No abstract

To enhance the performance of humanoids, mobile robots and manipulators, motors are desired to be able to provide high torque without relying on gears. To be able to drive joint motors with high output, the current value that can flow needs to be increased. However, the heat generated by the high current drive can cause motor failure, so cooling is necessary. We used thermoelectric cooling as a new cooling method for high-power drive of motors. By developing a thermoelectric cooling module for motors and conducting experiments, the effectiveness of thermoelectric cooling was verified. In the experiment, the motor was kept running at a high current for a long period of time. The comparison with the motor alone or with water cooling showed that the thermoelectric cooling module can significantly reduce the rise in temperature of the motor. Furthermore, based on the results of the voltage value measurements, it was expected that the increase in coil resistance due to higher coil temperatures would be kept lower than in other cases. The effect on rise in internal temperature was also considered to be greater than that of water cooling. These experimental results show that the thermoelectric cooling module can be used to increase the upper limit of the current at which the motor is continuously driven.

Joint motors of legged robots and manipulators need to withstand temporary high loads during walking, posture maintenance, and contact with external objects. To only increase the torque, the gear ratio can be increased; however, this decelerates the movement. To increase the power of the motor, improving the torque-current characteristics or applying a high current is necessary. When a high current is applied, a large amount of heat is generated by the motor, which can cause motor failure. In this study, we used thermoelectric cooling as a new cooling method for robot joint motors and verified its effectiveness.We developed a thermoelectric cooling module that can significantly cool a motor before it experiences a high current. Experiments were conducted in which a motor was subjected to a high-load motion, and the results with and without the thermoelectric cooling module were compared. It was shown that the developed thermoelectric cooling system improved the performance of the motor.