Control of gimbal dynamics via sensitivity models for uncertainty in friction parameters

Tracking control of the beta gimbals for the solar array panels on the space station Freedom is investigated. In particular, the issue of control in the presence of uncertainty in motor friction parameters is addressed. The impact of parametric uncertainty on gimbal performance is analyzed by incorporating sensitivity functions in the feedback loop to desensitize the gimbal control law to parameter variations. The simulation results indicate that the inclusion of one particular sensitivity function yields some improvements in closed-loop performance when friction parameters are varied from their nominal values