# Drones toss and catch inverted pendulum

Ever see flying robots doing stuff that you never suspected flying robots could do? I have.

First, a state estimator was used to accurately predict the pendulum’s motion while in flight. Unlike the ball used in the group’s earlier demonstration of quadrocopter juggling, the pendulum’s drag properties depend on its orientation. This means, among other things, that a pendulum in free fall will move sideways if oriented at an angle. Since experiments showed that this effect was quite large for the pendulum used, an estimator including a drag model of the pendulum was developed. This was important to accurately estimate the pendulum’s catching position.

Another task of the estimator was to determine when the pendulum was in free flight and when it was in contact with a quadrocopter. This was important to switch the quadrocopter’s behavior from hovering to balancing the pendulum.

Second, a fast trajectory generator was needed to quickly move the catching quadrocopter to the estimated catching position.

Third, a learning algorithm was implemented to correct for deviations from the theoretical models for two key events: A first correction term was learnt for the desired catching point of the pendulum. This allowed to capture systematic model errors of the throwing quadrocopter’s trajectory and the pendulum’s flight. A second correction term was learnt for the catching quadrocopter’s position. This allowed to capture systematic model errors of the catching quadrocopter’s rapid movement to the catching position.

### 50

1. Needs ‘Entry of the Gladiators’ by Julius Fucik

1.  Respect for the Julius Fucik reference.

2. Mitchell Glaser says:

Amazing! But it’s an inverted pendulum, not an inverted pyramid as the headline suggests. I’d like to see them do it with a pyramid, though.

3. I, for one, welcome our new pole-juggling flying robot overlords.

1. CaptainPedge says:

Damnit! Beat me to it.

1.  Tell you what–when they make me Grand Vizer of North America, I’ll give you Delaware.

4. Jeffrey Martin says:

Is that a robot narrating the video about robots?

5. Donald Petersen says:

Neato.  And yet my terror grows.

I know, I know.  The things aren’t out to get me.  But when the day dawns that they are, it turns out they’ll be able to outmaneuver and overwhelm me and my dwindling allies by a couple of orders of magnitude.

On a totally unrelated note, are they EMP-resistant?  Flame-retardant?  Waterproof?

1. Finnagain says:

Like kids’ pajamas, they can be flame-retardant, or non-carcinogenic. But not both.

1. austinhamman says:

yeah but the killer robots don’t care if the humans also get cancer.

2. cellocgw says:

Yeah, but all hilarity aside,  those ‘flame-retardant’ chemicals are not.   The whole thing was a scam perpetrated by the tobacco industries to pull attention away from people who died from smoking while falling asleep.  http://media.apps.chicagotribune.com/flames/index.html

6. It seems to use external processing, with cameras looking for the dark coloured copters and rods against the white background.

1. nixiebunny says:

Yes, it does seem to. Dead reckoning would be stretching the capabilities of quadrocopters a bit.

I’ll give them a year to work that out.

7. Oh good , can’t wait till skynet is fully operational. A little ai and government official saying nothing to worry about will get this really going. :)

1. allotrope says:

Droney says you have nothing to worry about. The reasons why are of course classified.

1. Boundegar says:

I dunno, man, I’ve never seen them catching the caber.

8. s2redux says:

I’ll be impressed when it brings me a sammich.

9. Well, fellow humans, we’ve had a good run.

Consider yourself warned, Pakistan.

11. theophrastvs says:

so they manage to sustain a three ball juggle and that’s “the singularity”?

1.  Just picture the ball as one of our heads and it all comes into focus…

12. peregrinus says:

Circus performers are gonna be pissed.

1. Heyyy.. Maybe someone should start a robot circus where robots would perform instead of animals?

Double inverted pendulum trick looks rather neat too:

13. Finnagain says:

Unpossible.

14. franko says:

i was already jaw-droppingly impressed, and then he mentioned the learning algorithms.
…. *mind blown*

15. they’ll be tossing us around like that one day…!

16. Stephen Olsen says:

I know it’s not the point… but these things have no actual knowledge of their absolute position. Their position is tracked with a mocap system. It doesn’t make it any less impressive… but it does make you realize just how crazy it would be get these things to be aware of their position without help.

1. Donald Petersen says:

How crazy?  I’m no roboticist, but how big a stretch is GPS and an altimeter?

1. austinhamman says:

oh a few orders of magnitude in precision.

1. Donald Petersen says:

Seems if a Googlemobile can drive itself across a crowded continent without help, it won’t be too terribly long before a quadcopter drone will be delivering my pizza, photographing me in the bath, and chasing me down the stairwell and down the traffic-filled street.

Even rocket science ain’t rocket science anymore.

1. ldobe says:

Google driverless cars don’t have to work with movements that total a centimeter in length.  They also don’t accelerate to 35 mph in a second and a half.  Additionally the cars can’t move in three dimensions, and they don’t invert their orientation through a 360 degree flip (in any normal circumstance).

These little quad copters do all of that, and can play Peter Gunn the James Bond Theme to boot.

2. Donald Petersen says:

Yeah, I get all that.  Is the point that these won’t be able to navigate an environment unassisted by external mocap equipment anytime soon?

‘Cause I don’t believe that.  When Mr Olsen said

how crazy it would be get these things to be aware of their position without help.

I assumed he meant difficult and prohibitively complicated.  Seems to me it’s just a question of miniaturizing and optimizing existing terrain-navigation algorithms and such.  No, I can’t do it.  But my ignorant ass predicts we’ll see completely self-contained dronebots that are fully aware of their position well before the next big election.

Or maybe we won’t actually see them.

(Never mind guys, I’m talking out that selfsame ignorant ass anyway.)

3. ldobe says:

@boingboing-096f32c997988c54d6d7c09ff0be4d32:disqus Oh, I’d say it’s inevitable that these little guys will eventually be able to do all these tricks autonomously.  But I don’t think it’s going to happen before the next election.  As far as I’ve seen, (and I could be wrong by now) these little helicopters aren’t doing any processing on their own.  They have a server rack doing all the motion capture, image and video analysis, and all the flight control and the learning algos to hone their accuracy.  And these copters are just the moving pieces they dedicate large amounts of hardware to control.

4. rob_cornelius says:

thats the James Bond theme… but still damn impressive

5. ldobe says:

@boingboing-dba13d1fac2d5327964cbf74122e5460:disqus

oops XD

Little brain fart.

2. theophrastvs says:

yeah – good point.  but maybe “in the field” you could designate three or four of your enumerable drones to serve as the external motion-capture references?

17. Preston Sturges says:

And, in related news, calculus is now cool.

1. ldobe says:

When hasn’t calculus been cool?  All the cool kids these days are on their skateboards or throwing their footballs, or figuring out the lengths of shorelines (I had a shoreline-calculating-heavy textbook in high school calculus.)

18. They’ve been signed up to Cirque Du Soleil for a six figure sum. Expect to see them playing vegas in  2013

19. planettom says:

quadrocopter1: “Shall we decide the humans’ fate in a microsecond?”
quadrocopter2: “Naw, let’s toss this thing around some more!”

1. Felton / Moderator says:

That’s how we’ll beat the machines, by distracting them with games of catch, just like they’ve distracted us with videos of cats.

20. Wait did it just fart @ 1:34?

21. Look out Cirque du Soleil. Pretty cool, at least until you envision one of these things chasing you with a box cutter.

1. Finnagain says:

Or more than three ounces of any liquid.