Study on Ankle Mechanisms for Walking Robots -Fundamental Considerations on its Functions and Morphology-

Walking robots need terrain adaptive ankle and sole mechanism to move stably on rugged ground. In this paper, the designs of the ankle mechanism for walking robots are discussed. First, we consider required functions for ankle mechanism. An effective ankle mechanism requires the following characteristics: 1) lightweight and robust mechanism, 2) ability to adapt to the ground, 3) sensing function, 4) torque generating or freezing its shape function after landing. Next, we explain the validity of the remote center mechanism and connected differential mechanism. The actual designs of passive terrain adaptive ankle mechanisms are discussed. Finally, the ankle mechanism of quadruped walking robot “TITAN-IX,” which is developed for mine detection and removal tasks, is mentioned. In order to examine the validities of proposed mechanisms, basic experiments were carried out using one-leg model of TITAN-IX.