Flight-Test Evaluation of a Loss-of-Control Mitigation System

Abstract

For more than a decade, researchers have been developing novel adaptive flight control systems that provide a means to safely operate an air vehicle in the presence of damage or failures. Although these systems show great promise, integration of exemplar systems in flight-test aircraft at NASA has revealed the potential for unfavorable pilot–vehicle coupling, including pilot-induced oscillations. To address this issue directly, the Smart Adaptive Flight Effective Cue system was developed that features an adaptive command path gain to mitigate oscillation tendencies and an inceptor force-feedback cue to alert the pilot that the system is active. To evaluate the system, a representative adaptive controller that had been successfully evaluated in previous flight-test programs and the Smart Adaptive Flight Effective Cue system were implemented in a Calspan Learjet in-flight simulator. Flight-test evaluations consisted of three test pilots conducting two sorties each to evaluate the effectiveness of the combined system in the presence of failures. Pilot opinion ratings and quantitative assessments of performance indicated that the Smart Adaptive Flight Effective Cue system successfully eliminated the oscillation tendencies that can lead to loss of control. Furthermore, the system restored a more linear vehicle response that allowed the pilots to successfully complete the evaluation tasks with near baseline aircraft performance.