Multivariable Control Law Design for a Tailless Airplane

In this paper, a manual flight control system for the combined longitudinal and lateral-directional dynamics of a tailless fighter airplane is presented. The design method used is dynamic inversion combined with structured singular value synthesis to address the issues of stability, performance, and robustness to plant uncertainties. Design objectives are formulated in terms of stability, flying qualities, and robustness achieved by the closed-loop system. The overall design structure consists of an inner loop in which the airplane dynamics across the flight envelope are equalized to desirable dynamics and an outer loop in which structured singular value synthesis is used to obtain a robust dynamic controller to track ideal model responses to the pilot commands. A prefilter which can be scheduled according to the airplane flight condition is then used to shape the input to the system to achieve the desired flying qualities.