Construction of small humanoids with a new joint actuator module

Successful construction of a humanoid largely depends on the performance of the actuators which are used at ankles, knees, and/or hip joints. For the reasons of control convenience and relative accuracy of position, DC servo-motors are widely used as the actuator of the humanoid. Most of the actuators for small humanoids are the RC-type DC servo-motors because it is convenience to use them with their relatively small size. However, since the RC-type motor does not have feedback information, we cannot control the position and the force accurately. Moreover, the motors are connected to the central processor of the humanoid with the star type peer-to-peer connection, which results in the complicated line connections. In this paper, we develop a modular type joint actuator which overcomes the shortcomings of the existing actuators for constructing humanoid robots. The proposed actuator is composed of DC motor, reduction gear, potentiometer, motor controller, and processor. And this actuator is characterized by modular structure, instruction based control, multi-drop networking, low backlash, and hybrid dynamic control using position and force feedback. Furthermore, the actuator has some intelligent functions like alarms for over-current and overheating, shutdown function, and batch motion function by installing the processor. Though the proposed actuator has been designed mainly for humanoid robots, it can be also applied to VR and haptic systems, medical equipment, control parts of the automobile, and main part of factory automation equipment, etc.