Piloted Simulator Evaluation of a Model-Independent Fault-Tolerant Flight Control System

Abstract

This paper for the first time evaluates the real-time performance of a sensor-based nonlinear dynamic inversion (SB-NDI) controller by means of a piloted proof-of-concept evaluation in a six degree of freedom research flight simulator. This fault-tolerant controller is completely model-independent and as a result does not require online identification. The inner loop of the controller incorporates an approximate dynamic inversion controller in combination with Lyapunov stability within a nonlinear dynamic inversion (NDI) framework and results in an adaptive model-free controller. The real-time performance, the fault-tolerant capabilities and the required physical workload of the controller are evaluated in the SIMONA research flight simulator with two flight scenarios consisting of approach procedures for the Flight1862 aircraft configuration and a vertical tail loss. The results are compared with full manual control and with an NDI attitude rate controller with a fixed aerodynamic model taken from literature. The results of this evaluation indicates that the designed multi-loop SB-NDI controller is capable of extending the survivability of the aircraft beyond what is possible with the baseline NDI controller. It also shows that the SB-NDI reduces pilot workload after a significant failure to levels comparable to the nominal aircraft.