| Magnetic levitation technology is applied to gantry moving numerical control machine tool in this paper in order to solve the friction problem. The moving crossbeam is levitated on the still rail and is far away from the rail so that the friction can be eliminated thoroughly. The main goal is that presents an effective measure for the levitation principle of crossbeam and the control process of the high rigidity of levitation gap. It can eliminate the different disturbances that affect the levitation height and guarantee the levitation stability and accuracy.First, on the basis of reading many foreign and domestic references, it summarizes the development and status of magnetic levitation technology. The characteristic and application of magnetic levitation technology are expounded.Second, the structure of levitated crossbeam of gantry moving numerical control machine tool is introduced in detail and the levitation theory of moving crossbeam is analyzed. The mathematical model is built. At the same time, the nonlinear model is linearized by using feedback linearization method. The linear voltage control model and current control model are obtained respectively. Then, classical control strategy-linear state feedback control and PI state feedback control are adopted to design controllers that are validated in magnetic levitation system.Lastly, the modern control technology-sliding mode control is introduced. Sliding mode control has invariability when the parameters change and the disturbances exist. The different controllers are applied to the system respectively by MATLAB in this paper. The simulation results are gained and compare with the control performances of the different control methods. Sliding mode control has very strong robustness and high reliability. |
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