Nonlinear Modeling and Feedforward-Robust Adaptive Moving Average Control of SICM Micro-Positioning Stage
The high-precision positioning at the micro-nano scale is an important precondition for three-dimensional reconstruction using scanning ion conductance microscope (SICM). Piezoelectric ceramic micro-positioning stage is often used for such high-precision positioning. However, the hysteresis characteristic of piezoelectric ceramic is the main crux for nonlinear characteristics and control accuracy defects. In order to solve this problem, A T.C. Hsia method is proposed to analyze the piezoelectric ceramic actuator. Accordingly, a polynomial model with the expected displacement as input and the control voltage as output is established, which is used as a feedforward controller to compensate the hysteresis effect of piezoelectric ceramics directly. Meanwhile, robust adaptive moving average control method is adopted for feedback control. The results indicate that the hysteresis model based on A T.C. Hsia method can fit the hysteresis curve well. The maximum fitting error value is 1.0354, or error rate of 1.294%. The composite control of feedforward control and RAMAC reduced the hysteresis level from 17.64% to 3.64%, which decreased the effect of the hysteresis characteristics, and improved the performance of the piezoelectric ceramic controller in tracking the desired displacement.