Elastic Force Feedback CPG-based Gait Control for a Quadruped Robot with a Bioinspired Leg Mechanism

Dynamic locomotion of a quadruped robot, ensuring stability and agility, is crucial for practical use. Our research group has devised an elastic leg mechanism inspired by the muscle-tendon complex of the gastrocnemius and the achilles tendon in the lower limbs of animals. While we have accomplished dynamic locomotion with our quadruped robot, integrating motion control that considers its behavior remains crucial to harness the advantages of this biological normative mechanism. Gait control, implemented through central pattern generator (CPG) that provides feedback on environmental interactions detected using toe force sensors, holds the potential to actively incorporate the influences of leg mechanisms that inherently respond to movement in locomotion control. In this paper, we proposed a leg elastic force feedback CPG model aimed at effectively utilizing the bioinspired leg mechanism to quadrupedal locomotion by realizing coordinated movements among the limbs of a quadruped robot, instead of using force sensors at toes. This coordination is based on the state of the elastic leg spring and the phase of the toe trajectory. The proposed model enabled the expansion of the stable running region and facilitated faster movements during locomotion by utilizing elastic force feedback.