Most quadrupeds, which make up the majority of mammals, walk in step (gait) from walk (grounding in the order of left hind leg, left front leg, right hind leg, right front leg) to trot (diagonal) depending on the movement speed. It is known that the legs spontaneously transition to the most energetically efficient gait (grounding with the legs synchronized) and gallop (grounding with the front and back almost synchronized). ..However, its control mechanism was not clear.

　This time, we adopted the approach of "clarifying the mechanism by reproducing the movement of animals on a robot".A walking experiment was conducted on the developed four-legged robot on a treadmill (running machine).As a result, we succeeded in creating a gait transition phenomenon simply by executing a very simple control rule that "when a load is applied to the legs, we try to continue to support the body as it is". ..Furthermore, it was found that the footsteps reproduced by the four-legged robot were excellent in energy efficiency and matched well with the characteristics obtained from horses and the like.

　This result is thought to contribute to the elucidation of the mechanism by which quadrupeds move efficiently by spontaneously changing their footsteps, and how they skillfully manipulate the many degrees of freedom that animals have in their bodies. ..In addition, by developing this result, it can be expected that it will become a basic technology for the engineering realization of robots with motor ability comparable to that of quadrupeds.

Publication information: [Scientific Reports electronic version] A Quadruped Robot Exhibiting Spontaneous Gait Transitions from Walking to Trotting to Galloping