Marc Raibert
speaker
243 appearances
1 recordings
1 series
first heard Feb 2024
last heard Feb 2024
Marc Raibert’s voice in public audio — every appearance, attributed to the second.
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Lex Fridman Podcast · #412 – Marc Raibert: Boston Dynamics and the Future of Robotics · 16 Feb 2024
podcast
She would nudge, roll, flatten with her knife, things like that, and none of them was grasping.
First of all, the Leg Lab actually started at Carnegie Mellon. I was a professor there starting in 1980, about 1986. And so that's where the first hopping machines were built. I guess we got the first one working in about 1982, something like that. That was a simplified one. Then we got a three-dimensional one in 1983.
The quadruped that we built at the Leg Lab, the first version, was built in about 1984 or 5 and really only got going about 86 or so. It took years of development to get it to work.
Well, I'm going to start on the, not the technical side, but the, I guess we could call it the motivational side or the funding side. So before Carnegie Mellon, I was actually at JPL, at the Jet Propulsion Lab for three years.
And while I was there, I connected up with Ivan Sutherland, who is sometimes regarded as the father of computer graphics because of work he did both at MIT and then University of Utah and Evans and Sutherland.
Anyway, um, I got to know him and at one point he said, uh, he encouraged me to, uh, do some kind of project, uh, at Caltech, even though I was at JPL, you know, those are kind of related institutions. And, uh, So I thought about it, and I made up a list of three possible projects. And I purposely made the top one and the bottom one really boring sounding.
And in the middle, I put Pogo Stick Robot. When he looked at it, Ivan is a brilliant guy, brilliant engineer, and a real cultivator of people. He looked at it and knew right away what the thing that was worth doing. He had an endowed chair, so he had about $3,000 that he gave me to build the first model for
which I went to the shop and with my own hands made a first model, which didn't work and was just a beginning shot at it. Ivan and I took that to Washington. In those days, you could just walk into DARPA and walk down the hallway and see who's there. Ivan, who had been there in his previous life, We walked around and we looked in the offices. Of course, I didn't know anything.
I was basically a kid, but Ivan knew his way around. We found Craig Fields in his office. Craig later became the director of DARPA, but in those days, he was a program manager. We went in. I had a little Samsonite suitcase. We opened and it had just the skeleton of this one-legged hopping robot. We showed it to him. And you could almost see the drool going down his chin of excitement.
And he sent me $250,000. He said, okay, I want to fund this. And I was between institutions. I was just about to leave JPL, and I hadn't decided yet where I was going next. And then when I landed at CMU, he sent $250,000, which in 1980 was a lot of research money.
Like, all the fundamentals are there. Yeah, I mean, I think that was the motivation to try and get more at the fundamentals of how animals work. But the idea that it would result in, you know, machines that were anything like practical... like we're making now. That wasn't anywhere in my head, no.
As an academic, I was mostly just trying to do the next thing, make some progress, impress my colleagues if I could.
Well, in the very early days, I needed some better engineering than I could do myself. And I hired Ben Brown. We each had our way of contributing to the design. And we came up with a thing that could start to work. I had some stupid ideas about how the actuation system should work. And we sorted that out.
It wasn't that hard to make it balanced once you get the physical machine to be working well enough and have enough control over the degrees of freedom. And then we very quickly, you know, we started out by having it floating on an inclined air table. And then that only gave us like six foot of travel.
So once it started working, we switched to a thing that could run around the room on another device. It's hard to explain these without you seeing them, but you probably know what I'm talking about, a planarizer. And then the next big step was to make it work in 3D, which that was really the scary part.
With these simple things, you know, people had inverted pendulums at the time for years and they could control them by driving a cart back and forth. But could you make it work in three dimensions while it's bouncing and all that? But it turned out, you know, not to be that hard to do, at least at the level of performance we achieved at the time.
Yes.
The simple story is that there's three things going on. There's something making it bounce. We had a system that was estimating how high the robot was off the ground. Using that, there's energy that can be in three places in a pogo stick. One is in the spring, one is in the altitude, and the other is in the velocity. And so when at the top of the hop, it's all in the height.
And so you could just measure how high you're going and thereby have an idea of a lot about the cycle, and you could decide whether to put more energy in or less. So that is one element. Then there's a part that you decide where to put the foot. And if you think when you're landing on the ground with respect to the center of mass, so if you think of a pole vaulter,
The key thing the pole vaulter has to do is get its body to the right place when the pole gets stuck. If they're too far forward, they kind of get thrown backwards. If they're too far back, they go over. And what they need to do is get it so that they go mostly up to get over the thing. And high jumpers is the same kind of thing.
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