Intelligent Sliding Mode Control Of Permanent Magnet Linear Synchronous Motor Based On Friction Compensation

Permanent magnet linear synchronous motor（PMLSM）has the advantages of stable operation,low noise,large acceleration and deceleration,and can directly produce unidirectional or reciprocating precision control displacement.Therefore,it is the prefer feed driving device for mechanical forming,semiconductor manufacturing and other equipment that often do linear feed motion.However,due to the lack of elastic buffer of intermediate mechanical transmission parts in PMLSM,the nonlinear time-varying factors such as friction,load disturbance and end effect in the system act directly on the servo motor without weakening,resulting in large tracking error in PMLSM servo system.Therefore,an intelligent sliding mode control based on friction compensation was designed to improve the tracking accuracy of PMLSM servo system and its robustness to nonlinear time-varying factors such as friction and load disturbance.Firstly,this thesis introduced the application development and control strategy of PMLSM and the research status of friction compensation technology of servo system.According to the principle of motor,the mathematical model of PMLSM was established.Then,the disturbance that affects servo performance was briefly summarized and the PMLSM vector control system was established.Secondly,aiming at the problem that PMLSM is easy to be affected by nonlinear timevarying factors such as friction and load disturbance when tracking the desired position signal,a nonsingular fast terminal sliding mode control system based on friction compensation was established.NFTSMC was used to improve the convergence rate of the state error of the servo system and make the system non-singular.On this basis,the friction model compensation term identified off-line by the natural selection particle swarm algorithm was used to reduce the adverse effect of friction on the PMLSM servo system.By comparing the simulation results,the NFTSMC method based on friction compensation reduces the convergence time of system state error,improves the position tracking accuracy effectively,and enhances the robustness of the system against friction.Finally,when the PMLSM servo system adopts the NFTSMC method based on friction compensation for position tracking,the position tracking curve deviates from the expected position curve after the system is disturbed.Therefore,an intelligent NFTSMC method based on friction compensation was designed.The fuzzy neural network with compensation operator was used to approach the nonlinear time-varying factors such as friction identification error and load disturbance in the system,its output value was compensated to PMLSM servo system through control gain feedforward to realize the comprehensive compensation of the disturbance.The simulation results show that the intelligent NFTSMC method based on friction compensation can not only improve the position tracking accuracy,but also ensure the robustness to disturbance,and weaken the chattering of the system.