Listen to body's message: Quadruped robot that fully exploits physical interaction between legs

Versatile gait patterns that depend on the locomo- tion speed, environmental conditions, and animal species are observed in quadrupeds. Locomotor patterns are generated via the interlimb coordination, which is partially controlled by an intraspinal neural network called the “central pattern generator” (CPG). However, there is currently no clear understanding of the adaptive interlimb coordination mechanism. We hypothesize that the interlimb coordination should rely more on the “physical” interaction between leg movements through the body rather than the interlimb neural connection. To understand the coordination mechanism, we developed a simple-structured quadruped robot and proposed an unconventional CPG model that consists of four decoupled oscillators with only local force feedback in each leg. Experimental results show that our CPG model allows the robot to exhibit steady gait patterns, adaptability to changes in body properties, and adaptive gait transition between walking and trotting. Our robot mimics locomotor patterns of real quadrupeds following which it can capture the basic mechanism underlying the adaptive interlimb coordination.