January 17, 2001

1 min read

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A Superior Spherical Motor

By Kate Wong

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Image: Keith Weller

Researchers have developed a spherical motor that may let robots loosen up. Unlike a conventional motor, which turns on an axis, the new device can rotate in any direction. As such, the globe-shaped motor, which utilizes computer-controlled electromagnets, could one day impart greater flexibility to robotic arms.

To build their better motor, mechanical engineer Gregory S. Chirikjian and doctoral student David Stein of Johns Hopkins University mounted 80 magnets inside a hollow sphere, which was then lowered into a cradle lined with electromagnets. Activating two or more of these electromagnets attracts certain magnets within the sphere, pulling it into a new position.

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The researchers have high hopes for their creation¿including replacing the conventional motors found in today's robot arms. In fact, using the shoulder-joint-like spherical motors in place of today's motors, which are elbow-like, "you'd be able to use far fewer joints because each motor would have more freedom of motion," Chirikjian notes. "This would also enable the robotic arm to be more accurate because every time you have a joint, you introduce a little bit of play, a little bit of wiggle to the arm."

The spherical motor could also make its way into your computer mouse. "Right now most everything on a computer is visual in nature," Chirikjian observes. "But one can imagine that in the future this interaction will involve more of the sense of touch.

Kate Wong is an award-winning science writer and senior editor for features at Scientific American, where she has focused on evolution, ecology, anthropology, archaeology, paleontology and animal behavior. She is fascinated by human origins, which she has covered for nearly 30 years. Recently she has become obsessed with birds. Her reporting has taken her to caves in France and Croatia that Neandertals once called home to the shores of Kenya’s Lake Turkana in search of the oldest stone tools in the world, as well as to Madagascar on an expedition to unearth ancient mammals and dinosaurs, the icy waters of Antarctica, where humpback whales feast on krill, and a “Big Day” race around the state of Connecticut to find as many bird species as possible in 24 hours. Wong is co-author, with Donald Johanson, of Lucy’s Legacy: The Quest for Human Origins. She holds a bachelor of science degree in biological anthropology and zoology from the University of Michigan. Follow her on Bluesky @katewong.bsky.social

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