Global Adaptive Control for Feedforward Nonlinear Systems with Unknown Output Coefficient

This paper investigates the global state regulation problem of a class of uncertain feedforward nonlinear systems with unknown output coefficient (or called measurement sensitivity). Particularly, the nonlinear terms of the considered systems are supposed to be bounded by unknown positive constant multiplied by states, moreover the unknown measurement sensitivity is allowed to be non-differentiable and varies in a positive interval. To deal with relaxed measurement sensitivity, the extended Lyapunov matrix inequalities are quoted. Then based on the dual domination idea, the problem of global state regulation is solved by adaptive output feedback. The proposed controllers guarantees that the states of controlled systems asymptotically converge to zero. Finally, an example is given to illustrate the usefulness of the output-feedback controllers in this paper.