Semi-global output regulation of nonminimum-phase nonlinear systems via error feedback

We consider semi-global output regulation of single-input single-output nonminimum-phase nonlinear systems via error feedback. Onishi et al. introduced the method like backsteppings to solve some global output regulation problems via state feedback in non-minimum phase nonlinear systems. Yang et al. introduced a comprehensible idea to achieve semi-global stabilization via output feedback. We use these ideas. The regulator has saturation to prevent that sudden observation noise make the state of the whole system escape from origin neighborhood. This method requires the solvabilities of some partial differential equations and a linear growth condition.