Modeling and control of a permanent magnet spherical stepper motor

This paper describes a simplified torque calculation method with the non-linear system dynamic model and the controller design to implement the 3D real-time motion control under the presented continuous trajectory tracking mode. The perturbation of the system parameters, the model error and the external disturbance result in the actual system uncertainties, which have a great effect on the control performance of the motor. In order to improve the trajectory tracking robust stability and overcome the undesired influence of the uncertainties, a controller based on the robust control principle has been developed. The analysis and simulation results have shown that the system has an excellent tracking performance and robust stability against the model error and disturbance, which proves the validity of the presented model and control strategy.