Hafid Smaili

Assessment Criteria as Specifications for Reconfiguring Flight Control

To obtain a quantitative measure of predicted FTFC system performance in degraded modes, specifications need to be defined to assess proper functioning under realistic operational flight conditions. The goal of the benchmark specifications modelling, as described in this chapter, is to create a set of assessment criteria in order to evaluate the quality of the performance of fault detection and identification (FDI) and reconfigurable control algorithms. The lay-out of this chapter is as follows. First, the specifications modelling process is introduced by discussing the benchmark scenario. Subsequently, the general evaluation criteria will be considered by defining two classes of test manoeuvres. Thereafter, focus is placed on the test manoeuvres for FTFC qualification, which is the major topic of this chapter. After the discussion on how the assessment quantities of interest can be divided into two categories, four qualification test manoeuvres are discussed in depth. These include straight flight, right turn and localizer intercept, glideslope intercept and final approach with sidestep. Finally, a summary of the specified assessment quantities is given for the different FTFC qualification test manoeuvres. These criteria have also been published in Ref. [3].

Pilot-in-the-loop evaluation of fault-tolerant flight control systems

Abstract Human operator interaction with aircraft flight control systems can have a significant impact on the overall systems safety and efficiency. A new flight control system, whether it is operated manually by the pilot or has the pilot monitoring automatic operation, must therefore be tested with a human operator in the loop before it can be deployed. This paper describes a flight simulator campaign to evaluate several fault-tolerant flight control systems under realistic failure conditions. It covers the online implementation of the controllers, the configuration of the simulator, and the evaluation scenarios and metrics. Some typical results are also included.

Some Aspects of Upset Recovering Simulation On Hexapod Simulators

Considered are some aspects of motion cueing on hexapods in simulation of upset/stall recovering maneuver, as a result of project SUPRA of the 7 European Framework Program. Inadequate motion cueing or large motion cues distortions can distort pilot’s opinion about the maneuver and affect training results. In the paper, the main attention is paid to motion fidelity aspects, which are determined, on the one hand, by the accuracy of the “useful” motion cues reproduction and, on the other hand, by inevitable false cues. On the basis of the experimental data on the effect of large G-loads on pilot’s perception of angular and linear motion and the data available on the motion fidelity criteria, the methods are discussed to optimize (adapt) the “classical” filters for the upset recovery simulation. The results of the optimizations are tested in experiments with test pilots. The objective and subjective measurements received in the experiments demonstrate both the effectiveness of the proposed optimization and the necessity to conduct pilot training on moving-base hexapod-type simulators.

RECOVER: A Benchmark for Integrated Fault Tolerant Flight Control Evaluation

Fault tolerant flight control (FTFC), or intelligent self-adaptive control, enables improved survivability and recovery from adverse flight conditions induced by faults, damage and associated upsets. This can be achieved by ’intelligent’ utilisation of the control authority of the remaining control effectors in all axes consisting of the control surfaces and engines or a combination of both. In this technique, control strategies are applied to restore vehicle stability, manoeuvrability and conventional piloting techniques for continued safe operation and a survivable landing of the aircraft.

Piloted Evaluation Results of a Nonlinear Dynamic Inversion Based Controller Using Online Physical Model Identification

As the survey of major aircraft accidents and incidents in Chapter 1 has shown, it is sometimes still physically possible to control a damaged aircraft while components such as control surfaces, engines or parts of the structure have failed. In some cases, (differential) engine control was used by the pilot to replace conventional control via the ailerons and elevators due to loss of the hydraulic system. In other cases, some control surfaces may still be operating to replace the failed ones. This redundancy can be exploited by an automated reconfigurable system which identifies the remaining control options and drives the available surfaces. Ideally, the system would also be able to cope with unforeseen failures and adapt itself accordingly. If the system takes the form of a manual fly-by-wire flight control algorithm, as opposed to a fully automatic system, the requirements on the (degraded) handling qualities also need to be taken into account. The system must provide the pilot with good handling qualities in normal flight conditions and acceptable handling qualities in failed conditions.