Eagle-eyeing researchers design swooping quadrotors with claws (w/ video)

Mar 17, 2013 by Nancy Owano report
A still image comparison between the eagle and the quadrotor. Credit: Justin R. Thomas

(Phys.org) —Scientists working on robots often concentrate on how to mimic the shape and movements of animals that show exceptional efficiencies in varied tasks; a recent team accomplishment takes a page out of the study of eagles, in order to create a flying robot that can similarly swoop down and grab objects the way an eagle can fish with its natural claws. Fundamentally, they were after a goal of devices capable of high-speed aerial grasping and manipulation. Scientists at the University of Pennsylvania made a quadrotor equipped with a special gripper that can grasp objects while in flight.

The team discussed their work in their paper, "Avian-Inspired Grasping for Quadrotor Micro-UAVs." The authors are Justin R. Thomas, Joe J. Polin, Koushil Sreenath, and Vijay Kumar of the GRASP Lab at the University of Pennsylvania.

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These robotics scientists designed a gripping arm like a talon as part of a small (UAV). These quadrotors are shown in the team's video as high-speed devices flying with their attached to motorized legs and snatching objects as they fly by. The researchers referred to their creation as "a novel appendage design, inspired by the articulation of an eagle's legs and claws."

They took inspiration not only in how the birds are shaped but in strategies that they use at the crucial dive and swoop pickup point. Movement strategy was key. To ensure they catch their , the birds sweep legs and claws backwards to gain time to make a secure grip without having to reduce speed. As they described in the paper, "an Eagle sweeps its legs and claws backwards during its capture phase, thereby reducing the relative velocity between the claws of the predator and the prey."

They said the backwards strategy gives the birds near-zero relative velocity of the claw while grasping the target and not slowing down, resulting in a high rate of success, even with, in a fish-grabbing scenario, other luckier fish detecting a soon enough in advance and moving out of the way.

The researchers plan to take the project and move in further directions. They said they want to try accomplishing the same results without using the Vicon motion capture system. They intend to try algorithms in which "the errors between the desired target position and actual position in the retina drive the robot."

They said that since an eagle can navigate using only its visual and inertial sensors, "a quadrotor should be able to make in-flight corrections using data from an on-board camera."

Another agenda item for future research will be designs for making appendages with lower inertia, to enable more agile grasping as well as perching strategies.

Explore further: Socially-assistive robots help kids with autism learn by providing personalized prompts

More information: www.seas.upenn.edu/~koushils/P… ations/IDETC2013.pdf
www.seas.upenn.edu/~koushils/research.html

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User comments : 18

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gwrede
3.7 / 5 (3) Mar 17, 2013
This raises images of small autonomous air vehicles doing all kinds of nifty tasks. Imagine one that changes bulbs on street lights, just for an example. Or one that actually goes fishing for you. :-)

Much nicer than monster UAVs killing arabs.
baudrunner
not rated yet Mar 17, 2013
Insects tuck their appendages, like the preying mantis. That could apply to landing legs or grasping arm. These UAV's will probably get way better, good enough to snatch up any type of object that lies or stands on the ground, because there seems to be another clever Penn engineer behind this one.
TheGhostofOtto1923
2.3 / 5 (4) Mar 17, 2013
This story just goes to show you that complex animal activity may not be as difficult to mimic and improve upon, as some might have thought. I think this is even more amazing:
http://www.youtub...a_player

How soon until they have driverless cars at Indianapolis?
h20dr
3 / 5 (2) Mar 17, 2013
Next... Extraordinary rendition by drone.
GSwift7
5 / 5 (1) Mar 18, 2013
I recently got into flying remote control helicopters, and I picked up a micro quad rotor a couple weeks ago. The technology available in these things is amazing. Of course, the limiting factor is battery power. The best battery on the market right now is called a lithium polymer battery, but they aren't cheap. With a really good battery pack, the best flight time you can expect on one of these quads is around 15 minutes, but if you add something heavy like the arm in the video above it's gonna be more like 5 minutes or less. You run into the law of diminishing returns if you try to add bigger batteries. If money, size and safety aren't an issue then you could build a really big one with a real helicopter turbine, but then you're talking about a really big, expensive and dangerous beast.

