AOCS FOR AGILE SCIENTIFIC SPACECRAFT WITH MINI-CMG's

摘要

Mini Control Moment Gyros are electrical inertial actuators which can generate very high torque, wrt the reactions wheels. These momentum exchange devices are attractive for the attitude control system due to recoverable energy source and high actuation capability. They would be very convenient for low altitude scientific satellites, like Land Surface Processes and Interaction Mission, which would increase considerably the number of image acquisitions by decreasing the manoeuvres duration. The high pointing accuracy and stability required by this kind of satellites are compatible with such a technology. ALCATEL has developed in the frame of an ESA contract an AOCS simulator of Normal Operation Mode actuated by Mini-CMG's. It is based on fine equipment models, on some CMG's steering laws, and on additional tools. This software makes possible the sizing of a CMG's cluster wrt specified satellite missions and allows a fine evaluation of achievable performances with Mini-CMG's. Studies on AOCS with Mini-CMG's and more on the gimbal steering law have mainly been performed under CNES / DGA contract, in collaboration with CERT (ONERA). This software has been applied to demonstrate the improvement of the LSPIM ESA missions by using Mini-CMG 's. This paper demonstrates the feasibility of an efficient agile AOCS based on Mini-CMG's.