The state of the art in copter drones and flight control systems

https://www.mdpi.com/1424-8220/24/11/3349

by PaulHoule • 2 years ago

114 34 2 years ago

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• 2 years ago

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• 2 years ago

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• 2 years ago

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.

ipunchghosts2• 2 years ago

Mdpi should fix its format as a third of any given article is whitespace.

Oh, and hi Paul!

ipunchghosts2• 2 years ago

Ok, maybe its a quarter.

hiddencost2• 2 years ago

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...

otabdeveloper42• 2 years ago

Citing blatant propaganda during an active war phase?

Now that's what I call research!

hiddencost2• 2 years ago

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.

paganel• 2 years ago

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• 2 years ago

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.

PaulHoule3• 2 years ago

Go take a look at Frontiers.

light_hue_1• 2 years ago

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.

Eddy_Viscosity2• 2 years ago

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...

kragen4• 2 years ago

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

PaulHoule3• 2 years ago

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.

godelski2• 2 years ago

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.

bambax2• 2 years ago

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• 2 years ago

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• 2 years ago

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

bambax2• 2 years ago

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• 2 years ago

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• 2 years ago

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• 2 years ago

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• 2 years ago

What a tragedy that would be - nothing replaces the visceral whump of a shell going off. I love it so much!

falcor84• 2 years ago

nothing replaces the visceral whump of a shell

Expect for having PTSD

The state of the art in copter drones and flight control systems

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