Experimental verification of cusp catastrophe in the gait transition of a quadruped robot driven by nonlinear oscillators with phase resetting

In this paper, we investigated the dynamic characteristics in the gait of a quadruped robot, which is controlled by an oscillator network constructed based on the physiological concept of central pattern generators and the physiological evidence of phase resetting. From the observation in humans, two-parameter cusp catastrophe is suggested to be embedded in the walk-run transition with the locomotion speed and additional load as control parameters. In our previous work, simulation studies revealed that a quadruped robot model produces the walking and trotting gaits depending on the locomotion speed and it shows the cusp bifurcation due to additional weights similar to humans through dynamic interactions among the robot's mechanical system, the oscillator network system, and the environment. The aim of the present study is to verify such dynamic characteristics in the cusp catastrophe of the gait transition in the locomotion of our quadruped robot model in the real world by using a quadruped robot.