Revealing the inherent running mechanism of quadruped mammals based on a novel bionic stiffness model

In this paper, the limb of a goat is chosen as the research object, and according to mammalian anatomy, a bionic model called the quasi inverted pendulum with "J" curve spring (QIPJCS) model with nonlinear stiffness is built, and the equations of motion are derived. Based on these equations, the advantages of the QIPJCS model are illustrated from the aspect of the stable motion region by the SFA (step-to-fall analysis) numerical simulation method. These results are compared with the traditional SLIP model. Furthermore, the ARM (Apex-Return-Map) of this model is built, and the fixed points are analyzed. Finally, according to the locomotion law of goats running with gallop gaits and the analysis of the dead-point support effect, the dynamic motion mechanism of goat limbs is elucidated, and the equivalent mechanism model is built. Based on the mechanism, the dynamic mechanical analysis indicates that the joint driving torque can be minimized to conserve energy by optimizing the landing angle. The running mechanism research of quadruped mammals, which is based on the novel bionic stiffness model, provides theoretical support for the design of high-performance mechanical legs and the motion control of bionic robots.