Robust Speed Control of Motor-Driven Servo Systems via an Adaptive Disturbance Rejection Terminal Sliding Mode Controller

To suppress speed fluctuations under time-varying load torque and high-frequency disturbances, this article proposes an adaptive disturbance rejection terminal sliding mode controller (ADRTSMC) for motor-driven servo systems. Based on the continuous nonsingular terminal sliding mode controller (CNTSMC), the proposed ADRTSMC integrates an extended sliding mode observer (ESMO) for disturbance compensation. Considering the disturbance frequencies can be near or beyond the limited bandwidth of ESMO, a disturbance rejection attractor is established based on the derivative of the observed disturbance after filtering to adaptively enhance the robustness margin, reduce the stable boundary layer and address the disturbance observation errors of ESMO. Simulations on a permanent magnet synchronous motor (PMSM) and experiments on an induction motor (IM) are conducted, compared to PI control, PI control with ESMO, SMC with ESMO, and CNTSMC with ESMO. The results show that the mean absolute error regarding the speed fluctuations of the proposed ADRTSMC can be reduced by more than 62.89%, compared to PI control with ESMO.