Quadrupedal template model for parametric stability analysis of trotting gaits

Simple template models have proven useful for understanding the underlying dynamics of legged locomotion. The most common one, the SLIP model, considers the legs as linear springs with constant stiffness, and it explains well the radial dynamics of the legs. However, in order to study the influence of the leg swing dynamics and leg segmentation on gait stability, more complex models are required. This paper introduces a novel template model for quadrupedal gait, which considers these additional aspects. The dynamic behavior of the model is analyzed via numerical simulation, using a continuation approach. By conducting a parametric analysis on the trotting gait and analyzing its stability, we identify the influence of the main model parameters, leading to marginally unstable limit cycles. These numerical results are applicable to the design of more efficient elastic quadrupedal robots.