Human-like Walking of Biped Robot with Foot Rotation Using Passive Metatarsophalangeal Joint

In the process of walking, humans are accompanied by the important action of foot rotation. The foot rotates taking the heel and toe as the axis of rotation when landing on and leaving the ground, respectively. Although having high similarity to humans, many biped robots do not reproduce this important feature. This paper describes a method for adding foot rotation into biped robots using the passive metatarsophalangeal joint. Firstly, the biomechanics of human metatarsophalangeal joint during walking is analyzed. Then, the control strategy based on finite state machine for human-like biped walking with foot rotation is proposed for a simplified biped robot model that is composed of eight joints. Finally, the simulation results of the walking gait of the biped robot in MATLAB demonstrate the effectiveness of the control strategy.