Upset Recovery Controller Based on Maximum Control Effectiveness for a High-Performance Over-Actuated Aircraft

Abstract:

Current flight control systems fail to recover to safe flight conditions in off-nominal flight conditions and require a more advanced upset recovery methodology which is able to provide full control authority. Existing upset recovery methods are focused on fast recovery taking into account the current flight conditions while neglecting nonlinear effects. This paper implements a new approach for upset recovery which aims for maximum control effectiveness of control effectors given the flight conditions by means of incremental nonlinear dynamic inversion. A recovery control strategy based on reducing angular body rates and aerodynamic angles generates inner and outer loop commands. Pseudo control inputs defined as required moment increments are derived using a nonlinear Jacobian model of the control effectors. This pseudo control input and Jacobian determine the direction of control effector effectiveness gradient optimization. The upset recovery system is implemented on the Innovative Control Effectors (ICE) aircraft, a high performance over-actuated aircraft with 13 highly nonlinear, interacting and coupled control effectors. Real-time simulation results show that the upset recovery system is fault tolerant, considerably faster, and more reliable compared to nominal flight control in terms of recovering angular body rates and aerodynamic angles, and is applicable in every aircraft upset condition.