Abstract
We propose a miniature spherical motor for 3-DOF axis rotations using iron-gallium alloy (Galfenol). This motor consists of four U shape cores of Galfenol with wound coil for two legs, a permanent magnet, an iron yoke and a spherical rotor sandwiched by the cores. The magnetomotive force of the magnet provides bias magnetostriction for the cores. When currents of same phase flow in coils of two legs (180° phase different in opponent cores), torque for X or Y axis rotation is exerted on the rotor by expansion of one core and contraction of another. On the other hands, 4 cores bend with currents of 180° phase different flow in two legs due to the expansion of one legs and contraction of another, which exerts torque for Z axis rotation. Rotation for X, Y and Z axis is realized by a sawtooth current, such that the rotor rotates with slow expansion and slips at the rapid contraction. We measured the displacements of each cores and verified the principle of 3-DOF rotations.
