Design of point-contact type foot with springs for biped robot

This paper presents a new foot system for biped walking on rough terrain and its design flow. To achieve the stable biped walking on rough terrain, the following functions are required. 1) Stabilization of contact states between foot and ground. 2) Landing to unknown terrain. The conventional rigid and flat foot changes its contact states and is separated from the ground easily. In addition, the impulsive impact force at landing on rough terrain must be suppressed. We propose a point-contact type foot with springs (PCFS). The proposed foot has the following advantages. 1) Stabilization of contact state. 2) Estimation of stability index, and 3) Absorption of landing impact. A design method of primary parameters for PCFS is presented to increase the stability of the robot and reduce the impact force at the landing. The validity of the proposed design method is shown experimentally.