Research On Position Detection And Torque Calculation And Other Issues Of Spherical Wheel Motor

The spherical wheel motor has an extensive application prospect in the future because it has compact structure, three degrees of freedom movement. Although expert in the world has made deeply research on spherical wheel motor, some problems still retain to be unsolved, especially in the area of position detection, current calculation and control. This paper has done some work on these problems. The main work is as follows.1. A method to detect the rotor position through measuring the magnetic flux density of the fixed point on the space is proposed. A cylindrical permanent magnet is placed above the shaft as magnetic resource. Three dimensional hall sensor is used to measure the magnetic induction intensity of special point in the space. The position of the rotor in the reference coordinate can be achieved through processing of measured date by a certain algorithm. Simulation results validate the feasibility of the method.2. Finite element analysis software Magnet is used to calculate the torque-angle parameter of the known structure of spherical wheel motor and a function expression to calculate the torque-angle parameter is got by fitting with discrete date points using exponential functions. The formula to calculate the generated torque in the reference coordinate is given. The paper proposes an algorithm to get the optimal currents to generate a certain torque under the constrained conditions. The given example shows the correct of the algorithm.3. Kinematics and dynamics models of the spherical wheel motor are established according to rigid body kinematics and dynamics. The optimal path planning of spherical wheel motor is studied in this paper. The control scheme to realize the optimal movement is given, and simulation verifies the correction of the scheme.This work is supported by National Natural Science Foundation of China (51177001,51307001) and Natural Science Foundation of Anhui Province (1308085QE82).