Development of a Spherical Motor Based on Truncated Octahedron and Regular Dodecahedron: A Technique to Change Rotation Axis

When a robot system is developed by only normal motors that rotate around an axis, the necessary number of motors is the same as that of joints resulting in large and complicated system. On the other hand, spherical motors will realize a small and simple mechanism because they can rotate in various directions. The authors developed a spherical motor in which a permanent magnet is placed on each apex of a truncated octahedron for the rotor and an electro-magnet is place on either the apex or the middle point of two apexes of a regular dodecahedron for the stator. The spherical motor has two kinds of rotation axes and rotates totally around six axes. This study proposes a technique to change rotation axis and develops a control electronic circuit to generate PWM signals depending on the axis and direction of rotation. The circuit is composed of several micro-controllers applying CAN technique for data communication. The results of experiments to change rotation axis show that the proposed a technique work successfully.