Robert Full: Learning from the gecko's tail

50,199 views ・ 2009-06-12

TED


Please double-click on the English subtitles below to play the video.

00:18
Let me share with you today an original discovery.
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But I want to tell it to you the way it really happened --
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not the way I present it in a scientific meeting,
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or the way you'd read it in a scientific paper.
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It's a story about beyond biomimetics,
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to something I'm calling biomutualism.
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I define that as an association between biology and another discipline,
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where each discipline reciprocally advances the other,
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but where the collective discoveries that emerge are beyond any single field.
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Now, in terms of biomimetics,
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as human technologies take on more of the characteristics of nature,
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nature becomes a much more useful teacher.
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Engineering can be inspired by biology
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by using its principles and analogies when they're advantageous,
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but then integrating that with the best human engineering,
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ultimately to make something actually better than nature.
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Now, being a biologist, I was very curious about this.
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These are gecko toes.
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And we wondered how they use these bizarre toes
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to climb up a wall so quickly.
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We discovered it. And what we found was
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that they have leaf-like structures on their toes,
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with millions of tiny hairs that look like a rug,
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and each of those hairs has the worst case of split-ends possible:
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about 100 to 1000 split ends that are nano-size.
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And the individual has 2 billion of these nano-size split ends.
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They don't stick by Velcro or suction or glue.
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They actually stick by intermolecular forces alone,
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van der Waals forces.
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And I'm really pleased to report to you today
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that the first synthetic self-cleaning, dry adhesive has been made.
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From the simplest version in nature, one branch,
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my engineering collaborator, Ron Fearing, at Berkeley,
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had made the first synthetic version.
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And so has my other incredible collaborator,
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Mark Cutkosky, at Stanford --
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he made much larger hairs than the gecko,
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but used the same general principles.
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And here is its first test.
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(Laughter)
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That's Kellar Autumn, my former Ph.D. student,
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professor now at Lewis and Clark,
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literally giving his first-born child up for this test.
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(Laughter)
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More recently, this happened.
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Man: This the first time someone has actually climbed with it.
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Narrator: Lynn Verinsky, a professional climber,
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who appeared to be brimming with confidence.
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Lynn Verinsky: Honestly, it's going to be perfectly safe. It will be perfectly safe.
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Man: How do you know?
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Lynn Verinsky: Because of liability insurance. (Laughter)
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Narrator: With a mattress below and attached to a safety rope,
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Lynn began her 60-foot ascent.
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Lynn made it to the top in a perfect pairing
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of Hollywood and science.
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Man: So you're the first human being to officially emulate a gecko.
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Lynn Verinsky: Ha! Wow. And what a privilege that has been.
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Robert Full: That's what she did on rough surfaces.
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But she actually used these on smooth surfaces --
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two of them -- to climb up, and pull herself up.
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And you can try this in the lobby,
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and look at the gecko-inspired material.
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Now the problem with the robots doing this
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is that they can't get unstuck,
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with the material.
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This is the gecko's solution. They actually peel their toes away
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from the surface, at high rates,
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as they run up the wall.
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03:22
Well I'm really excited today to show you
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the newest version of a robot, Stickybot,
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using a new hierarchical dry adhesive.
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Here is the actual robot.
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And here is what it does.
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And if you look,
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you can see that it uses
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the toe peeling,
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just like the gecko does.
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If we can show some of the video, you can see it climbing up the wall.
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(Applause)
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There it is.
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And now it can go on other surfaces because of the new adhesive
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that the Stanford group was able to do
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in designing this incredible robot.
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(Applause)
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Oh. One thing I want to point out is, look at Stickybot.
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You see something on it. It's not just to look like a gecko.
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It has a tail. And just when you think you've figured out nature,
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this kind of thing happens.
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The engineers told us, for the climbing robots,
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that, if they don't have a tail,
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they fall off the wall.
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So what they did was they asked us
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an important question.
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They said, "Well, it kind of looks like a tail."
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Even though we put a passive bar there.
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"Do animals use their tails when they climb up walls?"
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What they were doing was returning the favor,
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by giving us a hypothesis to test,
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in biology, that we wouldn't have thought of.
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So of course, in reality, we were then panicked,
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being the biologists, and we should know this already.
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We said, "Well, what do tails do?"
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Well we know that tails store fat, for example.
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We know that you can grab onto things with them.
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And perhaps it is most well known
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that they provide static balance.
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(Laughter)
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It can also act as a counterbalance.
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So watch this kangaroo.
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See that tail? That's incredible!
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Marc Raibert built a Uniroo hopping robot.
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And it was unstable without its tail.
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Now mostly tails limit maneuverability,
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like this human inside this dinosaur suit.
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(Laughter)
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My colleagues actually went on to test this limitation,
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by increasing the moment of inertia of a student, so they had a tail,
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and running them through and obstacle course,
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and found a decrement in performance,
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like you'd predict.
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(Laughter)
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But of course, this is a passive tail.
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And you can also have active tails.
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And when I went back to research this, I realized
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that one of the great TED moments in the past,
