Iterative learning variable structure controller for high-speed and high-precision point-to-point motion

In this paper, an iterative learning variable structure controller is proposed for the fast point-to-point motion. The motion is first divided into two stages: high-speed motion and high-precision positioning. Then the controllers are designed for these two stages, respectively. An iterative learning law is developed to determine the switch position. Based on this switch position a controller is proposed for the high-speed motion. Subsequently, a sliding controller is designed for the high-precision positioning stage. This controller is implemented on an X–Y positioning table. The results of the experiments show that it performs well and almost no overshoot exists if the discontinuous projection is used. The settling time is also reduced greatly, which is very important in the point-to-point motion in this paper.