Research on modeling and robust adaptive control of a novel permanent magnet spherical stepper motor

The real-time torque calculation and dynamic modeling have been the difficulties in the motion control of the permanent magnet spherical stepper motor. Based on the presented continuous trajectory tracking control mode, a simplified torque calculation method and the non-linear system dynamic model have been proposed. 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, so a robust adaptive control strategy is developed. The controller consists of nonlinear PD control and adaptive feedback control, so that the high level initial torque can be reduced. The analysis and simulation results have shown that the system has excellent tracking performance and robust stability against the model error and disturbance, which proves the validity of the presented model and control strategy.