Study On The PID Control Method Applied To Multi-mode System

This article is the theoretical studies carried out to improve the multi-model pressure loading system control accuracy of the wheel radial fatigue testing machine. And apply the research findings to other similar systems.The device’s pressure loading system is divided into no-load and load sessions, the system model of which are completely different. Loading stage model can be simplified for second-order large inertial system, which respond slowly; During no-load phase, the system respond quickly, but with large steady-state error. Due to the characteristics of the load model and the impact of no-load phase, the system would be a serious overshoot, and adjusted for a long time, using the normal PID controller to control the multi-model pressure loading system. Thus, this paper presents a relatively variable coefficients PID control algorithm to solve the system overshoot problem of the loading phase. And the combination-type PID controller is presented which is the combination of the relatively variable coefficients PID control algorithm and several improved PID control to eliminate the impact of no-load phase on the system and the shock of the no-load phase, improve anti-jamming ability of controllers and make the system respond quickly and smoothly in the whole running process.Finally simulate the system controlled by the combination-type PID controller via MATLAB/Simulink. The simulations proved that the use of combination-type PID controller significantly reduced the overshoot and the adjustment time of the multi-model pressure loading system, and meet the Technical Specifications. The simulations also proved that the relatively variable coefficients PID control algorithm has excellent control effect to the other large, pure delay system.