Improved sliding-mode control for a class of disturbed systems based on a disturbance observer

The stabilization problem for a class of disturbed systems is dealt with by proposing an improved sliding-mode control (SMC) scheme in this paper. Through designing a new time-varying switching gain and a sliding surface, a nonlinear disturbance observer (DOB)-based improved SMC is developed to counteract disturbances’ influence on the system and make the closed-loop system asymptotically stable. The novel control scheme exhibits two benefits. One is that the time-varying switching gain is a function of exponential decay, which greatly alleviates the chattering problem. The other is that a new function dependent on the disturbance estimation is defined as the switching gain coefficient, which ensures the proposed method can retain the nominal performance of systems, i.e., the improved SMC law degenerates to the baseline SMC law without disturbances. A simulation example verifies that the developed control scheme is feasible and advantageous by comparisons.