Control of residual vibrations in the Space Shuttle remote manipulator system

This paper presents a new control algorithm for eliminating flexible structure residual oscillations. The pulse active damping (PAD) algorithm is developed and applied on the Space Shuttle Remote Manipulator System (RMS), which is probably the best existing example of a practical flexible manipulator. The proposed control algorithm is activated at the end of an RMS manoeuvre in order to damp out the end-effector oscillation in a fast manner. Basically, this is achieved by injecting torque pulses at the shoulder yaw and shoulder pitch joints so that associated cancelling oscillations at the end-effector are excited to "cancel" out the observed in-plane and out-of-plane end-effector vibrations. Robustness of this algorithm to the estimated natural frequency of the system is addressed and improved by a two-pulse control scheme. It is shown that high oscillations can be eliminated efficiently by PAD.