Advances in theoretical and computational nonlinear control - Dedicated to the 80th birthday of Professor Arthur J. Krener.

Using the dynamic state compensation method developed recently, we show in this paper that a nested saturation feedback control law with gain-dependent saturation levels, whose gain is updated online, is a natural non-identifier based adaptive compensator for feedforward systems with unknown parameters and delays. Such saturated adaptive controllers are “universal” with respect to: (i) parametric uncertainty; (ii) a large constant delay in the input, and (iii) large constant delays in both state and input. In all the three cases, it is proved that there exists a single delay-free universal controller, achieving adaptive regulation with global stability simultaneously.