| The Permanent Magnetic Spherical Motor (PMSM) has attracted more and more attention because it can achieve multi-degrees of freedom motions. In this paper, the torque model of PMSM is analyzed, the control method for stepping motion of PMSM is proposed, the coil current of PMSM is simulated when different stepping motions performed, the control module for current has been designed and preliminary experiment is carried out.The main contribution of this paper can be discussed as follows.1. The effects on torque characteristics of three-degrees of freedom permanent magnet spherical motor caused by the structure parameters of stator coils are analyzed. The torque characteristics between single pair of stator and rotor with interaction of three-degrees of freedom permanent magnet spherical motor are studied, so that the linear superposition torque model of permanent magnet spherical motor has been established. Thus, the control method for stepping motion of permanent spherical motor, which is regulating the current of stator coils, has been supposed.2. Firstly, the current of single coil under hysteresis-loop tracking control is simulated. Secondly, three simulations under different specific torques of the PM spherical motor are implemented. First simulation is made when output shaft steppingly spins at initial position, second simulation is made when output shaft steppingly rotates around the Z-axis with a certain tilted angle to Z-axis, third simulation is made when output shaft steppingly spins with a certain tilted angle to Z-axis3. A preliminary experiment platform is set up. According to the control method applied to simulation experiments, the schematics of control scheme were designed. Moreover, the control module and associated program are completed so that the preliminary experiment for stepping motion can be carried out. The feasibility and the validity of control method is proved by experiment results. The work is supported by the National Natural Science Foundation of China (51100771,51307001), the National Science Research Key Program of Anhui Provincial Education Department (KJ2013A012) and Anhui Provincial Science Foundation (1308085QE82). |
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