Output-feedback stabilization for a class of nonlinear systems with unknown control coefficients

The problem of global stabilization by output-feedback is investigated for a class of nonlinear systems with unknown control coefficients. We firstly show that a coordinate transformation, the unknown control coefficients are lumped together and the original system is transformed into a new system for which control design becomes feasible. Secondly, for the new system, an appropriate state observer is introduced, and then based on the backstepping technique, the output-feedback controller is designed. It is shown that global asymptotic stability of the closed-loop system is guaranteed by appropriately choosing design parameters. Finally, an example is provided to demonstrate the effectiveness of the proposed design method.