Model suggests that swing leg dynamic decoupling is crucial for explaining bipedal walking dynamics

Understanding the dynamics of bipedal walking is essential for advancements in biomechanics and robotics. This study examines the impact of swing-leg dynamics on overall gait mechanics using an augmented inverted pendulum model that incorporates a swing leg and an upper-body segment (HAT). We hypothesized that the HAT segment compensates for swing-leg dynamics, thereby minimizing their effect on ground reaction forces (GRFs). Contrary to expectations, our findings reveal that the trunk contributes minimally to this compensation, leading to significant GRF modulation during active swing-leg propulsion. However, introducing an initial velocity to the swing leg during terminal stance markedly reduces these modulations, aligning simulated GRFs with experimental data for human walking. This result highlights the need to dynamically decouple the swing leg from upper-body dynamics to achieve efficient, human-like locomotion. The presented model provides a framework for optimizing bipedal gait designs in humanoid robotics and advancing our understanding of human biomechanics.