A stability-guaranteed smooth-scheduled MIMO robust emergency autopilot for a lateral surface jammed UAV

Abstract

This paper investigates a methodology for autopilot design for an unmanned air vehicle where one of the lateral control surfaces, i.e. the aileron or rudder, becomes jammed and unusable. The autopilot handles the automatic recovery, autonomous guidance and landing of the disabled unmanned aerial vehicle. An accurate nonlinear aircraft model is used to build local flight control laws using loop-shaping to decouple longitudinal and lateral channels. The design is carried out in a way to allow smooth scheduling over the local controllers without losing stability and performance, culminating in a robust emergency autopilot over the full flight envelope. The autopilot is tested on an example distress scenario involving aileron surface jam. It is confirmed through simulations that the autopilot design is capable of resuming safe flight and autonomous navigation under the fault scenario and is able to safely land the unmanned aerial vehicle to a target runway.