Gait Patterns of Quadrupeds and Natural Vibration Modes

Abstract

Quadruped animals switch gait patterns with walking frequency for energy-effective walking. This is similar to the phenomenon that excited natural vibration modes are switched with vibration frequency in a MDOFs system. Therefore, in this paper, it is assumed that quadruped animals walk by using the natural vibration of their own musculoskeletal systems. In the simplest rigid-body-link model consisting of a body and four legs, there are the natural vibration modes similar to the gait patterns (trot, pace and gallop) of quadruped animals. However, all the natural frequencies in the model exist near the natural frequency in the free leg, and are accordingly different from the walking frequencies of actual quadruped animals. In the rigid-body-link model added a scapular and a pelvic on observations of quadrupted walking, the natural frequency of the gallop mode corresponding to high speed walking raises greatly and approaches the walking frequency. If the physical characteristics of horses were applied to the rigid-body-link model added the leg's joints, the natural vibration in the model is close to the gait patterns of horses.