Development of a Spherical Ultrasonic Motor with an Attitude Sensing System using Optical Fibers

We present a spherical ultrasonic motor (SUSM) and an attitude sensing system using optical fibers for the SUSM. The SUSM is constructed from three ring-shaped stators and a spherical rotor, and has three degrees of freedom (DOF). It has good responsiveness, high positioning accuracy, and strong magnetic field compatibility. In the attitude sensing system, a flat mirror is built in the spherical rotor. Light is emitted to the mirror, and the reflection is caught by optical fibers. The light intensities captured by the optical fibers are processed by a neural network and are converted to attitude information for the spherical rotor. We describe a system comprising the SUSM and the attitude sensing system with its design derived from mechanics and optics. The prototype SUSM is 26mm in diameter and was actuated by the attitude sensing system. Position errors with respect to x and y axes are less than 0.5deg.