You guys should look up the Walkera QR Ladybird V1. I've been having a TON of fun flying mine around, though it's grounded for repairs right now.

Notice they DIDN'T do their experiment in wind!!
TheGhostofOtto1923
1 / 5 (2) Mar 18, 2013
Like most tech, the power source is the key. Internal combustion created the car and the airplane. Ever see this?
http://www.youtub...a_player

-You could fly around and steal your own batteries-
QuixoteJ
1 / 5 (2) Mar 18, 2013
So in 10 years, the Big Dog will be knocking your front door down, and this thing will be pecking your eyes out from the sky when you run out the back door to try and get away? It's so awesome!
GSwift7
5 / 5 (3) Mar 18, 2013
Yeah, my daughter made me watch that video one night. That guy has a whole bunch of videos online. He almost got burned by that gasoline at the end of that video. You could see the ground light up right in front of him.

As for first person view drones, you can get little ones fitted with video cameras and a radio remote with a color lcd screen for under $200. The range on the video is only about 100 meters on those though.

I just don't understand what the point of the grabber arm above would be. Wind tends to make these fixed pitch drones bob up and down quite a bit. They usually come with gyroscopes and accelerometers, so they stay still from side to side pretty well. It's the up/down motion they can't deal with. With a fixed pitch rotor, you have a delayed reaction vertically because you have to get the motors to speed up or slow down. I can't see using that grabber arm in real world conditions successfully. They make a motorized winch for the toy ones and it's hard to do.
TheGhostofOtto1923
3 / 5 (4) Mar 18, 2013
I just don't understand what the point of the grabber arm above would be. Wind tends to make these fixed pitch drones bob up and down quite a bit.
You can imagine that military versions of the scale of a predator drone will have the AI avionics and the power source to act with blinding speed and pinpoint accuracy.

Imagine the ability to swoop down on a crowd and grab an individual. Or retrieve wounded from the battlefield or out of the water. Grabbing things on the fly has many possibilities.

Presently, drones lack precision and still threaten collateral damage. These guys could sneak right up behind a bad guy and put him down. AI could make them useful in rescue ops in caves or burning buildings.
TheGhostofOtto1923
3 / 5 (4) Mar 18, 2013
Imagine grabbing an enemy drone out of they sky. That would be pretty cool. Brings to mind the scene in the latest iron man movie where hes flying around, grabbing people falling out of an airplane.
GSwift7
5 / 5 (2) Mar 19, 2013
Presently, drones lack precision and still threaten collateral damage. These guys could sneak right up behind a bad guy and put him down


They make quite a bit of noise, and it's a high pitched noise that is easy to locate directionally. Also, there's a large down-draft under the drone.

AI could make them useful in rescue ops in caves or burning buildings


Anything that flies has a very hard time in enclosed spaces. They create their own turbulence. Also, there's a ground effect under it that makes it want to side-slip when you get near the ground, and if you get too close to the ceiling, you get the opposite effect that will try to suck it upwards.

These quad rotor aircraft MUST be made extremely light-weight or you can't fly them very long. The lighter weight makes them extremely vulnerable to turbulence/wind.

The thing they are being used for now is aerial photography and visual inspections.
TheGhostofOtto1923
1 / 5 (2) Mar 19, 2013
Anything that flies has a very hard time in enclosed spaces. They create their own turbulence. Also, there's a ground effect under it that makes it want to side-slip when you get near the ground, and if you get too close to the ceiling, you get the opposite effect that will try to suck it upwards
Sure. AI and avionics will be able to anticipate and compensate.
These quad rotor aircraft MUST be made extremely light-weight or you can't fly them very long. The lighter weight makes them extremely vulnerable to turbulence/wind.
This is only a power source limitation. Mil and civil machines in the near future will cost a lot more, as do predators, and be capable of a LOT more. They can employ variable pitch blades, alternate thrusters for stationkeeping, gps, etc and who knows what else.
http://www.troybu...UAS.html
http://www.smartr...tems.ca/
gwrede
3 / 5 (2) Mar 19, 2013
@Otto's video: Recon mission, indeed!