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from Nathan,
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we've talked about an active tail.
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Video: Myhrvold thinks tail-cracking dinosaurs
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were interested in love, not war.
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Robert Full: He talked about the tail being a whip for communication.
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It can also be used in defense.
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Pretty powerful.
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So we then went back and looked at the animal.
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And we ran it up a surface.
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But this time what we did is we put a slippery patch
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that you see in yellow there.
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And watch on the right what the animal is doing with its tail
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when it slips. This is slowed down 10 times.
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So here is normal speed.
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And watch it now slip,
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and see what it does with its tail.
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It has an active tail that functions as a fifth leg,
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and it contributes to stability.
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If you make it slip a huge amount, this is what we discovered.
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This is incredible.
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The engineers had a really good idea.
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And then of course we wondered,
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okay, they have an active tail, but let's picture them.
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They're climbing up a wall, or a tree.
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And they get to the top and let's say there's some leaves there.
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And what would happen if they climbed on the underside of that leaf,
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and there was some wind, or we shook it?
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And we did that experiment, that you see here.
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(Applause)
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And this is what we discovered.
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Now that's real time. You can't see anything.
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But there it is slowed down.
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What we discovered was the world's fastest air-righting response.
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For those of you who remember your physics, that's a zero-angular-momentum
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righting response. But it's like a cat.
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You know, cats falling. Cats do this. They twist their bodies.
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But geckos do it better.
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And they do it with their tail.
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So they do it with this active tail as they swing around.
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And then they always land in the sort of superman skydiving posture.
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Okay, now we wondered, if we were right,
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we should be able to test this in a physical model, in a robot.
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So for TED we actually built a robot,
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over there, a prototype, with the tail.
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And we're going to attempt the first air-righting response
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in a tail, with a robot.
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If we could have the lights on it.
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Okay, there it goes.
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And show the video.
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There it is.
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And it works just like it does in the animal.
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So all you need is a swing of the tail to right yourself.
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(Applause)
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Now, of course, we were normally frightened
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because the animal has no gliding adaptations,
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so we thought, "Oh that's okay. We'll put it in a vertical wind tunnel.
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We'll blow the air up, we'll give it a landing target, a tree trunk,
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just outside the plexi-glass enclosure, and see what it does.
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(Laughter)
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So we did. And here is what it does.
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So the wind is coming from the bottom. This is slowed down 10 times.
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It does an equilibrium glide. Highly controlled.
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This is sort of incredible. But actually it's quite beautiful,
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when you take a picture of it.
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And it's better than that, it -- just in the slide -- maneuvers in mid-air.
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And the way it does it, is it takes its tail
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and it swings it one way to yaw left, and it swings its other way to yaw right.
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So we can maneuver this way.
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And then -- we had to film this several times to believe this --
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it also does this. Watch this.
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It oscillates its tail up and down like a dolphin.
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It can actually swim through the air.
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But watch its front legs. Can you see what they are doing?
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What does that mean for the origin of flapping flight?
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Maybe it's evolved from coming down from trees,
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and trying to control a glide.
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Stay tuned for that.
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(Laughter)
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So then we wondered, "Can they actually maneuver with this?"
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So there is the landing target. Could they steer towards it
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with these capabilities? Here it is in the wind tunnel.
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And it certainly looks like it.
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You can see it even better from down on top.
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Watch the animal.
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Definitely moving towards the landing target.
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Watch the whip of its tail as it does it. Look at that.
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It's unbelievable.
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So now we were really confused,
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because there are no reports of it gliding.
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So we went, "Oh my god, we have to go to the field,
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and see if it actually does this."
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Completely opposite of the way you'd see it on a nature film, of course.
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We wondered, "Do they actually glide in nature?"
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Well we went to the forests of Singapore and Southeast Asia.
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And the next video you see is the first time we've showed this.
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This is the actual video -- not staged, a real research video --
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of animal gliding down. There is a red trajectory line.
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Look at the end to see the animal.
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But then as it gets closer to the tree,
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look at the close-up. And see if you can see it land.
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So there it comes down. There is a gecko at the end of that trajectory line.
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You see it there? There? Watch it come down.
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Now watch up there and you can see the landing. Did you see it hit?
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It actually uses its tail too,
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just like we saw in the lab.
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So now we can continue this mutualism
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by suggesting that they can make an active tail.
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And here is the first active tail, in the robot,
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made by Boston Dynamics.
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So to conclude, I think we need to build biomutualisms, like I showed,
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that will increase the pace of basic discovery in their application.
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To do this though, we need to redesign education in a major way,
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to balance depth with interdisciplinary communication,
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and explicitly train people how to contribute to, and benefit from other disciplines.
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And of course you need the organisms and the environment to do it.
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That is, whether you care about security, search and rescue or health,
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we must preserve nature's designs,
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otherwise these secrets will be lost forever.
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And from what I heard from our new president,
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I'm very optimistic. Thank you.
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(Applause)
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