MSFC) began developing a capability to quantify the relative magnitude of side loads caused by different types of nozzle contours. The MSFC Nozzle Test Facility was modified to measure nozzle side loads during simulated nozzle start. Side load results from cold flow tests on two nozzle test articles, one with a truncated ideal contour and one with a parabolic contour are provided. The experimental approach, nozzle contour designs and wall static pressures are also discussed

Ruf, Joseph H.; McDaniels, David M.; Brown, Andrew M.

2009-01-01

316

Experimental results for a two-dimensional supersonic inlet used as a thrust deflecting nozzle  

NASA Astrophysics Data System (ADS)

Nearly all supersonic V/STOL aircraft concepts are dependent on the thrust deflecting capability of a nozzle. In one unique concept, referred to as the reverse flow dual fan, not only is there a thrust deflecting nozzle for the fan and core engine exit flow, but because of the way the propulsion system operates during vertical takeoff and landing, the supersonic inlet is also used as a thrust deflecting nozzle. This paper presents results of an experimental study to evaluate the performance of a supersonic inlet used as a thrust deflecting nozzle for this reverse flow dual fan concept. Results are presented in terms of nozzle thrust coefficient and thrust vector angle for a number of inlet/nozzle configurations. Flow visualization and nozzle exit flow survey results are also shown.

Johns, Albert L.; Burstadt, Paul L.

317

F-15B ACTIVE in flight from above  

NASA Technical Reports Server (NTRS)

Sporting brilliant red, white and blue plumage, this highly-modified F-15B (Serial #71-0290) is being flown in the Advanced Control Technology for Integrated Vehicles--or ACTIVE--research program at NASA's Dryden Flight Research Center, Edwards, California. The most prominent features of the two-seat F-15 are the canards ahead of the wings and the multi-axis thrust-vectoring engine exhaust nozzles, which are linked to an advanced flight control system. A joint program between NASA, the U.S. Air Force, F-15 manufacturer McDonnell-Douglas and engine builder Pratt and Whitney, the ACTIVE program is developing technologies to improve cruise and maneuvering capabilities of future military and civilian aircraft at both subsonic and supersonic speeds.

1996-01-01

318

Bias Momentum Sizing for Hovering Dual-Spin Platforms  

NASA Technical Reports Server (NTRS)

An atmospheric flight vehicle in hover is typically controlled by varying its thrust vector. Achieving both levitation and control with the propulsion system places considerable demands on it for agility and precision, particularly if the vehicle is statically unstable, or nearly so. These demands can be relaxed by introducing an appropriately sized angular momentum bias about the vehicle's yaw axis, thus providing an additional margin of attitude stability about the roll and pitch axes. This paper describes an approach for specifying the appropriate size of such angular momentum bias, based on the vehicle s physical parameters and its disturbance environment. It also describes several simplifications that provide a more physical and intuitive understanding of the dynamics. This will enhance the possibility of practically applying this technology to a flying vehicle.

Lim, K. B.; Shin, J-Y.; Moerder, D. D.

2005-01-01

319

Thrust-induced effects on low-speed aerodynamics of fighter aircraft. [Langley 4- by 7-meter tunnel  

NASA Technical Reports Server (NTRS)

Results of NASA Langley has conducted wind-tunnel investigations of several fighter configurations conducted to determine the effects of both thrust vectoring and spanwise blowing are reviewed. A recent joint NASA/Grumman Aerospace Corporation/U.S. Air Force Wright Aeronautical Laboratory wind-tunnel investigation was conducted to examine the effects of spanwise blowing on the trailing-edge flap system. This application contrasts with the more familiar method of spanwise blowing near the wing leading edge. Another joint program among NASA/McDonnell Aircraft Company/U.S. Air Force Wright Aeronautical Laboratory investigated the effects of reverse thrust on the low-speed aerodynamics of an F-15 configuration. The F-15 model was fitted with a rotating van thrust reverser concept which could simulate both in-flight reversing for approach and landing or full reversing for ground roll reduction. The significant results of these two joint programs are reported.

Banks, D. W.; Quinto, P. F.; Paulson, J. W., Jr.

1982-01-01

320

Finite Element Simulation of a Space Shuttle Solid Rocket Booster Aft Skirt Splashdown Using an Arbitrary Lagrangian-eulerian Approach  

NASA Technical Reports Server (NTRS)

Explicit finite element techniques employing an Arbitrary Lagrangian-Eulerian (ALE) methodology, within the transient dynamic code LS-DYNA, are used to predict splashdown loads on a proposed replacement/upgrade of the hydrazine tanks on the thrust vector control system housed within the aft skirt of a Space Shuttle Solid Rocket Booster. Two preliminary studies are performed prior to the full aft skirt analysis: An analysis of the proposed tank impacting water without supporting aft skirt structure, and an analysis of space capsule water drop tests conducted at NASA's Langley Research Center. Results from the preliminary studies provide confidence that useful predictions can be made by applying the ALE methodology to a detailed analysis of a 26-degree section of the skirt with proposed tank attached. Results for all three studies are presented and compared to limited experimental data. The challenges of using the LS-DYNA ALE capability for this type of analysis are discussed.

Melis, Matthew E.

2003-01-01

321

A Boiling-Potassium Fluoride Reactor for an Artificial-Gravity NEP Vehicle  

NASA Technical Reports Server (NTRS)

Several years ago a rotating manned spacecraft employing nuclear-electric propulsion was examined for Mars exploration. The reactor and its power conversion system essentially served as the counter-mass to an inflatable manned module. A solid-core boiling potassium reactor based on the MPRE concept of the 1960s was baselined in that study. This paper proposes the use of a liquid-fluoride reactor, employing direct boiling of potassium in the core, as a means to overcome some of the residual issues with the MPRE reactor concept. Several other improvements to the rotating Mars vehicle are proposed as well, such as Canfield joints to enable the electric engines to track the inertial thrust vector during rotation, and innovative "cold-ion" engine technologies to improve engine performance.

Sorensen, Kirk; Juhasz, Albert

2007-01-01

322

Imaging of the Outer Planets and Satellites (Article published in the Space Science Reviews special issue on 'Outer Solar System Exploration - An Overview', ed. by J. E. Long and D. G. Rea.)  

Microsoft Academic Search

Imaging is the most widely applicable single means of exploring the outer planets and their satellites and also complements other planet-oriented instruments. Imaging generally is more effectively carried out from a three-axis stabilized spacecraft than from a spinning one. Both specific experimental and broader exploratory goals must be recognized. Photography of Jupiter from terrestrial telescopes has revealed features which were

Bruce C. Murray

1973-01-01

323

X-31 Being Loaded into C-5 Cargo Plane  

NASA Technical Reports Server (NTRS)

The X-31 Enhanced Fighter Maneuverability Technology Demonstrator Aircraft, based at the NASA Dryden Flight Research Center, Edwards, California, begins rolling aboard an Air Force Reserve C-5 transport which ferried it on May 22, 1995 to Europe where it was flown in the Paris Air Show in June 1995. To fit in the C-5 the right wing of the X-31 had to be removed. At the air show, the X-31 demonstrated the value of using thrust vectoring (directing engine exhaust flow) coupled with advanced flight control systems to provide controlled flight at very high angles of attack. The X-31 Enhanced Fighter Maneuverability (EFM) demonstrator flew at the Ames- Dryden Flight Research Facility, Edwards, California (redesignated the Dryden Flight Research Center in 1994) from February 1992 until 1995 and before that at the Air Force's Plant 42 in Palmdale, California. The goal of the project was to provide design information for the next generation of highly maneuverable fighter aircraft. This program demonstrated the value of using thrust vectoring (directing engine exhaust flow) coupled with an advanced flight control system to provide controlled flight to very high angles of attack. The result was a significant advantage over most conventional fighters in close-in combat situations. The X-31 flight program focused on agile flight within the post-stall regime, producing technical data to give aircraft designers a better understanding of aerodynamics, effectiveness of flight controls and thrust vectoring, and airflow phenomena at high angles of attack. Stall is a condition of an airplane or an airfoil in which lift decreases and drag increases due to the separation of airflow. Thrust vectoring compensates for the loss of control through normal aerodynamic surfaces that occurs during a stall. Post-stall refers to flying beyond the normal stall angle of attack, which in the X-31 was at a 30-degree angle of attack. During Dryden flight testing, the X-31 aircraft established several milestones. On November 6, 1992, the X-31 achieved controlled flight at a 70-degree angle of attack. On April 29, 1993, the second X-31 successfully executed a rapid minimum-radius, 180-degree turn using a post-stall maneuver, flying well beyond the aerodynamic limits of any conventional aircraft. This revolutionary maneuver has been called the 'Herbst Maneuver' after Wolfgang Herbst, a German proponent of using post-stall flight in air-to-air combat. It is also called a 'J Turn' when flown to an arbitrary heading change. The aircraft was flown in tactical maneuvers against an F/A-18 and other tactical aircraft as part of the test flight program. During November and December 1993, the X-31 reached a supersonic speed of Mach 1.28. In 1994, the X-31 program installed software to demonstrate quasi-tailless operation. The X-31 flight test program was conducted by an international test organization (ITO) managed by the Advanced Research Projects Office (ARPA), known as the Defense Advanced Research Projects Office (DARPA) before March 1993. The ITO included the U.S. Navy and U.S. Air Force, Rockwell Aerospace, the Federal Republic of Germany, Daimler-Benz (formerly Messerschmitt-Bolkow-Blohm and Deutsche Aerospace), and NASA. Gary Trippensee was the ITO director and NASA Project Manager. Pilots came from participating organizations. The X-31 was 43.33 feet long with a wingspan of 23.83 feet. It was powered by a single General Electric P404-GE-400 turbofan engine that produced 16,000 pounds of thrust in afterburner.

