Rappelling by a humanoid robot based on transition motion generation and reliable rope manipulation

For robots to act in outdoor environments, the ability for locomotion is an important factor because it influences the range of activities. Humanoid robots are acquiring the ability for locomotion in horizontal directions so far, and the ability for vertical locomotion is now required in order to extend their range of activities further. Therefore, we propose rappelling as a method for vertical locomotion. Rappelling is a method to descend from a high place using a rope and a belay device. With this method, humanoid robots are expected to get the ability for vertical locomotion without additional actuators. In this paper, we propose a full-body motion for rappelling based on the sequential transition of the centroid position and the contact states. We also propose the reliable manipulation of a rope grasped by both hands. With the proposed methods, we conducted an experiment of rappelling with HRP2, and it could successfully descend from a height of 2m50cm in 277 seconds.