Vision Measurement of Twisting a Double-Bimorph Piezoelectric Actuator

Piezoelectric actuators are devices that convert electrical energy into mechanical energy. One of the applied structures of such actuators is a cantilever beam, which is composed of a nonpiezoelectric carrier layer and one or more piezoelectric active layers. The twisting motion of such a beam can be generated by using a double-bimorph structure, in which the beam twisting can be generated by the appropriate control of each of the two bimorphs. However, obtaining the desired twist angle requires the displacements of both bimorphs to be measured. The need to measure these displacements significantly limits the applicability of this type of actuator for generating twisting motions, because the size of the displacement sensors and their mounting components, which can significantly exceed the size of the beam actuator itself, means that a large space is needed to implement the twist angle measurement system. It is, therefore, necessary to develop techniques for controlling such an actuator based on a mathematical model. In this paper, a vision method was proposed to verify the mathematical model of a double-bimorph actuator. The results of these experiments can be used to synthesize a control system of the twist angle of the double-bimorph actuator without the need for displacement measurements of both bimorphs.