1995-01-01

324

X-31 Loaded in C-5 Cargo Bay  

NASA Technical Reports Server (NTRS)

The X-31 Enhanced Fighter Maneuverability Technology Demonstrator Aircraft, based at the NASA Dryden Flight Research Center, Edwards Air Force Base, California, is secured inside the fuselage of an Air Force Reserve C-5 transport. The C-5 was used to ferry the X-31 from Europe back to Edwards, after being flown in the Paris Air Show in June 1995. The X-31's right wing, removed so the aircraft could fit inside the C-5, is in the shipping container in the foreground. At the air show, the X-31 demonstrated the value of using thrust vectoring (directing engine exhaust flow) coupled with advanced flight control systems to provide controlled flight at very high angles of attack. The X-31 Enhanced Fighter Maneuverability (EFM) demonstrator flew at the Ames- Dryden Flight Research Facility, Edwards, California (redesignated the Dryden Flight Research Center in 1994) from February 1992 until 1995 and before that at the Air Force's Plant 42 in Palmdale, California. The goal of the project was to provide design information for the next generation of highly maneuverable fighter aircraft. This program demonstrated the value of using thrust vectoring (directing engine exhaust flow) coupled with an advanced flight control system to provide controlled flight to very high angles of attack. The result was a significant advantage over most conventional fighters in close-in combat situations. The X-31 flight program focused on agile flight within the post-stall regime, producing technical data to give aircraft designers a better understanding of aerodynamics, effectiveness of flight controls and thrust vectoring, and airflow phenomena at high angles of attack. Stall is a condition of an airplane or an airfoil in which lift decreases and drag increases due to the separation of airflow. Thrust vectoring compensates for the loss of control through normal aerodynamic surfaces that occurs during a stall. Post-stall refers to flying beyond the normal stall angle of attack, which in the X-31 was at a 30-degree angle of attack. During Dryden flight testing, the X-31 aircraft established several milestones. On November 6, 1992, the X-31 achieved controlled flight at a 70-degree angle of attack. On April 29, 1993, the second X-31 successfully executed a rapid minimum-radius, 180-degree turn using a post-stall maneuver, flying well beyond the aerodynamic limits of any conventional aircraft. This revolutionary maneuver has been called the 'Herbst Maneuver' after Wolfgang Herbst, a German proponent of using post-stall flight in air-to-air combat. It is also called a 'J Turn' when flown to an arbitrary heading change. The aircraft was flown in tactical maneuvers against an F/A-18 and other tactical aircraft as part of the test flight program. During November and December 1993, the X-31 reached a supersonic speed of Mach 1.28. In 1994, the X-31 program installed software to demonstrate quasi-tailless operation. The X-31 flight test program was conducted by an international test organization (ITO) managed by the Advanced Research Projects Office (ARPA), known as the Defense Advanced Research Projects Office (DARPA) before March 1993. The ITO included the U.S. Navy and U.S. Air Force, Rockwell Aerospace, the Federal Republic of Germany, Daimler-Benz (formerly Messerschmitt-Bolkow-Blohm and Deutsche Aerospace), and NASA. Gary Trippensee was the ITO director and NASA Project Manager. Pilots came from participating organizations. The X-31 was 43.33 feet long with a wingspan of 23.83 feet. It was powered by a single General Electric P404-GE-400 turbofan engine that produced 16,000 pounds of thrust in afterburner.

1995-01-01

325

X-31 Unloading Returning from Paris Air Show  

NASA Technical Reports Server (NTRS)

After being flown in the Paris Air Show in June 1995, the X-31 Enhanced Fighter Maneuverability Technology Demonstrator Aircraft, based at the NASA Dryden Flight Research Center, Edwards Air Force Base, California, is off-loaded from an Air Force Reserve C-5 transport after the ferry flight back to Edwards. At the air show, the X-31 demonstrated the value of using thrust vectoring (directing engine exhaust flow) coupled with advanced flight control systems to provide controlled flight at very high angles of attack. The X-31 Enhanced Fighter Maneuverability (EFM) demonstrator flew at the Ames- Dryden Flight Research Facility, Edwards, California (redesignated the Dryden Flight Research Center in 1994) from February 1992 until 1995 and before that at the Air Force's Plant 42 in Palmdale, California. The goal of the project was to provide design information for the next generation of highly maneuverable fighter aircraft. This program demonstrated the value of using thrust vectoring (directing engine exhaust flow) coupled with an advanced flight control system to provide controlled flight to very high angles of attack. The result was a significant advantage over most conventional fighters in close-in combat situations. The X-31 flight program focused on agile flight within the post-stall regime, producing technical data to give aircraft designers a better understanding of aerodynamics, effectiveness of flight controls and thrust vectoring, and airflow phenomena at high angles of attack. Stall is a condition of an airplane or an airfoil in which lift decreases and drag increases due to the separation of airflow. Thrust vectoring compensates for the loss of control through normal aerodynamic surfaces that occurs during a stall. Post-stall refers to flying beyond the normal stall angle of attack, which in the X-31 was at a 30-degree angle of attack. During Dryden flight testing, the X-31 aircraft established several milestones. On November 6, 1992, the X-31 achieved controlled flight at a 70-degree angle of attack. On April 29, 1993, the second X-31 successfully executed a rapid minimum-radius, 180-degree turn using a post-stall maneuver, flying well beyond the aerodynamic limits of any conventional aircraft. This revolutionary maneuver has been called the 'Herbst Maneuver' after Wolfgang Herbst, a German proponent of using post-stall flight in air-to-air combat. It is also called a 'J Turn' when flown to an arbitrary heading change. The aircraft was flown in tactical maneuvers against an F/A-18 and other tactical aircraft as part of the test flight program. During November and December 1993, the X-31 reached a supersonic speed of Mach 1.28. In 1994, the X-31 program installed software to demonstrate quasi-tailless operation. The X-31 flight test program was conducted by an international test organization (ITO) managed by the Advanced Research Projects Office (ARPA), known as the Defense Advanced Research Projects Office (DARPA) before March 1993. The ITO included the U.S. Navy and U.S. Air Force, Rockwell Aerospace, the Federal Republic of Germany, Daimler-Benz (formerly Messerschmitt-Bolkow-Blohm and Deutsche Aerospace), and NASA. Gary Trippensee was the ITO director and NASA Project Manager. Pilots came from participating organizations. The X-31 was 43.33 feet long with a wingspan of 23.83 feet. It was powered by a single General Electric P404-GE-400 turbofan engine that produced 16,000 pounds of thrust in afterburner.

1995-01-01

326

Operating Systems.  

ERIC Educational Resources Information Center

A computer operating system spans multiple layers of complexity, from commands entered at a keyboard to the details of electronic switching. In addition, the system is organized as a hierarchy of abstractions. Various parts of such a system and system dynamics (using the Unix operating system as an example) are described. (JN)

Denning, Peter J.; Brown, Robert L.

1984-01-01

327

Mechanical Systems  

NASA Technical Reports Server (NTRS)

The presentation provides an overview of requirement and interpretation letters, mechanical systems safety interpretation letter, design and verification provisions, and mechanical systems verification plan.

Davis, Robert E.

2002-01-01

328

Operating Systems  

NSDL National Science Digital Library

CSC 342. Operating Systems (3) Prerequisite: CSC 332. Study of supervisory programs. System services and file systems; CPU scheduling; memory management; virtual memory; disk scheduling. Deadlock characterization, prevention, and avoidance; concurrent processes; semaphores; critical sections; synchronization. Distributed systems and communication protocols.

Ferner, Clayton

2003-04-21

329

Compact Ejector Thrust Augmentation.  

National Technical Information Service (NTIS)

Ejectors offer interesting means for resolving problems arising from the additional power requirements of V/STOL aircraft. They are capable of turning and augmenting the cruise engine's thrust vector, but their efflux also serve to control circulation lif...

B. P. Quinn

1973-01-01

330

77 FR 53182 - 36(b)(1) Arms Sales Notification  

Federal Register 2010, 2011, 2012, 2013

...the guidance section, warhead section, transition section, propulsion section, control section and Thrust Vector Control (TVC). The guidance section and transition section and technical documentation to be provided under this sale are classified...

2012-08-31

331

78 FR 47000 - Federal Property Suitable as Facilities To Assist the Homeless  

Federal Register 2010, 2011, 2012, 2013

...Hazardous Water Staging Shelter; Hazardous Water Staging Fac.; First Wash Bldg.; Thrust Vector Control Deserving Bldg.; Robot Wash Bldg. Comments: Public access denied & no alternative method to gain access w/out compromising nat'l security...

2013-08-02

332

Fluid Management System (FMS) fluid systems overview  

NASA Technical Reports Server (NTRS)

Viewgraphs on fluid management system (FMS) fluid systems overview are presented. Topics addressed include: fluid management system description including system requirements (integrated nitrogen system, integrated water system, and integrated waste gas system) and physical description; and fluid management system evolution.

Baird, R. S.

1990-01-01

333

Cardiovascular system  

MedlinePLUS Videos and Cool Tools

The cardiovascular system is composed of the heart and the network of arteries, veins, and capillaries that transport blood throughout the ... carries waste products from the tissues to the systems of the body through which they are eliminated. ...

334

Magnetospheric Multiscale (MMS) Mission Attitude Ground System Design  

NASA Technical Reports Server (NTRS)

This paper describes the attitude ground system (AGS) design to be used for support of the Magnetospheric MultiScale (MMS) mission. The AGS exists as one component of the mission operations control center. It has responsibility for validating the onboard attitude and accelerometer bias estimates, calibrating the attitude sensors and the spacecraft inertia tensor, and generating a definitive attitude history for use by the science teams. NASA's Goddard Space Flight Center (GSFC) in Greenbelt, Maryland is responsible for developing the MMS spacecraft, for the overall management of the MMS mission, and for mission operations. MMS is scheduled for launch in 2014 for a planned two-year mission. The MMS mission consists of four identical spacecraft flying in a tetrahedral formation in an eccentric Earth orbit. The relatively tight formation, ranging from 10 to 400 km, will provide coordinated observations giving insight into small-scale magnetic field reconnection processes. By varying the size of the tetrahedron and the orbital semi-major axis and eccentricity, and making use of the changing solar phase, this geometry allows for the study of both bow shock and magnetotail plasma physics, including acceleration, reconnection, and turbulence. The mission divides into two phases for science; these phases will have orbit dimensions of 1.2 x 12 Earth radii in the first phase and 1.2x25 Earth radii in the second in order to study the dayside magnetopause and the nightside magnetotail, respectively. The orbital periods are roughly one day and three days for the two mission phases. Each of the four MMS spacecraft will be spin stabilized at 3 revolutions per minute (rpm), with the spin axis oriented near the ecliptic north pole but tipped approximately 2.5 deg towards the Sun line. The main body of each spacecraft will be an eight-sided platform with diameter of 3.4 m and height of 1.2 m. Several booms are attached to this central core: two axial booms of 14.9 m length, two radial magnetometer booms of 5 m length, and four radial wire booms of 60 m length. Attitude and orbit control will use a set of axial and radial thrusters. A four-head star tracker and a slit-type digital Sun sensor (DSS) provide input for attitude determination. In addition, an accelerometer will be used for closed-loop orbit maneuver control. The primary AGS product will be a daily definitive attitude history. Due to power limitations, the star tracker and accelerometer data will not be available at all times. However, tracker data from at least 10 percent of each orbit and continuous DSS data will be provided. An extended Kalman filter (EKF) will be used to estimate the three-axis attitude (i.e., spin axis orientation and spin phase) and rotation rate for all times when the tracker data is valid. For other times, the attitude is generated by assuming a constant angular momentum vector in the inertial frame. The DSS sun pulse will provide a timing signal to maintain an accurate spin phase. There will be times when the Sun is occulted and DSS data is not available. If this occurs at the start or end of a definitive attitude product, then the spin phase will be extrapolated using the mean rate determined by the EKF.

Sedlak, Joseph E.; Superfin, Emil; Raymond, Juan C.

2010-01-01

335

Expert systems and fuzzy systems  

SciTech Connect

This book examines the design of the expert computer system and how fuzzy systems can be used to deal with imprecise information. As the author explores the effects of semantic systems on decision support systems, he asserts that the utilization of fuzzy set theory can help an expert system draw from its knowledge base more efficiently and therefore make more accurate and reliable decisions. The book includes realistic status reports in approximate reasoning and knowledge representation that are supported by a ''theory of categories'' mathematical approach. The differences between symbolic and semantic manipulation are outline, and detailed information is given on the actual theory of knowledge-based systems.

Negoita, C.

