Driving And Control Research Of Piezoelectric Ceramic For Ultra-Precision Positioning

Piezoelectric ceramic is a functional material which can make a conversion between mechanical energy and electrical energy. Mechanical stresses in the piezoelectric materials produce measurable electric charge, which is referred to the direct piezoelectric effect. Vice verse, mechanical strains are geneeated in response to an applied electric field and this is called the inverse piezoelectric effect. Piezoelectric actuator is a precise positioning mechanism which is utilized the inverse piezoelectric effect.Piezoelectric actuator has been widely used in the fields of micro and nano positioning applications such as aerospace, data storage, optical communication,ultra-precision machining, biological engineering and semiconductor technology, due to the excellent advantages of small volume, fast response time, extremely fine resolution, large mechanical force and noiseless. In this paper, the actuator is applied in cavity ring-down spectroscopy(CRDS), In the detection of trace gas in atmosphere by CRDS, the precision and stability of length of optical cavity have a great influence on the final result, so it is necessary to control the length of the cavity precisely.According to system requirements, the positioning accuracy of the cavity length is3 nm.This paper studies the positioning principle and driving method of piezoelectricactuator, design and construct a control system of piezoelectric actuator based on stm32. In the system, a digital-analog conversion unit, a power amplifier unit, a displacement detection unit and a analog-digital conversion unit have been included,the designed system has advantages such as small size,easy control,and versatility.The testing results show that outputs of the control system have a good performance,and fit the design requirement well.Besides, piezoelectric actuator suffers from the inherent hysteresis effect because of loss phenomena taking place inside piezoelectric materials, the hysteresis effect exhibits complex nonlinear characterisitics, which usually introduces descent of accuracy or oscillation and even instability. In aim to reduce the influence of hysteresis nonlinear, this paper studies the theory and methodology of hysteresis modeling, nonlinear compensation and control, a Prandtl-Ishlinskii(PI) model has been proposed to describe the hysteresis loop of actuator, and radient descent method has been utilized to identify the model parameters, through the simulation of Matlab/Simulink, we can found that the model output and the actual data are well fitted. According to the PI model, a compounding control method with feedforward compensation based on inverse model has been designed, an inverse hysteresis compensator is developed to cancelate hysteresis in the feedforward loop, and a PID controller has been designed as a feedback controller to minimize the tracking errors.The simulation results demonstrate the effectiveness of the proposed control method.Finally, an experiment has been carried out, and the results show that the average positioning error is 10.5nm, the main reasons why there existing a gap when compared to the expected are the drawback of circuit designing and PCB layout, the test environment also have an influence on the results.