Decentralized Sliding Mode Control for Output Tracking of Large-Scale Interconnected Systems

In this paper, a class of nonlinear interconnected systems with matched and unmatched uncertainties is considered. The isolated subsystem dynamics are described by linear systems and nonlinear part. The matched uncertainties and unmatched unknown interconnection terms are assumed to be bounded by known functions. Based on sliding mode techniques, a state feedback decentralized control scheme is proposed such that the outputs of controlled interconnected systems track the given desired signals uniformly ultimately. The desired reference signals are allowed to be time-varying. Using multiple transformations, the considered system is transferred to a new interconnected system with an appropriate structure to facilitate the design of sliding surface and decentralized controller. A set of conditions is proposed to guarantee that the designed controller drives the tracking errors onto the sliding surface and the sliding mode of the error dynamics are uniformly ultimately bounded. The developed results are applied to river quality control. Simulation results show that the proposed decentralized control strategies are effective and feasible.