1985-01-01

336

System Effectiveness  

SciTech Connect

An effective risk assessment system is needed to address the threat posed by an active or passive insider who, acting alone or in collusion, could attempt diversion or theft of nuclear material. It is critical that a nuclear facility conduct a thorough self-assessment of the material protection, control, and accountability (MPC&A) system to evaluate system effectiveness. Self-assessment involves vulnerability analysis and performance testing of the MPC&A system. The process should lead to confirmation that mitigating features of the system effectively minimize the threat, or it could lead to the conclusion that system improvements or upgrades are necessary to achieve acceptable protection against the threat. Analysis of the MPC&A system is necessary to understand the limits and vulnerabilities of the system to internal threats. Self-assessment helps the facility be prepared to respond to internal threats and reduce the risk of theft or diversion of nuclear material. MSET is a self-assessment or inspection tool utilizing probabilistic risk assessment (PRA) methodology to calculate the system effectiveness of a nuclear facility's MPC&A system. MSET analyzes the effectiveness of an MPC&A system based on defined performance metrics for MPC&A functions based on U.S. and international best practices and regulations. A facility's MC&A system can be evaluated at a point in time and reevaluated after upgrades are implemented or after other system changes occur. The total system or specific subareas within the system can be evaluated. Areas of potential performance improvement or system upgrade can be assessed to determine where the most beneficial and cost-effective improvements should be made. Analyses of risk importance factors show that sustainability is essential for optimal performance. The analyses reveal where performance degradation has the greatest detrimental impact on total system risk and where performance improvements have the greatest reduction in system risk. The risk importance factors show the amount of risk reduction achievable with potential upgrades and the amount of risk reduction actually achieved after upgrades are completed. Applying the risk assessment tool gives support to budget prioritization by showing where budget support levels must be sustained for MC&A functions most important to risk. Results of the risk assessment are also useful in supporting funding justifications for system improvements that significantly reduce system risk.

Powell, Danny H [ORNL] [ORNL; Elwood Jr, Robert H [ORNL] [ORNL

2011-01-01

337

Microfluidic Systems Integrated Microfluidic Systems**  

E-print Network

Microfluidic Systems Integrated Microfluidic Systems** Rustem F. Ismagilov* Keywords: analytical methods · enzymes · microfluidics · microreactors · protein structures Microfluidic systems use networks of channels thinner than a human hair to manipulate nanoliter volumes of re- agents. The goal of microfluidics

Ismagilov, Rustem F.

338

High Energy Astronomy Observatory star tracker search program  

NASA Technical Reports Server (NTRS)

The development of a control system to accommodate the scientific payload of the High Energy Astronomy Observatory (HEAO) is discussed. One of the critical elements of the system is the star tracker subsystem, which defines an accurate three-axis attitude reference. A digital computer program has been developed to evaluate the ability of a particular star tracker configuration to meet the requirements for attitude reference at various vehicle orientations. Used in conjuction with an adequate star catalog, the computer program provides information on availability of stars for each tracker and on the ability of the system to maintain three-axis attitude reference throughout a representative sequence of vehicle orientations.

Weiler, W. J.

1972-01-01

339

Operating Systems  

NSDL National Science Digital Library

Rashid Bin Muhammad at Kent State University presents his page of lectures notes and other instructional materials on operating systems. The site is divided into a number of topics about operating systems: history, structure, process, threads, Solaris-2, CPU / process scheduling, schedule algorithm, interprocess communication, deadlock, important UNIX commands, and references. The site is then followed by links to outside resources to help supplement the material presented here. This is a great resource for computer science instructors teaching students about operating systems.

Bin Muhammad, Rashid

2009-06-24

340

Anticipatory systems as linguistic systems  

NASA Astrophysics Data System (ADS)

The idea of system is well established although not well defined. What makes up a system depends on the observer. Thinking in terms of systems is only a convenient way to conceptualize organizations, natural or artificial, that show coherent properties. Among all properties, which can be ascribed to systems, one property seems to be more outstanding than others, namely that of being anticipatory. In nature, anticipatory properties are found only in living organizations. In this way it can be said to separate non-living systems from living because there is no indication that any natural phenomenon occurring in systems where there is no indication of life is anticipatory. The characteristic of living systems is that they are exposed to the evolution contrary to causal systems that do not undergo changes due to the influence of the environment. Causal systems are related to the past in such a way that subsequent situations can be calculated from knowledge of past situations. In causal systems the past is the cause of the present and there is no reference to the future as a determining agent, contrary to anticipatory systems where expectations are the cause of the present action. Since anticipatory properties are characteristic of living systems, this property, as all other properties in living systems, is a result of the evolution and can be found in plants as well as in animals. Thus, it is not only tied to consciousness but is found at a more basic level, i.e., in the interplay between genotype and phenotype. Anticipation is part of the genetic language in such a way that appropriate actions, for events in the anticipatory systems environment, are inscribed in the genes. Anticipatory behavior, as a result of the interpretation of the genetic language, has been selected by the evolution. In this paper anticipatory systems are regarded as linguistic systems and I argue that as such anticipation cannot be fragmented but must be holistically studied. This has the implication that anticipatory behavior can only partially be described in a computer language and, furthermore, it shows that only a restricted class of anticipatory systems can be transferred to computers.

Ekdahl, Bertil

2000-05-01

341

ECONOMIC SYSTEMS  

NSDL National Science Digital Library

The information you will explore is: List and categorize the four main types of Economic Systems in our world today. Create graphic Illustrations of thoughts and concepts. Express how economic system structures effect the lives of the people living in that system. Write to express an opinion or point of view. Experience a simulation of the marketplace. Research a country of your choice and find important factors about their economic system. Each country structures their economic system after one of the four main types or a combination of these. The assignments on this page will help you to gain a better understanding of the characteristics of the four main types of economic systems. Process: 1. Click on the following link Marketing Calendar Open the Global Economy power point. Use the Chapter 4 listening guide with the power point. chap4 listening guide 2. List the four main economic systems and find the main characterisitics of each. Compare strengths and weaknesses of each. Economic Systems Characteristics 3.Create a ...

Mrs.owen

2006-10-10

342

Digestive System  

NSDL National Science Digital Library

The digestive system is investigated in this learning activity to help participants learn how food is broken down and prepared for absorption, and list the components of the digestive system as well as their functions. Organs investigated include the mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus.

Bidlack, Jim

343

Multimedia Systems  

NSDL National Science Digital Library

CSC 304. Multimedia Systems (3) Prerequisite: CSC 121. Introduction to technologies of the Internet and networked multimedia systems. Issues in web page design; Internet client/server programming; collaborative computing and group work; network publishing; security and encryption; audio and video compression; ethical issues and privacy; e-commerce; and distributed object computing. Open only to students of junior or senior standing.

Patterson, Ms L.

2003-04-21

344

Power system  

DOEpatents

A power system includes a prime mover, a transmission, and a fluid coupler having a selectively engageable lockup clutch. The fluid coupler may be drivingly connected between the prime mover and the transmission. Additionally, the power system may include a motor/generator drivingly connected to at least one of the prime mover and the transmission. The power-system may also include power-system controls configured to execute a control method. The control method may include selecting one of a plurality of modes of operation of the power system. Additionally, the control method may include controlling the operating state of the lockup clutch dependent upon the mode of operation selected. The control method may also include controlling the operating state of the motor/generator dependent upon the mode of operation selected.

Hickam, Christopher Dale (Glasford, IL)

2008-03-18

345

System Toolbox  

NSDL National Science Digital Library

System Toolbox is designed for system administrators who deal with a variety of platforms. The site covers Windows NT, General Unix, Novell, Linux, Solaris, HP-UX, and the Mac OS. The "toolbox" for each platform offers annotated links to Tools (Disk Management, Anti-Virus, Security, etc.), Articles, and other useful Links. While the information here is hardly comprehensive, the site offers useful, if often basic, resources for administrators. System Toolbox's brand new History section looks promising, with two articles currently posted, "Von Braun's Slide Rule" and "The Godfather of Computing - Charles Babbage." The Comments section allows users to post questions or comments.

2001-01-01

346

Umbilical positioning using ultrasonic sensors  

Microsoft Academic Search

The paper describes the development of an autonomous umbilical positioning system. The umbilical positioning system shall provide electrical power and fiber optic data cable connections between two simulated vehicles 100 meter apart. The Omnibot is used to provide the mobile base for the system. The mate-in umbilical plate is mounted on a three axis Cartesian manipulator, which is installed on

Nasser Houshangi

2000-01-01

347

American Institute of Aeronautics and Astronautics APPLICATION OF VECTORIZED ATTITUDE DETERMINATION  

E-print Network

DETERMINATION USING GLOBAL POSITIONING SYSTEM SIGNALS John L. Crassidis Senior Member AIAA Assistant Professor-by-point (deterministic) attitude solution of a vehicle using Global Positioning System phase difference measurements Global Positioning System (GPS) receivers provides a novel approach for three-axis attitude determination

Crassidis, John L.

348

Systems and Components Fuel Delivery System, Water Delivery System, ...  

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

Systems and Components - Fuel Delivery System, Water Delivery System, Derrick Crane System, and Crane System Details - Marshall Space Flight Center, F-1 Engine Static Test Stand, On Route 565 between Huntsville and Decatur , Huntsville, Madison County, AL

349

Respiratory System  

NSDL National Science Digital Library

The purpose, components, and functions of the respiratory system are presented in this learning through disussion and visualizations. Participants learn about the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli.

Bidlack, Jim

350

Respiratory system  

NASA Technical Reports Server (NTRS)

The general anatomy and function of the human respiratory system is summarized. Breathing movements, control of breathing, lung volumes and capacities, mechanical relations, and factors relevant to respiratory support and equipment design are discussed.

Bartlett, R. G., Jr.

1973-01-01

351

Digestive System  

MedlinePLUS

... of the immune system to a protein called gluten, which is found in wheat, rye, and barley ... and even depression when they eat foods with gluten. Symptoms can be managed by following a gluten- ...

352

Digestive System  

MedlinePLUS

... of the immune system to a protein called gluten, which is found in certain foods. People with ... nutrients from their food because eating things with gluten damages the lining of the intestines over time. ...

353

Systems Vaccinology  

PubMed Central

Vaccination is one of the greatest triumphs of modern medicine, yet we remain largely ignorant of the mechanisms by which successful vaccines stimulate protective immunity. Two recent advances are beginning to illuminate such mechanisms: realization of the pivotal role of the innate immune system in sensing microbes and stimulating adaptive immunity, and advances in systems biology. Recent studies have used systems biology approaches to obtain a global picture of the immune responses to vaccination in humans. This has enabled the identification of early innate signatures that predict the immunogenicity of vaccines, and identification of potentially novel mechanisms of immune regulation. Here we review these advances, and critically examine the potential opportunities and challenges posed by systems biology in vaccine development. PMID:21029962

Pulendran, Bali; Li, Shuzhao; Nakaya, Helder I

2010-01-01

354

Earth Systems  

NSDL National Science Digital Library

This self-contained module on Earth systems includes a range of fun activities that students can perform in the classroom and at home with family members. They impart important concepts such as observation, identification, measurement, and differentiation.

Science, Houghton M.

