Global adaptive output regulation for nonlinear output feedback affine systems

In this paper, the global output regulation problem (ORP) for nonlinear output feedback affine systems with unknown functions (UFs) and unmeasured states is studied. Firstly, a Lemma is proposed to solve not only the global ORP of nonlinear systems, but also the 'explosion of terms' problem of backstepping. Secondly, the control scheme is designed based on backstepping method, which avoids an Assumption to solve the ORP. Therefore, the algorithm reduces the conservatism and increases the applicability. Finally, the algorithm is applied to Duffing system to verify the effectiveness of the algorithm.