Research On Position Control Method Of Permanent Magnet Synchronous Linear Motor Based On Fast Terminal Sliding Mode Control

Permanent magnet synchronous linear motor(PMSLM)has the characteristics of high control accuracy,high power density and fast response speed.It is widely used in some occasions that need to do linear motion,such as industrial assembly,transportation scenarios.However,due to the strong coupling and nonlinear characteristics of linear motor,it is difficult to establish a precise mathematical model.At the same time,the parameter changes,external interference and load changes in the operation process also bring the uncertainty of linear motor system.Therefore,how to design a suitable control strategy to make the linear motor system have good rapidity,stability and robustness to system parameter changes and load disturbances is of great significance.Sliding mode control is an effective control method to deal with nonlinear perturbations,external disturbances and uncertain parameters.It has been widely used in practical engineering since it was proposed.Moreover,the sliding mode control method can ensure that the closed-loop system has good robustness and interference suppression performance.The traditional sliding mode control will bring the chattering problem to the system,while the fast terminal sliding mode control does not contain the switching term,and its control law is continuous,so it can effectively eliminate the chattering phenomenon of the system,and can ensure the system quickly converges to the equilibrium state in a limited time.In this paper,the PMSLM is taken as the research object.Firstly,the basic structure and working principle of the permanent magnet synchronous linear motor are introduced,and the mathematical model of the permanent magnet synchronous linear motor in dq coordinate system is established.Then a fast non-singular terminal sliding mode controller is designed for the linear motor system to suppress chattering and improve the tracking accuracy.In addition,considering that there is a trade-off between the dynamic constraints and the control performance of the fast non-singular terminal sliding mode control,a new finite time disturbance observer is proposed to estimate the lumped disturbance in real time and realize feed-forward compensation,which is an effective method to guarantee the control performance and improve the robustness of load disturbance.Considering that the speed signal of linear motor system is not easy to measure and the installation of speed sensor will increase the volume and mass of motor,and also increase the hardware cost of the system,this paper proposes a finite time extended state observer,which only uses the position information of linear motor output to estimate Based on the estimation of speed and disturbance,a non-singular terminal sliding mode controller based on output feedback is designed to improve the fast response and anti-interference ability of linear motor.At the same time,based on Lyapunov stability theory,the rigorous stability proof of closed-loop system is given.Finally,the control performance of the proposed strategy is simulated in Matlab environment.The simulation results show that the control strategy can make the closed-loop system have good interference suppression and tracking performance.