[HN Gopher] The state of the art in copter drones and flight con...
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The state of the art in copter drones and flight control systems
Author : PaulHoule
Score : 112 points
Date : 2024-06-03 16:45 UTC (2 days ago)
(HTM) web link (www.mdpi.com)
(TXT) w3m dump (www.mdpi.com)
| nick7376182 wrote:
| Ref 61 as the single citation for a lot of content in Section 3
| claiming that hex and octa copters have more endurance than
| quads. I'm not sure I agree with that statement and it needs a
| lot of qualifiers if it is to be relied upon.
| K0balt wrote:
| As a hypothesis at least it seems probable, just based on lift
| disk size and proximity. Lift disks closer together form more
| of an annular lift ring around the craft, for more uniform
| flow, and larger disk areas in general should lead to increased
| hovering efficiency.
| dylan604 wrote:
| In my experience flying octa vs quad, the octa definitely
| outperforms the quad. This was some time ago and DJI has made
| improvements in leaps and bounds to something like 30mins for a
| Mavic now? But back then, the octa easily had longer flights as
| it had larger capacity which was filled by larger batteries. It
| was also easier to fly/handle. Essentially, I'm just
| repeating/agreeing with everything they said on pages 11&12.
| serf wrote:
| this has been my experience, too.
|
| more rotors = more power consumption capability, but in
| practice it yields lower duty cycles for each of the motors.
| That effect, along with additional lift capacity for batteries,
| creates a platform that generally stays up longer.
|
| as others mentioned there are also aerodynamic advantages as
| long as we're staying away from coaxial designs.
| ipunchghosts wrote:
| Mdpi should fix its format as a third of any given article is
| whitespace.
|
| Oh, and hi Paul!
| ipunchghosts wrote:
| Ok, maybe its a quarter.
| hiddencost wrote:
| Note that the authors are two Latvians and a Ukrainian.
|
| First sentence of today's ISW briefing: "Select Russian military
| commentators continue to complain about superior Ukrainian drone
| and electronic warfare (EW) capabilities on the battlefield,
| continuing to highlight the rapid and constant tactical and
| technological innovation cycles that are shaping the battlespace
| in Ukraine."
|
| https://www.understandingwar.org/backgrounder/russian-offens...
| otabdeveloper4 wrote:
| Citing blatant propaganda during an active war phase?
|
| Now that's what I call research!
| hiddencost wrote:
| I'm not sure exactly which direction your critique is
| oriented. The functioning of the Russian milblogger space
| serves multiple functions, and there are competent ways to
| learn things from it.
|
| If you're calling the ISW propaganda, _shrug_.
|
| I think the point stands: if you're interested in the state
| of the art in drone tech, you're almost certainly paying
| attention to the Ukrainians and Latvians.
| SiempreViernes wrote:
| The ISW is so blatantly biased in their coverage they are
| indeed best though of as an classy looking info-warrior
| than something like to a neutral observer.
|
| For a long while I only distrusted their political
| commentary, as it was so obviously shit, at just rolled my
| eyes when they pretended the Ukrainians didn't send troops
| on raids toward Belogorod, but otherwise trusted that they
| at least covered military movements accurately.
|
| Lately I have however seen accusations that they are also
| uselessly slow at reporting Ukrainian withdrawals, so at
| this point I wouldn't trust their milblogger coverage to
| deliver more than selected defeatist posts.
|
| All that said, I think your point that (some of) the state
| of the art in drone tech is being desperately pushed in
| Ukraine is a good one. Though I'd add the qualifier that
| they have very specific concerns and constraints on their
| drone use (the one-way trips being a prominent one).
| otabdeveloper4 wrote:
| > if you're interested in the state of the art in drone
| tech, you're almost certainly paying attention to the
| Ukrainians and Latvians
|
| Definitely not to the ISW, though. (Just lmao.)
| paganel wrote:
| I wouldn't cite ISW for anything serious regarding this war.
| Yes, I am pro-Russia when it comes to this war, but at the same
| time I respect opinions "from the other side" which are not
| complete bollocks. ISW is not doing that, unfortunately for
| them.
|
| Later edit: Just to make sure, I'm not calling bollocks on ISW
| for this particular statement of theirs (even though I find it
| highly debatable), but on the information generally coming out
| of ISW
| PakG1 wrote:
| For what it's worth, MDPI has a lot of criticisms from academia
| as a publisher. Criticisms regarding editorial reliability,
| methodology acceptance, rigour, etc, etc. Here's just a
| smattering:
| https://en.wikipedia.org/wiki/MDPI#Evaluation_and_controvers...
|
| It's been enough where I end up automatically ignoring MDPI
| papers unless someone I respect recommends one to me. For better
| or worse. But MDPI made it's own bed in many ways.
