Robust Controller Design And Simulation For Linear Motor Levitation Platform

Taking the project supported by specialized research fund for the doctoral program ofministry of education as background, the research object of the thesis is the levitationplatform constituted by a linear motor. According to the characteristic of the linear motorlevitation platform system and the requirements of strong robustness and high precision,the structured singular value μ theory, H∞robust control theory and L₂robust control arecombined to research the uncertainties problem and the nonlinear coupling problem of thesystem. The main contents are as follows:The linear motor levitation platform system uses the direct driving method, so thesystem is easily affected by the uncertainties including parameter variations、 loaddisturbances、 end effect and cogging. μ-H∞robust control strategy combined with H_∞robust control theory and the D-K iterative method of μ theory was used to solve the aboveproblem, based on the feedback linearization to the original system, μ-H∞robustcontrollers were designed for both the horizontal axis and the vertical axis. This methodnot only overcame the conservative of the H∞control, and had faster calculate speed thanthe μ controller. Simulation results show that this control strategy effectively inhibited theinfluence caused by the uncertainties and ensured the requirements of high positioningaccuracy and strong robustness.Nonlinear L₂robust control strategy was used to design nonlinear L₂speed controllersfor both the horizontal axis and the vertical axis for the nonlinear coupling problem of thelinear motor levitation platform system. This method realized directly decoupling based onthe nonlinear mathematical models instead of joining independent decoupling module.Simulation results show that this control strategy effectively solved the nonlinear couplingproblem, and effectively inhibited the influence caused by the uncertainties, satisfied the requirements of high positioni ng accuracy and strong robustness.