Closed-Loop Control of Photovoltage for Photovoltaic-Electrostatic Driven Servo System

It is experimentally confirmed that the response speed of photo-induced deformation lags far behind the photovoltage and it is difficult to control the magnitude of the photo-induced electric field in PLZT ceramic due to the serious residual photovoltage. The primary purpose of this article is to control the photovoltage of PLZT for a photovoltaic-electrostatic driven servo system proposed in this paper. The control equations of photovoltage for photovoltaic-electrostatic driven servo system are derived based on the mathematical model of PLZT with coupled multi-physics fields. Parameters of photovoltage of PLZT ceramic during the illumination phase and light off phase are identified through the static experiment. Based on simple on-off control strategy, real-time switching the UV light via an optical shutter is adopted to achieve the desired photovoltage. Then, the closed-loop photovoltage control experiments for photovoltaic-electrostatic driven servo system based on PLZT ceramic are carried out. The experimental results show that the photovoltage can be successfully controlled at the target degree by switching the UV light with an optical shutter. The control strategy can be applied in the photovoltaic-electrostatic driven servo system to achieve the target degree of angular or displacement deflection.