A Bio-Robotic Toe & Foot & Heel Models of a Biped Robot for More Natural Walking: Foot Mechanism & Gait Pattern

Humans possess a complex physical structure and can perform difficult movement tasks. Over the past few decades, many researchers around the world have concentrated on achieving human-like artificial mobility or dexterity either on humanoid robots or during the implementation of robotic assistive devices. In particular, humanoid-type robots mainly focused on hands to understand the mechanical and dynamical functions of ourselves. On the other hand, there have been few researches to achieve human like foot. Until now, human-like skillful mobility has not been achieved on humanoid robots, since the robotic feet are far from adaptation to keep stable contact on the ground and the current kinematic structures of a humanoid foot is different from that of a real human foot. Stability related issues have been the main goal for humanoid robots in relevant researches. Initially, humanoid robots were built so that they can walk stably with flat foot (Sakagani et al., 2002; Okada et al., 2004 ). These initial walking patterns were optimized for the highest stability, and the resulting walking pattern had knee bending and flat-feet walking. A more advanced strategy was developed for generating biped walking pattern involving heel strike and toe off motion in (Huang et al., 2001). However, because of the mechanism’s limitation the knee bending walking patterns were always chosen for the benefit of stability, thus making it less natural. Today, more advanced control approaches, faster and more powerful actuators, and more sophisticated walking pattern generation strategies have helped the research goal to be shifted to pursue more natural walking patterns for biped robots, with the expectation that someday humanoid robot can coexist with human. To improve walking capacity of humanoid-type robots, toe mechanisms with 1-dof was suggested earlier, (Ahn et al., 2003; Takahashi et al., 2004). For walking in a straight direction, 1-dof toe mechanism can supply faster walking for a robot. In addition, relative toe motion can increase the naturalness of robot walking and help to reduce the load on the knee joints, where high force and speed are required to achieve robot locomotion (Nishiwaki & Kagami, 2002). However, the foot device with 1-dof toe mechanism cannot