| PaulHoule wrote:
| Go take a look at _Frontiers_.
| light_hue_1 wrote:
| There are reasonable MDPI journals, and reasonable Frontiers.
| Just like there are predatory IEEE journals and conferences.
|
| You can't just look at the publisher.
|
| A quick shortcut is to look at who are the
| editors/organizers. If you don't see affiliations from the
| West, it's unfortunately a very bad sign.
| PaulHoule wrote:
| ... and plenty of ethical problems in terms of the very
| business model of _Science_ , _Nature_ , Elsevier and all
| that. Not to mention what they've done to maintain their
| comfortable position.
|
| MDPI is the most active RSS feed by far in my collection,
| they publish a lot of stuff. I'd be interested in getting
| feeds of Open Access papers on other journals (say from
| _Science_ ) but so far no dice.
| Eddy_Viscosity2 wrote:
| I've heard this and actually had a paper published in an MDPI
| journal. My personal experience was that it was astonishing
| quick to do so. Usually the
| submission/review/acceptance/publishing process is many months
| but this was less than two if I remember correctly. The paper
| was reviewed and the reviewer comments were reasonable. Not
| just editorial but with technical comments. So that seemed
| fine. As soon as we submitted the revised manuscript it was
| pretty much published immediately. So all the normal steps were
| followed, just at a faster rate it seemed.
|
| Again, this is my one and only experience with them. I'd be
| interested if others have any...
| kragen wrote:
| those criticisms are from people who think that publishers and
| reviewers should evaluate scientific papers, when obviously the
| right way to evaluate papers is by the larger research
| community over the course of many years. worse, many of the
| criticisms are from institutions that are attempting to use
| bibliometrics for hiring and tenure decisions, which is an
| obviously stupid idea
|
| most papers are worthless, but when they are first written, it
| is too early to tell which ones they are; of course reviewers'
| suggestions are often helpful in improving the quality of a
| paper, but they cannot improve a worthless paper into a
| groundbreaking one
|
| pre-publication peer review was instituted mostly in the mid-
| twentieth century and should be regarded as a failed experiment
| belonging to the age of paper. most _peer-reviewed_ papers are
| worthless, and peer review often serves merely to retard
| progress
|
| most of the papers i see on mdpi are mediocre, but some are
| useful, and it certainly isn't vixra-style garbage
| PaulHoule wrote:
| Accusations against MDPI, _Frontiers_ and such take this form
|
| https://en.wikipedia.org/wiki/Predatory_publishing
|
| the claim is that they are ripping off the scientists. Note
|
| https://en.wikipedia.org/wiki/Jeffrey_Beall
|
| was forced to retract his claim that MDPI was predatory.
| kragen wrote:
| some do take that form, yes; others are simply complaints
| that tenure and hiring boards were going to have to
| evaluate the quality of candidates' research for themselves
| because mdpi wasn't doing it for them
| godelski wrote:
| Peer review is great in theory, but fails because it makes
| too many assumptions and because the incentive structure. And
| it certainly doesn't scale well. It's important to remember
| that the point of publishing is communication. Anything more
| or less is ill founded.
|
| It is obtuse to think that a few people can read a paper and
| know it's validity. It's falsifiable but even that's fuzzy.
| The problem then comes down to the incentive structures. Why
| do people cheat? Because we're lazy evaluators. It's odd to
| me that we won't read the works of peers in a department,
| lab, whatever. But doing that would be a much stronger form
| of evaluation than anything that could be inferred from
| citations, h-index, conference ranking, etc. Plus, the
| structure is to push novelty fast and frequently. That's not
| only not possible but ignores a fundamental aspect of
| science: reproducibility.
|
| But this also doesn't mean there aren't scam publishers and
| publishers scammers prefer. But I'd say that those are a
| result of the former issue. Because metrics are not being
| treated as guides. It's just Goodhart's Law in action.
| kragen wrote:
| entirely agreed
|
| i don't think mdpi is a scam publisher, but then, i don't
| read mdpi papers from following some kind of latest-mdpi-
| papers feed; i read them because other papers cite them, so
| i couldn't tell you if the utter-bullshit-paper percentage
| on mdpi is 1% or 99%
|
| i just know i heave a sigh of relief when the paper i'm
| looking for turns out to be on mdpi, because i know that
| not only will i be able to read it without hassle, it will
| have a clearly marked creative-commons license that permits
| me to archive and redistribute the paper. same with hindawi
| actually, though i'm mmaybe a bit prejudiced against
| hindawi papers
| godelski wrote:
| Yeah I can't say anything about MDPI, and this isn't in
| my domain. My domain is in ML and all I can say there is
| that the signal to noise ratio over conference
| publications and arxiv papers is within error. But
| research continues for the same reasons it always has,
| because people are communicating and niches know their
| niches. But I think it doesn't bode well for Academia or
| even industry, who are letting the metrics dictate how
| they evaluate people. Especially for industry, where
| things have to end up working. I think Gemini is doing a
| great job at showing how being great on benchmarks
| doesn't mean you're a great tool. It's because benchmarks
| are only guides. When they aren't, they will be hacked
| (if they already aren't). And that's a dangerous
| situation to be in.
