Publication:
Development of precision pointing controllers with and without vibration suppression for the NPS precision pointing hexapod

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Authors
Bishop, Ronald Michael
Subjects
Advisors
Agrawal, Brij
Date of Issue
2002-12
Date
Publisher
Monterey, California. Naval Postgraduate School
Language
Abstract
Satellite optical payloads demand better vibration control and finer precision pointing than ever before. Fortunately, the Stewart-Gough platform offers the potential of accomplishing both of these simultaneously. Using the Precision Pointing Hexapod at NPS (a Stewart-Gough platform), several controllers for precision pointing, with and without vibration disturbances, were developed. Unlike the traditional means of pointing a hexapod, (i.e. sensing and controlling strut length to orient payload), this research used the payload orientation derived from payload mounted position sensors to determine orientation and provide feedback to the actuator controller. Small and large angle controllers were developed and evaluated for accuracy using static pointing and dynamic tracking tasks. The pointing controllers were then added to an Adaptive Disturbance Canceller and evaluated for pointing accuracy and vibration suppression performance given a single tone disturbance. The results showed a static pointing accuracy of Å 0.008Ê» and a dynamic pointing accuracy ranging from Å 0.05Ê» to Å 0.2Ê», depending on the size and speed of the circular trajectory. Vibration suppression down to the noise floor was achieved in all static orientations tested. As for dynamic circle-tracking performance, at least a 20 dB reduction in the fundamental disturbance was obtained without degradation in pointing accuracy.
Type
Thesis
Description
Series/Report No
Department
Aeronautics and Astronautics
Organization
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NPS Report Number
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Format
xvi, 99 p. : ill. (some col.) ;
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Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
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