Hybrid 3K Compound Planetary Reduction Gearbox With a Roller Transmission Mechanism

Reduction gears are used in the joints of the robots. While precision and efficiency are required for industrial robot gearboxes, humanoid robots are expected to become more popular in the future. Flexibility must be considered in humanoid robots, and high back drivability shall be required. In this study, we aimed at realizing high efficiency, and high-precision reduction gears with high reduction ratios by maximizing the efficiency equation, hybridizing a 3K compound planetary reduction gearbox and traction drive, experimentally determining the efficiency, backlash, and angular velocity variation, and demonstrating the effectiveness of the proposed mechanism from a control perspective. In the experiments, we achieved a maximum forward driving efficiency of 90.90%, backward driving efficiency of 90.58%, and a minimum backlash of 1.18 arcmin.