Robust Control And Performance Analysis For Permanent Magnet Linear Motor Servo System In Numerical Control Machine

Recently with the trend in high degree of accuracy of all parts,precision nc machine tool linear servomechanism with superb location and tracing performance is needed. Owing to internal and external reasons of linear servo system,the parameter and external disturbance of linear servo system have large uncertainty.In order to raise system control quality,robust controller designed for permanent magnet linear motor servo system in numerical control machine is studied.Robust control for permanent magnet linear motor servo system in numerical control machine is a comprehensive project,which is on the basis of robust control theory, permanent magnet linear motor as controlled plant and solves control problem of permanent magnet linear motor servo system with uncertainty.For the characteristic of linear motor suffering from the effect of load disturbances and parameter variations,the dynamic quality is identified on-line based on model reference adaptive control. Simultaneously,H₈ control andμsynthesis control for permanent magnet linear motor servo system are used to resolve robust control problem of servo system.The research of this dissertation is based on two aspects.The research work is as follows:(1) Study on permanent magnet linear motor model and dynamic quality identification. Based on mathematical model of permanent magnet linear motor,reference model and variable model mathematical equation can be gained from discretization mechanical movement mathematical equation.Model reference adaptive arithmetic also can be obtained owing to landau discrete time recursion parameter identification machine processed.Reference model and variable model are combined with model reference adaptive arithmetic,and the model reference adaptive identification can be realized. According to simulation results,the dynamic quality can be effectively identified and adjusted on-line based on model reference adaptive arithmetic designed. (2) Study ofμsynthesis control for permanent magnet linear motor servo system.The problem of the speed controller in permanent magnet linear motor servo system is turned into standard H₈ control by being set up mathematical model of servo system robust control in state space.For standard H₈ control problem,analytic expression of controller is obtained through solving an algebraic matrix Riccati inequality.Based on the H₈ speed controller,μ-K iteration inμsynthesis is used to design aμsynthesis controller.Compared with the pure H_∞controller,this speed controller is better in robustness against load disturbances and parameter uncertainties,and its acquisition is faster than that of the pure H_∞controller.Finally,feasibility and validity of the design method are verified by virtue of computer simulation.