Decentralized adaptive control for interconnected strict-feedback systems with unknown time delays

In this paper, we propose a new decentralized adaptive control approach for interconnected strict-feedback systems with unknown time delays. The time-delayed interaction terms are bounded by uncertain nonlinear bounding functions and are compensated by choosing appropriate Lyapunov-Krasovskii functionals. For the simple local controller design, the dynamic surface control technique is extended to nonlinear systems with time-delayed interconnections. All the signals in the closed-loop system are semiglobally uniformly bounded and the control errors converge to an adjustable neighborhood of the origin. Finally, an example is presented to illustrate the effectiveness of the proposed control scheme.