${cal L}_1$ Adaptive Output Feedback Controller for Systems of Unknown Dimension

This note presents novel adaptive output feedback control methodology for systems of unknown dimension in the presence of unmodeled dynamics and time-varying uncertainties. The adaptive output feedback controller ensures uniformly bounded transient and asymptotic tracking for the system´s both signals, input and output, simultaneously. The performance bounds can be systematically improved by increasing the adaptation rate. Simulations of an unstable nonminimum phase system verify the theoretical findings.