Robustness Analysis of Nonlinear Flight Controllers

The development of robustness analysis tests is presented for quasi-linear-parameter-varying models in the presence of time-varying, parametric uncertainty. The tests are applied for the robustness analysis of nonlinear dynamic inversion control laws giving sufficient conditions for assessing the nonlinear system’s performance in the presence of bounded disturbances and uncertainty. The tests are formulated as linear minimisation problems subject to linear matrix inequality constraints and solved by using a gridding procedure. A detailed example is presented in which two nonlinear dynamic inversion control laws for the short-period dynamics of an aircraft are analysed and compared.