Investigation of Parallel Connection Circuit by Hydraulic Direct-Drive System for Biped Humanoid Robot Focusing on Human Running Motion

Abstract

We are developing the biped humanoid robot WATHLETE-1 (Waseda ATHLETE humanoid No.1) that has the same mass arrangement, link ratio, and output characteristics as humans. It is not possible to mount high-power electromagnetic motors and mechanical transmissions that satisfy the hip joint output at running because its weight makes it impossible to realize human body characteristics. To realize the characteristics of the human body, we adopted a hydraulic drive system that has a more advanced design than a mechanical transmission mechanism, that concentrates on the joints, and that can distribute output by splitting and merging oil. We propose a hydraulic circuit that improves the output of the actuator by connecting two hydraulic direct drive systems (HDDs) in parallel, independently mounted on the ankle and the hip joints using proportional valves. As a result, it has been confirmed that hip joint speed was improved by 200% compared to a single HDDs and with the potential of simulating the hip joint output required for a human running at 2.0 m/s.