高频响伺服刀架的建模与控制

Model and control of high-frequency response servo tool

考虑目前应用压电陶瓷驱动器的伺服刀架只能提供单向驱动力,设计了一种基于双压电陶瓷驱动器的快速伺服刀架。涉及的两个压电陶瓷驱动器分别为刀具的进给和回复提供驱动力,其呈对称布置,用于有效提高刀架的整体刚度。为了对两个压电陶瓷驱动器进行联动协调控制,建立了PI迟滞模型和其逆模型,并设计了相应的联动协调控制方法。利用PI逆模型作为PID反馈控制的前馈环节构成复合控制用于调节快速伺服刀架的输出位移。实验验证了新型快速伺服刀架的响应频率、响应时间、位移响应特性和定位精度。结果显示:新型快速伺服刀架的响应频率为871.86 Hz,响应时间为0.000 45s;三角波信号的最大定位误差为3.366 1μm,误差百分数为7.63%,平均绝对误差为0.698 0μm,误差百分数为1.58%;正弦波信号的最大定位误差为3.244 4μm,误差百分数为7.67%,平均绝对误差为0.930 9μm,误差百分数为2.20%。

As the fast servo tool based on piezoelectric actuators only provides one-way driving force, a new fast servo tool based on dual piezoelectric actuators was designed. The two piezoelectric actuators in the fast servo tool were used to provide driving forces for feeding and recovery of tools and they were symmetrically arranged for effectively enhancing the overall stiffness of the servo tool. To con- trol the two piezoelectric actuators, a PI model of dual piezoelectric actuators and its inverse model were established, and corresponding linkage coordinate control method was presented. Then, the PI inverse model was used as a feed-forward segment of PID feed-back control to construct a composite control to adjust the output displacement of fast servo tool . Experimental results show that the re- sponse frequency of new fast servo tool is 871.86 Hz, and response time is 0. 000 45 s. When the in- putting signal is a triangular wave, the maximum positioning error is 3. 366 1 μm and the average ab- solute error is 0. 698 0 μm. When the inputting signal is a sine wave, the maximum positioning erroris 3.94 4μm and the average absolute error is 0. 930 9μm.