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  • Sometimes she likes toe wrap around me like this, and it's a little yeah, getting her out again.

  • That's the problem.

  • So my area is bio inspired robotics and howto learn from living animals to make robots function as well as living animals because anyone can string a bunch of servo motors together to make a snake robot, for instance.

  • But what makes snake so special is how they actually control their locomotion.

  • Is those control algorithms that we're trying to figure out that gives them the versatility they need to move through their habitat.

  • We start by analysing how they move, so we use motion, capture cameras and study their motion.

  • We use instruments to study the forces.

  • We're currently embarking on a project to understand their muscles.

  • But also T aspect is going to be understanding what happens when they encounter disturbance that they're moving through a Siri's of objects and one of them yields and breaks.

  • How does the snake respond to that disturbance that gives us insight into what they're controlling?

  • Are they controlling force velocity position?

  • How are they handling this?

  • We have a robot that's capable of three of the four modes of snake locomotion.

  • You were very limited.

  • Motors are nowhere near is but his muscle yet in a variety of ways, we can't.

  • Our snake robot, for instance, has 24 servo motors, whereas a real snake.

  • She has over 200 vertebrae in her body and several dozen Maurin her tail, each of which has 40 different muscles crossing every single joint.

  • Yeah, we're still a ways away from replicating the true elegance of snake locomotion.

  • So you're obviously well for the Yeah, The snake is arguably the most famous part of the labs, and I'm finally I'm working on a grant for him, but she's poking through the scythe.

  • No radios.

  • Move this.

  • I really need to pay them to put more power outlets in this place.

  • Source.

  • You'll love them.

  • Yeah, by biology.

  • Comparative biomechanics.

  • Bio robotics.

  • Because it goes both ways, we can use the animals to help us understand how to build better robots.

  • But the great thing about robots is unlike animals.

  • Robots will do what you tell them to do every single time, and they'll do the same thing every single time.

  • So it makes it easy to test hypotheses, including sort of what if hypotheses.

  • What if the animal didn't do the thing that it does to adjust to a particular environmental change, or what happens?

  • Would it fail?

  • We don't know, because the animal won't do it with robot will.

  • So because we tell it to Robot is actually quite simple.

  • It's just a series of dynamics.

  • Will servo Motors Dynamics?

  • L XL three twenties.

  • So these air commercially available servos and dynamic Sal's.

  • They have their own controller, but it's basically a modified Arduino Artemis No based code, so on and so forth.

  • So in this round on DDE, it doesn't even is not even that good of an order.

  • We know it's not like a mega or anything.

  • There we go.

  • I need to fiddle with those parameters.

  • So yeah, so this one, the snake robot is performing side winding.

  • Let's give it a little boost for speed.

  • Side Winding is this strange mode of locomotion used by a variety of desert snakes and continues side winding to move on.

  • Shifting desert sands does.

  • Sand is very hard to move on for a variety of reasons, but the short version is you press it one way.

  • It solidifies like a solid if you press it another way, yields and flows like a fluid and predicting which is going to happen is very difficult.

  • And so snakes have evolved this method that allows them to move across a huge range of sand substrates very easily, and it's robust to the different types of sand.

  • They don't have to test for exactly what the sand is doing.

  • So I did some previous work at Georgia Tech with the actual saw.

  • You want to rattle snakes, and that's how we came up with the algorithm for this, which is really just to sign waves.

  • They have a vertical horizontal wave, right toe left along the body and a vertical wave.

  • You can see how it's lifted, its body clear of the substrate here.

  • So he's got this lifting and lowering sort of system going on.

  • As a result, it can transitioned a lateral undulation and then back to side winding.

  • But basically we have a signed way for left to right, a sign way for up and down and they're slightly offset and that's it.

  • The actual code to produce this is maybe 15 lines, and so is similarly for lateral undulation.

  • Me fiddle with the parameters for that one before it swaps over so snakes could move through this typical slithering gate.

  • And this is still a pale imitation of the grace and beauty of really snakes.

  • But this is just a single wave.

  • We're working on more complex implementations, and finally, it can even perform something called concertina locomotion.

  • And so once it gets to that point, we'll finish a cycle.

  • So this is what they do inside of a tunnel.

  • If it hit the tunnel wall, it would be detecting that.

  • Unfortunately, I don't have the tunnel set up at the moment, but basically it stretches its body forwards like you see here.

  • And then it feels for the wall of the tunnel.

  • And if there was a real tunnel, it would detect that and automatically adjust itself and then inchworm its way forward, just like the real snake.

  • It's actually not terribly efficient form of locomotion, and that's true for these guys as well.

  • Their endurance drops dramatically when you do this.

  • It's sort of a last resort mode of locomotion, so the only one it's missing so far is actually a form called rectilinear, and that's actually where they can ripple their belly scales alone.

  • It's a form of locomotion powered entirely by the skin, and unfortunately, we don't have skin actuators that are good enough for that yet.

  • But we're working on it.

