Synchronous Control For Magnetic Suspension System Of Gantry-Moving Type Numerically Controlled Machine Tool

The magnetic suspension technique is widely used in the field of transportation, metallurgy and mechanic industry such as Magnetic levitate train and Active magnetic bearing. It has lots of merits, such as no mechanical contact, no need of lubrication, less noise. It can improve the service time of the equipments. Synchronous control technique is widely used in the modern production practice. Good control precise and work stability is obtained if synchronous control technique is adopted. Magnetic suspension technique is put forward to eliminate the friction between the moving part and static rail in the gantry-moving type numerically controlled machine tool. Fuzzy self-adjusting PID control is adopted to design synchronous controller and solve the asynchronous suspension problem.First, on the basis of reading many foreign and domestic references, the research status and application area of magnetic suspension technique are summarized. Overseas and domestic development status of synchronous control technique, the actual control method and control precise are summarized.Second, the work principle of magnetic suspension technique is summarized. The single electromagnet is taken to establish the mathematic model. The nonlinear mathematic model is locally linearized near the equilibrium point. The linear the mathematic model is obtained. The basic structure of synchronous control is given. On basis of it, the synchronous control structure used in this paper is presented. PI state feedback control is adopted to design the single electromagnet suspension system controller. Simulation results show that the system output follows the input exactly and there is no steady error. State feedback control is adopted to compare.Third, fuzzy self-adjusting PID controller design method is discussed. After designing the magnetic suspension system controller, fuzzy self-adjusting PID control strategy is adopted to design the system synchronous controller. In this paper, the two same magnetic suspension systems are used and the same input is given. The output error of two magnetic suspension systems is the input of synchronous controller. The synchronous suspension is realized by the feedback compensate control of this controller. Simulation results show that the control scheme used in this paper is effective. Dynamic synchronous error is very small when disturbance is added to the system, and it is limited in the allowable range. In this paper, PID control, fuzzy control and fuzzy self-adjusting PID control are compared when disturbance is different.