Research On Second Order Sliding Mode Control For PMLSM Suspension Platform

The project supported by Specialized Research Foundation of Ministry of Education Doctoral Program as background, and suspended platform driven by permanent magnet linear synchronous motor (PMLSM) with a unilateral core as the research object. respectively using the discrete second order sliding mode control and the control strategy with discrete second order sliding mode position control, to study the precise positioning of the PMLSM suspended platform which has many uncertainty such as variables has nonlinear coupling, Levitation stiffness is low and has parameters change, end effect and the load disturbance. The thesis mainly includes the following components:Based on the analysis of PMLSM Floating platform system model, against the problems that the servo performance is affected by the nonlinear coupling between vertical thrust and normal force, load disturbance and parameters uncertainty. In order to ensure the mover positioning strictly of the PMLSM levitation platform, the second-order sliding (2-SMC) controllers of the horizontal axis and vertical axis are designed to directly decoupling control. Control law is achieved by twisting algorithm. The discontinuous control effects on the high order differential of variables, in theory, can reduce buffeting. Simulation results show that the control strategy can decouple between horizontal direction and vertical direction, enhance the robustness performance of the system against parameter variations and load disturbances and improve the positioning precision.Discretion on the system, in order to make the controller have good usability in the actual project, and the discrete second order sliding mode position controller is designed using default convergence law algorithm for discrete system. Simulation results show that the discrete second order sliding mode control is still able to make the PMLSM levitation platform have high positioning accuracy, and strong robustness for uncertainties such as load disturbance and parameters change, and weakening the chattering at the same time.