Output feedback sliding mode control based on adaptive sliding mode disturbance observer

In this paper, an adaptive sliding mode disturbance observer is designed to counteract the disturbance actively. By designing the adaptive laws, the assumptions on the disturbance are relaxed in the proposed observer, its first derivative upper bound is considered to be unknown. Based on the proposed disturbance observer, an output feedback sliding mode controller is constructed for the continuous-time linear systems with unknown external disturbance. The proposed controller incorporates only the system output information and has less chattering of the control input. The feasibility of the proposed strategy is shown by numerical simulations.