Modal force based input shaper for vibration suppression of flexible payloads

Input shaping is a simple but effective method for vibration reduction of linear flexible systems. When systems exhibit nonlinear dynamics, the performance of an input shaper may be degraded. In this paper, a new shaper design scheme is developed for a nonlinear system which consists of a rigid robotic manipulator and a flexible sheet metal payload being grasped at several points by the robot gripper. The new scheme utilizes a parallel shaper structure based on the modal forces of payload vibration. A feedforward/feedback control law is also presented to drive the system to follow its shaped trajectory and to stabilize it at its desired position. Simulation results of a rest-to-rest robot motion control illustrate improved performance of the proposed input shaper, and verify the effectiveness of the control strategy.