Decentralised static output feedback tracking control for nonlinear interconnected systems using sliding mode techniques

In this paper, a sliding mode technique based decentralised static output feedback control scheme is proposed for system output tracking for a class of nonlinear interconnected systems where both nonlinear nominal subsystems and unknown interconnections are considered. A composite sliding surface is designed in terms of tracking error at first and then the corresponding sliding motion stability is analysed based on the Lyapunov approach. In order to guarantee the reachability, a decentralised output tracking control is designed based on system output and the pre-given desired output signals such that the effect of the interconnections can be tolerated and the tracking error dynamical systems are driven to the sliding surface maintaining a sliding motion thereafter. The proposed method depends on available information only and can reduce conservatism by fully exploring and adopting known information. An appropriate coordinate transformation is employed to facilitate the sliding mode control design. The effectiveness of the proposed approach is demonstrated through simulation applied to a river pollution system.