| More and more researchers pay attention to spherical motors,which can operate in multiple degree-of-freedom(DOF)with a single motor.In this dissertation,a three DOF permanent magnet spherical motor is proposed,and its mechanical structure and three DOF motion performance are introduced.The magnetic field,torque and motion singularity of permanent magnet spherical motor are analyzed.The description method of rotor motion of permanent magnet spherical motor is given,and the dynamic model of permanent magnet spherical motor are deduced.The rotor position measurement method of the spherical motor is studied.A rotor position measurement method of permanent magnet spherical motor based on optical feature points recognition is proposed and verified by experiments.The inverse kinematics of permanent magnet spherical motor is solved,the method of stator coil electrification for permanent magnet spherical motor is determined,the driving circuit of permanent magnet spherical motor is designed,the simulation and experimental research were carried out.Relevant research results can provide reference for similar motor research.The main work of this dissertation includes the following aspects:1、The structure of permanent magnet spherical motor is introduced,and the structure of stator and rotor is introduced in detail.Stator static coordinate system and rotor dynamic coordinate system are defined to help describe the rotation of spherical motor,and the motion performance of spherical in three DOF is analyzed.With the help of ANSOFT software,the magnetic field of permanent magnet spherical motor is analyzed by finite element method,and the electromagnetic moment produced by the interaction between a single coil and a single permanent magnet was derived by virtual displacement method.On this basis,the angle and torque equations of the stator and rotor of the permanent magnet spherical motor are obtained by superposition theorem.The motion singularity of the permanent magnet spherical motor is analyzed,which prove the permanent magnet spherical motor is far from the motion singularity.2、Using Euler angle and quaternion to describe the motion of the rotor of permanent magnet spherical motor,and introducing the principles of the two methods,the expressions of the two methods are given.On the basis of Lagrange equation and Euler angle,the dynamic model of permanent magnet spherical motor is deduced.The quaternion method can be used to deduce the position information of MEMS sensors in the comparative experiment of position measurement of permanent spherical motor.3、A rotor position measurement method for permanent magnet spherical motor based optical feature points recognition is proposed.The camera imaging model based on pinhole model is analyzed,and the composition of the optical feature points generation module is given.The optical feature points in the image obtained by the camera are extracted and identified by imaged processing method.The camera’s internal parameter matrix can be obtained by Zhang’s calibration method,and the camera’s external parameter matrix can be obtained by the position relationship between the high-speed camera,spherical motor and the optical feature generation module.After obtaining the internal and external parameters of the camera,the actual position of the optical feature points in the world coordinate system is obtained through the images which taken by the camera,and the method of calculating the rotor position of the spherical motor is further given.Finally,the rotor position measurement experiments are carried out through three basic movements of the spherical motor,which are spinning motion at center point,edge spinning motion and axial tilting motion,respectively.The experimental results show that the detection method can detect the rotor position information of the spherical motor accurately,and the rotor position measurement results are quantitatively analyzed and calculated through three angles,which are tilting angle,yaw angle and rotation angle,respectively.4、Inverse kinematics of permanent magnet spherical motor is solved,and on the basis of solved three angles,combined with the current and expected position,as well as the angular torque equation of the stator and rotor,the stator coils for electrification are determined,the magnitude and direction of the electrified current are calculated.The electrification methods of spinning motion at center point,axial tilting motion and edge spinning motion for permanent magnet spherical motor are given,and the electromagnetic torque generated in the process of electrification is simulated and analyzed.A permanent magnet spherical motor drive circuit consisting of 24 constant current drive module circuits is designed,The maximum output current of each constant current drive module circuit is 5A,and the current direction was adjustable,control instructions can be sent to all constant current drive module circuits through 485 bus,which can realize the driving control of stator coils of spherical motor.The experiments on spinning motion at center point,axial tilting motion and edge spinning motion are carried out,the experimental results verify the validity of the electrification method and driving circuit. |
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