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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Metal hydride heat pump engineering demonstration and evaluation model

Future generations of portable life support systems (PLSS's) for space suites (extravehicular mobility units or EMU's) may require regenerable nonventing thermal sinks (RNTS's). For purposes of mobility, a PLSS must be as light and compact as possible. Previous venting PLSS's have employed water sublimators to reject metabolic and equipment heat from EMU's. It is desirable for long-duration future space missions to minimize the use of water and other consumables that need to be periodically resupplied. The emission of water vapor also interferes with some types of instrumentation that might be used in future space exploration. The test article is a type of RNTS based on a metal hydride heat pump (MHHP). The task of reservicing EMU's after use must be made less demanding in terms of time, procedures, and equipment. The capability for quick turnaround post-EVA servicing (30 minutes) is a challenging requirement for many of the RNTS options. The MHHP is a very simple option that can be regenerated in the airlock within the 30 minute limit by the application of a heating source and a cooling sink. In addition, advanced PLSS's must provide a greater degree of automatic control, relieving astronauts of the need to manually adjust temperatures in their liquid cooled ventilation garments (LCVG's). The MHHP includes automatic coolant controls with the ability to follow thermal load swings from minimum to maximum in seconds. The MHHP includes a coolant loop subsystem with pump and controls, regeneration equipment for post-EVA servicing, and a PC-based data acquisition and control system (DACS).

Lynch, Franklin E.↗
NASA NTRS1978

Use of piloted simulation for studies of fighter departure/spin susceptibility

The NASA-Langley Research Center has incorporated into its stall/spin research program on military airplanes the use of piloted, fixed-base simulation to complement the existing matrix of unique research testing techniques. The piloted simulations of fighter stall/departure flight dynamics are conducted on the Langley Differential Maneuvering Simulator (DMS). The paper reviews the objectives of the simulation research, presents the rationale underlying the simulation methods and procedures used in the evaluation of airplane characteristics, and discuss in detail the evaluation steps used to assess fighter stall/departure characteristics. Simulation results are presented to illustrate the flight-dynamics phenomena dealt with. The use of the piloted simulation methods and procedures described has been found very effective in identifying stability and control problem areas and in developing automatic control concepts to alleviate many of these problems. A good level of correlation between simulated flight dynamics and flight-test results has been obtained over the many fighter configurations studied in the simulator.

Gilbert, W. P.↗
NASA NTRS1978

Use of piloted simulation for studies of fighter departure/spin susceptibility

The NASA-Langley Research Center has incorporated into its stall/spin research program on military airplanes the use of piloted, fixed-base simulation to complement the existing matrix of unique research testing techniques. The piloted simulations of fighter stall/departure flight dynamics are conducted on the Langley Differential Maneuvering Simulator (DMS). The objectives of the simulation research are reviewed. The rationale underlying the simulation methods and procedures used in the evaluation of airplane characteristics is presented. The evaluation steps used to assess fighter stall/departure characteristics are discussed. Simulation results are presented to illustrate the flight dynamics phenomena dealt with. The considerable experience accumulated in the conduct of piloted stall/departure simulation indicates that simulation provides a realistic evaluation of an airplane's maneuverability at high angles of attack and an assessment of the departure and spin susceptibility of the airplane. This realism is obtained by providing the pilot a complete simulation of the airplane and control system which can be flown using a realistic cockpit and visual display in simulations of demanding air combat maneuvering tasks. The use of the piloted simulation methods and procedures described were found very effective in identifying stability and control problem areas and in developing automatic control concepts to alleviate many of these problems. A good level of correlation between simulated flight dynamics and flight test results were obtained over the many fighter configurations studied in the simulator.

Gilbert, W. P.↗
NASA NTRS1991

Docking System With Video Feedback

Video-sensor/electronic-feedback control system being developed to provide automatic control of final stage of approach of active vehicle to passive vehicle or object. No communication between vehicles necessary. Docking target, mounted on post on passive vehicle, has three reflective dots, positions of which measured in image to determine relative position and orientation of target and vehicle. Control channels process video-sensor feedback into motion-control signals (thrustor commands in spacecraft or motor commands in robot). Conceived for use aboard chasing spacecraft to control its maneuvers in docking with chased spacecraft, concept also useful in controlling coupling of aircraft in flight or vessels on water or in controlling approach of robot to object to be manipulated.

