Development of terrain adaptive sole for multi-legged walking robot

Foot mechanism of walking robots needs to adapt to rough terrain enough because the walking robot is requested to have the ability to walk stably on rugged ground. However, the foot mechanism of multi-leg walking robots have been often modeled as a point foot or a disc sole so far, and there is a problem that the robot can not fully use the sole area as a support polygon on rough terrain. To solve the problem, the terrain adaptive sole is developed which can adapt to the ground with small ruggedness and support the ankle moment to acquire stable footholds on uneven terrain. The terrain adaptive sole is composed of a deformation mechanism, a shape-fixing mechanism and a vertical force sensor, which are developed for quadruped walking robot TITAN VIII. The deformation mechanism changes the shape of the foot according to the terrain and the shape-fixing mechanism fixes the shape after the foot landing. These functions are achieved by a passive mechanism to be robust and lightweight. We demonstrate that TITAN VIII with the proposed terrain adaptive sole can successfully negotiate a rough terrain.