Enhanced Quadruped Locomotion of a Rat Robot Based on the Lateral Flexion of a Soft Actuated Spine

Yuhong Huang, Zhenshan Bing, Florian Walter, Alex Rohregger, Zitao Zhang, Kai Huang, Fabrice O. Morin, Alois C. Knoll

Abstract: In nature, the movement of quadrupeds is completed under the combined action of the spine and the legs. Inspired by this, this paper explores the effect of a lateral flexing spine on the locomotion of a rat robot. Benefiting from the regular lateral flexion of a soft actuated spine, the rat robot exhibits enhance step length of its hind legs and increased translational velocity by coordinating the opposite movements of the left and right sides. Furthermore, this paper introduces a mathematical model of the effect of the flexible spine on the robot velocity. Finally, extensive experiments are conducted in simulations and on the physical rat robot. Compared with the locomotion without a flexing spine, the simulation results show that the velocity of the robot can be increased up to 218.29%, which is in line with the theoretical results from the proposed mathematical model. Limited by the gap between simulation and the real world, the experiment results of the physical rat robot show a slight performance than the theoretical results. But the physical rat robot can still enhance its translational velocity with the help of a lateral flexing spine.