Adaptive control of non-linear systems with unknown virtual control coefficients

This paper deals with state feedback adaptive control of parametric-strict-feedback (triangular) non-linear systems with unknown virtual control coefficients. A priori knowledge of the signs of the virtual coefficients is not required, and control signals and adaptive laws are smooth. Asymptotic tracking of smooth reference signals is achieved while all the variables remain bounded. The proposed algorithms make use of backstepping and tuning functions, and enlarge the class of non-linear systems with unknown parameters for which asymptotic output tracking can be achieved. Copyright (C) 2000 John Wiley & Sons, Ltd.