Aircraft guidance during upset operations
Fly-by-wire (FBW) in its digital version constitutes today an industrial standard for large civil aircraft. This system’s main advantages include sophisticated computer control of aircraft flying, flight envelope protection and pilot workload alleviation, to name a few. For the next generation of aircraft, the challenge will be extension of GNC functions to make the flight task easier while optimising the aircraft’s performance. The EU-funded consortium RECONFIGURE (Reconfiguration of control in flight for integral global upset recovery) was formed with this aim. Ten private companies, universities and research centres joined their efforts to develop advanced GNC functions that support handling of off-nominal events. The new technology should assist pilots by automatically reconfiguring the aircraft to its optimal flight condition, maintaining easiness of piloting. To this end, project partners evaluated sophisticated parameter estimation, fault diagnosis approaches and advanced control techniques. In addition, they addressed the lack of research into issues arising from the integration of parameter estimation and fault diagnostic systems with reconfigurable GNC systems. The RECONFIGURE team recognised a gap in the certification of both individual and integrated techniques that precludes taking full advantage of them. Moreover, research on the FBW system clearance, a prerequisite for certification, had in the past focused almost exclusively on fixed control. Researchers explored a wide range of GNC design and validation methods and tools. These were applied to the Airbus benchmark, that is a very high-fidelity aircraft model, offering a platform for simulations of realistic fault scenarios and abnormal situations. The aircraft model inherited components from benchmarks used in previous European projects. Its development represents a notable increase in the technological readiness of simulation models and also implied the definition of constraints and requirements for industrial verification and validation analysis. Three abnormal scenarios were considered: sensor faults, uncertain aerodynamic effects (icing conditions) and actuator faults. RECONFIGURE achieved small but important steps to initiate a change in the FBW design of tomorrow. The aeronautical industry currently favours a conservative design over a performance-oriented one. The solutions proposed can improve the design of the GNC systems implemented in the current FBW flight control.
Keywords
Aircraft guidance, ‘guidance, navigation and control’, off-nominal events, FBW, RECONFIGURE
