Adaptive nonlinear regulation: equation error from the Lyapunov equation

An adaptive controller for nonlinear, linearly parameterized systems is presented. The new features introduced in the design are: (1) parameter estimation is performed on the scalar Lyapunov equation instead of the n-dimensional equation of the system itself. This allows non-Lipschitz uncertainties to be tolerated, especially when the stabilizing laws are not feedback linearization plus linear control. (2) Double estimation is used. One estimate is used for the stabilizing control, and the other is used to cancel the perturbation terms introduced by the adaptation, if possible. This is proposed to solve the problem of the implicit definition of the controller which arises when one tries to do this cancellation.<<ETX>>