Output‐feedback control for large‐scale uncertain systems with unknown delays and nonlinearly growing interconnections

Abstract This paper investigates the global output‐feedback control problem for a family of large‐scale uncertain nonlinear systems with unknown delays and nonlinearly growing interconnections. Different from the existing literature, the system interconnections meet a nonlinear growth of the unmeasurable (delayed) states multiplied by an unknown constant and input‐output functions. The complicated interconnections, especially the nonlinear growth of unmeasurable (delayed) states, and the unknown input delays make the problem more challenging. By smartly applying the gain‐scaling technique and skillfully constructing Lyapunov–Krasovskii functionals, a suite of novel output‐feedback controllers with multiple correlated dynamic gains are proposed to guarantee the global convergence of the original system states and the global boundedness of the closed‐loop system states. Numerical examples are given to illustrate the effectiveness of the proposed control strategy.