A Third-Order Sliding-Mode Controller for a Stepper Motor

This paper deals with the robust control problem of a stepper motor subject to parameter uncertainties and load torque perturbation. The developed algorithm is based on third-order sliding-mode control such that a desired angular motor position is accurately tracked. The proposed scheme requires the measurement or the estimation of the motor speed and acceleration for feedback. To avoid the use of tachometers and accelerometers which add cost and energy consumption, a robust second-order sliding-mode observer is presented. Experimental results illustrate the performance and the advantages of the proposed controller.