Switching adaptive control for nonlinear systems

We extend the controllers presented previously by Kosmatopoulos to the case of linear-in-the-parameters multi-input (MI) nonlinear systems whose dynamics are concatenated by bounded disturbances. By making use of the notion of robust control Lyapunov function introduced by Freeman-Kokotovic (1996), we develop stabilizing controllers for large classes of nonlinear systems including feedback linearizing systems and parametric-pure-feedback (PPF) systems. In particular for the case of PPF systems, the restrictive assumption made by Kokotovic et al. (1991, 1995) and Seto et al. (1994) does not need to hold any more. Another very important feature of the proposed controller is that, in the case of feedback linearisable and PPF systems, it does not need any knowledge about the signs of the input vector-fields, thus removing the assumption we made previously. Moreover, the external disturbances are allowed to affect nonlinearly the system dynamics