Researchers build flying robotic 'tree helicopter' (w/ Video)

Jan 25, 2011 By Lisa Zyga feature
A natural samara is positioned next to the smallest and lightest robotic samara constructed to date. The wing of the vehicle is similar in size to a natural samara wing. Image credit: Ulrich, et al.

(PhysOrg.com) -- Many trees disperse their seeds by releasing "helicopters," those single-winged seeds that are also called "samaras." As these seeds fall to the ground, their wing causes them to swirl and spin in a process called autorotation, similar to man-made helicopters. In a new study, researchers have designed and built a mechanical samara whose dynamics are very similar to those of nature’s samaras. After testing the mechanical samara, the researchers then built a variety of remote-controlled robotic samaras with onboard power sources.

The researchers, Evan Ulrich, Darryll Pines, and Sean Humbert from the University of Maryland, have published their study on the robotic samaras in a recent issue of Bioinspiration & Biomimetics. The idea for building a flying robotic device based on samaras originated several years ago, after researchers attempted to scale down full-size .

“Full-scale helicopters have a high aerodynamic efficiency,” Ulrich, a PhD candidate, told PhysOrg.com. “But the aerodynamic efficiency is disproportionate, so a scaled-down helicopter has stability issues and is unfeasible. Dr. Pines, my advisor, realized that the simplest system in nature that achieves vertical flight and can autorotate like a helicopter is the samara, which is a naturally stable system.”

After further investigating the samara in order to better understand its flight dynamics, the researchers found that the winged seed is also one of nature’s most efficient fliers. The samara is a monocopter, meaning it has a single wing. For this reason, the samara has no stationary frame of reference, unlike a two-winged helicopter, and appears to fall in a complex way. However, through free-fall testing, the researchers could quantitatively measure the samara’s flight dynamics and use this information to control the samara’s autorotation and flight path.

After designing and building a mechanical samara, the researchers measured its in free-fall by dropping it from a height of 12 meters. Then the scientists used this data to develop three different designs of powered robotic samaras, ranging in size from 7.5 cm to 0.5 m. In flight tests, they demonstrated that the carbon fiber-based robotic samaras could be remotely steered to a desired location by altering the wing pitch, which changes the radius at which the vehicles turn. The robotic samaras could also hover, climb, and translate.

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Robotic samaras in flight.

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Evan Ulrich demonstrates the robotic samara.

The researchers noted that the concept of a single-wing rotating aircraft is not new, with the first such vehicle being flown in 1952 by Charles McCutchen near Lake Placid, New York. Since then, several other single-winged rotating aircraft have been developed, but none of these designs has used autorotation or been based on the samara.

The samara-inspired autorotation process has several advantages compared to other small-scale aircraft that perform vertical take-off and landing. For instance, the robotic samaras are extremely damage-tolerant. If they lose power while flying, they can autorotate down and land without sustaining any damage due to their flexible structure that deflects upon impact. The robotic samaras are also passively stable, inexpensive, mechanically simple, and have a high payload capacity. Flight time is around 30 minutes, but depends on the battery size.

In the future, Ulrich plans to start a company to license and develop the technology for commercialization. In addition to developing the robotic samara into a toy, he said that the device could also have applications in satellite communications and 3D mapping.

Various designs of robotic samaras. Image credit: Ulrich, et al.

“We want to take advantage of the autorotation mode since it doesn’t require power for flight,” he said. “If we can find a vertical column of air, it can stay aloft indefinitely. One possibility is using it as an autorotating communications platform to carry small components for satellites, without the requirement of a huge launch cost.”

In addition, since the device is continuously spinning, an onboard camera could be used to take 360° images and build a 3D map. The robotic samara spins about 15 times per second and can navigate through small areas and avoid obstacles, giving it advantages over larger vehicles such as helicopters and airplanes.

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More information: Evan R. Ulrich, et al. “From falling to flying: the path to powered flight of a robotic samara nano air vehicle.” Bioinsp. Biomim. 5 (2010) 045009 (16pp). DOI:10.1088/1748-3182/5/4/045009

4.4 /5 (38 votes)

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User comments : 15

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mrcircumspect
4.3 / 5 (4) Jan 25, 2011
I wonder if two wings in spaced sequence or stacked would add lift and decease the need for thrust? It would seem there would be lots of commercial possibilities for an advanced device in this genera.
Quantum_Conundrum
2.3 / 5 (3) Jan 25, 2011
I think if he mounted the camera vertically, and used some optics that could give him a very wide angle view, it would be more useful for things like navigation and maybe surviellance or mapping terrain.
scoop
5 / 5 (2) Jan 25, 2011
"Unlike a helicopter, this can autorotate and land without causing any damage".

