The Iterative Learning Control for the Position Tracking of the Hydraulic Cylinder

The iterative learning control (ILC) learns the unknown information from repeated control operations. The tracking error from previous stages is used as the correction factor for the next control action. Therefore, the ILC controller can make the system tracking error converge to a small region within the limited numbers of iterations. In this paper, a proportional-valve-controlled hydraulic cylinder system with repeated external loads is built to perform the position tracking control experiments. The PID and ILC controllers are implemented in these experiments and the results are compared. The P-type update law with delay parameter is used for its position tracking control. Experimental results show that the ILC controller can effectively controls the system to track the repetitive position trajectory, especially in transient response that traditional control methods can't follow appropriately. Therefore, in this application, the control performance of the ILC is superior to the traditional PID controller.