Robots with real muscles
A robotic fish powered by real muscles could boost artifical limbs
When Hugh Herr put his robotic fish into its tank, it swam off looking surprisingly lifelike. But a few minutes later, it was flagging-and eventually came to a complete stop. It wasn't faulty: it just needed a break. The reason? Herr's robot is the first one to be powered by real muscles.
Researchers have known for centuries that they can make muscles contract in the lab: in 1786, Luigi Galvani discovered that electricity made a dissected frog's leg twitch. But until now, no one has ever tried to harness the phenomenon to power a machine.
So Herr and his colleagues at the Massachusetts Institute of Technology's Biomechatronics group built themselves a robotic fish. Inside it, a microprocessor sends electric signals to frog muscles on either side of the fish, making them contract. Tendons on the muscles are sewn to the nose and tail so the "fish" wiggles and swims in response to the signals. The muscles get their energy from the glucose solution the fish is swimming in (see video at www-personal.umich.edu/~bobden/biomechatronic_devices.html).
One of Herr's aims is to power prosthetic limbs with real muscles. Artificial limbs tend to be much stiffer than real ones and can't adapt to different surfaces, so they behave the same way whether you are walking on cement or sand. [...]