Structured robust control-loop design with input saturations for tandem ducted fan vehicle

We propose the structured two-loop flight control system of a novel tandem ducted fan vehicle for near hover flight in consideration of actuator saturations on its dynamics. The prescribed controller architecture consists of static output feedback inner loop and four PI outer loop, which is a desirable and intuitive structure for practical implementation. The effect of a limited control activity on the control performance cannot be disregarded since it may lead to performance degradation or even instability. Moreover, at times, the input effort commanded by the control law is approaching the saturation levels in maneuvering flight or in the presence of wind gust disturbances. Therefore, a static anti-windup compensator is employed to preserve the closed-loop stability and performance. Both the feedback controller and the anti-windup compensator are computed simultaneously using recently available nonsmooth optimization techniques. Simulations using both a linearized model and a full nonlinear model of the vehicle under strong wind disturbances are presented to demonstrate its performance.