Soft-handling gripper driven by piezoceramic bimorph strips

This paper is a study on the hybrid position/force control of a two-fingered miniature gripper driven by piezoelectric bimoph cells. The system is composed of the flexible cantilevers and a compact force sensor attached to the tip of one finger. Control action is applied by two piezoelectric bimorph strips placed at the base of each finger. The theoretical model of the electro-mechanical system is developed and applied to the study of a control problem where the gripper is commanded to grasp its object with a time-constant force 0.01 N at a prescribed commanded fingertip position. The PID control algorithm is introduced to drive the gripper. The system control behaviour is examined both theoretically and experimentally.