An inverse-free technique for attitude control of spacecraft using CMGS
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This paper presents a technique for CMG-based attitude control of spacecraft that does not require calculating the pseudo-inverse of the CMG Jacobian matrix. In order to obtain a steering law, the transpose of the Jacobian matrix is used rather than its pseudo-inverse. The transpose-based method alleviates some of the problems inherent in the existing steering laws that use the pseudo-inverse, such as high gimbal rates near singularities. The proposed method provides viable rates for the CMGs even when the gimbals pass through a singular configuration. The validity of the steering law is demonstrated using Liapunov's stability theorem, and it is shown that the method provides superior results when compared with conventional steering laws that use the pseudo-inverse of the CMG Jacobian Matrix. In addition, the redundant feature of the 4-gimbal CMG system is exploited to force the gimbals to attain certain specified angles while the spacecraft's attitude is being controlled. This is done by adding appropriate null motion to the CMGs. The specified angles for the gimbals can be arbitrary as long as their net momentum is consistent with the requirements of the spacecraft. 1997 Elsevier Science Ltd. All rights reserved.
