Abstract-The objective of this study was to realize the free swimming of the crawl stroke with the previously developed swimming humanoid robot. The upper body of the robot was remodeled to fit a free swimming test. The developed robot was simulated to raise feasibility of the crawl stroke. Through the simulation, two improved models were proposed. In the experiment, the swimming humanoid robot was fitted to the two simulation models and both realized the crawl stroke successfully. The measured roll angle was about ± 60 degrees and the swimming speed was between 0.2 m/s and 0.24 m/s.

The primary objective of this study was to develop a robot for research of human swimming. In order to address this objective, we developed the upper body of an underwater humanoid robot and realized the human swimming stroke. The developed humanoid robot had the same body proportions and appearance at half the size of a real human. The upper limbs were actuated by 12 motors, and one motor was installed for the waist. The motor case and gear housing were newly designed for waterproofing and space saving. Each arm had six degrees of freedom; four were for the shoulder and two were for the elbow. On the shoulder, we installed additional joints imitating human's scapular retraction to avoid singularities during the swimming stroke. We demonstrated the importance of an additional joint by realizing the crawl stroke arm motion, which is the most complicated of the four strokes.

Abstract-In this study, the swimming humanoid robot SWUMANOID for research of human swimming was developed. It was half the size of a real human and had the same body proportions and appearance; mass distribution was considered, as well. It was actuated by 20 motors, which were waterproofed and compactly designed. Swimming motions were determined based on human swimming movements. To realize the swimming arm stroke, a joint imitating the human's scapular retraction was installed and the methodology to realize the swimming motion with that joint was established. Finally, the efficiency of the design was validated by simulation and representatively, the crawl stroke was successfully realized in the water tank.

The objective of this study was to develop a humanoid robot for research about human swimming. In order to replace a swimmer as a subject, a humanoid robot “SWUMANOID” was developed imitating the details of a human, such as appearance and body properties. To reproduce the swimming motion based on that of an actual swimmer, a joint imitating the human’s scapular retraction was installed and the methodology to realize the swimming motion with that joint was established. To validate the performance of the robot, two experiments were conducted. The crawl stroke motion was examined in the fixed state and the swimming performance was validated by a free swimming experiment.

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