Originally Posted by
FlightDetent
Utterly wrong. Although perfectly irrelevant to the thread, the danger of complete misunderstanding of the ‘bus haptic feedback necessitates my remark, apologies.
Are you referring to limit protection at alpha prot through to alpha floor as a feed back? (FCTM 2.60.6)
Possibly for the current Airbus, haven't flown one for a couple of years, however haptic control feedback was patented (assigned to Honeywell who were involved in the bus FCS) in 2006 but appears to have lapsed. TU Delft ran studies on the benefits of that as a proposed enhancement on an A330 in 2016, all following Billings work in 1996. The bus SSC's I have used had an SSC resistive force proportional to stick deflection and velocity from passive mechanical spring/dampers. If they were smarter than that, I missed that in the testing. The bus provides an increase in resistance to the SSC order to over bank the aircraft, that is an advisory of the envelope protection. That is a cueing of a limit rather than a feedback of the flight vehicles condition. If you had asymmetry in lift between the wings, the system is going to absorb that and the flight crew will be given the normal passive constraints per a normal condition. Thats roll... for pitch, if you are off speed, well, you never are, the aircraft is doing its own thing, and there is no cue that the aircraft is off speed (aoa) as a consequence. That leaves pitch to be either passive in nature until a limit condition occurs e.g., alpha prot/ alpha floor. The G500/G600 SSCs incorporating tactile feedback with BAE Systems’ “Active Inceptor System,” was headlined as the first civil aircraft use of that concept, around 2015. The G's also were synchronous SSC's which seems to make some sense, would have been handy for AF447 at least. Crew flying a 330 into a fun strip have the Captain comment to the FO on the taxi in that he could have used some more pitch in the flare. The FO knew that he had full back stick on at the time, Captain only knew when the FO 'fessed up on the taxi in. Synchronous controls would have given a bit more info.
If AI had previously applied haptic feedback would appreciate a reference to that effect. I can't find any reference to a haptic feedback system incorporated in the 320.330 or 340 FCOMs or FCTM of mine (alpha prot/alpha floor notwithstanding).
Note: the evaluation of the A330 FCS adapted to having haptic feedback was interesting and should not be surprising. For the primary tasks that were evaluated, there was either no observable difference or negligible difference in tracking accuracy, or workload, that would be expected in pitch considering the flight path demand logic of the airbus, but it was interesting in the roll side, where little benefit was observed. The test series was constrained in scope, which may explain the observed lack of benefit in roll.
Now going to synchronous SSC design, and even on the ATS would be interesting to test near limit conditions for S.A. Suspect any bus driver flying the G's SSC would note the difference.
P.S.: The one time that feed back would be quite handy in the Airbus system and could help in a tracking task would be in direct law, as possibly such feed back would assist in trim input to the pilot. However, as direct law comes about following degradations which have potential sources in the sensing that would be needed for the feedback system, CAS, AOA etc... then sometimes it just sucks to have an electrojet, and you get to work with a trim system to a control that has performance outcome as its feedback rather than force.
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Billings,C.E.(1996). Aviation Automation:The Search for a Human-Centered Approach. CRC Press,1st edition.
Ellerbroeck, J., Rodriguez Martin, M.J.M., Lombaerts, T., van Paassen, M.M., & Mulder, M.; (2016) Design and evaluation of a Flight Envelope Protection haptic feedback system. Paper, IFAC (International Federation of Automatic Control).
https://doi.org/10.1016/j.ifacol.2016.10.481
EP1918196A1, EP1918196B1, Abel, S.G., Hanion, C., Pilot Flight Deck Control Stick Haptic Feedback System and Method.
US9156546B2 Irwin J.G. III., Einthoven P.G., Miller, D.G., Spano, M.S., Active-inceptor tactile-cueing hands-off rate-limit