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Old 8th Aug 2017, 17:00   #1 (permalink)
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Join Date: Feb 2000
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Impact of system latency upon controllability ?

I've just been wading through a (non aviation) document on system latency that claims to be showing me some wonderful lessons about how critical system latency (input-response delay) is to controllability. No sh1t Sherlock!

However, when I went and had a rummage around the usual sources, I can't seem to find any good documentation to support what I believe I intuitively know either for aircraft, or the other obvious user of such principles - computer game design.

Can anybody point me at a good document on the topic?

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Old 9th Aug 2017, 09:55   #2 (permalink)
 
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When I passed through NASA Dryden (Edwards AFB) in '69, they were doing some serious research on that, related to deliberate crashing an unmanned aircraft in a controlled way (they didn't wan't an uncontrolled crash, for some reason). I can't find anything from then in my library, but the first reference on the link below may be of relevance.

https://tinyurl.com/y7deuqjz
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Old 9th Aug 2017, 11:08   #3 (permalink)
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Thanks Fitter, but I suspect it isn't. I can't see drone command signal latency having much relevance to the problem of control / FBW direct input response latency?

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Old 9th Aug 2017, 21:27   #4 (permalink)
 
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This looks interesting:
https://etd.ohiolink.edu/pg_10?0::NO...yton1418340523
It presents a study carried out on a flight sim F-16 Flight Control System model, so I understand that the latency limits they found between a stable and unstable behaviour are related to the flight sim model they used and do not necessarily reflect what you would find on a real F-16. On the other side, I suppose the investigation method would be applicable to a real case as well.

The relevant paragraphs are 3.12 and 6.2.

Edit: The link to the .pdf file with the full text of the thesis is at the bottom of the webpage and not very conspicuous, so I enclose it below.
https://etd.ohiolink.edu/!etd.send_f...ion=attachment

Last edited by aerolearner; 9th Aug 2017 at 21:43. Reason: Add link to pdf
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Old 9th Aug 2017, 23:57   #5 (permalink)
 
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Genghis,
Not my specialty as I more ensured that the overall AFCS met requirements & certification, but my recollection is that what you're asking was a fairly closely held outcome of programmes such as Bombardier's Active Control Technology (ACT) run in conjunction with Rockwell Collins' Flight Controls group. PM me if you need potential authors for a search.

A quick search on Latency on the SFTE website only brought up one paper but, again, my memory from around 10 years ago is that there were several such papers as smaller manufacturers looked at FBW. This is the link: https://www.sfte.org/component/conte...?paper_id=1264
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