Prototype Fabrication and Torque Measurement of Three-Degree-of-Freedom Spherical Actuator Driven by Four-Phase

Three-DOF spherical actuators can drive three degrees of freedom by a single unit and are expected to be applied to various positioning mechanisms. However, because spherical actuators cannot use general reduction gears, they require a complex 3-D arrangement of many coils and permanent magnets to obtain a large torque, making it difficult to miniaturize the actuator. Therefore, the authors proposed a three-DOF spherical actuator driven by a four-phase single inverter for mechanisms that do not require high-torque continuous rotation. This article describes the torque characteristics of the actuator when the coil shape is changed. The fabrication of a prototype that has not been fabricated before and the experimental verification of the torque using the fabricated prototype are also described.