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Control-structure interaction in precision pointing servo loopsThe control-structure interaction problem is addressed via stability analysis of a generic linear servo loop model. With the plant described by the rigid body mode and a single elastic mode, structural flexibility is categorized into one of three types: (1) appendage, (2) in-the-loop minimum phase, and (3) in-the-loop nonminimum phase. Closing the loop with proportional-derivative (PD) control action and introducing sensor roll-off dynamics in the feedback path, stability conditions are obtained. Trade studies are conducted with modal frequency, modal participation, modal damping, loop bandwidth, and sensor bandwidth treated as free parameters. Results indicate that appendage modes are most likely to produce instability if they are near the sensor rolloff, whereas in-the-loop modes are most dangerous near the loop bandwidth. The main goal of this paper is to provide a fundamental understanding of the control-structure interaction problem so that it may benefit the design of complex spacecraft and pointing system servo loops. In this framework, the JPL Pathfinder gimbal pointer is considered as an example.
Document ID
Document Type
Reprint (Version printed in journal)
Spanos, John T.
(California Institute of Technology Jet Propulsion Laboratory, Pasadena, United States)
Date Acquired
August 14, 2013
Publication Date
April 1, 1989
Publication Information
Publication: Journal of Guidance, Control, and Dynamics
Volume: 12
ISSN: 0731-5090
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