Piezoelectric self-sensing technique for tweezer style end-effector

This paper presents the application of a piezoelectric self-sensing technique based on discharged current to robotic tweezers incorporating a rhombus strain amplification mechanism driven by serially connected piezoelectric stack actuators. Connecting a shunt resistor in series with a piezoelectric element allows it to be used simultaneously as an actuator and a sensor by measuring the current generated by the piezoelectric element. This allows the displacement and force to be measured without extra sensors or the loss of actuation capability. Applying an inverse model of the nested structure allows the force and displacement at the tip of the tweezers to be determined. The accuracy of this method is then examined by experiment for the case of free displacement.