Rotor Orientation Detection Of Permanent Magnet Spherical Motor Based On Digital Image Measuring

Permanent magnet spherical motor(PMSM)is a new type of multi-dimensional motor,which can accomplish the three-dimensional motion.Among them,the rotor orientation measurement of spherical motor is an important part of the closed-loop control system of permanent magnet spherical motor,and is one of the key technologies in the motor control system.Based on the analysis of the current situation and trend of the rotor orientation measurement method of the spherical motor,this paper studies a permanent magnet spherical motor.Firstly,this paper introduces the mechanical structure and operation principle of permanent magnet spherical motor prototype.By analyzing the characteristics of the parameters describing the spatial orientation of the rigid body,the Euler angle representation with fewer parameters is selected as the basic physical parameters to describe the orientation of the spherical rotor of permanent magnet spherical motor.Based on the analysis of the three-degree-of-freedom motion of the sliding rail supporting frame,the forward and reverse kinematics model of spherical motor is obtained,which provides an important theoretical basis for the research of rotor azimuth detection of spherical motor.Secondly,this paper presents a method of rotor orientation measurement for spherical motor with two degrees of freedom based on monocular vision.The structure of the vision measuring device is determined by the mechanical structure of the spherical motor.The circular mark is sprayed on the surface of the spherical rotor and the output shaft,and the spherical rotor is photographed in real time by the combination of the camera and the illuminating light source.The coordinates of the feature points with rotor orientation information are obtained by analyzing the images obtained by the camera,and the rotor orientation corresponding to the feature points in the actual space is calculated by geometric relations.The static performance of the method is analyzed,including the resolution,measurement range,single frame image processing time,and the error is discussed in detail,which provides a reference for the system design in the next step.Finally,the correctness and feasibility of the image measurement method are studied experimentally.According to the theoretical basis of the monocular vision measurement method,the experimental analysis and design are carried out in turn,and the orientation of the spherical rotor with two-degree-freedom is obtained by the MATLAB image processing algorithm.The rotor orientation of permanent magnet spherical motor(PMSM)is measured by three photoelectric encoders.The system uses hardware circuit to double frequency,detect phase,count and transmit the output pulse of three photoelectric encoders installed on the slide rail support frame,and calculates the orientation by low-power STC12C5A60S2single-chip microcomputer.The ZYX Euler angle representing spatial orientation is displayedby LCD12864,which simplifies the measurement method effectively.The experimental results show the feasibility of the image measurement method.