Distributed control of nonlinear uncertain systems: A cyclic-small-gain approach

This paper presents a cyclic-small-gain approach to distributed control of nonlinear multi-agent systems in the strict-feedback form for output agreement. Through a novel nonlinear control law design, the output agreement problem is transformed into a stabilization problem, and the closed-loop multi-agent system is transformed into a large-scale system composed of input-to-output stable (IOS) subsystems which are interconnected with each other through redefined outputs. The cyclic-small-gain theorem is employed as a fundamental tool to guarantee the IOS of the closed-loop large-scale system and the practical output-agreement of the multi-agent system. Moreover, if the system is disturbance-free, then accurate output-agreement is achievable. Interestingly, the closed-loop multi-agent system is also robust with respect to bounded time-delays in information exchange.