Abstract: An active damping and relative position control system is proposed for spacecraft with large antenna in this paper. This system employs a camera to measure the vibration of the antenna, and an active pointing ultra quiet platform for actuation. Research efforts are made in the modeling and control design of such a system, and the performance of the system is evaluated through both numerical and experimental tests. Because the camera measures the tip motion of the antenna and the actuators are placed at the root of the antenna, non collocated control techniques must be employed. A controller is proposed that can achieve both active damping and position control of the antenna. The controller consists of an integral controller and a structural filter in series connection. It can also be interpreted as a proportional integral differential control with a low pass filter. The controller provides active damping for the first flexible mode while stabilizing higher order modes. Based on this controller, a two stage controller is also designed for the coupled spacecraft antenna dynamics. Numerical and experimental tests show that the proposed control system can rapidly attenuate the vibration of the antenna, and the settling time is shorten to 1/10~1/100 of that of free vibration. It is also demonstrated that the proposed control system provides rapid position control capability for the antenna.

Key words: flexible spacecraft, active damping, active pointing ultra quiet platform, non collocated control, experimental demonstration