Now that any smart boy can build such things, I think there will be a new kind of arms race in the third world. Let's see what that leads to.
GSwift7
5 / 5 (2) Mar 19, 2013
Yeah, Otto, in some distant sci-fi future I'm sure you're right. For now the battery problem isn't going away soon. The LiPo batteries that are used are the best thing around, but they aren't really safe. I can't see the military using them, since they tend to explode if you get them too hot or cold, or scratch them, or short them out, or overload them, or overcharge them.

Yes, there are collective pitch drones, even for hobbyists like me. They eat up battery even faster than the fixed pitch ones though. It's a simple matter of mechanical friction. The other problem with the variable pitch ones is durability. The direct drive motors are the simplest and most durable, as well as easy to repair.

As for GPS, the hobby ones have that already. They can even return to home autonomously. Some have locator beacons on them too. There's water-activated floatation devices too. There are squirt guns, pellet guns, lights, cameras, bubble blowers.. all kinds of stuff.
GSwift7
5 / 5 (2) Mar 19, 2013
continued:

The problem with trying to give one of these an AI is once again weight. You really don't understand how limited you are on weight with these. Every extra gram cuts down your max flight time exponentially, as well as making it fly poorly. I'm not sure how you intend to get a computer into a quad unless you want to make a full scale one, but that's not going to be stealthy or safe to use around people. You should see how scary it is to be around blades that spin that fast. Imagine a lawnmower without a cover that spins 100 times faster. Even the little guys can do damage.

I can't wait to get home today. The replacement parts for my drone should be in the mailbox and the weather looks great. I split one of the carbon fiber booms out of the central frame with a "hard landing". All this talk about them is really making me want to get her back out again. My helicopters are a bit too wild for casual fun, and certainly not inside the house.
TheGhostofOtto1923
1 / 5 (2) Mar 19, 2013
Yeah, Otto, in some distant sci-fi future I'm sure you're right. For now the battery problem isn't going away soon. The LiPo batteries that are used are the best thing around, but they aren't really safe.
Military drones dont use batteries. They use internal combustion.
http://strikefigh...copters/
http://en.wikiped...re_Scout

-Why dont you think this would be used on quadrotors?
http://en.wikiped...iltRotor
GSwift7
not rated yet Mar 21, 2013
Once again, you are talking about an entirely different class of vehicle. I said you could make a big one and use a turbine engine, but then you are talking about a very complex, expensive, difficult to maintain/repair, loud and dangerous machine.

There's a huge difference between reality and your dream world. There's a famous aeronautical engineering quote that goes something like "Cheap, Light, Strong; pick two". The technology that makes micro-quad aerial vehicles possible has only been around for a short time. Light and powerful servos, light and powerful batteries, light fast and accurate gyroscopes and accelerometers, etc. Designing one is a balancing act between various undesirable choices. In a military situation, what good is a UAV with a very short range? What is the advantage of a quad rotor versus a fixed wing drone for their intended puposes? The US Army is using a hand-launched foam glider with a tiny motor/prop to keep altitude which can stay airborn all day long.
TheGhostofOtto1923
3 / 5 (2) Mar 21, 2013
Once again, you are talking about an entirely different class of vehicle. I said you could make a big one and use a turbine engine, but then you are talking about a very complex, expensive, difficult to maintain/repair, loud and dangerous machine
Thats what I was talking about from the beginning. These researchers arent trying to improve your hobbying experience. They are looking to enable robots for construction, defense, exploration, etc.
http://www.youtub...Z3UnnS_0

Tech is increasing exponentially. I think in 2 years we could be having this conversation from a different perspective altogether. Like the guy who told me 2 years ago that self-driving cars were laughable. Haha.