Fault-Tolerant Control Allocation on a Compound Helicopter in Cruise

Abstract

The present study provides a comparison of an adaptive versus a robust baseline pseudoinverse control allocation method on a 20,110 lb compound helicopter post-actuator failure. Failure scenarios such as locking of the main rotor swashplate actuators and aerosurface actuators are taken into consideration in forward flight. A range of tolerable positions for locked-in-place actuator failures is established for the aircraft at a cruise speed of 150 knots. A full authority model following linear dynamic inversion control architecture is implemented for the nonlinear simulation model. Stability margins, phase delay, bandwidth, and disturbance rejection specifications for the aircraft were evaluated under different actuator failures with adaptive and robust control allocations. Nonlinear simulations are used to examine the benefits and drawbacks of an adaptive and robust control allocation schemes when the aircraft is subjected to different actuator failure at their extreme positions.