Batbot: Building a functionally correct bat wing robot

Batbot is a project wherein the researchers are attempting to mimic the biological structure of a bat wing for flight. The desire is to attain the maneuverability and agility you see in bat flight due to the ever changing shape of their wings. Also, bats look really cool.  In attempting to mimic the structure, they have decided to use SMA based artificial muscles and steel tendons as opposed to the typical cam linkage you would see in most ornithopters.

Unfortunately, there’s no video of this bot attempting to fly. There is a video (below) of a presentation on the project that explains in detail what they are doing, and how they are doing it. It also has some really cool slow motion footage of real bats doing what they do.

[via Adafruit]

21 thoughts on “Batbot: Building a functionally correct bat wing robot

  1. Hmm about using SMA. That requires a counterforce to stretch it back out and the process is slow. I suppose it would be fine for moving control surfaces ocassionally, but it could not be changed quickly.

    A bat glides, of course, and doesn’t really “fly” in normal sense, so you wouldn’t need much changes to the control surfaces to do that, but speed and agility is going to be a problem with the cycle rate of SMA.

    Unless I am missing something?

      1. Well, yeah, sorta. I guess I really meant is that they can’t generate significant lift from a standstill. But you are correct, they can fly, and can add lift, accelerate, etc… once they are in the air already. Good point.

      2. justice099:
        The definition of flight or gliding has nothing to do with where one takes off from, it’s whether further acceleration is performed by internal(beating wings or turning propellers) or external(thermals and updrafts) application of power. Plenty of flying machines and creatures must be dropped or launched to become airborne, and many gliders are still able to take off from a grounded start(paragliders).

        Most birds and many airplanes can even switch between gliding and powered flight while in the air. This is how soaring birds are able to maintain long flight times with very little energy usage.

    1. Found on a page about vampire bats. There’s one other type of bat that can take off from the ground, but I can’t remember which type it is. I think it’s the fox bat.

      To take off from the ground the bat must generate lots of lift. Common Vampire Bats have very long thumbs. As the bat prepares to take off it crouches close to the ground and then, by contracting its chest muscles, flings itself skyward. The thumbs provide extra leverage for takeoff.

      Not all bats can do this though. Most do the drop to gain speed thing.

    2. - It looks like SMA is only used in the ‘elbow’ joint, and it does look like SMA tech is still comparatively ‘slow’. (around .2 seconds or more for activation, they are using a product from http://www.migamotors.com, although that can be sped up with higher activation voltages for short periods) A servo looks to be used for the shoulder which would have faster response times and be able to generate the flapping. I would love to see a video of this…

  2. A bat glides, of course, and doesn’t really “fly” in normal sense

    I am puzzled by this statement. Are you referring to real bats or this robot modeled after a bat?

    If the first, they fly in the same sense that birds fly. If the latter, perhaps it would be clearer to say something like “This bat glides…”

    1. Agreed, my statement was a little silly. However the way they fly is quite different than how a bird flies. In fact, as I understand it, we currently have not been able to completely figure out how they can. Maybe my knowledge of that is outdated, but the fact that THIS contraption isn’t flying either tells me, probably not.

  3. The small bats i could see in the evening when i was a kid never glided, they seemed to always be beating their wings frantically.
    I read somewhere that part of the secret to the bats successful flight was that their wings were made of thin strong membranes, with properties that are hard to redo artificially when it comes to thickness and strength

    1. Unlike birds, I’ve never seen a bat take off from the ground. They always seem to have to climb up something and drop into the air.

  4. I think the membranes have stretches of denser muscle either in the membrane, as for larger bats or along the anchoring surfaces for the smaller species. This allows them serious micro control of the shape of the membrane causing ridges and hollows along not only the length of the wing but also the width close to the anchor points. This produces an ultimately more controllable variety of surface shapes which, because the membranes are lighter than birds feathers (air up weight), gives them more control.

    I think.

  5. Oh, and the smaller ones can take of from the ground especially if you’re chasing them with a lawn mower. (Not intentional before I get nasty comments)

  6. Yeah, I know it’s not an ornithopter, but anyone interested in bird replicas should check out:

    http://www.ornithopter.org/history.electric.shtml

    These are available commercially, and I played with a number of windup ones several decades ago. As toys, they’ve been around for centuries.

    Just add a micro and a motor and you’ve got something cool. Larger slow flapping ones have been built. One drawback – they break easily, and have a fondness for trees and power lines.

  7. Don’t forget Clement Ader 1895. Steam power may have flown before the Wright brothers. It had folding bat wings. A high def pic of the replica makes great wallpaper on the computer. There is much debate as to weather or not it flew, but his 1881 stereo sound demo was dead on. Still not matched with standard studio technique.

    1. I love me some steampunk technology – and I fully believe people were flight testing long before O&W.

      However, all of these early planes were junk. Thank Goodness someone finally managed to overturn their patents on that silly wing warping.

      Adler’s work was excellent (the french were way ahead of anyone in submarine and flight technology) but all of these inventors were hampered by lack of decent metallurgy and engine technology. There was a lot to learn.

      I believe his wings were sprung to resemble bat wings, but that’s because everyone tried to copy the da vinci drawings. I don’t think anyone got flapping to work at a large scale, and many of the failures are on film and readily available.

      If you read these accounts, they were all mostly flying in ground effect, and all of the crashes were either structural (civil engineering doesn’t prepare one for flight calculations) or occurred as they transitioned out of ground effect into the first boundary layers.

      People who haven’t flown in small planes have no idea what happens 50 – 100′ above their heads – it’s like wading into a river. These guys certainly didn’t know what was coming; many of the very best and promising inventors died of internal injuries as they flight tested.

      I suspect that learning to fly while you learn about aerodynamics, proper engineering and quality control, aircraft design and accident survivability is pretty close to impossible.

      As soon as the news got out that it had been done, thousand of airplanes and flying machines were designed. Hundreds of them were built and flown. Most had terrible results and caused many, many horrible deaths… all long since forgotten.

      I will have a cognac in their honor this evening.
      You know you’re really a hacker when you trust your prototype to take you to visit god, and it actually does.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s