Torque Evaluation Method for Multi-Degree-of-Freedom Spherical Actuators Considering Cogging Torque under Current Limiting

Multi-Degree-of-Freedom (Multi-DOF) actuating systems are composed of several single-DOF motors, which results in large, heavy and complicated structures. In order to solve these problems, various multi-DOF spherical actuators have been actively studied. Among them, a spherical actuator can generate torques in arbitrary positions and directions. However due to this, it is difficult to evaluate the torque characteristics at any position all over the movable range. In order to evaluate the spherical actuators, we proposed a torque evaluation method under copper loss limiting. However, in the proposed method, only copper losses can be considered. In this paper, we propose a new torque evaluation method considering a maximum current limiting. Finally, the torque characteristics of our multi-DOF actuators are evaluated using the proposed method and the effectiveness of the proposed method is verified.