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A Gyroless Safehold Control Law using Angular Momentum as an Inertial Reference VectorA novel safehold control law was developed for the nadir-pointing Vegetation Canopy Lidar (VCL) spacecraft, necessitated by a challenging combination of constraints. The instrument optics did not have a reclosable cover to protect them from potentially catastrophic damage if they were exposed to direct sunlight. The baseline safehold control law relied on a single-string inertial reference unit. A gyroless safehold law was developed to give a degree of rebustness to gyro failures. Typical safehold solutions were not viable; thermal constraints made spin stabilization unsuitable, and an inertial hold based solely on magnetometer measurements wandered unacceptably during eclipse. The novel approach presented here maintains a momentum bias vector not for gyroscopic stiffness, but to use as an inertial reference direction during eclipse. The control law design is presented. The effect on stability of the rate-deficiency of magnetometer-based rate derivation is assessed. The control law's performance is evaluated by simulation.
Document ID
20080032779
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Stoneking, Eric
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Lebsock, Ken
(Orbital Sciences Corp. Greenbelt, MD, United States)
Date Acquired
August 24, 2013
Publication Date
August 18, 2008
Subject Category
Solar Physics
Meeting Information
Meeting: AIAA GNC Conference
Location: Honolulu, HI
Country: United States
Start Date: August 18, 2008
End Date: August 21, 2008
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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