On passive quadrupedal bounding with translational spinal joint

Abstract

This paper studies the effect of a flexible linear torso on the dynamics of passive quadruped bounding. A reduced-order passive and conservative model with translational spinal joint and springy legs is introduced. Numerical return map studies reveal the existence of a confined area of fixed points generating high-speed cyclic bounding motions by exploiting the natural dynamics of the model. The corresponding motion features extensive bidirectional spine deformation. The model displays interesting techniques that result in high-speed locomotion, such as increased flight phase duration and stride length. The obtained results show that the corresponding robot gaits and the associated performance resemble those of its natural counterparts even though the spinal joint lies beyond the bioinspired regime.