Experimental development of stiffness adjustable foot sole for use by bipedal robots walking on uneven terrain

This research aims to develop a novel foot sole mechanism which utilizes the jamming transition effect of granular material enclosed in an air tight bag, for use by bipedal robot walking on uneven ground. The mechanism is designed to make the foot sole be soft and compliant to adapt to the surface of an uneven terrain, and be stiff when the robot is in the support phase of the walking gait. The stiffness-variable property of the mechanism according to the internal air pressure of the bag is investigated. To measure the tilting stability when center of pressure is moved across the proposed foot sole, a test using an inverted pendulum apparatus had been carried out and compared to when using a rigid flat foot sole.