Output Feedback Stabilization for a Class of Nonlinear Systems with Unknown Output Function

This article proposes an output feedback control method for a class of nonlinear systems in non-triangular form with unknown output function. A state observer and observer-based controller are designed to globally stabilize the nominal system. Then, the coordinate transformation is introduced into the original nonlinear system to make its form consistent with the nominal system. On this basis, a homogeneous observer and controller are designed to regulate the nonlinear system states to zero. Finally, the correctness of the theoretical derivation is verified by an example.