Chirikjian first enlisted Hopkins math professor Edward Scheinerman to solve the placement riddle. Then he and graduate student David Stein glued 80 magnets in a precise pattern inside a plastic sphere about the size of a typical globe of the world you might find in any library. Chirikjian and Stein mounted the sphere atop a hollowed-out hemispherical saddle lined with 16 circular electromagnets. They marked each electromagnet with a number to allow them to write the necessary computer program that would control the motion of the spherical motor. By activating two or more of these electromagnets, an operator can create a force that pulls on certain permanent magnets within the sphere and spins it in the desired direction.
Scientists see tremendous potential in spherical motors.
The robotic arms used widely today require at least six conventional motors to replicate the three-dimensional motion of a human limb. But because the spherical motor more accurately simulates the motion and force projection of a human shoulder, robotic arms using spherical motors would only need three of Chirikjian's inventions to achieve a far greater range of motion than their one-dimensional counterparts. And fewer joints would allow robotic arms to be more accurate. Each joint adds a little bit of play, a little bit of wiggle to the arm. Spherical motors could also be used to create omni-directional gears, even tactile sensations.