Research On Nonlinear PID Controller On NC Machine Tool Position Tracking

The position control system of the NC machine is used to produce the position controlled variable. Because of the principle is simple and easy to implement, the classical traditional proportion, integral, differential (PID) control technology is widely used on the NC machine. And it is widely used on the occasion that the requirements are not very high. But with the developing of the actual production requirements, the processing speed, accuracy and stability are need to improve. The traditional PID controller also exposed its weakness:bad adaptable ability and lower anti-interference ability, and due to the reason of the algorithm itself there is a weakness difficult to overcome:that is unable to achieve rapid adjustment and small overshoot at the same time. Therefore, develop new control method aimed at position control system of the NC machine has a lot of necessity. This article mainly designed three PID position controller of the NC machine from three aspects.(1)The nonlinear function control method:three nonlinear functions of each part are established on the basis of the variation tendency of each section in the traditional PID controller. This control method can let the control parameters be changed with the deviation, and to some extent it has the ability of self-adaption.(2)The fuzzy control method:fuzzy control is an intelligent control method that is established on the basis of expert knowledge or the skilled operators' experience. This paper disgusted the working principle in detail, and designed a fuzzy self-adaptive PID controller of the NC machine.(3)The immune feedback control method:This paper analyses the immune feedback theory, and get the Immune feedback control law, then designed the fuzzy immune PID position controller of the NC machine.The simulation research of the NC machine position controller:The mathematic model of the dc servo system is established on the basis of analysing the foundation of the dc servo system. The system simulation model is established by the MATLAB/Simulink software. Simulations aimed at the NC feed servo system through the step representation signal proves that this three PID controllers have better control performance than the traditional one.