Output feedback control of uncertain feedforward nonlinear time-delay systems with unknown output function

This paper studies the problem of global output feedback control for a class of feedforward nonlinear systems with unknown multiple time-varying delays and unknown output function. We allow that system nonlinearities satisfy the linear growth condition on unmeasured states multiplying the unknown constant, input function and polynomial-of-output growth rates. By skillfully introducing dynamic gain method, backstepping method and Lyapunov-Krasovskii theorem, a delay-independent output feedback controller can be developed with only one dynamic gain to guarantee the boundedness of closed-loop system signals and the convergence of original system states and their corresponding observer states.