Semiglobal nonlinear output regulation with adaptive internal model

We address the problem of output regulation for nonlinear systems driven by a linear exosystem whose natural frequencies are not known a priori. We present a classical solution in terms of the parallel connection of a robust stabilizer and an internal model, where the latter is adaptively tuned to the device that reproduces the control required to maintain the output-zeroing condition. We obtain robust regulation (i.e. in presence of parameter uncertainties) with a semiglobal domain of convergence for a significant class of nonlinear minimum-phase system.