Robot beats all animals for highest jump
A record-breaking robot that can jump over a house and generate G forces 30 times greater than a fighter pilot would feel, is the brainchild of engineer Elliot Hawkes. As scientists are turning their attention back to the Moon, with trips there planned for the near future, machines capable of this sort of giant leap could become very attractive as a way of getting about. Harry Lewis heard how nature was the inspiration for the new robot…
Elliot - In animals, you're limited by basically the work your muscle can do in a single stroke. If you imagine you're lifting a weight with your arm or something, the energy you can produce is basically the one contraction of your bicep; and that's it. If you're a flea, fleas jump by storing energy in a spring and then rapidly releasing it, so the upper bound of their jump height is set by the energy they can produce in one stroke. The best jumper out there is a galago, a bush baby is another name for it. It's got long legs and a long tail. Its real secret is that it has more jumping muscle per body mass than really any other creature.
Harry - How on earth Elliot does the bush baby link to robotics?
Elliot - In robotics, we have this thing called 'bio-inspired design biomimicry', where we often look at animals and say, "Okay. Well, this is how animals have evolved to do it. It's probably a pretty good solution for our problem. Maybe we should build something kind of like that." What we found here though, is that there's some pretty fundamental differences between a jumping animal and a jumping robot. They don't have to use a motor that's like a muscle in that you only get this one contraction. What this means is you're not limited to that single stroke, like the muscle of the animal is, you can basically produce as much energy as you want and store it into a spring for a single jump. Your limit is no longer your muscle, for an engineered jumper it's really the spring.
Harry - You've applied this knowledge to a natural prototype.
Elliot - Yeah, exactly. In animals that spring is a very small percent of their body mass. That's because it should all be muscle. You want to maximize your muscle; you don't need much spring. Because you just can't store that much energy, you don't need much spring. We can store tons of energy for a robot. What we did is we made the motor as small as possible, because they can just keep winding for a long time if you have plenty of time between jumps. If you're constrained in your time between jumps, then you need a bigger motor. But we were saying, 'how high can you jump with all the time in the world?' We put on a tiny, tiny motor and then made the robot all spring. Relative to body mass, it has about 100x more spring mass than an animal. The key to performance is how much energy you can store in that spring per unit mass of the spring, so a lot of the work went into how can we optimize this spring?
Harry - And what was the result? How high can your robot jump?
Elliot - The animal jumps 2.25 metres and ours jumps 32.9 metres. I should mention the thing is only 30 centimetres tall. It takes off 30 meters per second. It goes from 0 metres per second when it's crouched and ready to jump to 30 metres per second and it does that in 9 milliseconds. If you start doing some of the calculations there, you can think about the acceleration that this little thing is going through; it's something like 315G's.
Harry - Can we compare that to something?
Elliot - Yeah. A fighter pilot experiences around 8G and that's about the limits of what a human can withstand before they pass out.
Harry - I take it this is the most impressive jump made by a robot today. Is it?
Elliot - I mean, you never know, but we believe it is the highest jump ever by anything in the history of the world. Which is kind of a fun thing to think about.
Harry - That's awesome. That's so good. Okay so take the fun out of it and let me ask the million dollar university funding question. Why?
Elliot - We've been working with NASA on this project and it turns out the moon is an incredibly benign place to jump because gravity is about 1/6 what it is on earth and it has almost no atmosphere. It turns out on the moon, you could jump about 125 metres high while jumping forward half of a kilometre in a single jump. One of the applications that we've discussed with NASA is actually jumping down into craters. They have steep sides and they're rocky and the jumping robot could just hop down into there, collect potentially a little sample, and hop back out.