Research On H_∞ Control Of Permanent Magnet Linear Servo System Based On Genetic Algorithm

It is a gravely transform that the linear server driving technology applied to numerically controlled machine tool.The linear permanent magnet synchronous motor (PMLSM) has avoided the effects of the mechanical transmission chains from rotary motions to linear ones,and has strong electromagnetism thrust,lower cost,small electrical time constant and rapid response etc.However,just because the linear motor is driven in direct way and have not the mechanical transmission chains,influence caused by the perturbation of system model and the disturbance of load reflect to the system directly without any buffer between them.Therefore,the strictly demands are requested to the control technology.Otherwise,with many system uncertainties considered adequately,the system should have a high robust stability and robust quality under all circumstances. H_∞robust control method just is a control strategy that aim,at the system uncertainties and try to keep the robust stability and robust quality of system.In this paper,the large influence of load disturbances and parameter changes on PMLSM servo system was resolved by H_∞robust control strategy.After ensure the bound of load disturbances and parameter changes,choose a set of perfect weighting functions by try and error.And translate the PMLSM into the standard H_∞control problem by speed H_∞controller designed by MATLAB toolbox.Simulation conclusion indicated that under the occurrence of disturbances and parameter changes,the proposed control method has excellent tracking performance and resisting disturbances performance.However,although the H_∞control has well robustness,the results of control depend on the choice of the weighting functions to a great extent.Due to between the weighting functions and the robustness have no material method can be followed,the improved results mostly found by the testing method.If the adjustment parameter is overfull,this testing method is difficult of carry out.Therefore,this paper put forward another method that choose the weighting functions by genetic algorithm,it will performance index to objective function and design the H_∞optimization controller.Simulation conclusion indicated that the design method is logical.