Energy harvesting from a piezoelectric bender through rigid body motion of a two-link manipulator

Harvesting energy from persistent ambient vibrations for powering small electronic components has been an attractive subject for researchers in recent years. The direct piezo-electric effect of piezoceramic materials makes them very appealing for such applications. Typically, a piezoelectric harvester is a cantilevered bender with one or more piezoceramic layers. Usually, such harvester is located on a vibrating host structure for energy harvesting. The problem of extracting electrical outputs from structural vibrations by this approach has been examined in the literature. In this paper, we investigate a different approach for piezoelectric energy harvesting through a particular application. Rather than the structural vibrations of the host structure, we focus on its inertial fluctuations due to the rigid body motion. The host structure we consider is a typical two-link manipulator which executes a pick-place operation. The piezoelectric bender is located at a point on the elbow link of the manipulator and it vibrates due to the periodic rigid body motion of this link. The kinematics of a two-link manipulator is reviewed to obtain the acceleration at the base of the harvester for a given pick-place motion trajectory of the end effector. The analysis of the piezoelectric harvester is then presented based on a recently developed distributed parameter electromechanical model. The idea and the analysis presented here may be useful for powering sensors and other small electronic components attached to two-link manipulators and more sophisticated industrial robots