Generalized output regulation problem for a class of nonlinear systems using error feedback

We address the problem of output regulation for nonlinear systems driven by a partially unknown non-autonomous exosystem via error feedback. We generalize the classical output regulation problem in order to expand the class of reference or disturbance signals. Our study of the above problem, referred to as the so-called generalized output regulation problem depends on the classical notion of the exact disturbance decoupling. A local necessary and sufficient conditions for the solvability of the problem are given.