The “RunBot”, developed by researchers from Germany and Scotland, is the fastest robot on two legs – for its size. At 30 centimetres high, it can walk at 3.5 leg-lengths per second, beating the previous record holder – MIT’s Spring Flamingo – which is four times as tall but manages just 1.4 leg-lengths per second.
The robot is controlled by a program that mimics the way neurons control reflexes in humans and other animals. Unlike most other two-legged robots, RunBot has few sensors and can detect just two things – when a foot touches the ground, and when a leg swings forward.
When one of the robot’s feet touches the ground, the opposite leg swings forward, throwing it off balance. The knee of the swinging leg bends automatically until a sensor in the hip causes it to straighten out, ready to hit the ground. When this leg touches the ground, the cycle starts again.
The team mimicked biology to make their robot walk efficiently. “Humans have simple neural systems that learn a few basic modes of movement that function as reflexes,” says Florentin Wörgötter, from the University of Göttingen. “RunBot works the same, putting it on the ground triggers the reflex.”
Software that mimics neuronal control allows RunBot to learn to walk more quickly. It tries different things, Wörgötter explains: “If a change doesn’t help its speed, RunBot tries something else.” In testing, this enabled the robot to accelerate to three times its initial speed.