[en] nonlinear systems ; adaptive control ; feedback passivation
[en] An adaptive controller is developed for a class of nonlinear systems for which other approaches (e.g. backstepping) may fail to be applicable. The new design employs feedback passivation and an explicit construction of a Lyapunov function for the zero dynamics with respect to a relative degree 1 output. As an illustration a longstanding "nonlinear benchmark problem" is solved.