Saturday, January 24, 2004
Robot belly-dancer shakes her stuff
She can shimmy, she can roll, she can backbend. She even sports a teasing, low-slung skirt around her waist.

But the performer of these undulations is no fleshy temptress. Instead, she is a belly-dancing robot whose moves are driven by the wriggles of a fish.

Her creator, Jimmy Or of Waseda University in Tokyo, Japan, said he gained inspiration watching Lucy Liu sashay her stomach in the film Charlie's Angels. The sight prompted him to sign up for dance lessons of his own.

Watching his instructor bend and sway, Or was struck by her similarity to his other object of affection, the lamprey - a primitive eel-like creature that scythes through water like a snake. "I decided to combine the fields and work on my idea secretly," he says.

Several years on, Or has created a squat, shimmying robot with a flexible spine called Waseda Belly Dancer No. 1. It has so far mastered a particularly difficult belly-dancing move, the Camel, which involves sending waves rippling along the torso.

Headless chicken
To generate the robot's undulations, Or borrowed a computer program built by Swedish researchers that simulates a network of nerves in the lamprey called a central pattern generator (CPG). The CPG directs the lamprey's movements without the help of the brain or sensory feedback.

Similar nerve networks are thought to exist in most vertebrates. In chickens, it is a CPG that allows a headless bird to briefly sprint around the yard before keeling over, for example. In humans, a CPG is thought to produce an automatic walking motion in toddlers or people who have had spinal-cord injuries when they are placed on a treadmill.

Because the CPG computer program is relatively simple, Or hopes that it might be cheaply incorporated into future humanoid machines. "I consider it as a prototype for the next generation of robot," he says.

State-of-the-art humanoid machines such as Honda's ASIMO and Sony's running machine, QRIO, can flex their arms and legs, but "still look a bit awkward" says Peter Stone, who designs robots at the University of Texas at Austin. To create more advanced movements, "it may very well be that the spine is the way to go", says Stone.

Conscious effort
The strange invention has also provided some lessons for biologists, revealing that the CPG of a fish can drive human-like movements. But this doesn't mean that humans carry an innate program for belly-dancing, says Fred Delcomyn, who studies CPGs at the University of Illinois at Urbana-Champaign. In humans, the dance undoubtedly requires far more conscious effort, and the human CPG is probably focused on our leg and arm muscles to help trigger walking. "The whole idea of making it belly-dance is kind of quirky," says Delcomyn.

Or admits that he made Waseda Belly Dancer No. 1 partly as an entertainment; he is currently refining its workings and choosing some fetching jewellery for it. But he maintains that robots with a flexible spine have a future. "A robot that can bow is very important in Japanese society," Or says.

© Nature News Service / Macmillan Magazines Ltd 2004

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