355

Fueling systems  

SciTech Connect

This report deals with concepts of the Tiber II tokamak reactor fueling systems. Contained in this report are the fuel injection requirement data, startup fueling requirements, intermediate range fueling requirements, power range fueling requirements and research and development considerations. (LSR)

Gorker, G.E.

1987-01-01

356

Microelectromechanical Systems  

NASA Technical Reports Server (NTRS)

Micro-electromechanical systems (MEMS) is an enabling technology that merges computation and communication with sensing and actuation to change the way people and machines interact with the physical world. MEMS is a manufacturing technology that will impact widespread applications including: miniature inertial measurement measurement units for competent munitions and personal navigation; distributed unattended sensors; mass data storage devices; miniature analytical instruments; embedded pressure sensors; non-invasive biomedical sensors; fiber-optics components and networks; distributed aerodynamic control; and on-demand structural strength. The long term goal of ARPA's MEMS program is to merge information processing with sensing and actuation to realize new systems and strategies for both perceiving and controlling systems, processes, and the environment. The MEMS program has three major thrusts: advanced devices and processes, system design, and infrastructure.

Gabriel, Kaigham J.

1995-01-01

357

Immune System  

MedlinePLUS

... New Scientists Identify Important Genetic Changes in 21 Autoimmune Diseases —Oct. 29, 2014 New Regulator of Autoimmune Cells ... 26, 2014 All Immune System News Releases All Autoimmune Diseases News Releases All Primary Immune Deficiency Disease News ...

358

Systemic Mastocytosis  

Microsoft Academic Search

Mastocytosis is a term used for a group of disorders defined by an abnormal accumulation of mast cells (MCs) in one or more\\u000a organ systems. Clinical symptoms result from MC-derived mediators and\\/or from infiltration of MCs in the tissues. Cutaneous\\u000a mastocytosis (CM) is a benign disease of the skin and often regresses spontaneously. Systemic mastocytosis (SM) is a persistent\\u000a clonal

Peter Valent

359

Mechanical Systems  

Microsoft Academic Search

\\u000a In this chapter, several different control applications for mechanical systems are examined. The first system discussed is\\u000a an autobalancing application. A perfectly balanced rotating object (i.e., the center of geometry and center of mass are coincident)\\u000a will usually not undergo any vibration. However, due to the errors associated with geometric dimensions and the nonhomogeneity\\u000a of the raw material, the construction

Warren E. Dixon; Aman Behal; Darren M. Dawson; Siddharth P. Nagarkatti

360

Digestive System  

NSDL National Science Digital Library

The digestive system is amazing: it takes the foods we eat and breaks them into smaller components that our bodies can use for energy, cell repair and growth. This lesson introduces students to the main parts of the digestive system and how they interact. In addition, students learn about some of the challenges astronauts face when eating in outer space. Engineers figure out how to deal with such challenges.

Integrated Teaching And Learning Program

361

Systems Studies  

SciTech Connect

The Systems Studies Activity had two objectives: (1) to investigate nontechnical barriers to the deployment of biomass production and supply systems and (2) to enhance and extend existing systems models of bioenergy supply and use. For the first objective, the Activity focused on existing bioenergy markets. Four projects were undertaken: a comparative analysis of bioenergy in Sweden and Austria; a one-day workshop on nontechnical barriers jointly supported by the Production Systems Activity; the development and testing of a framework for analyzing barriers and drivers to bioenergy markets; and surveys of wood pellet users in Sweden, Austria and the US. For the second objective, two projects were undertaken. First, the Activity worked with the Integrated BioEnergy Systems (TBS) Activity of TEA Bioenergy Task XIII to enhance the BioEnergy Assessment Model (BEAM). This model is documented in the final report of the IBS Activity. The Systems Studies Activity contributed to enhancing the feedstock portion of the model by developing a coherent set of willow, poplar, and switchgrass production modules relevant to both the US and the UK. The Activity also developed a pretreatment module for switchgrass. Second, the Activity sponsored a three-day workshop on modeling bioenergy systems with the objectives of providing an overview of the types of models used to evaluate bioenergy and promoting communication among bioenergy modelers. There were nine guest speakers addressing different types of models used to evaluate different aspects of bioenergy, ranging from technoeconomic models based on the ASPEN software to linear programming models to develop feedstock supply curves for the US. The papers from this workshop have been submitted to Biomass and Bioenergy and are under editorial review.

Graham, R.L.

1998-03-17

362

Systemic trauma.  

PubMed

Substantial theoretical, empirical, and clinical work examines trauma as it relates to individual victims and perpetrators. As trauma professionals, it is necessary to acknowledge facets of institutions, cultures, and communities that contribute to trauma and subsequent outcomes. Systemic trauma-contextual features of environments and institutions that give rise to trauma, maintain it, and impact posttraumatic responses-provides a framework for considering the full range of traumatic phenomena. The current issue of the Journal of Trauma & Dissociation is composed of articles that incorporate systemic approaches to trauma. This perspective extends conceptualizations of trauma to consider the influence of environments such as schools and universities, churches and other religious institutions, the military, workplace settings, hospitals, jails, and prisons; agencies and systems such as police, foster care, immigration, federal assistance, disaster management, and the media; conflicts involving war, torture, terrorism, and refugees; dynamics of racism, sexism, discrimination, bullying, and homophobia; and issues pertaining to conceptualizations, measurement, methodology, teaching, and intervention. Although it may be challenging to expand psychological and psychiatric paradigms of trauma, a systemic trauma perspective is necessary on both scientific and ethical grounds. Furthermore, a systemic trauma perspective reflects current approaches in the fields of global health, nursing, social work, and human rights. Empirical investigations and intervention science informed by this paradigm have the potential to advance scientific inquiry, lower the incidence of a broader range of traumatic experiences, and help to alleviate personal and societal suffering. PMID:24617751

Goldsmith, Rachel E; Martin, Christina Gamache; Smith, Carly Parnitzke

2014-01-01

363

Solid Rocket Booster (SRB) - Evolution and Lessons Learned During the Shuttle Program  

NASA Technical Reports Server (NTRS)

The Solid Rocket Booster (SRB) element integrates all the subsystems needed for ascent flight, entry, and recovery of the combined Booster and Motor system. These include the structures, avionics, thrust vector control, pyrotechnic, range safety, deceleration, thermal protection, and retrieval systems. This represents the only human-rated, recoverable and refurbishable solid rocket ever developed and flown. Challenges included subsystem integration, thermal environments and severe loads (including water impact), sometimes resulting in hardware attrition. Several of the subsystems evolved during the program through design changes. These included the thermal protection system, range safety system, parachute/recovery system, and others. Obsolescence issues occasionally required component recertification. Because the system was recovered, the SRB was ideal for data and imagery acquisition, which proved essential for understanding loads and system response. The three main parachutes that lower the SRBs to the ocean are the largest parachutes ever designed, and the SRBs are the largest structures ever to be lowered by parachutes. SRB recovery from the ocean was a unique process and represented a significant operational challenge; requiring personnel, facilities, transportation, and ground support equipment. The SRB element achieved reliability via extensive system testing and checkout, redundancy management, and a thorough postflight assessment process. Assembly and integration of the booster subsystems was a unique process and acceptance testing of reused hardware components was required for each build. Extensive testing was done to assure hardware functionality at each level of stage integration. Because the booster element is recoverable, subsystems were available for inspection and testing postflight, unique to the Shuttle launch vehicle. Problems were noted and corrective actions were implemented as needed. The postflight assessment process was quite detailed and a significant portion of flight operations. The SRBs provided fully redundant critical systems including thrust vector control, mission critical pyrotechnics, avionics, and parachute recovery system. The design intent was to lift off with full redundancy. On occasion, the redundancy management scheme was needed during flight operations. This paper describes some of the design challenges, how the design evolved with time, and key areas where hardware reusability contributed to improved system level understanding.

Kanner, Howard S.; Freeland, Donna M.; Olson, Derek T.; Wood, T. David; Vaccaro, Mark V.

2011-01-01

364

Spacecraft attitude calibration/verification baseline study  

NASA Technical Reports Server (NTRS)

A baseline study for a generalized spacecraft attitude calibration/verification system is presented. It can be used to define software specifications for three major functions required by a mission: the pre-launch parameter observability and data collection strategy study; the in-flight sensor calibration; and the post-calibration attitude accuracy verification. Analytical considerations are given for both single-axis and three-axis spacecrafts. The three-axis attitudes considered include the inertial-pointing attitudes, the reference-pointing attitudes, and attitudes undergoing specific maneuvers. The attitude sensors and hardware considered include the Earth horizon sensors, the plane-field Sun sensors, the coarse and fine two-axis digital Sun sensors, the three-axis magnetometers, the fixed-head star trackers, and the inertial reference gyros.

Chen, L. C.

1981-01-01

365

Robotic System  

NASA Technical Reports Server (NTRS)

A complicated design project, successfully carried out by New York manufacturing consultant with help from NERAC, Inc., resulted in new type robotic system being marketed for industrial use. Consultant Robert Price, operating at E.S.I, Inc. in Albany, NY, sought help from NERAC to develop an automated tool for deburring the inside of 8 inch breech ring assemblies for howitzers produced by Watervliet Arsenal. NERAC conducted a search of the NASA data base and six others. From information supplied, Price designed a system consisting of a standard industrial robot arm, with a specially engineered six-axis deburring tool fitted to it. A microcomputer and computer program direct the tool on its path through the breech ring. E.S.I. markets the system to aerospace and metal cutting industries for deburring, drilling, routing and refining machined parts.

1984-01-01

366

Manufacturing Systems  

NSDL National Science Digital Library

Objective 7:05 - Students will develop an awareness of the designed World through : Describing a manufacturing system; listing and describing the basic type of manufacturing; defining production and manufacturing enterprise;defining AGV, CAD, CIM, CAM, CNC, production tooling, automation, and material processes. Day 1: Introduction/Background Objective Preassessment: Use a KWL chart to assess your students prior knowledge. This will also help you deal with any misconceptions regarding manufacturing system. Students will use the curriculum companion PowerPoint and Objective 7.05 Outline to develop an awarness of: Define manufacturing List and describe the basic types of Manufacturing Student ...

Wallace, S.

2010-07-16

367

Solar System  

NSDL National Science Digital Library

This site is part of the space page of the British Broadcasting Corporation (BBC), and provides information about the Sun, the planets and their moons, and other bodies in the solar system. It contains a travel guide to the Solar System including such topics as what to see, reason to visit, how to get there, and local history. A similar travel guide is then available for the Sun, each of the planets, asteroids, and comets. In addition, multiple links for more detailed information as well as space games and puzzles are provided.

2007-12-12

368

Neuromodulatory systems  

PubMed Central

We examine the interactions and interdependencies between Neuroglia, the Brain-Cell Microenvironment, and the processes commonly subsumed under Neuromodulation. The interactions of the component processes covering a wide spectrum of frequencies are designated as Neuromodulatory Systems (NMS). This implies NMS's scale-invariance as the capacity of linking actions across many time scales, and self-similarity at any scale. These features endow NMS with the ability to respond adaptively to neural impulse traffic of an unpredictably wide frequency spectrum. In this preliminary perspective, the components of NMS are only outlined based on concepts of Complex Systems Dynamics. However, their interactions must be formally elaborated in further investigations. PMID:23532509

Werner, Gerhard; Mitterauer, Bernhard J.

