Commercial aircraft fault tolerant control (FTC) strategies in the flight control system (FCS) are based on fail-safe approaches whereby a nominal control law is switched first to a robust solution and then if necessary to a direct law controlling the actuators surfaces. Each component of the control law set is designed off-line and has a different level of robustness and performance. The reasons for this conservative FTC approach are:
- Lack of demonstrated maturity of reconfigurable guidance and control (G&C) methods for commercial aircraft
- Lack of research in the practical interaction limitations between reconfigurable G&C systems and estimation / diagnostic systems.
- A definite gap on the clearance problem for such G&C systems.
The goal of RECONFIGURE is to investigate and develop aircraft G&C technologies that facilitate the automated handling of off-nominal events and optimize the aircraft status and flight while maintaining, or even improving, its safety level. These technologies will extend the operation of the current G&C functionalities that assist the pilot and optimize the aircraft performance. Thus, the aim is to provoke a change in aircraft transport towards: full-time, all-event availability of performance-enhancement electrical fly-by-wire.
The objectives of the project will be achieved by developing:
- Advanced parameter and fault estimation/diagnosis approaches
- Reconfigurable G&C approaches
- Integration and integrated approaches for estimation, diagnosis and G&C
- Advanced clearance approaches for such systems
The investigation will focus on off-nominal/abnormal event scenarios directly affecting the aircraft flight control system. The techniques will offer the capability to adjust and adapt to the abnormal event during flight.
Enhancing aircraft safety in abnormal events
An EU-funded project is developing advanced techniques for a fault-tolerant flight control system to make automated handling easier and alleviate the pilot's workload during off-nominal events.
Aircraft with fly-by-wire (FBW) flight controls (an electronic interface that replaces conventional manual flight controls) require computer-controlled flight control modes that are capable of determining the operational mode. The most well-known control modes (laws) are normal, alternate, direct and mechanical. Current fault-tolerant control strategies are based on fail-safe approaches whereby a normal control law is switched to a direct law. However, the latter flight control law is the least sophisticated, with a minimal level of stability augmentation.
Switching to the direct law in case of abnormal events is increasing demands on the pilot's side. Nevertheless, this state of practice is fully compliant with airworthiness regulations and fits well in the certification process.
The EU-funded project http://reconfigure.deimos-space.com/ (RECONFIGURE) (Reconfiguration of control in flight for integral global upset recovery) is addressing the gap in sophisticated guidance and control (G&C) functions that make automated handling of abnormal events easier. This technology will greatly assist the pilot by automatically reconfiguring the aircraft to its optimal flight condition, maintaining stability.
To achieve project goals, partners are working on advanced parameter estimation and fault diagnosis approaches as well as reconfigurable G&C. In addition, they are addressing the lack of research into issues arising from the interaction of reconfigurable G&C systems with the estimation and diagnostic systems.
Project partners have thoroughly studied a wide range of advanced G&C design and clearance methods and tools. These will be applied to the Airbus benchmark that is a high-fidelity aircraft model.
Over the next project period, partners will evaluate the technological readiness level of the developed approaches by performing a traditional industrial verification and validation analysis.
RECONFIGURE will provide solutions that can extend operability and improve the design of the G&C functions implemented in the current FBW flight control. This should assist the pilot in keeping the flight safe, making the flight task easier.