An alternate optimal formulation for robust eigenstructure assignment

An alternative eigenstructure assignment formulation which has inherent advantages over a previous formulation is introduced. A highly nonlinear performance index has been replaced by a quadratic one at the expense of an increase in the nonlinearity and number of constraints. Overall, the present formulation presents a significantly simpler problem from a numerical optimization viewpoint. Additionally, the gap between the achievable eigenstructure and the desired eigenstructure appears explicitly in the performance index as opposed to implicitly in its prior counterpart. The capability of the new formulation is illustrated in the design of a mode-decoupled roll-yaw autopilot for a generic non-axisymmetrical airframe