| Magnetic levitation is a relatively new technology in mechanic and electronics and has been paid special attention to in the scientific community of the world, because of its many merits such as no mechanical friction, no wear, no need of lubrication, long longevity, low power loss, and no noise, etc. The performance of magnetic levitation is determined mainly by the characteristic of its controller and solving the problems of the high precision, high response frequency, output immune from the disturbance, the parameter perturbation and the uncertain factors from outside is very difficult. The traditional methods can not meet the needs of the system. So it has great significance to study the control method of magnetic levitation.In this paper, the dynamic model of magnetic levitation is discussed firstly. According to linear model, magnetic levitation is unstable in essence and it needs the controller's stable control.The traditional control linearizes the system partially in the balance point nearby mostly , when the disturbance is too big ,it will make the system deviate a balance point far away, resulting in the controller deteriorating quickly and influencing the system's stabilization possibly. So nonlinear model is set up in this paper.Considering the difficulty of giving the exact mathematical model of MA401 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.Taking account of a nonlinear characteristic of magnetic levitation and in view of an energy-balancing point, a PCH system model is established based on the Port-Controlled Hamiltonian theory. Using the mature passivity method of interconnection and damping assignment, the passivity controller of magnetic levitation is designed to study MA401 magnetic levitation. The result indicates that the system has rapid response ,good robustness and strong adaption to the variance of load. |
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