Intelligent Incremental Sliding Mode Control For Permanent Magnet Linear Motor Servo System

As the mark of judging the development level of manufacturing,linear motor servo system should meet the requirement of high speed and precision.Because of the advantages such as high energy density,high ratio between thrust and volume,permanent magnet linear synchronous motor(PMLSM)is widely applied to industrial fields such as semiconductor manufacturing,underwater detection,robot control,X-Y driving devices and so on.In order to improve robustness and tracking precision,and reduce chattering,incremental sliding mode control(ISMC)method,adaptive incremental sliding mode control(AISMC)method and intelligent incremental sliding mode control(IISMC)method were proposed for PMLSM servo system which is vulnerable to the influence of the uncertainties including parameter variations,external disturbances and inherent end effect.Firstly,the structure and the operating principle of PMLSM are introduced.The mathematical model of PMLSM is established.Then the theory and the design of discrete sliding mode control(DSMC)are introduced.In order to reduce chattering and improve robustness,PMLSM servo system based on ISMC is designed.The previous control and state of system are taken into consideration when control law and sliding surface are designed.Saturated function is adopted to replace the switching function.In order to eliminate the influence on chattering and response speed from the gain of the switching function,PMLSM servo system based on AISMC is designed,which combines adaptive control and ISMC.The adaptive law is designed to adjust the gain of the switching function in real time.Then PMLSM servo system based on IISMC is designed in order to suppress interference of the uncertainties and improve tracking precision.Wavelet neural network(WNN)is used to observe the uncertainties and compensate the control law in real time.In order to improve learning capacity of WNN,improved particle swarm optimization(IPSO)algorithm is used to adjust the learning rate of WNN,which takes the worst positions of particles into consideration.Finally,according to the proposed control methods,PMLSM servo system simulation models based on DSMC,ISMC,AISMC,IISMC are established respectively.The analyses of simulation results verify that the proposed methods can reduce chattering improve robustness and control precision of system effectively.The comparison shows that IISMC has better control performance.