Sliding mode control with unidirectional auxiliary surfaces based on double power reaching law and disturbance observer

For a class of nonlinear continuous systems, this paper proposes a sliding mode control with unidirectional auxiliary surfaces (UAS-SMC) based on a double power reaching law and a disturbance observer (DO). Firstly, according to the nonlinear continuous systems, the switching surfaces and the controller based on the proposed law and DO are designed to weaken the chattering phenomenon caused by disturbance variable. Then, theoretical analyses prove that the system states can converge to the switching surfaces in a finite time and slide to the origin on the surface afterwards. The formula of the convergence time was presented. Finally, the simulation results show that the UAS-SMC method based on double power reaching law (UASDPRL-SMC) has faster convergence speed and better ability to suppress the chattering than ordinary UAS-SMC and UAS-SMC based on the power reaching law (UASPRL-SMC).