2013-01-01

369

Systemic mastocytosis.  

PubMed

An unusual disease, mastocytosis challenges the pathologist with a variety of morphologic appearances and heterogeneous clinical presentations ranging from skin manifestations (pruritus, urticaria, dermatographism) to systemic signs and symptoms indicative of mast cell mediator release, including flushing, hypotension, headache, and anaphylaxis among others. In this article, we focus on recognizing the cytology, histopathology, clinical features, and prognostic implications of systemic mastocytosis, a clonal and neoplastic mast cell proliferation infiltrating extracutaneous organ(s) with or without skin involvement. Diagnostic pitfalls are reviewed with ancillary studies to help unmask the mast cell and exclude morphologic mimics. PMID:22054735

George, Tracy I; Horny, Hans-Peter

2011-10-01

370

Branching Systems  

NASA Astrophysics Data System (ADS)

For a digraph G = (V, E) with a specified subset R(j) of V, its nodes, a branching B(j) rooted at R(j) is a forest in G such that for each node u in V - R(j) there is exactly one edge of B(j) entering u. A branching system B = [B(j): j ? J] is a collection of edge-disjoint branchings, with specified root-sets, in G. Given costs c(i) on the edges i of G, and given root sets R(j), we survey the use of matroids to find a least cost branching system, B.

Edmonds, Jack

371

Computer systems  

NASA Technical Reports Server (NTRS)

In addition to the discussions, Ocean Climate Data Workshop hosts gave participants an opportunity to hear about, see, and test for themselves some of the latest computer tools now available for those studying climate change and the oceans. Six speakers described computer systems and their functions. The introductory talks were followed by demonstrations to small groups of participants and some opportunities for participants to get hands-on experience. After this familiarization period, attendees were invited to return during the course of the Workshop and have one-on-one discussions and further hands-on experience with these systems. Brief summaries or abstracts of introductory presentations are addressed.

Olsen, Lola

1992-01-01

372

Complex Systems  

PubMed Central

Physiologic systems in health and disease display an extraordinary range of temporal behaviors and structural patterns that defy understanding based on linear constructs, reductionist strategies, and classical homeostasis. Application of concepts and computational tools derived from the contemporary study of complex systems, including nonlinear dynamics, fractals and “chaos theory,” is having an increasing impact on biology and medicine. This presentation provides a brief overview of an emerging area of biomedical research, including recent applications to cardiopulmonary medicine and chronic obstructive lung disease. PMID:16921107

Goldberger, Ary L.

2006-01-01

373

Nanoelectromechanical Systems  

E-print Network

Nanoelectromechanical systems (NEMS) are nano-to-micrometer scale mechanical resonators coupled to electronic devices of similar dimensions. NEMS show promise for fast, ultrasensitive force microscopy and for deepening our understanding of how classical dynamics arises by approximation to quantum dynamics. This article begins with a survey of NEMS and then describes certain aspects of their classical dynamics. In particular, we show that for weak coupling the action of the electronic device on the mechanical resonator can be effectively that of a thermal bath, this despite the device being a driven, far-from-equilibrium system.

M. P. Blencowe

2005-02-24

374

Solar Dynamics Observatory Guidance, Navigation, and Control System Overview  

NASA Technical Reports Server (NTRS)

The Solar Dynamics Observatory (SDO) was designed and built at the Goddard Space Flight Center, launched from Cape Canaveral on February 11, 2010, and reached its final geosynchronous science orbit on March 16, 2010. The purpose of SDO is to observe the Sun and continuously relay data to a dedicated ground station. SDO remains Sun-pointing throughout most of its mission for the instruments to take measurements of the Sun. The SDO attitude control system (ACS) is a single-fault tolerant design. Its fully redundant attitude sensor complement includes sixteen coarse Sun sensors (CSSs), a digital Sun sensor (DSS), three two-axis inertial reference units (IRUs), and two star trackers (STs). The ACS also makes use of the four guide telescopes included as a part of one of the science instruments. Attitude actuation is performed using four reaction wheels assemblies (RWAs) and eight thrusters, with a single main engine used to provide velocity-change thrust for orbit raising. The attitude control software has five nominal control modes, three wheel-based modes and two thruster-based modes. A wheel-based Safehold running in the attitude control electronics box improves the robustness of the system as a whole. All six modes are designed on the same basic proportional-integral-derivative attitude error structure, with more robust modes setting their integral gains to zero. This paper details the final overall design of the SDO guidance, navigation, and control (GN&C) system and how it was used in practice during SDO launch, commissioning, and nominal operations. This overview will include the ACS control modes, attitude determination and sensor calibration, the high gain antenna (HGA) calibration, and jitter mitigation operation. The Solar Dynamics Observatory mission is part of the NASA Living With a Star program, which seeks to understand the changing Sun and its effects on the Solar System, life, and society. To this end, the SDO spacecraft carries three Sun-observing instruments: Helioseismic and Magnetic Imager (HMI), led by Stanford University; Atmospheric Imaging Assembly (AIA), led by Lockheed Martin Space and Astrophysics Laboratory; and Extreme Ultraviolet Variability Experiment (EVE), led by the University of Colorado. The basic mission is to observe the Sun for a very high percentage of the 5-year mission (10-year goal) with long stretches of uninterrupted observations and with constant, high-data-rate transmission to a dedicated ground station to be located in White Sands, New Mexico. These goals guided the design of the spacecraft bus that will carry and service the three-instrument payload. Overarching design goals for the bus are geosynchronous orbit, near-constant Sun observations with the ability to fly through eclipses, and constant HGA contact with the dedicated ground station. A three-axis stabilized ACS is needed both to point at the Sun accurately and to keep the roll about the Sun vector correctly positioned with respect to the solar north pole. This roll control is especially important for the magnetic field imaging of HM I. The mission requirements have several general impacts on the ACS design. Both the AIA and HMI instruments are very sensitive to the blurring caused by jitter. Each has an image stabilization system (ISS) with some ability to filter out high frequency motion, but below the bandwidth of the ISS the control system must compensate for disturbances within the ACS bandwidth or avoid exciting jitter at higher frequencies. Within the ACS bandwidth, the control requirement imposed by AIA is to place the center of the solar disk no more than 2 arc sec, 3 , from a body-defined target based on one of the GTs that accompany the instrument. This body-defined target, called the science reference boresight (SRB), was determined from the postlaunch orientation of the GTs by averaging the bounding telescope boresights for pitch to get a pitch SRB coordinate, and by averaging the bounding boresights for yaw toet the yaw SRB coordinate. The location of this SRB in the 0.5-deg field-of-view for each GT then

Morgenstern, Wendy M.; Bourkland, Kristin L.; Hsu, Oscar C.; Liu, Kuo-Chia; Mason, Paul A. C.; O'Donnell, James R., Jr.; Russo, Angela M.; Starin, Scott R.; Vess, Melissa F.

2011-01-01

375

Digestive System  

NSDL National Science Digital Library

This site contains a section of an online Biology Textbook - developed by Dr. Michael Gregory of Clinton Community College - providing a concise overview of the digestive system. It describes the enzymes, carbohydrates, proteins, and lipids involved in digestion and outlines the role that each part of the body plays from the mouth the large intestine.

Gregory, Michael

1969-12-31

376

D System  

NSDL National Science Digital Library

D-System is conducting research into program analysis, code generation, and programming tools for data-parallel languages like High Performance Fortran. If this research is successful, computational scientists and engineers will be able to write machine-independent, data-parallel programs for a broad spectrum of scientific applications, and achieve high performance with these programs on a variety of parallel architectures.

377

Embedded Systems  

NSDL National Science Digital Library

The April 2003 issue of ACM Queue, the online magazine of the Association for Computing Machinery, is dedicated to embedded systems. Seven articles are included in the issue, dealing with the design and construction process of embedded devices, programming, and the hardware/software interface.

2008-02-08

378

Manufacturing Systems  

NASA Technical Reports Server (NTRS)

Advanced Process Systems designed a portable purge unit for NASA use. The unit is designed to protect flight and ground crews from toxic fumes and to provide a post-landing controlled environment for sensitive electronic equipment. Although the work has future spinoff potential, it has also led to a research and development program in conjunction with several universities.

1986-01-01

379

Ant System  

Microsoft Academic Search

Ant System, the first Ant Colony Optimization algorithm, sho wed to be a viable method for attacking hard combinatorial optimization problems. Yet, its performance, when com- pared to more fine-tuned algorithms, was rather poor for larg e instances of traditional benchmark problems like the Traveling Salesman Problem. To show that Ant Colony Opti- mization algorithms could be good alternatives to

Libre de Bruxelles; Holger H. Hoos

380

POWER SYSTEMS  

Microsoft Academic Search

Low power output of other devices at this time dictates the use of ; nuclear-reactor systems for manned space explorations. Work up to the present is ; briefly reviewed, and progress and utilization of other power supplies are ; discussed. Pros and cons of solar cells, fuel cells, and thermoelectric and ; thermionic devices are included as well as consideration

1962-01-01

381

Irrigation System  

NASA Technical Reports Server (NTRS)

Under contract with Marshall Space Flight Center, Midwest Research Institute compiled a Lubrication Handbook intended as a reference source for designers and manufacturers of aerospace hardware and crews responsible for maintenance of such equipment. Engineers of Lindsay Manufacturing Company learned of this handbook through NASA Tech Briefs and used it for supplemental information in redesigning gear boxes for their center pivot agricultural irrigation system.

1984-01-01

382

Systems overview  

NASA Technical Reports Server (NTRS)

Charts and accompanying text are presented that provide a brief synopsis of the contracted efforts for FY-92 in assessing nuclear thermal propulsion requirements, concepts, and associated issues. The objective of the effort is to provide NASA LeRC with assistance in space nuclear propulsion system requirements management and public acceptance planning.

Corban, Robert

1993-01-01

383

Immune System  

EPA Science Inventory

A properly functioning immune system is essential to good health. It defends the body against infectious agents and in some cases tumor cells. Individuals with immune deficiencies resulting from genetic defects, diseases (e.g., AIDS, leukemia), or drug therapies are more suscepti...

384

System Dynamics  

NASA Astrophysics Data System (ADS)

System dynamics is an approach for thinking about and simulating situations and organisations of all kinds and sizes by visualising how the elements fit together, interact and change over time. This chapter, written by John Morecroft, describes modern system dynamics which retains the fundamentals developed in the 1950s by Jay W. Forrester of the MIT Sloan School of Management. It looks at feedback loops and time delays that affect system behaviour in a non-linear way, and illustrates how dynamic behaviour depends upon feedback loop structures. It also recognises improvements as part of the ongoing process of managing a situation in order to achieve goals. Significantly it recognises the importance of context, and practitioner skills. Feedback systems thinking views problems and solutions as being intertwined. The main concepts and tools: feedback structure and behaviour, causal loop diagrams, dynamics, are practically illustrated in a wide variety of contexts from a hot water shower through to a symphony orchestra and the practical application of the approach is described through several real examples of its use for strategic planning and evaluation.

