Dynamic Adaptation Gains for Nonlinear Systems With Unmatched Uncertainties

We present a new direct adaptive control approach for nonlinear systems with unmatched and matched uncertainties. The method relies on adjusting individual adaptation gains to cancel the effects of unmatched parameters whose transients could otherwise destabilize the closed-loop system. The method guarantees the restoration of the adaptation gains to their nominal value and can readily incorporate direct adaptation laws for matched uncertainties. The proposed framework is general as it only requires stabilizability for all possible models.