Comparison between sliding mode load-torque observer techniques for DC motor without torque sensor

Abstract

External load-torque estimation for electrical motor is important in order to improve the performance of the control and to have a better overview of the system state. In this paper, the external load torque applied upon the shaft of a DC motor is estimated by means of three different typologies of SMO (Sliding Mode Observer), namely, a first order sliding mode, a quasi-sliding mode and a super-twisting sliding mode observer. The observers are based on the position and speed measurement of the rotor without the need for a torque sensor. The estimation algorithm is implemented on an Embedded System with a DC motor. In this work, the performance as well as the computational effort and the robustness of these observers are compared experimentally.