  • So can you say right, go over there and that sort of thing?

  • This is a purely feed forward mechanism, so it does not yet have external sensors.

  • That's another area that we're working on, how to control this thing.

  • So right now, the biggest issue is there still tethered because they wind up drawing a tremendous amount of energy when they, I mean, this thing is pulling over an AMP at any given time.

  • So it sucks down the energy pretty fast.

  • It's Yeah, we're a ways away from fully autonomous snake bots, but we're getting there bit by bit.

  • I like to say that snake robots are sort of where humanoid robots were 20 years ago.

  • When now look a Boston Dynamics.

  • And in fact, Boston Dynamics is an excellent example of this all of those magnificent robots.

  • They're based on the the control mechanisms observed for human locomotion.

  • So when we walk, we use an inverted pendulum sort of vault over a stiff limb.

  • And when they run, Arlen becomes springy.

  • And by controlling those dynamics, that's how Boston Dynamics is able to make their robots do.

  • Amazing things is because they're trying to control just the center of mass trajectory and the spring iness of the effective limb, which can be multiple limbs if it's one of their quality, or peds, and then they have sort of secondary processes.

  • I imagine that they handle all the little sort of details of what joint gets, how many volts and things like that, just like with us.

  • It's all handled in our spinal cord.

  • There's a lot of that stuff where we're walking.

  • Our brain is just sending a few signals saying, Go roughly this fast in this direction and the spinal cord takes care of all of that stuff.

  • Which muscle turns on, when and how, and responses to a perturbation like missing a step or something like that.

  • So there's a lot of decentralization, even Inhumans.

  • So is this something anyone could do?

  • Absolutely.

  • This is just off the shelf Servo Motors XL three twenties with three D printed brackets connecting them.

  • But I've built tons of others with regular high tech servos, and then you just impose a sine wave.

  • What I basically do is I I say, Here's a song I compute a sine wave and I say every motor has a certain phase offset.

  • And then I impose a global phase offset on the sine wave at successive time intervals.

  • And the trick is, I sort of tweak the time interval so that the motors have enough time to get where they're going.

  • Thea other thing is dynamic souls are great because you can daisy chain them.

  • So if I call this out so it's not long no longer doing anything so I can string one input along for six motor.

  • So this is the vertical lead, the horizontal lead.

  • For these six, you can technically go more than six, but I wind up having problems with the voltage drops at the end, and the motors aren't quite doing what they need to.

  • You could see that a little bit of the tail.

  • Sometimes the voltage drops a little bit of the tail, um, normal serving motors.

  • It's just a simple 11 thing you can hook him up in parallel with a lot of sauntering.

  • If you want, but my personal favorite for snake robots that aren't dynamics ALS is actually the links motion controller links like the animal, and it has 32 servo channels.

  • I use pipe phone because aids, snake name and I like snakes.

  • But also that's what my predecessor used.

  • And so he just sent a serial command that says Channel number 13 go to position seven of 750 take 700 milliseconds to do it.

  • And then you just repeat that.

  • Send all the commands in a chain and the robot will go to that position.

  • And then you wait for a little bit, go to the next time set, move it to the next position.

  • So on and so forth these air more sophisticated than regular servos for all sorts of reasons.

  • But yeah, the ultimate endgame for this is snakes.

  • The whole reason snakes of all the whole reason they lost their limbs and got this elongate body form is to move through cluttered, complex and confined environments.

  • So they're really good at dealing with those sort of things like, say, exploring Mars or a building has collapsed and you want to find out if there's people under there or you want to go sneak into a bad guy's house and see what they're talking about through the walls and the cabling and things like that.

  • That's what snakes are excellent.

  • And that's why this elongate, limbless swarm of body has actually evolved over 24 independent times.

  • Justin Lizards Snakes are merely the most successful of those.

  • There's actually 23 other groups of limitless lizards, plus a bunch of other times.

  • So it's a very, very common strategy.

  • And it's always associated with these cluttered, confined environments, which is where Lindh robots and things with more sort of chunky, boxy bodies don't do as well.

  • In fact, if you or a dog or an insect runs across a cluttered field of rocks and logs debris in order to not fall down, we get slower.

  • We have to slow ourselves down to accommodate this complexity.

  • Snakes actually get faster because when they're doing that undulating form of locomotion, what they're doing their body is hitting those obstacles, and using them is push points so they get faster, the more clutter their environment ISS, and so that's a real advantage in something that people are keen on capitalizing on.

  • So you've got this motion capture system, and we're gonna be looking at the r boreal locomotion of snakes.

  • And so the idea is that we will take a snake and will put little reflective markers message, maybe offending a video.

  • Suddenly, the band with becomes actually a bit of a problem.

  • This may not be an issue, depending on the application.

Sometimes she likes toe wrap around me like this, and it's a little yeah, getting her out again.

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B1 中級

機器人蛇 - Computerphile (Robot Snake - Computerphile)

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    林宜悉 發佈於 2021 年 01 月 14 日
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