Research On Fuzzy Neural Network Contour Control Of Direct Drive H-type Platform

Direct drive H-type platform is widely used in precision engineering and other fields because of its high rigidity,high acceleration and high thrust.The direct drive H-type platform is driven by a permanent magnet linear synchronous motor(Permanent Magnet Linear Synchronous Motor,PMLSM)in the X direction and by two parallel permanent magnet linear synchronous motors in the Y direction.The machining accuracy of H-type platform will be affected by the anti-disturbance ability of single-axis PMLSM and the mismatch of dynamic characteristics between the axes of the platform.Therefore,the two most important indexes to evaluate the machining accuracy are the tracking error of single axis and the contour error caused by multi-axis linkage.The purpose of this thesis is to adopt advanced control strategy to improve the contour accuracy of direct drive H-type platform by reducing the tracking error and contour error of H-type platform.The main work of this thesis is as follows:First of all,the development status of direct drive H-type platform at home and abroad is introduced,and the factors that affect the machining accuracy of H-type platform are analyzed,and the related control strategies of H-type platform are introduced.In line with the mathematical model of permanent magnet linear synchronous motor,the mathematical model of direct drive H-type platform is deduced and established considering the torsion pendulum force of X-axis motor to Y-axis motor.Secondly,in view of the fact that the single-axis PMLSM of H-type platform is easily affected by uncertain factors such as load disturbance and thrust fluctuation,a global integral sliding mode single-axis position controller is designed to ensure the tracking accuracy of single-axis.The traditional sliding mode controller is designed,on the basis of which the global integral sliding mode controller is designed.In order to further weaken the buffeting phenomenon of the system,the saturation function is introduced.The stability of the designed control system is proved by using Lyapunov function,and the simulation models based on traditional sliding mode control and global integral sliding mode control are built in Matlab/Simulink.The simulation results show that the single-axis robustness of the global integral sliding mode control is better than that of the traditional sliding mode control,and the tracking error is smaller.Finally,aiming at the contour error of H-type platform,a fuzzy neural network contour error compensator based on cross-coupling is designed.The definition of contour error is introduced,and the contour errors of straight line trajectory and circular trajectory are deduced.The contour error model of H-type platform based on close circle is established,and on the basis of this model,a fuzzy neural network contour error compensator based on cross-coupling is designed.The simulation model of fuzzy neural network coupling control is built in Matlab/Simulink and compared with no cross coupling control.The simulation results show that the fuzzy neural network cross coupling contour control can obviously reduce the contour error of the system and improve the contour accuracy of the H-type platform compared with the no cross coupling contour control.