超磁致伸缩致动器的广义预测-多模PID控制

为了克服超磁致伸缩致动器的磁滞现象对精密驱动定位精度的影响,在进行磁滞补偿的前提下,研究了自校正PID控制方法,提出了基于广义预测控制的广义预测-多模PID控制方法。介绍了广义预测控制的主要思想,并由此导出PID参数与被控对象待估参数的关系,实现了广义预测PID控制;针对起动阶段控制效果不平稳的问题,提出了多模PID控制模式转换条件;最后,根据PID参数变化情况,建立致动器的多模PID控制方法,实现广义预测PID与常规PID的在线控制模式转换与控制。实验结果表明,采用广义预测-多模PID控制器,虽然单次平均运算时间比广义最小方差-模糊PID控制器长7ms,但跟踪误差均方差减少了0.066μm;同时改善了起动平稳性。提出的控制方法能有效消除由扰动带来的影响,提高跟踪精度,改善起动平稳性,适用于对实时性、控制精度要求较高的精密定位领域。

Generalized predictive-multimode PID control for giant magnetostrictive actuators

In order to overcome the significant impact of hysteresis on positioning precision when Giant Magnetostrictive Material Actuators(GMAs)are applied to fine positioning, an adaptive PID control method is studied and a multimode PID control method based on Generalized Predictive Control (GPC)principle is established under the condition of the hysteresis compensation. Firstly, the relation between the parameters of PID controller and the parameters to be estimated is derived from GPC principle, and GPC-PID control is realized. Then, for the quibble problem at the beginning stage, the control mode switch condition of multimode PID control is put forward. Finally, a multimode PID controller for the actuator is setup to switch the control modes from the regular PID to the GPC-PID in real time based on PID parameter variability. Experimental results indicate that although the GPC-multimode PID controller extends the consuming time of each execution step slightly by 7 ms, the RMS of tracking error is reduced by 0.066 μm as compared with a Generalized Minimum Variability-Fuzzy PID (GMV-Fuzzy PID) controller, and at the same time, it improves the stability of the beginning stage. These results show that the multimode PID controller can overcome the impact of system disturbance, smooth the beginning status and can be suitable for the precision positioning with high accuracy and real time.