Morecroft, John

385

Investigating Army systems and Systems of Systems for value robustness  

E-print Network

This thesis proposes a value robustness approach to architect defense systems and Systems of Systems (SoS). A value robust system or SoS has the ability to provide continued value to stakeholders by performing well to meet ...

Koo, Kevin C. K. (Kevin Cheng Keong)

2010-01-01

386

Analytical investigation of the dynamics of tethered constellations in Earth orbit (phase 2)  

NASA Technical Reports Server (NTRS)

The deployment maneuver of three axis vertical constellations with elastic tethers is analyzed. The deployment strategy devised previously was improved. Dampers were added to the system. Effective algorithms for damping out the fundamental vibrational modes of the system were implemented. Simulations of a complete deployment and a subsequent station keeping phase of a three mass constellation is shown.

Lorenzini, E.; Arnold, D. A.; Grossi, M. D.; Gullahorn, G. E.

1985-01-01

387

DETECTION WITHIN THE WELLBORE OF SEISMIC SIGNALS CREATED BY HYDRAULIC FRACTURING  

Microsoft Academic Search

Early in 1978, Sandia Labs participated in massive hydraulic fracture mapping experiments with Amoco in the Wattenburg area. On two of these massive hydraulic fractures in the Sussex formation, a downhole, wall clamped, three-axis geophone was tested. On the first experiment, the system was clamped in the open hole section during the breakdown phase. On the second experiment, the system

Carl Schuster

1978-01-01

388

Iterative Magnetometer Calibration  

NASA Technical Reports Server (NTRS)

This paper presents an iterative method for three-axis magnetometer (TAM) calibration that makes use of three existing utilities recently incorporated into the attitude ground support system used at NASA's Goddard Space Flight Center. The method combines attitude-independent and attitude-dependent calibration algorithms with a new spinning spacecraft Kalman filter to solve for biases, scale factors, nonorthogonal corrections to the alignment, and the orthogonal sensor alignment. The method is particularly well-suited to spin-stabilized spacecraft, but may also be useful for three-axis stabilized missions given sufficient data to provide observability.

Sedlak, Joseph

2006-01-01

389

Design of smart composite platforms for adaptive trust vector control and adaptive laser telescope for satellite applications  

NASA Astrophysics Data System (ADS)

This paper presents design of smart composite platforms for adaptive trust vector control (TVC) and adaptive laser telescope for satellite applications. To eliminate disturbances, the proposed adaptive TVC and telescope systems will be mounted on two analogous smart composite platform with simultaneous precision positioning (pointing) and vibration suppression (stabilizing), SPPVS, with micro-radian pointing resolution, and then mounted on a satellite in two different locations. The adaptive TVC system provides SPPVS with large tip-tilt to potentially eliminate the gimbals systems. The smart composite telescope will be mounted on a smart composite platform with SPPVS and then mounted on a satellite. The laser communication is intended for the Geosynchronous orbit. The high degree of directionality increases the security of the laser communication signal (as opposed to a diffused RF signal), but also requires sophisticated subsystems for transmission and acquisition. The shorter wavelength of the optical spectrum increases the data transmission rates, but laser systems require large amounts of power, which increases the mass and complexity of the supporting systems. In addition, the laser communication on the Geosynchronous orbit requires an accurate platform with SPPVS capabilities. Therefore, this work also addresses the design of an active composite platform to be used to simultaneously point and stabilize an intersatellite laser communication telescope with micro-radian pointing resolution. The telescope is a Cassegrain receiver that employs two mirrors, one convex (primary) and the other concave (secondary). The distance, as well as the horizontal and axial alignment of the mirrors, must be precisely maintained or else the optical properties of the system will be severely degraded. The alignment will also have to be maintained during thruster firings, which will require vibration suppression capabilities of the system as well. The innovative platform has been designed to have tip-tilt pointing and simultaneous multi-degree-of-freedom vibration isolation capability for pointing stabilization. Analytical approaches have been employed for determining the loads in the components as well as optimizing the design of the system. The different critical components such as telescope tube struts, flexure joints, and the secondary mirror mount have been designed and analyzed using finite element technique. The Simultaneous Precision Positioning and Vibration Suppression (SPPVS) smart composites platforms for the adaptive TVC and adaptive composite telescope are analogous (e.g., see work by Ghasemi-Nejhad and co-workers [1, 2]), where innovative concepts and control strategies are introduced, and experimental verifications of simultaneous thrust vector control and vibration isolation of satellites were performed. The smart composite platforms function as an active structural interface between the main thruster of a satellite and the satellite structure for the adaptive TVC application and as an active structural interface between the main smart composite telescope and the satellite structure for the adaptive laser communication application. The cascaded multiple feedback loops compensate the hysteresis (for piezoelectric stacks inside the three linear actuators that individually have simultaneous precision positioning and vibration suppression), dead-zone, back-lash, and friction nonlinearities very well, and provide precision and quick smart platform control and satisfactory thrust vector control capability. In addition, for example for the adaptive TVC, the experimental results show that the smart composite platform satisfactorily provided precision and fast smart platform control as well as the satisfactory thrust vector control capability. The vibration controller isolated 97% of the vibration energy due to the thruster firing.

Ghasemi-Nejhad, Mehrdad N.

2013-04-01

390

The Nervous System Nervous System Functions  

E-print Network

1 The Nervous System Nervous System Functions The primary functions of the nervous system are...the whole nervous system #12;5 Nervous System Organization Central Nervous System (CNS) Brain Spinal Cord Peripheral Nervous System Somatic NS--receives/sends messages to muscles Autonomic NS

Brown, Christopher A.

391

Advanced Airborne Hyperspectral Imaging System (AAHIS)  

NASA Astrophysics Data System (ADS)

The design, operation, and performance of the fourth generation of Science and Technology International's Advanced Airborne Hyperspectral Imaging Sensors (AAHIS) are described. These imaging spectrometers have a variable bandwidth ranging from 390-840 nm. A three-axis image stabilization provides spatially and spectrally coherent imagery by damping most of the airborne platform's random motion. A wide 40-degree field of view coupled with sub-pixel detection allows for a large area coverage rate. A software controlled variable aperture, spectral shaping filters, and high quantum efficiency, back-illuminated CCD's contribute to the excellent sensitivity of the sensors. AAHIS sensors have been operated on a variety of fixed and rotary wing platforms, achieving ground-sampling distances ranging from 6.5 cm to 2 m. While these sensors have been primarily designed for use over littoral zones, they are able to operate over both land and water. AAHIS has been used for detecting and locating submarines, mines, tanks, divers, camouflage and disturbed earth. Civilian applications include search and rescue on land and at sea, agricultural analysis, environmental time-series, coral reef assessment, effluent plume detection, coastal mapping, damage assessment, and seasonal whale population monitoring

Topping, Miles Q.; Pfeiffer, Joel E.; Sparks, Andrew W.; Jim, Kevin T. C.; Yoon, Dugan

2002-11-01

392

System Verification II Systems Engineering  

E-print Network

in safety critical systems to prevent unsafe values, e.g. high doses of radiation. Remember: not just should be able to: Explain the role & practice of debugging in the software process. Describe in detail the purpose, scope of, and activities comprising each of the three main phases of software testing. Conduct

Bryson, Joanna J.

393

Surveying System  

NASA Technical Reports Server (NTRS)

Sunrise Geodetic Surveys are setting up their equipment for a town survey. Their equipment differs from conventional surveying systems that employ transit rod and chain to measure angles and distances. They are using ISTAC Inc.'s Model 2002 positioning system, which offers fast accurate surveying with exceptional signals from orbiting satellites. The special utility of the ISTAC Model 2002 is that it can provide positioning of the highest accuracy from Navstar PPS signals because it requires no knowledge of secret codes. It operates by comparing the frequency and time phase of a Navstar signal arriving at one ISTAC receiver with the reception of the same set of signals by another receiver. Data is computer processed and translated into three dimensional position data - latitude, longitude and elevation.

1988-01-01

394

Solar Systems  

NASA Technical Reports Server (NTRS)

The solar collectors shown are elements of domestic solar hot water systems produced by Solar One Ltd., Virginia Beach, Virginia. Design of these systems benefited from technical expertise provided Solar One by NASA's Langley Research Center. The company obtained a NASA technical support package describing the d e sign and operation of solar heating equipment in NASA's Tech House, a demonstration project in which aerospace and commercial building technology are combined in an energy- efficient home. Solar One received further assistance through personal contact with Langley solar experts. The company reports that the technical information provided by NASA influenced Solar One's panel design, its selection of a long-life panel coating which increases solar collection efficiency, and the method adopted for protecting solar collectors from freezing conditions.

1979-01-01

395

Systemic treatment.  

PubMed

In the last years the management of patients with liver cancer has been improved. The BCLC staging/treatment strategy identifies the optimal candidates for each treatment option and sorafenib is the only effective systemic treatment. Others (sunitinib, brivanib, linifanib, everolimus, ramucirumab) have failed in terms of safety/survival benefit. Some patients at intermediate/early stage, may be considered for systemic therapy when options of higher priority may have failed or not be feasible. The 800 mg/day is the recommended starting dose. Close follow-up and easy access for the patients so that they can report any adverse event and implement dose adjustments is the key point in the management of them. Development of early dermatologic adverse events has been correlated with better outcome and the pattern of radiologic progression characterizes better the prognosis/outcome of these patients. Treatment beyond progression may be considered if there is no option for a second line research trial. PMID:25260318

Reig, Maria; Gazzola, Alessia; Di Donato, Roberto; Bruix, Jordi

2014-10-01

396

Neuroendocrine System  

Microsoft Academic Search

The physiological systems of the human body are placed under a great deal of stress during the process of exercise training.\\u000a Within elite athletes this stress can be of enormous levels because of the volume and intensity of work they perform in their\\u000a training regimes . When training stress is of an appropriate level then there is a positive adaptation

A. C. Hackney

397

Clinical systems  

Microsoft Academic Search

The computerization of clinical care is needed for several reasons. Paper records cannot efficiently support new models of care, clinical governance, or clinical decision-making; and they are not always available. The British Government's strategy for computerizing the NHS in England is embodied in the National Programme for Information Technology (NPfIT). Modern, patient-centric, electronic patient record systems that incorporate clinical decision-support

Anthony P Madden

2004-01-01

398

Imaging System  

NASA Technical Reports Server (NTRS)

The 1100C Virtual Window is based on technology developed under NASA Small Business Innovation (SBIR) contracts to Ames Research Center. For example, under one contract Dimension Technologies, Inc. developed a large autostereoscopic display for scientific visualization applications. The Virtual Window employs an innovative illumination system to deliver the depth and color of true 3D imaging. Its applications include surgery and Magnetic Resonance Imaging scans, viewing for teleoperated robots, training, and in aviation cockpit displays.

