Design of a Robotic Foot with Midtarsal Joint Locking Mechanism

Abstract

Understanding the intrinsic softness of the human foot and implementing its essential functions in a biped robot could improve walking performance. In this study, we propose a design of a robotic foot with bioinspired midtarsal joint locking mechanism. The proposed foot has joints to form the arch of the human foot, and the stiffness of the foot can be changed by the locking mechanism. To investigate the dynamic behavior of the mechanism during walking, we conducted experiments on the proposed foot with different locking angles. We evaluated the results by comparing the ground reaction forces and propulsive forces. The proposed foot was mounted on a walking simulator to reproduce a single walking step. We confirmed two peaks in the ground reaction force, as observed in humans. We found differences in the second peak, which was caused by the midtarsal joint locking mechanism. A difference in the generated propulsive force was confirmed from the locking angle of the midtarsal joint. The results of this study could facilitate designing a robotic foot that utilizes its adjustable softness to realize walking in a biped robot.