Decentralized Adaptive Control of Interconnected Nonlinear Systems with Unknown Control Directions and Actuator Failure

In this paper, we propose a decentralized adaptive control scheme for a class of interconnected nonlinear systems without a priori knowledge of subsystems’ control directions and unknown actuator failure. To address this problem, a novel Nussbaum-type function is proposed and a key theorem is drawn which involves quantifying the interconnections of multiple Nussbaum-type functions of the subsystems with different control directions in a single inequality. The effect of actuator failures is successfully compensated. Global stability of the closed-loop system and asymptotic stabilization of subsystems’ output are proved and a simulation example is given to illustrate the effectiveness of the proposed control scheme.