采用改进PI迟滞模型的压电微夹钳前馈控制

为减小压电微定位平台的迟滞误差, 设计前馈控制器对其进行控制. 首先在使所建平台迟滞模型精度达到要求并使各阈值点精度相同的情况下, 对平台迟滞模型的阈值进行优化, 得到满足模型精度要求的最小算子数, 进而建立了平台的PI(Prandtl-Ishilinskii)迟滞模型通过对所建迟滞模型求逆, 设计出平台的前馈控制器; 最后在所设计的前馈控制作用下, 使平台达到5μm理想阶跃值的响应时间为0.01s稳态误差中线的变化范围为0.40~0.50μm 当期望平台输出最大值为17μm变幅值三角波位移时, 实测位移相对于理想位移的误差中线变动范围为1.15~ -0.05μm. 所设计前馈控制器可有效减小压电微定位平台的迟滞误差.

Feedforward control of a piezoelectric microgripper using improved PI hysteresis model

In order to reduce the hysteresis error of piezoelectric microgripper displacement, a feedforward controller is designed for controlling purposes. First, the dead-zone operator is introduced to the conventional PI hysteresis model, and the hysteresis model of piezoelectric microgripper is built for non singular symmetric and non convex curve of piezoelectric microgripper hysteresis. Then, through the inverse calculations of the hysteresis model, the feedforward control algorithm for piezoelectric micro-gripper is developed. Finally, the feedforward control of piezoelectric microgripper is tested. The results show that when the displacement of piezoelectric microgripper clamp is in the range of 0-15.2 μm, the center line of the hysteresis error is reduced from -1.35-1.50 μm with no control to -0.95-0.47 μm with the feed forward control. The feedforward controller can significantly reduce the hysteresis error of piezoelectric microgripper and improve the tracking accuracy of the reference input.