Easy to say when it weighs just a couple hundred grams. I'd like to see a three tonne version autorotate with zero damage. A helicopter scale build will probably have other things to worry about, such as tearing itself to pieces at altitude from material stress...

Hugely impressive though; I want one :)
Squeezle42
not rated yet Jan 25, 2011
Impressive! What are the current limitations of this in relation to payload and size (smaller and larger)?
ohjoy
not rated yet Jan 25, 2011
It reminds me of the manhacks from half-life 2.
Jodi_Cox
not rated yet Jan 25, 2011
Wow great little robot, It would be good to see it turned into a comercial flight application. It looks very dexterous. I hate to say it but the way it moves reminds me of a ufo from scifi movie.
eachus
not rated yet Jan 25, 2011
First, the whole idea is to make it small, scaling up is going the wrong way, whether you add a second wing or not. Second, if you are going to use this as a battlefield sensor, you would either need a counter-rotating camera (hard) or a single line CCD that is electronically integrated into an image. (Much easier, and today you can probably put the logic on the samara, at the cost of an extra gram or two.)

A lot of soldiers in Afghanistan would love to buy one of these as a "toy" and show it off to the kids there. The intel take from flying over rooftops would be a huge bonus.

Put a chemical sensor on it that can sense gunsmoke from an AK-47 when the gunner is not holding the weapon? Priceless. ;-)
Nyloc
5 / 5 (1) Jan 25, 2011
A better idea for a camera would be to sync the movie frame rate with the rotor spin, effectively taking one shot every revolution. The result would be the viewed illusion of standing still. To see in another direction would be as simple as adjusting the spin to frame-rate ratio.

Simple is good.
plasticpower
not rated yet Jan 26, 2011
A better idea for a camera would be to sync the movie frame rate with the rotor spin, effectively taking one shot every revolution. The result would be the viewed illusion of standing still. To see in another direction would be as simple as adjusting the spin to frame-rate ratio.

Simple is good.


This would give you 2 frames per second if you record at 30 fps, modern cameras can record at 120 fps so you could easily get 8 fps "omni-vision" this way. Sounds promising for gathering intel.

By the way, nice soundtrack for the video.
antialias
not rated yet Jan 26, 2011
"Unlike a helicopter, this can autorotate and land without causing any damage"

Since the 'blade' is always at the bottom with these designs the damage to the craft may be small - but not to any area it lands in. So i don't expect these to be scaled up to 'manned flight' proportions. Without a fixed center of rotation it might induce air-sickness pretty fast.

But for small applications I think it's a neat idea. Especially if you add another - counter rotating - setup on top for stability.
irjsiq
1 / 5 (1) Jan 26, 2011
" . . . samaras with onboard power sources."

Neigh-sayers endlessly overlook and ignore the capabilities of the Mind!
Solar Powered 'Aircraft' and road Vehicles ARE REALITY! And they will only get better, as more minds and more thoughts 'marry expertise and technology'!
It Has Been Done! "Lead, Follow, . . . But Get out of the way, the/we Dreamers are building 'for you' a Better Day, and a more Expeditious Tomorrow!
Roy J Stewart,
Phoenix AZ USA

Partial Quote from Article:
" . . . After testing the mechanical samara, the researchers then built a variety of remote-controlled robotic samaras with onboard power sources." (fragment heads comment) Rj
Forestgnome
1 / 5 (1) Jan 26, 2011
Single-bladed helicopters have already been built and flown. Someone researching in the field of aerodynamics needs to study aviation history.
Javinator
5 / 5 (2) Jan 26, 2011
You said:

Single-bladed helicopters have already been built and flown. Someone researching in the field of aerodynamics needs to study aviation history.


From the article:

The researchers noted that the concept of a single-wing rotating aircraft is not new, with the first such vehicle being flown in 1952 by Charles McCutchen near Lake Placid, New York. Since then, several other single-winged rotating aircraft have been developed, but none of these designs has used autorotation or been based on the samara.


You should probably actually read the article before commenting.
Steve_AB22
not rated yet Jan 31, 2011
The article is incorrect because it says that this is the first single blade helicopter to autorotate. That's not true, the single blade McCutchen helicopters autorotate perfectly. In fact I was flying one this last weekend and it was autorotating quite happily when the engine ran out of fuel. i've heard of others who have lost their McCutchen helicopters when they entered rising air and autorotated away out of sight!. As for them not being based on the Samurai seed pod; who is to say what McCutchen had in mind when he thought of the idea back in the 1950's?

You tube 'McCutchen Machine' and you will get some videos of them flying. You can probably find some plans online if you want to build one.

For what it's worth normal multi bladed helicopters can also autorotate; that's how they can survive engine failure. Autorotation is part of every helicopter pilot's training. Google 'helicopter autorotaion'.
ThanderMAX
not rated yet Jan 31, 2011
Night flight of that craft matches the popular UFO description