Research On Iterative Learning Control Algorithms

Iterative Learning Control is a relatively new addition to the control engineer's toolkit that, for a particular class of problems, can be used to overcome some of the traditional difficulties associated with performance design of control systems. Specifically, iterative learning control, or ILC, is a technique for improving the transient response and tracking performance of processes, machines, equipments or systems that execute the same trajectory, motion ori operation over and over. The approach is motivated by the observation that, if the system controller is fixed and if the system's initial operating conditions are the same each time it executes, then any errors in the output response will be repeated during each operations. These errors can be recorded during system operation and can then be used to compute modifications to the input signal that will be applied to the system during the next operation, or trial, of the system. In iterative learning control, refinements are made tothe input signal after each trial until the desired performance level is reached. Research in the field of iterative learning control primarily focuses on the algorithms that are used to update the input signal.In this dissertation, firstly, in chapter 1, the author introduced some concepts of iterative learning control, including its history, its ' problem description, and its connections with other control paradigms. In chapter 2, we proposed a PID-type closed loop ILC algorithm. This algorithm has advantages in excellent stableness, robustness and rapid learning rate. These advantages were proved by both theoretical and simulated examples. In chapter 3, learning rate of iterative learning control is presented. At the same time, the .author discussed three factors that have impacts on learning rate. Also, the ways improving the learning rate were suggested. Finally, the simulation examples were also provided. In the last chapter, the author forecasted the future developments of iterative learning control.