The Study Of Improved Model-free Controller For Large Time-delay System

Long time delay unit generally exists in the actual industrial production process, which raises the request of process control. In order to improve the quality of the productions, it is urgent to solve control problems in the large time delay system. After years of research by experts and scholars, variety of large delay system solutions are put forward, such as Smith predictive control, internal model control, model free control, and so on. Model free control is a control method that doesn’t rely on the mathematical model of the cotrolled system, and the“integration between modeling and control” is designed to avoid the situation that complex cotrolled system is difficult to build mathematical model, providing effective management plans for complex systems.In recent years, some scholars have done some researches on the model free control method in large time delay system. However, they focused on control stability, and ignored the fast convergence of control. Rapid control of large time delay system refers to the ability of a controlled object fast tracking the strong jump target output or quickly returning to the target output when meets the pulse jamming. Improving the speed of the model free control method is helpful to improve the control effect of the large time delay system. In order to improve the control speed, this article improves the model free controller from the controller structure and the parameter identification two aspects ensuring the model free control methods’ stability control in large time delay system. The main research contents are as follows:(1) Joining a “speed factor” v(k) that can adaptively adjust according to the deviation between target output and actual output in the basic model free control method of “Pan model”, so that the improved model free controller can adaptively adjust the control volume,improving the control speed.(2) The first condition of making model free control method work is that thej(k) in “pan model” needs real-time online identification, in other words, model free controller finally needs real-time online identification. This paper puts forward the objectives and constraints of the rapidity of large time delay system, and uses an improved constrained multi-objective particle swarm algorithm to optimize it to make the controller keep control stability and control speed simultaneously.The improved model free controller we propose can effectively improve the rapidity of model free control methods in large time delay system on the basis of stability by MATLAB simulation experiments.