Performance of Interior Permanent Magnet Spherical Synchronous Actuator

Abstract

　Multi-degree-of-freedom (multi-DOF) actuators have been developed for the fields of robotics and industrial machinery. We proposed an outer rotor type spherical synchronous actuator. In this actuator, permanent magnets are arranged at equal intervals inside the rotor. However, this actuator requires a spherical shell-shaped resin part for smoothing the surface of the rotor inner surface. This is because it directly supports the inside of the rotor. Due to this, there is a problem that the air gap length becomes long. In this paper, in order to remove the resin parts, an interior permanent magnet structure is applied to this actuator, and the torque characteristics are investigated. It was found that the air gap length was shortened due to an interior permanent magnet structure, and the torque was increased. In addition, by increasing the thickness of the inner yoke, the cogging torque decreased.