1995-01-01

399

Adrenergic System  

Microsoft Academic Search

\\u000a The adrenergic system is an essential regulator of cardiovascular, endocrine, neuronal, vegetative, and metabolic function.\\u000a The biological effects of the endogenous catecholamines epinephrine and norepinephrine are mediated by nine distinct G protein-coupled\\u000a receptor subtypes. These adrenergic receptors can be divided into three different groups, the a1-receptors (?1A, ?1B, ?1D), ?2-receptors (?2A, ?2B ?2C) ?-receptors (?1, ?2, ?3). In the absence

S. Engelhardt; L. Hein

400

Sterilization System  

NASA Technical Reports Server (NTRS)

Cox Sterile Products, Inc.'s Rapid Heat Transfer Sterilizer employs a heat exchange process that induces rapid air movement; the air becomes the heat transfer medium, maintaining a uniform temperature of 375 degrees Fahrenheit. It features pushbutton controls for three timing cycles for different instrument loads, a six-minute cycle for standard unpackaged instruments, eight minutes for certain specialized dental/medical instruments and 12 minutes for packaged instruments which can then be stored in a drawer in sterile condition. System will stay at 375 degrees all day. Continuous operation is not expensive because of the sterilizer's very low power requirements.

1990-01-01

401

Purification system  

NASA Technical Reports Server (NTRS)

A system for prolonging the life of a granulated activated charcoal (GAC) water treatment device is disclosed in which an ultraviolet light transparent material is used to constrain water to flow over carbon surfaces. It is configured to receive maximum flux from a UV radiation source for the purpose of preventing microbial proliferation on the carbon surfaces; oxidizing organic contaminants adsorbed from the water onto the carbon surfaces and from biodegradation of adsorbed microbial forms; disinfecting water; and oxidizing organic contaminants in the water.

Flanagan, David T. (inventor); Gibbons, Randall E. (inventor)

1992-01-01

402

Expert Systems: What Is an Expert System?  

ERIC Educational Resources Information Center

Describes expert systems and discusses their use in libraries. Highlights include parts of an expert system; expert system shells; an example of how to build an expert system; a bibliography of 34 sources of information on expert systems in libraries; and a list of 10 expert system shells used in libraries. (Contains five references.) (LRW)

Duval, Beverly K.; Main, Linda

1994-01-01

403

The Systems Man's Role in Systems Development.  

ERIC Educational Resources Information Center

At present most systems development is completely dominated by systems people. Such domination can lead to long delays in the development of systems, failures of many systems to ever become operational, costly redesigns for those that do, and a poor fit between systems and their users. Management and users, as well as systems programmers, need to…

Barnett, Arnold

404

ESMDIS: Earth System Model Data Information System  

Microsoft Academic Search

The goal of the development of the Earth System Model Data Information System (ESMDIS) are to provide Earth scientists with: 1) an output management system of Earth System Model (ESM) to browse the metadata and retrieve a desired subset of ESM output; 2) an analysis system of ESM output and other related datasets; 3) an automated pipelining system for ESM

Yuechen Chi; Carlos R. Mechoso; Michael Stonebraker; Keith Sklower; Richard Troy; Richard R. Muntz; Edmond Mesrobian

1997-01-01

405

Techniques utilized in the simulated altitude testing of a 2D-CD vectoring and reversing nozzle  

NASA Technical Reports Server (NTRS)

Simulated altitude testing of a two-dimensional, convergent-divergent, thrust vectoring and reversing exhaust nozzle was accomplished. An important objective of this test was to develop test hardware and techniques to properly operate a vectoring and reversing nozzle within the confines of an altitude test facility. This report presents detailed information on the major test support systems utilized, the operational performance of the systems and the problems encountered, and test equipment improvements recommended for future tests. The most challenging support systems included the multi-axis thrust measurement system, vectored and reverse exhaust gas collection systems, and infrared temperature measurement systems used to evaluate and monitor the nozzle. The feasibility of testing a vectoring and reversing nozzle of this type in an altitude chamber was successfully demonstrated. Supporting systems performed as required. During reverser operation, engine exhaust gases were successfully captured and turned downstream. However, a small amount of exhaust gas spilled out the collector ducts' inlet openings when the reverser was opened more than 60 percent. The spillage did not affect engine or nozzle performance. The three infrared systems which viewed the nozzle through the exhaust collection system worked remarkably well considering the harsh environment.

Block, H. Bruce; Bryant, Lively; Dicus, John H.; Moore, Allan S.; Burns, Maureen E.; Solomon, Robert F.; Sheer, Irving

1988-01-01

406

Refrigeration system  

SciTech Connect

This patent describes a chamber including an expandable refrigerant system associated therewith. The system comprises reservoir containing an expandable refrigerant coolant and lead piping connecting the reservoir to conduits carrying the coolant therein. The chamber comprises top, bottom and side walls, accordingly defining an interior and an exterior to the chamber, one of the walls comprises a door affording access into the chamber, each of the walls being insulated with insulating material. At least one of the walls comprises a first layer of the insulating material extending thereover adjacent the exterior and a second layer of the insulating material extending thereover adjacent the interior. The reservoir, lead piping and conduits are disposed intermediate the first and second layers of insulating material thereby isolating them from both the interior and exterior. Heat transferring through the at least one wall is substantially absorbed by the coolant and the insulating material cooled by the coolant, before it is able to penetrate through the at least one wall, permitting a product placed in the chamber to effectively maintain or substantially maintain a selected even temperature.

Pagani, R.F.; Clarke, K.J.; Avon, E.J.

1986-11-11

407

Gastrointestinal system  

PubMed Central

The functions of the gastrointestinal (GI) tract include digestion, absorption, excretion, and protection. In this review, we focus on the electrical activity of the stomach and small intestine, which underlies the motility of these organs, and where the most detailed systems descriptions and computational models have been based to date. Much of this discussion is also applicable to the rest of the GI tract. This review covers four major spatial scales: cell, tissue, organ, and torso, and discusses the methods of investigation and the challenges associated with each. We begin by describing the origin of the electrical activity in the interstitial cells of Cajal, and its spread to smooth muscle cells. The spread of electrical activity through the stomach and small intestine is then described, followed by the resultant electrical and magnetic activity that may be recorded on the body surface. A number of common and highly symptomatic GI conditions involve abnormal electrical and/or motor activity, which are often termed functional disorders. In the last section of this review we address approaches being used to characterize and diagnose abnormalities in the electrical activity and how these might be applied in the clinical setting. The understanding of electrophysiology and motility of the GI system remains a challenging field, and the review discusses how biophysically based mathematical models can help to bridge gaps in our current knowledge, through integration of otherwise separate concepts. PMID:20836011

Cheng, Leo K.; O’Grady, Gregory; Du, Peng; Egbuji, John U.; Windsor, John A.; Pullan, Andrew J.

2014-01-01

408

Solar System  

NSDL National Science Digital Library

NASA is charting a bold new course into the cosmos, a journey that will take humans back to the Moon, and eventually to Mars and beyond. Exploration of the solar system and beyond will be guided by compelling questions of scientific and societal importance. NASA exploration programs will seek profound answers to questions about the origins of our solar system, whether life exists beyond Earth, and how we could live on other worlds. The NASA Vision for space exploration calls for a combination of human and robotic missions to achieve new exploration goals. Robotic missions to the Moon will be followed by an extended human expedition as early as 2015. Lunar exploration will lay the groundwork for future exploration of Mars and other destinations. A new spacecraft to support these journeys--the Crew Exploration Vehicle--will be tested before the end of this decade. Space exploration holds a special place in the human imagination. Youth are especially drawn to Mars rovers, astronauts, and telescopes. If used effectively and creatively, space can inspire children to seek careers in math, science, and engineering. Exploration and discovery are key agents of growth in society--technologically, economically, socially, internationally, and intellectually. This module is a first step in engaging today's youth in space exploration and serves as an invitation to participate in the excitement of discovery.

National Science Teachers Association (NSTA)

2005-04-01

409

Skeletal System  

NSDL National Science Digital Library

Through this unit, written for an honors anatomy and physiology class, students become familiar with the human skeletal system and answer the Challenge Question: When you get home from school, your mother grabs you, and you race to the hospital. Your grandmother fell and was rushed to the emergency room. The doctor tells your family your grandmother has a fractured hip, and she is referring her to an orthopedic specialist. The orthopedic doctor decides to perform a DEXA scan. The result show her BMD is -3.3. What would be a probable diagnosis to her condition? What are some possible causes of her condition? Should her daughter and granddaughter be worried about this condition, and if so, what are measures they could take to prevent this from happening to them?

Vu Bioengineering Ret Program

410

Tracking system  

SciTech Connect

A system of tracking the sun each day of the year with compensation for changes in time of sunrise and time of sunset as well as sun declination on a day to day basis, declination being under control of a crank that makes one revolution per year. The equation of time is under control of a cam that also revolves once a year and resets the clock to reflect solar rather than mean solar time in order to properly follow the sun. The position of sun acquisition and loss are a function of the declination and the time is a function of the clock corrected via the cam for equation of time. Thus, when the declination is reset each day, it sets the position of acquisition and loss while the clock, now set for the change due to the equation of time, determines the time of acquisition and loss.

Leroy, V. A.; Gaedtke, H. D.

1985-10-15

411

Magnetic Disturbance Due to the Hemispherical Hole in the Ground for a Building at the Magnetic Test Site  

Microsoft Academic Search

At the Japan Aerospace Exploration Agency, a zero magnetic field is required to test the magnetic characteristics of spacecrafts, satellites and to calibrate magnetometers. This zero-magnetic field is realized by means of a three-axis coil system which can cancel the uniform earth's magnetic field, but cannot cancel magnetic disturbance because of no magnetically shielded room. Therefore, the magnetic disturbance within

Keita Yamazaki; Yasutoshi Hyakusoku; Kazuhiro Muramatsu; Hideki Kitamura; Koji Fujiwara; Koichiro Kobayashi

2006-01-01

412

Improvements in the transient fidelity of HWIL flight tables using acceleration feedback  

Microsoft Academic Search

Control system architecture will help eliminate or reduce non-linear behavior of flight table axes motions. This elimination and reduction will help improve dynamic transparency in HWIL simulations. This paper presents the design, analysis and test results of a three-axis hydraulic flight table using acceleration feedback as a part of the axes servo structure. This approach significantly improves the transient motion

Michael Swamp; Colin Stevens; Peter Hoffstetter

2002-01-01

413

Attitude determination and control for a small remote sensing satellite  

Microsoft Academic Search

In this paper, a fully autonomous magnetic attitude control system is proposed for a small satellite for remote sensing applications. The attitude determination hardware consists of a horizon sensor and a pair of two-axis magnetometers. Three-axis attitude control is performed by means of three magnetic torquers. Control laws are derived separately for the attitude acquisition and the station keeping phases.

Michele Grassi

1997-01-01

414

SAS-A spacecraft magnetic tests  

NASA Technical Reports Server (NTRS)

Magnetic tests were conducted on the spacecraft for: (1) alignment, compensation, calibration, and bias determination for the spacecraft three-axis vector magnetometer; (2) determination of permanent, induced, and stray magnetic moments of the spacecraft and compensation of permanent magnetic moments by permanent magnets; and (3) evaluation of the spin and attitude control system.

Boyle, J. C.

