压电微夹钳的复合控制模型及实验

Model and Experiments for Compound Control of a Piezoelectric Micro-gripper

为提高压电微夹钳的夹持性能,设计复合控制系统对其控制.通过引入死区算子对PI模型进行改进,建立了微夹钳的迟滞模型,进而设计出其前馈控制器;对常规PID算法进行改进,设计出抛物线积分与微分先行的微夹钳PID反馈控制器;将前馈控制同PID反馈控制相结合,设计出微夹钳的复合控制器.在复合控制作用下,微夹钳达到5μm阶跃目标位移的响应时间为0.09 s,略快于前馈控制,明显快于PID反馈控制;在最大位移为15.2μm的参考输入作用下,若不考虑传感器噪声,复合控制的稳态误差几乎为0.实验结果表明,同前馈控制与PID反馈控制相比,复合控制具有良好的综合控制效果,即响应速度快、稳态精度高.

To improve the gripping performance of a piezoelectric micro-gripper, a compound control system is designed. The hysteresis model of the piezoelectric micro-gripper is presented through improving the PI （proportional-integral） model by using the dead zone operator, and the feedforward controller based on the hysteresis model is designed. Then a PID （proportional-integral-derivative） feedback controller with a parabola integral and differential forward is designed by improv-ing the conventional PID control algorithm. Finally, a compound controller is proposed, which consists of the feedforward controller and the modified PID feedback controller. Under the compound control, the response time of the micro-gripper descends to 0.09 s for a desired step signal of 5 μm, which is a little faster than the feedforward control, and significantly faster than the PID feedback control. Under the input of a maximum displacement of 15.2 μm, the steady-state error of com-pound control is almost zero if excluding the sensor noise. Experimental results indicate that the proposed compound control possesses better performance comparing with the feedforward control and the PID feedback control, such as faster response speed and higher steady-state accuracy.