Trajectory Tracking Control Of Permanent Magnet Spherical Motor Based On Machine Vision

Permanent magnet spherical motor(PMSM)is increasingly popular among scientific researchers because of its novel structure and its ability to independently perform multiple degrees of freedom movement in space.However,position detection and trajectory tracking control still have problems such as insufficient accuracy and difficulty in realization,which limit the application of PMSM.This paper focuses on two aspects of position detection method and trajectory tracking control strategy of PMSM.The main research work of this dissertation is as follows:1.The mechanical structure of PMSM prototype is introduced,and the operating principle of PMSM is analyzed.According to the rotation transformation relationship between the stator coordinate system and the rotor coordinate system,the kinematics model of PMSM is constructed.Besides,the dynamic model of PMSM is deduced from Lagrange function.2.A method of rotor attitude detection based on machine vision is proposed for the problem of position detection of PMSM.The red and green mark point module is installed on the top of the rotor output shaft,and the Open MV smart camera is used to take pictures of the red and green mark points when the rotor is moving.The image is sent to the upper computer in real time,and the rotor position is calculated in the upper computer.The experimental results of rotor attitude detection show that the designed method has high detection accuracy.3.Aiming at the problem of trajectory tracking control of PMSM,a sliding mode control strategy of improved reaching law based on disturbance observer is addressed.The disturbance observer is used to observe the disturbance signals such as external disturbance and parameter perturbation in the dynamic model of PMSM on-line.The sliding mode controller is designed to compensate for the observation error.The reaching law composed of saturation function and anti-hyperbolic sine function is used to solve the chattering problem inherent in conventional sliding mode control.The experimental platform of PMSM trajectory tracking control system based on machine vision is built.According to the simulation and experimental results,the control algorithm studied in this paper can achieve high-precision trajectory tracking control,while ensuring that the control system has good dynamic response performance.