Nonfragile Consensus Strategy for Variable Fractional-Order Multiagent Systems Based on Disturbance Observer

This article proposes nonfragile leader–follower consensus control for variable fractional-order multiagent systems under disturbance generated by an exogenous system. The developed technique is directly applicable to fixed fractional-order and integer-order multiagent systems. First, a nonfragile variable fractional-order disturbance observer is introduced, which is able to tolerate a certain degree of parameter uncertainty. Second, by employing the disturbance observer, a novel robust nonfragile consensus control scheme is developed, which not only ensures asymptotic stability of the consensus error system, but also accommodates parameter uncertainty in the physical controller's implementation. Third, new suffi cient conditions for the desired consensus protocol are derived using linear matrix inequalities (LMIs), as well as graph and Lyapunov theory. Finally, simulation examples are presented to illustrate the validity of the theoretical results. The proposed order-dependent LMI condition is less conservative than existing order-independent alternatives.