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  • 1
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    Control and dynamics of an anti-friction levitation system (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A novel anti-friction levitator concept has been devised and analytically evaluated to overcome support bearing friction and thereby minimize the structural damping of the Large Spacecraft Control Laboratory (LSCL) experiment structure at JPL. A dynamic model and controller design have been developed for the new levitation system. Simulation results show excellent system performance even when the system is subjected to significant measurement noise and hardware saturation effects.
    Keywords: GROUND SUPPORT SYSTEMS AND FACILITIES (SPACE)
    Type: In: Dynamics and control of large structures; Proceedings of the 8th VPI&SU Symposium, Blacksburg, VA, May 6-8, 1991 (A93-29328 10-63); p. 615-630.
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  • 2
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    Experiments in multivariable adaptive control of a large flexible structure (1993)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 16; 1; p. 9-13.
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  • 3
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    Dynamics and control of a Shuttle-attached antenna experiment (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 8; 344-353
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  • 4
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    Space station dynamic modeling, disturbance accommodation, and adaptive control (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Dynamic models for two space station configurations were derived. Space shuttle docking disturbances and their effects on the station and solar panels are quantified. It is shown that hard shuttle docking can cause solar panel buckling. Soft docking and berthing can substantially reduce structural loads at the expense of large shuttle and station attitude excursions. It is found predocking shuttle momentum reduction is necessary to achieve safe and routine operations. A direct model reference adaptive control is synthesized and evaluated for the station model parameter errors and plant dynamics truncations. The rigid body and the flexible modes are treated. It is shown that convergence of the adaptive algorithm can be achieved in 100 seconds with reasonable performance even during shuttle hard docking operations in which station mass and inertia are instantaneously changed by more than 100%.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Proc. of the Workshop on Identification and Control of Flexible Space Struct., Vol. 1; p 103-139
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  • 5
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    Space Station dynamic modeling, control and simulation (1986)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Dynamic disturbances of many orders of magnitude greater than those of conventional spacecraft will be routine for the Space Station. Accurate knowledge of inflight structural dynamics and disturbances will be lacking. System identification will reduce uncertainties. To deal with the remaining model errors and time-varying elements, adaptive control may be required. Dynamic models for two Space Station configurations are derived. A direct model reference adaptive control algorithm is synthesized and evaluated with respect to the station model parameter errors and plant dynamics truncations. Both the rigid body and the flexible modes are treated. Simulation results show that convergence of the adaptive algorithm can be achieved in 100 to about 300 seconds with reasonable performance even during Shuttle hard docking operations in which station mass and inertia are instantaneously changed by more than 100 percent.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
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  • 6
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    An investigation of adaptive control techniques for space stations (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The present paper is concerned with control problems which arise in connection with the establishment and maintenance of space stations. Some of the arising problems are related to great changes in mass and an intensive shock load accompanying Shuttle docking. Such problems can be solved by making use of a robust adaptive control system. Space station configurations developed by NASA and the corresponding mass properties are discussed along with dynamic models for space stations, aspects of problem formulation and control architecture, adaptive control algorithms, a performance analysis, and practical considerations. Attention is given to adaptive regulator control with initial transient, adaptive control during Shuttle docking, and cases involving Shuttle hard docking with model switching and disturbance modeling.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
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  • 7
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    Dynamic modeling and adaptive control for space stations (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Of all large space structural systems, space stations present a unique challenge and requirement to advanced control technology. Their operations require control system stability over an extremely broad range of parameter changes and high level of disturbances. During shuttle docking the system mass may suddenly increase by more than 100% and during station assembly the mass may vary even more drastically. These coupled with the inherent dynamic model uncertainties associated with large space structural systems require highly sophisticated control systems that can grow as the stations evolve and cope with the uncertainties and time-varying elements to maintain the stability and pointing of the space stations. The aspects of space station operational properties are first examined, including configurations, dynamic models, shuttle docking contact dynamics, solar panel interaction, and load reduction to yield a set of system models and conditions. A model reference adaptive control algorithm along with the inner-loop plant augmentation design for controlling the space stations under severe operational conditions of shuttle docking, excessive model parameter errors, and model truncation are then investigated. The instability problem caused by the zero-frequency rigid body modes and a proposed solution using plant augmentation are addressed. Two sets of sufficient conditions which guarantee the globablly asymptotic stability for the space station systems are obtained.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-CR-176442 , JPL-PUB-85-57 , NAS 1.26:176442
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  • 8
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    Geometric error analysis for shuttle imaging spectrometer experiment (1984)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: The demand of more powerful tools for remote sensing and management of earth resources steadily increased over the last decade. With the recent advancement of area array detectors, high resolution multichannel imaging spectrometers can be realistically constructed. The error analysis study for the Shuttle Imaging Spectrometer Experiment system is documented for the purpose of providing information for design, tradeoff, and performance prediction. Error sources including the Shuttle attitude determination and control system, instrument pointing and misalignment, disturbances, ephemeris, Earth rotation, etc., were investigated. Geometric error mapping functions were developed, characterized, and illustrated extensively with tables and charts. Selected ground patterns and the corresponding image distortions were generated for direct visual inspection of how the various error sources affect the appearance of the ground object images.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-175665 , JPL-PUB-85-2 , NAS 1.26:175665
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  • 9
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    Flexible structure control laboratory development and technology demonstration (1987)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: An experimental structure is described which was constructed to demonstrate and validate recent emerging technologies in the active control and identification of large flexible space structures. The configuration consists of a large, 20 foot diameter antenna-like flexible structure in the horizontal plane with a gimballed central hub, a flexible feed-boom assembly hanging from the hub, and 12 flexible ribs radiating outward. Fourteen electrodynamic force actuators mounted to the hub and to the individual ribs provide the means to excite the structure and exert control forces. Thirty permanently mounted sensors, including optical encoders and analog induction devices provide measurements of structural response at widely distributed points. An experimental remote optical sensor provides sixteen additional sensing channels. A computer samples the sensors, computes the control updates and sends commands to the actuators in real time, while simultaneously displaying selected outputs on a graphics terminal and saving them in memory. Several control experiments were conducted thus far and are documented. These include implementation of distributed parameter system control, model reference adaptive control, and static shape control. These experiments have demonstrated the successful implementation of state-of-the-art control approaches using actual hardware.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: NASA-CR-184867 , JPL-PUBL-88-29 , NAS 1.26:184867
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  • 10
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    Experiments in multivariable adaptive control of a large flexible structure (1989)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A six-input/six-output multivariable adaptive controller is used to control a large 3-dimensional flexible structure experiment. For this purpose, the JPL/AFAL antenna-like experiment structure is used, with instrumentation distributed on both the hub and the ribs. This represents a significant increase in complexity relative to earlier adaptive control experiments performed on the same structure, utilizing a two-input/two-output set-up with instrumentation on the hub alone. The increase in instrumentation significantly increases spatial controllability, and excitation and control of a much larger set of modes. This paper documents multivariable adaptive control experiments on this structural configuration, and discusses many of the associated design and implementation issues required for successful operation.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA PAPER 89-3571 , AIAA Guidance, Navigation and Control Conference; Aug 14, 1989 - Aug 16, 1989; Boston, MA; United States
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