Study on the Dynamic Response Characteristics of Bionic Legs During Instantaneous Ground Contact

Musculoskeletal system vibrations are initiated at paw-strike in animal’s high-speed running. The short ground contact moment suggests that there exists a transient dynamic response of the impact between the leg and the ground, which is a high nonlinear problem and not well understood. From the anatomical measurement data of a domestic cat, a musculoskeletal system model of the quadruped animal was constructed in this study. The changes of muscle forces and joint moments were computed based on a high-speed motion sequence. The elastic moduli were measured and calculated for different parts of the tibia by a nano-indentation technique. On the basis of the measured material parameters, the substructure technique for dynamics was employed to numerically solve the contact-impact behavior of bio-materials and bionic components. To record the contact-impact process, high-speed videos (more than 10,000 fps) were taken during the capture experiments. Results demonstrated that multiple impacts existed in the tibia and the PLA leg at the moment of contact-impact. The results from this paper further reveal that the multiple contact-impact phenomena are adapted to cats during running, which may provide a certain support for selecting bionic components and improving the performance of the bionic mechanism.