Approximate decoupling flight control design with output feedback

The problem of approximate decoupling of nonlinear systems by output feedback is considered. The structure of the controller is high-gain proportional plus integral. Linearization of the nonIinear closed-loop equations results in the standard singular perturbation form. Based on the singular perturbation concept, a control law is found that accomplishes approximate decoupling with stability for nonlinear systems. Application of the proposed design scheme to the full six-degree-of-freedom nonlinear aircraft dynamics model is presented, demonstrating its validity.