Chattering-free terminal sliding-mode tracking control for uncertain nonlinear systems with disturbance compensation

In this work, an integral-type terminal sliding mode (TSM) controller with an asymptotic disturbance observer is developed. The proposed controller can be applied to a class of uncertain integrator systems with unknown external disturbances. In addition, the chattering phenomenon and the singularity problem in traditional TSM control and the influence of unknown external disturbances on the system are taken into consideration. For unknown external disturbances in practical applications, a disturbance observer with asymptotic estimation performance is constructed. Thus, the control strategy is developed to ensure chattering-free and eliminate the singularity problem. By comparing with the traditional TSM control, we expect to synthesize a more efficient chattering-free sliding mode controller. The integral-type TSM transforms the discontinuous sign function into the continuous smooth function. Furthermore, the proposed control algorithm can accurately compensate for the external unknown disturbance and exhibits better robustness. Finally, the simulation results demonstrate the effectiveness of the controller and the stability of the whole closed-loop system is strictly proved.