Nonlinear Adaptive Backstepping with Estimator Resetting Using Multiple Observers

A multiple model based observer/estimator for the estimation of parameters is used to reset the parameter estimation in a conventional Lyapunov based nonlinear adaptive controller. The advantage of combining both approaches is that the performance of the controller with respect to disturbances can be considerably improved while a reduced controller gain will increase the robustness of the approach with respect to noise and unmodeled dynamics. Several alternative resetting criteria are developed based on a control Lyapunov function.