On robust impact control via positive acceleration feedback for robot manipulators

In this paper, a long outstanding problem, robust impact control and force regulation with guaranteed stability is solved by adding a novel positive acceleration, feedback to the feedback loop in the direction of impact and force control for robot manipulators working in an unknown environment. A quick and stable transition can be accomplished with a nonzero impact velocity, and the transient force response can be controlled with minimum impact forces and minimum bouncing. In addition, a switching control strategy is designed to guarantee the stability of the impact control. Unexpected bouncing can be eliminated after finite switches. The output force and motion can be regulated simultaneously with high accuracy after contact is established. Rigorous stability analysis based on the Liapunov-like method is presented for the proposed control scheme. The control scheme was implemented and tested on a 6 DOF PUMA 560 robot arm. The experimental comparisons with other force control strategies were given to demonstrate the advantage of the proposed method. The result obtained in this paper can be applied to any system requiring impact control and force regulation