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Energy-Efficient Active Reflectors with Improved Mechanical Stability

Bradford, Samuel Case and Hofmann, Douglas C. and Roberts, Scott N. and Wojnar, Charles S. and Kochmann, Dennis M. (2015) Energy-Efficient Active Reflectors with Improved Mechanical Stability. In: 2nd AIAA Spacecraft Structures Conference. American Institute of Aeronautics and Astronautics , Reston, VA, Art. No. 2015-1400. ISBN 978-1-62410-345-2.

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Active reflectors use an array of distributed actuators to control static surface deformations. In addition to meeting mission requirements with lower mass and lower costs, an active reflector adds robustness to a mission design by allowing for correction of unexpected orbital deformations. To control the wavefront of an active reflector, first the surface aberration is measured (via, e.g., a Shack-Hartmann sensor, direct imaging of the reflector surface, interferometric metrology, image-based PSF estimation, or other methods). Based on an actuator sensitivity matrix, a voltage profile is calculated that best reduces the observed aberration. In addition to controlling the static wavefront, piezoelectric actuators can easily be used to control structural vibrations in the frequency ranges of interest for active reflectors (50 to 2000Hz). Operational vibrations (e.g., microdynamics, ACS-induced vibrations, slew, thermally-induced stick-slip events) can effectively be rejected from the reflector system. Launch load vibrations are typically drivers for structural requirements, and typical mission concepts would have reflector actuators unpowered or shorted during launch. By incorporating a vibration control system into the actuator power circuitry, launch loads on the fragile reflector structure can be significantly reduced. By improving the electromechanical coupling and deliberately operating in a new nonlinear piezoelectric regime, we have optimized the surface correction and use the same actuators developed for surface control as structural control elements. This has yielded improved performance in terms of power draw and also enabled vibration suppression for launch load and operational disturbances.

Item Type:Book Section
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Kochmann, Dennis M.0000-0002-9112-6615
Additional Information:© 2015 American Institute of Aeronautics and Astronautics. Published Online: 2 Jan 2015.
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AIAA Paper2015-1400
Record Number:CaltechAUTHORS:20191017-080904981
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Official Citation:Energy-Efficient Active Reflectors with Improved Mechanical Stability. Samuel Bradford, Douglas Hofmann, and Dennis Kochmann. 2nd AIAA Spacecraft Structures Conference. January 2015.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99320
Deposited By: Tony Diaz
Deposited On:22 Oct 2019 22:35
Last Modified:22 Oct 2019 22:35

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