Throwing and catching an inverted pendulum with quadrocopters

http://robohub.org/video-throwing-and-catching-an-inverted-pendulum-with-quadrocopters/

by eguizzo • 13 years ago

619 132 13 years ago

jawns• 13 years ago

I keep trying to think of practical implications for this technology, but every time I do, I just end up daydreaming about robot circuses.

trafficlight• 13 years ago

That's practical enough for me.

gojomo2• 13 years ago

I'd like to see an aerial battle-bots event. Imagine a giant transparent cube or orb 'stadium', with entry points for opposing fleets. There might be capture-the-flag or last-man-standing victory conditions, and a variety of units, perhaps including dirigibles.

stcredzero5• 13 years ago

> There might be capture-the-flag

How about "Transport the flag?" Or how about a bunch of flags? The other team is allowed to try and disrupt your transportation as well.

devindotcom2• 13 years ago

Something that popped into my head is a drone tossing a grenade through a window. The military would go nuts over this.

samstave• 13 years ago

It's sad that research like this is first thought to be most of value killing people.

Wingman4l74• 13 years ago

They are going nuts over this. Just look at DARPA drone research, all the manufacturing contracts, the increased battlefield use, the call for more pilots to be trained...

kunle• 13 years ago

They are already doing this: http://www.dailymail.co.uk/news/article-2281403/U-S-Air-Forc...

kruken• 13 years ago

Lots of scary things are possible as the hardware gets smaller/lighter/stronger and the control algorithms get more sophisticated.

Grenade lobbing is quite pedestrian compared to "precision targeting" in the video here: http://bit.ly/W6DnuO

sliverstorm5• 13 years ago

What happens when somebody else develops a drone to catch & return grenades thrown in through your window?

DGrutt• 13 years ago

Waiter, another beer please.

cadalac• 13 years ago

Please tilt head upward and open mouth.

theorique• 13 years ago

I heard that you can weaponize unmanned aerial vehicles ...

rcfox2• 13 years ago

Balancing an inverted pendulum is one of the classic "hard" problems in control theory. (At least, in undergrad.) Not only has he solved that on a flying platform, but he's going to the next levels.

Tossing sticks around between flying robots isn't inherently useful, but it means they have a foundation for further, more complex work.

hogu• 13 years ago

well you can do a single inverted pendulum pretty easily with a PID controller, it's the double inverted pendulum that is hard. But anything on a quadrocopter is really hard.

Create• 13 years ago

Indeed, the inverted pendulum is a textbook exercise. This is how cranes work: you don't want the heavy thing at the end of the cable to swing. This is how helicopter-cranes work too, but with added wind. They almost look as if they were nailed to the sky: the only trick is to have fast sensors, which are a given for literally decades now.

The only change is that sensors are manufactured in such large quantities, that they are so cheap that they are omnipresent (ie. almost every phone -- inconceivable decades ago). Quadcopters are also more stable by design than one would think (easier to stabilize than conventional ones).

Jplenbrook• 13 years ago

http://www.youtube.com/watch?v=SNPJMk2fgJU Aiming bullets, not poles.

huherto• 13 years ago

lol. I can only come up with gaming applications. flying robots that build stuff(jenga?), air battles.

I recently got a vacuum roomba and I am very entertained just on by watching it work. But I am a geek, probably not everybody is like that.

egypturnash• 13 years ago

My first thought was "I want to see these juggle three poles". Nothing wrong with robot circuses.

pseut• 13 years ago

Construction comes to mind immediately, but yeah, I'm a sucker for those videos.

lazyjones• 13 years ago

You could catch someone falling off a building or airplane with a (suitably large and fast) quadrocopter, I suppose.

primitur• 13 years ago

Building emergency shelters as quickly as possible?

Repairing wind-blown greenhouses in remote places as quickly as possible?

Building a water-pipe as quickly as possible?

Elevator-to-the-stars building mechanic?

