Research On Iterative Learning Control Method And Its Application For Fed-batch Process

Iterative learning control (ILC) is a new technique of intelligence control field for improving the transient response performance of systems that operate repetitively over a fixed time interval. Its fundamental principle is to acquire the current iterative input based on the former input signals and error signals. ILC can achieve the tracking of a desired output trajectory to a high precision.The main contents and results of this thesis are summarized as follows:(1) An open-closed loop PID-type ILC scheme for the control of linear, time-varying systems and a class of nonlinear systems with initial state error, non-repetitive model uncertainty and disturbance is proposed. Sufficient conditions for guaranteeing the convergence of the ILC algorithm are given. The scheme performs better than the open loop PID-type ILC scheme both in convergence rate and in robustness in the presence of uncertainties and disturbances. The effectiveness of the proposed method is illustrated by simulation experiments.(2) A high-order open-closed loop PID-type ILC algorithm with forgetting factor is presented for a class of repetitive nonlinear time-varying systems with non-repetitive model uncertainty and disturbance. The algorithm can weaken the influence of model uncertainty and non-repetitive disturbance to convergence of the ILC algorithm. Simulations illustrate the validation of the algorithm.(3) Monotonic convergence of open-closed loop P-type ILC algorithm is investigated using super-vector framework for linear time-unvarying discrete system. And sufficient condition for monotonic convergence of the algorithm is analyzed.(4) Based on iteration domain analyzing method, PID-type ILC algorithm with disturbance observer of iteration domain is given for linear time-unvarying discrete system with non-repetitive disturbance. The algorithm decreases the influence of the non-repetitive disturbance to convergence of the ILC algorithm. Simulations show that the algorithm is effective.(5) Application of ILC algorithm in fed-batch process control is discussed. The thesis gives a kind of ILC method with high-order, open-closed loop for the problem of appending stuff control in fed-batch fermentation process. Similarly, simulation experiments show effectiveness of the method.