Helicopter Reconfigurable Flight Control with Actuator Geometry Optimization

摘要

While reconfigurable flight control has been demonstrated on fixed-wing aircraft using control surface redundancies, such failure accommodations were widely believed to be impossible for single main rotor helicopters. In fact, on any such existing helicopter the failure of a main rotor actuator is catastrophic, resulting in a complete loss of control. This paper develops several reconfigurable flight control strategies for main rotor actuator failures on a single main rotor helicopter. First, the paper develops an actuator geometry that provides significant control axes cross coupling, a key to solving the reconfigurable flight control problem. An approach is taken to optimize the actuator geometry for reconfigurable flight control for the Apache helicopter. Prom this, several reconfiguration strategies are developed, and then combined, to form a robust reconfigurable flight control solution for main rotor actuator failures. In particular, a swashplate reconfiguration strategy is developed that allows the aircraft to be controlled in any two of the three control axes at a time, for example pitch and roll, despite a failure in any one of the main rotor actuators. Vertical control is then achieved by one of two methods: flying to a longitudinal velocity that supports the desired vertical velocity, or by using rotorspeed to change the aircraft's lift. The resulting reconfigurable flight control system is independent of the underlying flight control system, though only demonstrated for a classic PID controller here. All designs are performed for the Apache helicopter and are tested using FLYRT, a sophisticated nonlinear validated model of the Apache helicopter.