Robust Flight Control Law Development for Tiltrotor Conversion

In this work, a control algorithm for the longitudinal model of a tiltrotor aircraft during flight modes conversion is developed. The parameter perturbation in tiltrotor model caused by the variation of nacelle angle is considered in controller designing for conversion flight. In order to separate the uncertainty from nominal model, the uncertainty is expressed as a diagonal structure in the form of LFT, which avoided the unnecessary conservation. Then the flight control law is designed using the singular value technique and m-synthesis approach. Simulation results demonstrate the effectiveness of robust control design in tracking pitch angle, altitude and velocity commands, in that it can provide good robust stability and performance.