Antagonistically Twisted Round Belt Actuator System for Robotic Joints

[abstFig src='/00280006/08.jpg' width='300' text='Antagonistically twisted round belt actuator' ] In this study, a novel robotic joint mechanism is developed for enabling a robotic joint to rotate around the axis by twisting a small-diameter round belt. This twist drive actuator mechanism is composed of two small-diameter round belts with opposite configurations located near the joint. The two round belts are twisted by using individual DC motors; thus, the joint is activated because of the contraction forces generated by the twisting process. Experimental results, obtained using the proposed single-link robot, demonstrate that the joint can be controlled with a high position resolution by increasing and decreasing the amount of twisting. Using the experiments, we reveal that the antagonistic twist drive actuator system has a secondary role in speed reduction, which is capable of decreasing the velocity of the joint movement significantly. In addition, we indicate a linear relationship between the twist rotation and the joint angle of the robot. Furthermore, this paper formulates the Young’s modulus of the round belt used in the twist drive actuator. We demonstrate that the Young’s modulus decreases gradually with respect to the increase in the twisting of the round belt. Finally, we demonstrate a successful position control of the robotic joint, and the traditional PI controller is capable of suppressing the oscillatory motion by using a one-sided twin-twisted configuration.