Fault tolerant control based on differential engine thrust and ailerons of a damaged aircraft with vertical tail loss

TLDR: In this paper, the authors have made use of differential engine thrust together with ailerons deflection in the control column for the design reconfiguration of an emergency yaw damper to regain the lateral/ directional stability of a transport aircraft which has undergone severe damage to its vertical tail during flight.

Abstract: In this paper, authors have made use of differential engine thrust together with ailerons deflection in the control column for the design reconfiguration of an emergency yaw damper to regain the lateral/ directional stability of a transport aircraft which has undergone severe damage to its vertical tail during flight. An earlier version of the transport aircraft Boeing-747 is chosen as a working platform. At first the damage to the vertical tail and its effects on the aerodynamics of the aircraft are modeled and then the role of thrust dynamics and its utilization as a control effector is discussed. Engine thrust dynamics are modeled as a second order system to account for real time delays and for its inclusion in the simulation process. An optimal servo LQR controller is designed to minimize the control effort for the proposed model and simulated in Matlab Simulink environment to analyze the intended fault tolerant control design for different flight conditions. The simulation results are encouraging for the use of differential engine thrust as a control effector together with residual control surfaces and help recover the aircraft from the emergency situation successfully.