The Robot That Lost Its Legs

Back in my master's, the problem I was stuck on sounds a little cruel. If you suddenly take a leg off a robot that was walking just fine, can it walk again?

It sounds like a joke, but it was a serious question. Once a robot leaves the lab, sooner or later it breaks. A motor burns out, a joint bends the wrong way, a whole leg stops working. No one can run over and fix it every time. In the end, the robot has to realize on its own, "Oh, I'm missing a leg," and find another way to walk.

The hint came from harvestmen, those spiders with long, thin legs. Harvestmen can walk pretty well again within a day of losing a leg. They don't learn to walk from scratch. They take the gait they already knew and redistribute it across the legs they have left.

So our method worked the same way. While the robot is intact, we collect lots of its gaits and compress them into something small. When a leg is gone, we pull out a few of those compressed gaits and reassign them to the remaining legs. When we took two legs off a six-legged robot, it was walking forward again on a real floor, with no simulation, in under 10 minutes.

The first time I saw it, I felt something strange. A robot wobbling along on four legs didn't look cool so much as a little sad. It looked like it was trying, somehow, to find its way back to how it used to walk.

Most people lose legs too. Not real ones, of course.

The company you worked for disappears, the work you held onto for years comes to an end, a relationship you trusted is gone, your body isn't what it used to be. At times like that, we're quick to say, "Now I have to start completely over." As if everything we'd built had fallen off along with the lost leg.

But I don't think that's true. I moved from mechanical engineering to AI, went from building a companion app to building robots, and now I'm building something else again. Every time, it felt like starting from zero. Looking back, I never really started from scratch. The way I used to walk was always compressed somewhere, and I just redistributed it to fit a new body.

Of course, you can't walk exactly the same. A four-legged robot can't walk the way it did with six. It's a bit more awkward, a bit slower, and sometimes it drifts sideways. But it still moves forward. Isn't that enough?

When life changes, what we need isn't a perfect fresh start. It's figuring out how to hand the steps we've taken so far to the legs we have left. Don't throw them away. Reassign them.

Somewhere today, someone is walking with a leg or so missing. It's okay to stumble a little. If you remember how you used to walk, you'll be walking again sooner than you think.