ChuckMcM• 13 years ago

That is insanely cool. Quit your job and play with quadrocopters cool.

I'm surprised we've not seen larger versions of this platform for civilian use.

jws• 13 years ago

Give it time: http://www.kickstarter.com/projects/1671680066/incredible-hl...

That's a student project that needed funding.

• 50lb payload

• Two 12.5HP engines

• Distributing information (their most lucrative reward was the $250 "get a copy of all the information and data" at 10 copies.)

Definitely deadly. I would not be near it in operation.

sliverstorm5• 13 years ago

The system uses an external observer and external computer to track the bots and make decisions. Implementing this in a civilian setting would be much more difficult than simply making the bots larger.

Ao7bei3s3• 13 years ago

They have been in civilian (private/commercial) use for a few years (since 2008 or so). Mostly for taking pictures from above -- they are relatively well-suited for that. (And for fun flying of course)

For transporting big things: it's more efficient to have larger rotors than to have multiple rotors.

For transporting really big things: see above, and helicopters have been around for a long long time; "we" (not me) have decades of experience with helicopters; you probably really want something that is safe and reliable. You can't just scale up your model.

As for quadrocopter piloting: right now, all pilots crash. Repeatedly. Luckily, repairs are cheap (unless you happen to carry an expensive camera). For a full-size aircraft, crashing is probably not an option, so add lots of dev/testing time for safety features and pilot training.

BTW (somewhat unrelated): One huge problem with (smaller) quadrocopters is the many people that start new copter projects and get nowhere instead of contributing to one of the existing major projects or reusing its soft/hardware. Some of these projects are already way beyond what a single person or even a small team can achieve in a few years work.

eric-hu• 13 years ago

Can you explain the physics behind why it's more efficient to have larger rotors than multiple rotors?

greendestiny• 13 years ago

I would have thought the big contribution to this kind of dynamic balancing would be the eventual ease of piloting it would give. It still might not make sense efficiency wise though.

oceanician2• 13 years ago

I wonder which project you believe require the most help?

Would be fun to have a small working group in Manchester (UK) - shout if you're in the area and are interested.

SilasX• 13 years ago

Hell, I'm impressed enough with the quadrocopter simply controlling an inverted pendulum. Didn't know that was the starting point of the project!

Wingman4l74• 13 years ago

As an example, Draganfly already makes large quadcopters that can carry a DSLR camera, which can be purchased by civilians for ~$20,000 IIRC and have been used to report on various sporting events, etc.

iano2• 13 years ago

Unfortunately quadrotors don't scale up well. As the rotors get larger control input delay increases (because with this type of quadrotor you get your control input by rapidly changing the angular speed of the rotors). You can fix this by turning each of the 4 rotors into a conventional helicoptor rotor with collective pitch control, but at that point it makes sense to just go with a helicopter.

Scene_Cast22• 13 years ago

Helicopter rotors are much more complex than just pitch control. Quadcopters fly fine with 1DoF pitch control - relatively easy and cheap to do, while helis have non-trivial 3DoF. Also, there are quadcopters with 1DoF pitch control, your comment isn't exactly clear whether you know about those.

zacharydanger• 13 years ago

I couldn't figure out how the quadrocopters were coordinated. Turns out it's a high-speed motion capture. More here: http://www.flyingmachinearena.org/

ynniv2• 13 years ago

To first order, this is always true. It should also be noted that computation happens on a desktop computer.

sliverstorm5• 13 years ago

For quadrotors at least. Most of the projects I've seen coming out of Boston Dynamics are, as best I can tell, entirely self-contained.

(This is part of why BD impresses me so much)

michaelt• 13 years ago

Projects using quadrotors to do things like fly cooperatively and do acrobatics [1,2] will often use high speed motion capture systems with multiple fixed cameras. This decouples the problem of perceiving the environment from the problem of responding to the environment.