| bambax wrote:
| Regarding quadcopters, this video by "Verity Studio"
| https://www.youtube.com/watch?v=3h1Kh152ygU claims that they have
| developed a technology to enable drones to continue to fly a
| little, and then land safely, with just three motors and the
| fourth disabled.
|
| But to the best of my knowledge this hasn't been implemented
| anywhere, and today's drones simply fall out of the sky if one
| motor fails or its propellers are destroyed.
|
| Anyone know why that is? Is the video simply fake? (Comments on
| the video are disabled, which is not a good sign...)
|
| Even if the video is fake, this seems like an important area of
| research for drone safety; what's the state of the art?
| foobarbecue wrote:
| I remember a paper/ video from ETH Zurich demonstrating this
| sometime around 2015. There's nothing particularly difficult
| about it if your motors and controllers are sufficiently
| overspecced and you're willing to let the aircraft start
| spinning (you sacrifice yaw control).
|
| Edit: here it is, 2013 not 15. https://ethz.ch/en/news-and-
| events/eth-news/news/2013/12/new...
| krisoft wrote:
| > Is the video simply fake?
|
| I don't think so. At least there is nothing impossible about
| what they are claiming to have achieved.
|
| > Anyone know why that is?
|
| I think the problem is that it wouldn't gain you a new ability.
| If you are working on something where resilience against
| failures is important you are much better off with an octo- or
| hexacopter arrangement.
|
| With that algorithm if a failure occurs suddenly you are in a
| brand new control regime where the pilot is probably not as
| proficient. How will they know which way to push the stick when
| the drone is spinning like crazy? So you probably want a fully
| autonomous controlled drone (like the ones in the theatre
| production they are showing).
|
| > today's drones simply fall out of the sky if one motor fails
| or its propellers are destroyed
|
| There are many systems claiming some level of redundancy. Here
| is an octocopter setup with some motors intentionally disabled:
| https://www.youtube.com/watch?v=EeChr2JCfJs
| bambax wrote:
| > _it wouldn 't gain you a new ability (...) suddenly you are
| in a brand new control regime where the pilot is probably not
| as proficient_
|
| It would be an incredibly powerful marketing message.
|
| The pilot doesn't need to be able to control the drone; the
| drone would simply land where it is, which, depending on the
| location, could be not ideal, but in any case much better
| than falling like a brick...
| roshanj wrote:
| > But to the best of my knowledge this hasn't been implemented
| anywhere, and today's drones simply fall out of the sky if one
| motor fails or its propellers are destroyed.
|
| I'm a former Skydio[1] employee and our motion-planning &
| state-estimation teams implemented this on all our drones years
| ago. It wasn't completely fool-proof, but in many non-high-
| speed scenarios a loss of a motor was not catastrophic and the
| drone could 'emergency land' within a few meters of where it
| was flying. I wish I had proof for you but unfortunately no
| longer have access to any internal videos :)
|
| [1] https://skydio.com
| teleforce wrote:
| We have built drones with open source platform PX4 and NuttX OS
| for both fixed-wing and multi-rotor drones but each has their own
| limitations. Fixed-wing is very fuel efficient and travel far
| distance while multi-rotor drone is the opposite but can perform
| hovering easily. The hybrid VTOL is basically the combination of
| the both techniques as provided in Figure 1.
|
| However the taxonomy in Figure 1 is missing a very important
| class of drone namely gyrocopter or gyroplane. For full size
| manned gyrocopter it's a beast to control manually but unmanned
| drone gyroscope will be the way to go due to its energy efficient
| flight dynamics and it can perform complex manuevering not unlike
| multi-rotor drones and semi-hovering (can perform loitering but
| not vertical movements while hovering).
| JoeDaDude wrote:
| An omitted use case for the Affordable and Massively Used
| category of multi-rotor drones: Drone light shows. These are
| starting to replace fireworks shows as the latter bring up safety
| and fire hazard concerns.
| marssaxman wrote:
| What a tragedy that would be - nothing replaces the visceral
| _whump_ of a shell going off. I love it so much!
| falcor84 wrote:
| > nothing replaces the visceral whump of a shell
|
| Expect for having PTSD
| wcarss wrote:
| drones already / are gonna have this issue too -- funny how
| these two technologies fill both roles, each in very
| different ways.
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