  Quadrupeds transition spontaneously to various gait patterns (e.g., walk,
trot, pace, gallop) in response to the locomotion speed. The generation of
these gait patterns has been the subject of debate for a long time. We propose
a coupled oscillator model that is coupled with the physical interactions of
the body. The results of this study showed that the gait pattern transitions
spontaneously to walking/trotting/pacing/bounding in manner similar to that of
real quadruped animals when the resonating portion of the body is changed
according to the speed of leg movement. We also observed that pacing is
expressed exclusively instead of trotting by changing the physical
characteristics. In addition to leading to understanding of the principles of
locomotion in living things, the coupled oscillator model proposed in this
study is expected to lead to the creation of a legged robot that can select an
energy-efficient gait and transition to it spontaneously.
