Study On Magnetic Levitation System Base On Fuzzy PID Control

The magnetic levitation system is one of the most important platforms to study and research control theory.The research on the magnetic levitation system can be attributed to the research on the nonlinear and unstable system. This kind of complicated control object is difficult to describe precisely with mathematic formula, and is very difficult to obtain the better effect using the classical control methods. Therefore, it's great significant to obtain controlling means without depending on system mathematical model.Based on the magnetic levitation equipment MA401 that is made in Germany Amira Company, firstly, the structure and working principle of the single degree freedom magnetic levitation system are introduced, and it's dynamic model is analyzed in detail. The qualitative analysis to the magnetic levitation system based on linearization is carried on, it can be concluded that the magnetic levitation system is an unstable object. And the nonlinear mathematical model of the magnetic levitation system is established, where the singular perturbation method is used.Next, considering the difficulty of giving the exact mathematical model of magnetic levitation, a two-dimension fuzzy controller adding a integration element to avoid the error is constructed and the result shows the magnetic levitation has strong robustness.Finally, the nonlinearity dynamic model of maglev system is programmed by S-function in MATLAB. Based on both the advantages of PID controller and fuzzy controller, a fuzzy adaptive PID controller(FAPID) is proposed for the characteristics of magnetic levitation system, such as open-loop instability and strong nonlinearity, which the FAPID controller aggrandize the error of stability by simulation, though it's dynamic property is improved. Therefore, the algorithm of the improved fuzzy adaptive PID controller(IFAPID) is advanced and designed that by parted D controller from PID controller, the problem of strong nonlinearity of magnetic levitation system are solved by using nonlinear fuzzy mapping in the fuzzy controller, and the PID controller's P and I parameters are adapted by fuzzy controller. The results showed that the IFAPID controller has the advantages of higher anti-interference ability and adaptability to parameters' changing than conventional PID controller and FAPID, and better dynamic property and stability.