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  • 1
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    A hardware demonstration of distributed control for a flexible offset-feed antenna (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A fully instrumented hardware model of a flexible offset-feed antenna has been constructed for laboratory tests. Three rate gyros, four angular position laser sensors, and a set of ten distributed accelerometers are used to rconstruct the antenna state. Three control moment gyros are used to simultaneously orient the antenna, and to maintain a stable line of sight. A description is presented of the distributed antenna control system and experimental results.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: JPL Proc. of the Workshop on Identification and Control of Flexible Space Struct., Vol. 1; p 253-268
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  • 2
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    Hardware verification of distributed/adaptive control (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Adaptive control techniques are studied for their future application to the control of large space structures, where uncertain or changing parameters may destabilize standard control system designs. The approach used is to examine an extended Kalman filter estimator, in which the state vector is augmented with the unknown parameters. The associated Riccatti equation is linearized about the case of exact knowledge of the parameters. By assuming that parameter variations occur slowly, the filter complexity is reduced further yet. Simulations on a two degree-of-freedom oscillator demonstrate the parameter-tracking capability of the filter, and an implementation on the JPL Flexible Beam Facility using an incorrect model shows the adaptive filter/optimal control to be stable where a standard Kalman filter/optimal control design is unstable.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Proc. of the Workshop on Appl. of Distributed System Theory to the Control of Large Space Struct.; p 337-350
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  • 3
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    Distributed system modeling of a large space antenna (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A general approach for distributed parameter modeling of complex dynamical systems is described. The method consists of dividing the system in parts which can be modeled by simple partial differential equations and coupling the equations thus obtained by applying Hamilton's variational formalism to the entire system. The modeling of a large, offset-fed, wrap-rib antenna is presented to illustrate the approach. Although such models are perhaps not as precise as finite element models, they can be useful for initial physical insight and parametric design.
    Keywords: STRUCTURAL MECHANICS
    Type: Proc. of the Workshop on Appl. of Distributed System Theory to the Control of Large Space Struct.; p 89-102
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  • 4
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    Adaptive Filtering for Large Space Structures: A Closed-Form Solution (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: In a previous paper Schaechter proposes using an extended Kalman filter to estimate adaptively the (slowly varying) frequencies and damping ratios of a large space structure. The time varying gains for estimating the frequencies and damping ratios can be determined in closed form so it is not necessary to integrate the matrix Riccati equations. After certain approximations, the time varying adaptive gain can be written as the product of a constant matrix times a matrix derived from the components of the estimated state vector. This is an important savings of computer resources and allows the adaptive filter to be implemented with approximately the same effort as the nonadaptive filter. The success of this new approach for adaptive filtering was demonstrated using synthetic data from a two mode system.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: JPL Proc. of the Workshop on Identification and Control of Flexible Space Struct., Vol. 3; p 161-173
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  • 5
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    Experimental demonstration of the control of flexible structures (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Large Space Structure Technology Flexible Beam Experiment employs a pinned-free flexible beam to demonstrate such required methods as dynamic and adaptive control, as well as various control law design approaches and hardware requirements. An attempt is made to define the mechanization difficulties that may inhere in flexible structures. Attention is presently given to analytical work performed in support of the test facility's development, the final design's specifications, the control laws' synthesis, and experimental results obtained.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 7; 527-534
    Format: text
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  • 6
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    Control technology development (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The main objectives of the control technology development task are given in the slide below. The first is to develop control design techniques based on flexible structural models, rather than simple rigid-body models. Since large space structures are distributed parameter systems, a new degree of freedom, that of sensor/actuator placement, may be exercised for improving control system performance. Another characteristic of large space structures is numerous oscillatory modes within the control bandwidth. Reduced-order controller design models must be developed which produce stable closed-loop systems when combined with the full-order system. Since the date of an actual large-space-structure flight is rapidly approaching, it is vitally important that theoretical developments are tested in actual hardware. Experimental verification is a vital counterpart of all current theoretical developments.
    Keywords: LAUNCH VEHICLES AND SPACE VEHICLES
    Type: NASA. Langley Research Center Large Space Systems Technol., 1981; p 297-311
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  • 7
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    Spacecraft drag-free technology development: On-board estimation and control synthesis (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Estimation and control methods for a Drag-Free spacecraft are discussed. The functional and analytical synthesis of on-board estimators and controllers for an integrated attitude and translation control system is represented. The framework for detail definition and design of the baseline drag-free system is created. The techniques for solution of self-gravity and electrostatic charging problems are applicable generally, as is the control system development.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-CR-169141 , JPL-Pub-82-45 , NAS 1.26:169141
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  • 8
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    Estimation of distributed parameter systems (1982)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The estimation and control of large flexible space structures pose significant new control technology problems. One major problem area is the closed-loop stability of a structure that has been modeled with truncated modal dynamics. Stability problems arise due to the control design process beginning with a deficient model. This work provides the necessary conditions for the optimal estimation of infinite dimensional (partial-differential equation) systems. This approach can be particularly useful for initial control studies and for gaining considerable insight into what the optimal estimator for a truly infinite dimensional system should be. A detailed example of the estimation of the continuous shape of a string in tension is presented.
    Keywords: CYBERNETICS
    Type: Journal of Guidance; vol. 5
    Format: text
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  • 9
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    Distributed control of large space structures (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Theoretical developments and the results of laboratory experiments are treated as they apply to active attitude and vibration control, as well as static shape control. Modern control theory was employed throughout as the method for obtaining estimation and control laws.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-CR-164365 , JPL-PUB-81-15
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  • 10
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    Calculating Closed-Loop Sensitivity to Parameter Variations (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Performance sensitivity calculated by back substitution. Original Lyapunov equation differentiated two times with respect to parameter p. Each differential turns out to yield Lyapunov equation for first and second derivatives with respective to parameter p of steady-state covariance of state variables. Derivatives desired closed-loop performance sensitivities.
    Keywords: MATHEMATICS AND INFORMATION SCIENCES
    Type: NPO-15941 , NASA Tech Briefs (ISSN 0145-319X); 8; 3; P. 423
    Format: text
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