Improving Speed Characteristics of High-Torque-Density Motors for Physical Human–Robot Interaction Using an Independent Three-Phase Winding Structure

Abstract

Recently, due to the decrease in labor force, increase in labor costs, and the desire for improved quality of life, research on robots has been actively conducted to address these issues. However, it is currently difficult to find robots that physically interact with humans. The reason is that the actuators of robots do not have a high torque density on their own. To solve this problem, high-torque-density motors, such as proprioceptive actuators, are being researched. However, the torque density is still insufficient for physical interaction with humans, so a motor with higher torque density has been developed. However, high-torque-density motors have the disadvantage of lower speed characteristics due to increased Back EMF levels. Therefore, to address the deterioration of speed characteristics in the developed motor, we applied the independent three-phase winding structure to improve the speed characteristics. Consequently, through comparison with the Y-Connection and D-Connection, we propose the most suitable winding structure for high-torque-density motors intended for physical interaction with humans.

Keywords

• high-torque-density motor
• safe pHRI (physical human–robot interaction)
• independent three-phase
• motor controller