Study Of Intelligent Complementary Sliding Mode Control For Linear Servo System

With the rapid development of science and technology in our country, industrial sectors have put forward the requirements of high speed and high precision for numerical control processing. Permanent magnet linear synchronous motor(PMLSM) has the advantages of simple structure, high precision, large thrust, fast response and so on, so it is widely used in the field of CNC machining. In order to improve the tracking precision of linear servo system, enhance the system robustness and increase the system rapidity, complementary sliding mode control(CSMC) and intelligent complementary sliding mode control(ICSMC) are proposed for PMLSM which is vulnerable to uncertainty factors, such as inherent end effect, parameter variations, nonlinear friction force, external disturbances and so on.First of all, the basic structure of PMLSM and the operating principle of PMLSM are introduced. Reasons for the uncertainty factors affecting the linear servo system are analyzed. The mathematical model of PMLSM contains uncertainty factors is established. In order to improve the system tracking precision, PMLSM servo system based on CSMC is designed. Sliding surface of CSMC adopts the design with the combination of the generalized sliding surface and the complementary sliding surface. System position tracking error slides along the intersection of the two sliding surfaces towards a neighborhood of zero, so that the tracking performance of the system is improved. Switching function selects saturated function. System adopts sliding mode control outside the boundary layer, and uses continuous state feedback control within the boundary layer, thus the chattering weakens effectively. Furthermore, it is shown by Lyapunov theorem that the control method can guarantee the convergence of the tracking error system.After that, it is considering that the boundary layer thickness in CSMC selects by trial and error method, and system cannot have good tracking accuracy and strong robustness concurrently with incorrect selection of the boundary layer thickness. For this reason, PMLSM servo system based on ICSMC is designed. Sliding surface of ICSMC based on the design of two sliding mode surfaces employs RBF neural network in order to estimate system uncertainties on line, so that the robustness of the system is strengthened. The convergence of the tracking error system and the system stability are guaranteed by Lyapunov theorem.Finally, according to the proposed control method, PMLSM system simulation models based on traditional sliding mode control(SMC), CSMC and ICSMC are established respectively, and. The comparison analysis of simulation results show that ICSMC system compared with SMC system and CSMC system has higher position tracking precision, faster response and stronger robustness. Therefore, ICSMC has better control effect, and it is enough to satisfy the requirement of high speed and high precision in practical application.