More broadly in robotics there are plenty of people working on ground-based robots that don't rely on multiple fixed high speed cameras - self-driving cars [3] would be one example. There are also people working on cooperative ground based robots that don't rely on multiple fixed high speed cameras - for example, the RoboCupSoccer Middle-Size League [4]. There are also people working on quadrotors that don't cooperate/do acrobatics and who don't rely on fixed vision systems - for example people working on autonomous quadrotor mapping [5] and using IMUs and on-robot vision [6].

[1] http://www.youtube.com/watch?v=MvRTALJp8DM

[2] http://www.youtube.com/watch?v=wuSqwb13iw0

[3] http://www.youtube.com/watch?v=uoiJeIb0wBA

[4] http://www.youtube.com/watch?v=cXSGTkI390w

[5] http://www.youtube.com/watch?v=WoMrPKCpWXw

[6] http://www.youtube.com/watch?v=QKGZcTFambE

devindotcom2• 13 years ago

Yeah, kind of restricts to the lab, unfortunately, although a secondary camera drone meshed with the others might serve. Lighting would be a problem... though they could use IR beacons or something.

lucaspiller• 13 years ago

Lasers wouldn't have that issue. And make this even cooler.

beambot2• 13 years ago

I've ranted on this topic before [1]. I still think it's a bit dishonest... academics shouldn't promote their work to general audiences without properly denoting caveats. In this case... they're using a ~$50k vicon motion capture system that returns millimeter-precision pose estimates at ~1kHz.

[1] http://www.hizook.com/blog/2012/07/02/being-honest-robot-vid...

Without the vicon and (probably) a central control PC, this feat would be SUPER difficult -- by ~1-2 orders of magnitude. The real problem is: when someone does solve that herculean problem, the general public won't care. They'll just say, "eh, we've seen that before."

snowwrestler• 13 years ago

Who cares what the public thinks? The funding and eventual commercialization will come from people who do understand what is going on here.

I'm no expert, but I would imagine that research using remote viewing and centralized processing is just a first step that could make it easier to validate particular solutions, which can then be "baked into" self-contained platforms.

alwaysdoit2• 13 years ago

What if they demo it in a non-laboratory setting, especially one where noisy backgrounds would make vicon impossibly difficult. If I understand correctly, the main problem with vicon is that it can't really be used in a real world scenario, right? So if the demo shows what can be done with the non-vicon solution, it should still be effective.

kylebrown• 13 years ago

That must be the purpose of the spherical marker-balls on the "pendulum" (looks like a rod???), two of them dividing it into three segments. I wondered what they were for, I'm guessing they help with the motion capture/tracking.

chm• 13 years ago

Maybe, but they could also be used to fine-tune the rod's moment of inertia.

elteto• 13 years ago

They probably use them to track the center of gravity of the rod while in flight.

davidradcliffe• 13 years ago

Wow.

hemancuso• 13 years ago

Looking forward to when Amazon's warehouses are automated with quadrocopters.

Wingman4l74• 13 years ago

Kiva Systems already makes a warehouse robot. I didn't know if Amazon used them or not, so I did some quick Googling and it turns out Amazon bought the company! http://dealbook.nytimes.com/2012/03/19/amazon-com-buys-kiva-...

jayzee• 13 years ago

and it was the same guy Raff D'Andrea who started that company

cfos• 13 years ago

interestingly, Rafaello d'Andrea the leader of this drone research in the flying machine arena in Zürich is also one of the co-founders of KIVA systems.

other research groups (e.g. http://rpg.ifi.uzh.ch/) are working on bringing this technology out of the motion capture system by mounting cameras on the drones and use image processing algorithms to estimate the drones trajectory.

tel• 13 years ago

Could anyone put together a rough curriculum for the control theory needed to understand something like this? It's absolutely fantastic.

femto2• 13 years ago

Read any "control theory"[1] text, frequently used in undergraduate engineering courses. I hesitate to recommend the text from my undergraduate years, as it wasn't very good, and is probably dated by now. The inverted pendulum [2] is a canonical test in control engineering, frequently used to test feedback control algorithms. Consequently, it should be treated in most texts.