1970-01-01

415

Computer Systems Administrator  

E-print Network

Computer Systems Administrator Fort Collins, CO POSITION A Computer Systems Administrator (Non activities. RESPONSIBILITIES The System Administrator will provide Unix/Linux, Windows computer system or computer science, and three years computer systems administration experience. DURATION The work is planned

416

System of systems modeling and simulation  

Microsoft Academic Search

Analyzing the performance of a complex System of Systems (SoS) requires a systems engineering approach. Many such SoS exist in the Military domain. Examples include the Army's next generation Future Combat Systems 'Unit of Action' or the Navy's Aircraft Carrier Battle Group. In the case of a Unit of Action, a system of combat vehicles, support vehicles and equipment are

Craig R. Lawton; James E. Campbell; Dennis James Anderson; Bruce Miles Thompson; Dennis E. Longsine; Donald N. Shirah; Robert M. Cranwell

2005-01-01

417

Communication Engineering Systems Introduction to Communication Systems  

E-print Network

Communication Engineering Systems Introduction to Communication Systems (1) Assoc .. 4 #12;Outline Variety of Today's Communication SystemsVariety of Today s Communication Systems Design Challenges Basic of Communication Systems F d t l Li it tiFundamental Limitation Bandwidth

Kovintavewat, Piya

418

Communication Systems Chair of Communication Systems  

E-print Network

1 | 36 Communication Systems 24th lecture Chair of Communication Systems Department of Applied Sciences University of Freiburg 2009 #12;2 | 36 Communication Systems last to final lecture Extension;3 | 36 Communication Systems GSM interfaces and components #12;4 | 36 Communication Systems GSM

Schindelhauer, Christian

419

Systems Biology and Systems Medicine: Technology,  

E-print Network

Systems Biology and Systems Medicine: Technology, Measurement and Validation Lee Hood Institute for Systems Biology, Seattle How Might One Think About Systems Biology? #12;Radio Waves Sound Waves #12;Immune Response Intra- and inter- cellular networks Development Physiology #12;Contemporary Systems Biology

420

Elec 331 -Nervous System Nervous System  

E-print Network

Elec 331 - Nervous System 1 Nervous System · Central Nervous System ­ Brain ­ Spinal Chord · Peripheral Nervous System ­ "Conductive" network between CNS & organs ­ Neurones · Individual cells · May act Flow of Information neurone #12;Elec 331 - Nervous System 2 Cell States · Resting Potential (Vc = -70m

Pulfrey, David L.

421

Separation system  

DOEpatents

A separation system for dewatering radioactive waste materials includes a disposal container, drive structure for receiving the container, and means for releasably attaching the container to the drive structure. Separation structure disposed in the container adjacent the inner surface of the side wall structure retains solids while allowing passage of liquids. Inlet port structure in the container top wall is normally closed by first valve structure that is centrifugally actuated to open the inlet port and discharge port structure at the container periphery receives liquid that passes through the separation structure and is normally closed by second valve structure that is centrifugally actuated to open the discharge ports. The container also includes coupling structure for releasable engagement with the centrifugal drive structure. Centrifugal force produced when the container is driven in rotation by the drive structure opens the valve structures, and radioactive waste material introduced into the container through the open inlet port is dewatered, and the waste is compacted. The ports are automatically closed by the valves when the container drum is not subjected to centrifugal force such that containment effectiveness is enhanced and exposure of personnel to radioactive materials is minimized.

Rubin, Leslie S. (Newton, MA)

1986-01-01

422

System safety education focused on system management  

NASA Technical Reports Server (NTRS)

System safety is defined and characteristics of the system are outlined. Some of the principle characteristics include role of humans in hazard analysis, clear language for input and output, system interdependence, self containment, and parallel analysis of elements.

Grose, V. L.

1971-01-01

423

Onsite Wastewater Treatment Systems: Spray Distribution System  

E-print Network

Spray distribution systems for wastewater are much like lawn sprinkler systems, in that they spray treated wastewater over the surface of a yard. This publication explains how spray distribution systems work, what their design requirements are...

Lesikar, Bruce J.

2008-10-23

424

Examining Survivability of Systems of Systems  

E-print Network

Previous research has identified design principles that enable survivability for systems, but it is unclear if these principles are appropriate and sufficient for systems of systems as well. This paper presents a preliminary ...

Mekdeci, Brian

425

System architecture of offshore oil production systems  

E-print Network

This thesis presents an approach to applying Systems Architecture methods to the development of large, complex, commercial systems, particularly offshore oil and gas productions systems. The aim of this research was to ...

Keller, James (James Thomas)

2008-01-01

426

Systemic Risk in the International System  

E-print Network

The risk of systemic war seems dependant on the level of criticality and sensitivity of the International System, and the system's conditions. The level of criticality and sensitivity is dependant on the developmental stage of the International System. Initially, following a systemic war, the increase of the level of criticality and sensitivity go hand in hand. However, at a certain stage the sensitivity of the International System for larger sized wars decreases; as a consequence of a network effect, we argue. This network effect results in increased local stability of the System. During this phase the criticality of the International System steadily increases, resulting in a release deficit. This release deficit facilitates a necessary build up of energy to push the International System, by means of systemic war, into a new stability domain. Systemic war is functional in the periodic rebalancing of an anarchistic international system.

Ingo Piepers

2009-10-15

427

Testing of lift/cruise fan exhaust deflector. [for a tip turbine lift fan in short takeoff aircraft  

NASA Technical Reports Server (NTRS)

A lift/cruise exhaust deflector system for the LF336/A tip turbine lift fan was designed, built, and tested to determine the design and performance characteristics of a large-scale, single swivel nozzle thrust vectoring system. The exhaust deflector static testing was performed at the Ames Research Center outside static test stand facilities. The test hardware was installed on a hydraulic lift platform to permit both in and out of ground effect testing. The exhaust flow of the LF336/A lift fan was vectored from 0 degrees through 130 degrees during selected fan speeds to obtain performance at different operating conditions. The system was operated with and without flow vanes installed in the small radius bends to evaluate the system performance based on a proposed method of improving the internal flow losses. The program also included testing at different ground heights, to the nozzle exhaust plane, to obtain ground effect data, and the testing of two methods of thrust spoiling using a duct bypass door system and nozzle flap system.

Schlundt, D. W.

1975-01-01

428

X-33 Attitude Control Using the XRS-2200 Linear Aerospike Engine  

NASA Technical Reports Server (NTRS)

The Vehicle Control Systems Team at Marshall Space Flight Center, Structures and Dynamics Laboratory, Guidance and Control Systems Division is designing, under a cooperative agreement with Lockheed Martin Skunkworks, the Ascent, Transition, and Entry flight attitude control systems for the X-33 experimental vehicle. Test flights, while suborbital, will achieve sufficient altitudes and Mach numbers to test Single Stage To Orbit, Reusable Launch Vehicle technologies. Ascent flight control phase, the focus of this paper, begins at liftoff and ends at linear aerospike main engine cutoff (MECO). The X-33 attitude control system design is confronted by a myriad of design challenges: a short design cycle, the X-33 incremental test philosophy, the concurrent design philosophy chosen for the X-33 program, and the fact that the attitude control system design is, as usual, closely linked to many other subsystems and must deal with constraints and requirements from these subsystems. Additionally, however, and of special interest, the use of the linear aerospike engine is a departure from the gimbaled engines traditionally used for thrust vector control (TVC) in launch vehicles and poses certain design challenges. This paper discusses the unique problem of designing the X-33 attitude control system with the linear aerospike engine, requirements development, modeling and analyses that verify the design.

Hall, Charles E.; Panossian, Hagop V.

1999-01-01

429

40 HP Electro-Mechanical Actuator  

NASA Technical Reports Server (NTRS)

This report summarizes the work performed on the 40 BP electro-mechanical actuator (EMA) system developed on NASA contract NAS3-25799 for the NASA National Launch System and Electrical Actuation (ELA) Technology Bridging Programs. The system was designed to demonstrate the capability of large, high power linear ELA's for applications such as Thrust Vector Control (TVC) on rocket engines. It consists of a motor controller, high frequency power source, drive electronics and a linear actuator. The power source is a 25kVA 20 kHz Mapham inverter. The drive electronics are based on the pulse population modulation concept and operate at a nominal frequency of 40 kHz. The induction motor is a specially designed high speed, low inertia motor capable of a 68 peak HP. The actuator was originally designed by MOOG Aerospace under an internal R & D program to meet Space Shuttle Main Engine (SSME) TVC requirements. The design was modified to meet this programs linear rate specification of 7.4 inches/second. The motor and driver were tested on a dynamometer at the Martin Marietta Space Systems facility. System frequency response and step response tests were conducted at the Marshall Space Flight Center facility. A complete description of the system and all test results can be found in the body of the report.

Fulmer, Chris

1996-01-01

430

perovskite system  

NASA Astrophysics Data System (ADS)

Experiments using laser-heated diamond anvil cells combined with synchrotron X-ray diffraction and SEM-EDS chemical analyses have confirmed the existence of a complete solid solution in the MgSiO3-MnSiO3 perovskite system at high pressure and high temperature. The (Mg, Mn)SiO3 perovskite produced is orthorhombic, and a linear relationship between the unit cell parameters of this perovskite and the proportion of MnSiO3 components incorporated seems to obey Vegard's rule at about 50 GPa. The orthorhombic distortion, judged from the axial ratios of a/ b and monotonically decreases from MgSiO3 to MnSiO3 perovskite at about 50 GPa. The orthorhombic distortion in (Mg0.5, Mn0.5)SiO3 perovskite is almost unchanged with increasing pressure from 30 to 50 GPa. On the other hand, that distortion in (Mg0.9, Mn0.1)SiO3 perovskite increases with pressure. (Mg, Mn)SiO3 perovskite incorporating less than 10 mol% of MnSiO3 component is quenchable. A value of the bulk modulus of 256(2) GPa with a fixed first pressure derivative of four is obtained for (Mg0.9, Mn0.1)SiO3. MnSiO3 is the first chemical component confirmed to form a complete solid solution with MgSiO3 perovskite at the P- T conditions present in the lower mantle.

Li, Lin; Nagai, Takaya; Ishido, Tomoki; Motai, Satoko; Fujino, Kiyoshi; Itoh, Shoichi

2014-06-01

431

Denitrification system  

SciTech Connect

An improved multi-stage treatment system is described for biological denitrification of and suspended solids removal from water which comprises: a biological reactor, an aeration chamber and an automatic backwash filter, the reactor including a tank having a lower tank portion, a central tank portion and an upper tank portion, influent distribution means positioned in the lower tank portion, rigid media in the central tank portion capable of supporting denitrifying bacterial growths, and a plurality of collectors positioned in the upper tank portion, the collectors each including an outlet pipe, the chamber having a lower chamber portion, a central chamber portion and an upper chamber portion, aeration means positioned in the lower chamber portion, the outlet pipes of the collectors discharging into the lower chamber portion, and chamber outlet means associated with the central chamber portion, and the filter having a lower filter portion, a central filter portion, an upper filter portion and an effluent channel portion, the filter being divided into a plurality of seriate rectangular cells containing filter media, the chamber outlet means being associated with the central filter portion by which liquid contained in the aeration chamber may discharge into the filter to be filtered through the filter media, a separate port in each the cell beneath its the filter media for discharging filtered liquid from and charging backwash liquid to the respective the cell, the effluent channel portion being common to