Modal Design and Simulation of Automatic Flight Envelope Protection for Civil Aircraft

The automatic flight envelope protection of civil aircraft is independent of the envelope protection of the main flight control system, it is the first line of defense for aircraft stall or speeding, which can reduce the workload of pilots and ensure flight safety. Considering the complexity of air flight scene, many automatic flight modes are related and affect each other, which is easy to cause mode confusion. In order to solve this problem, the flight guidance modes are analyzed and classified, and a layered velocity threshold mode adjustment strategy based on the finite state machine (FSM) theory is proposed, which transforms the general problem of mode switching into a hierarchical switching problem, then, the velocity layer of the aircraft is marked as a constraint of the mode state. The simulation results show that the proposed scheme can meet the expectations in different flight scenarios at different flight stages.