A separate problem is the modelling and control of the quadcopter. I say separate, since the maths behind throwing an inverted pendulum should be similar, whether it is being thrown by quadcopters or industrial robots. The real (and more complex) story here is the quadcopter control algorithms. Using an inverted pendulum is a sexy way to show off the quadcopted control algorithms, compared to a dry graph of an error function.

[1] https://en.wikipedia.org/wiki/Control_theory

[2] https://en.wikipedia.org/wiki/Inverted_pendulum

catilac2• 13 years ago

I feel like a link has popped up on HN, but I can't find it.

Where can I buy a small quadrocopter which I can program, and build my own system with?

WA2• 13 years ago

I think you mean this one, right?

http://www.seeedstudio.com/depot/preorder-crazyflie-nano-qua...

catilac2• 13 years ago

Yes! Thank you. How did you search for that by the way?

pointernil• 13 years ago

"The Diamond Age: Or, a Young Lady's Illustrated Primer", Neal Stephenson

just saying ;) ...

pbhjpbhj2• 13 years ago

Why are you just saying that. Presumably that's a book suggestion, why is it pertinent?

Simucal• 13 years ago

"...then Bud made himself scarce, because the monitors - almond-sized aerostats with eyes, ears, and radios - had probably picked up the sound of the explosion and begun converging on the attack. He saw one hiss by him as he rounded the corner, trailing a short whip antenna that caught the light like a hairline crack in the atmosphere.

Aerostat meant anything that hung in the air. This was an easy trick to pull off nowadays. Nanotech materials were stronger. Computers were infinitesimal. Power supplies were much more potent...a device built with several thrusters pointed along different axes could remain in one position or indeed navigate through space." - The Diamond Age, by Neal Stephenson (1995)

jfoster• 13 years ago

TED talk that preceded this, featuring 3 quadcopters with a net and ball: http://www.youtube.com/watch?v=C4IJXAVXgIo

evo_9• 13 years ago

Congratulations - machines are one step closer to destroying the human race.

jeremyarussell• 13 years ago

And only 999,999 more steps to go.

mauricio-OH• 13 years ago

0.65s of pure robotics awesomness...

tunesmith2• 13 years ago

So, just get two larger quadrocopters and you could walk across a gorge. Each one would just catch each of your steps.

sodiumphosphate• 13 years ago

And possibly remove your foot.

flavorcountry• 13 years ago

I feel like it'd be insanely easier to, you know, ride one quadrocopter. Across the gorge.

tunesmith2• 13 years ago

But, but.... um...

Eliezer2• 13 years ago

Since this uses an explicit model of the world, Rodney-Brooks-style robotics is now officially dead.

mdda• 13 years ago

I was puzzled by your comment. Is this Brooks paper[1] the thinking that you're referring to?

[1] http://people.csail.mit.edu/brooks/papers/representation.pdf

Eliezer2• 13 years ago

Among others, but sure.

mikekij• 13 years ago

Holy crap, that's amazing. I'm excited when I can get MySQL started on my development machine.

Those are some smart dudes ( and / or ladies).

rmollo• 13 years ago

>dudes and ladies

You mean men and women. Although I didn't see any women in the video. (Better include them just in case, so my friends don't think I'm a sexist pig!)

deadwait• 13 years ago

how did they get arnold for the commentary?

borplk• 13 years ago

Imagine what kind of quadrocopters DARPA and similar agencies have these days.

sgoody• 13 years ago

Batteries not included.

speedyrev• 13 years ago

All fun and games until they fly in your window at night and kill you in your sleep.

jordan_clark• 13 years ago

Mathematics in motion is a beautiful thing.

Throwing and catching an inverted pendulum with quadrocopters

Related Stories