Dabrey, Richard↗
NASA NTRS1981

Comparative study of flare control laws

The development of a digital, three dimensional, automatic control law designed to achieve an optimal transition of a B-737 aircraft between glide slope conditions and the desired final touchdown condition is presented. The digital control law is a time invariant, state estimate feedback law, and the design is capable of using the microwave landing system. Major emphasis is placed on the reduction of aircraft noise in communities surroundings airports, the reduction of fuel consumption, the reduction of the effects of adverse weather conditions on aircraft operations, and the efficient use of airspace in congested terminal areas. Attention is also given to the development of the capability to perform automatic flares from steep glide slopes to precise touchdown locations.

Nadkarni, A. A.↗
NASA NTRS1965

Planetary camera control improves microfiche production

Microfiche is prepared using an automatic control system for a planetary camera. The system provides blank end-of-row exposures and signals card completion so the legend of the next card may by photographed.

Chesterton, W. L.↗
NASA NTRS1962

Study of an Automatic System for Control of the Terminal Phase of Satellite Rendezvous

An analytical and simulation study has been conducted of an automatic system for control of the terminal phase of rendezvous between two space vehicles. The basic system employs switching and thrust orientation criteria based upon relative-motion parameters first to establish a collision course and then to reduce the range and range rate to zero, simultaneously. In addition, a technique has been devised by which the system effects control based upon the total amount of fuel available for this phase of the space mission. The onboard equipment assumed for the intercepting vehicle includes a special-purpose computer, an attitude-control system, a single main rocket engine with, multi-start capabilities, and sensors capable of measuring range, line-of sight angles, and the time derivatives of these quantities. Techniques are developed. for employing control with either modulated thrust or on-off thrust at a constant level. The results of an analog simulation study of the automatic control system in which a six-degree-of freedom vehicle is assumed are presented for various initial conditions at the beginning of the terminal phase. The results of the study indicate that the automatic system can effectively control the terminal phase of rendezvous over a wide range of initial conditions and control-system requirements and, in addition, can utilize the available fuel in a very efficient manner.

RENDEZVOUS↗
NASA NTRS1975

System integration of pattern recognition, adaptive aided, upper limb prostheses

The requirements for successful integration of a computer aided control system for multi degree of freedom artificial arms are discussed. Specifications are established for a system which shares control between a human amputee and an automatic control subsystem. The approach integrates the following subsystems: (1) myoelectric pattern recognition, (2) adaptive computer aiding; (3) local reflex control; (4) prosthetic sensory feedback; and (5) externally energized arm with the functions of prehension, wrist rotation, elbow extension and flexion and humeral rotation.

Lyman, J.↗
NASA NTRS1993

Multivariable control of the Space Shuttle Remote Manipulator System using linearization by state feedback

This paper demonstrates an approach to nonlinear control system design that uses linearization by state feedback to allow faster maneuvering of payloads by the Shuttle Remote Manipulator System (SRMS). A nonlinear feedback law is defined to cancel the nonlinear plant dynamics so that a linear controller can be designed for the SRMS. First a nonlinear design model was generated via SIMULINK. This design model included nonlinear arm dynamics derived from the Lagrangian approach, linearized servo model, and linearized gearbox model. The current SRMS position hold controller was implemented on this system. Next, a trajectory was defined using a rigid body kinematics SRMS tool, KRMS. The maneuver was simulated. Finally, higher bandwidth controllers were developed. Results of the new controllers were compared with the existing SRMS automatic control modes for the Space Station Freedom Mission Build 4 Payload extended on the SRMS.

Gettman, Chang-Ching L.↗
NASA NTRS1984

Microwave ice accretion meter

A system for indicating ice thickness and rate of ice thickness growth on surfaces is disclosed. The region to be monitored for ice accretion is provided with a resonant surface waveguide which is mounted flush, below the surface being monitored. A controlled oscillator provides microwave energy via a feed point at a controllable frequency. A detector is coupled to the surface waveguide and is responsive to electrical energy. A measuring device indicates the frequency deviation of the controlled oscillator from a quiescent frequency. A control means is provided to control the frequency of oscillation of the controlled oscillator. In a first, open-loop embodiment, the control means is a shaft operated by an operator. In a second, closed-loop embodiment, the control means is a processor which effects automatic control.

Magenheim, Bertram↗
NASA NTRS1973

Control of a 30 cm diameter mercury bombardment thruster

Increased thruster performance has made closed-loop automatic control more difficult than previously. Specifically, high perveance optics tend to make reliable recycling more difficult. Control logic functions were established for three automatic modes of operation of a 30-cm thruster using a power conditioner console with flight-like characteristics. The three modes provide (1) automatic startup to reach thermal stability, (2) steady-state closed-loop control, and (3) the reliable recycling of the high voltages following an arc breakdown to reestablish normal operation. Power supply impedance characteristics necessary for stable operation and the effect of the magnetic baffle on the reliable recycling was studied.

Terdan, F. F.↗