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7 September 2006 SOFIE pointing control system
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The SOFIE pointing control system (PCS) locates and tracks the top edge of the sun and periodically scans the solar disk for calibration. Primary hardware components are a steering mirror assembly (SMA), sun sensor, vibration isolation system (VIS), and associated electronics. The SMA has a 100-Hz control bandwidth and is capable of ±1.6 mechanical degree deflection in azimuth and elevation axes. The sun sensor uses a 1024x1024 pixel, radiation-hardened focal plane array and coarse and fine tracking algorithms to report the solar centroid and edge positions to the PCS. The PCS control law uses this information to command the SMA. A change in launch loads necessitated the development of the VIS, which features passive viscoelastic damping to protect the SMA. A rapid prototyping methodology was used to develop the control laws for the inner SMA feedback loop and outer PCS feedback loop. The methodology features integrated end-to-end modeling of structural dynamics, controls, and optics; automatic C-code synthesis from block diagrams; real-time hardware-in-the-loop (HIL) testing; and the ability to change control parameters "on the fly." Extensive testing of the PCS shows stable pointing performance of about 2 arcsec in the presence of 60-arcsec disturbances, compared to the requirement of 15 arcsec.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Steven R. Wassom, Chad Fish, Mitch Whiteley, Dave Russak D.V.M., Joel Nelsen, Brian Thompson, Glen Hansen, Jason Wooden, Larry Gordley, John Burton, Mark Hervig, Paul Cucchiaro, and Dan Hammerle "SOFIE pointing control system", Proc. SPIE 6297, Infrared Spaceborne Remote Sensing XIV, 62970I (7 September 2006);


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