For trajectory tracking of a piezoelectric actuator system, an enhanced iterative learning control (ILC) scheme based on zero phase filtering is presented in this talk. The enhanced ILC scheme incorporates a state compensation in the ILC algorithm. The state compensation term is based on the difference of tracking error between the current and previous iterations at the present time. With the aid of this state compensation, iterative learning control can therefore take effect more precisely as desired, in comparison to the conventional D-type ILC and a proportional control aided D-type ILC. Further, the addition of the current error in the compensation term can also serve the role of feedback control to stabilize the system. The zero phase filter is adopted to filter learnable tracking errors without phase shift. Based on both a time-frequency ****ysis of tracking errors and a convergence bandwidth ****ysis of ILC, a suitable zero phase filteris chosen for ILC design in this study. The enhanced ILC scheme using zero phase filtering is applied to track a desired trajectory. Experimental results validate the efficacy of the enhanced ILC in terms of the speed of convergence and the level of long term tracking errors.
主持人:沈栋