An Improved Rocker-based Inverted Pendulum Walk Model for Human Gait

It is well-known that feet play an important role in human walking. Foot functions include heel-rocker, ankle-rocker, forefoot-rocker as well as toe-rocker, they produce a wheel-like rolling motion to make forward progression. This paper presents an improved rocker-based inverted pendulum walk model. From the static approaches, put out a new equation of roll factor, and take the vertical excursion of COM (Center Of Mass) as the criterion. Through experimental comparison, it is verified that the new model and the new equation of roll factor are more accurate. And it demonstrated that foot functions are related to roll factor. Furthermore, the gait characteristics (step length, cadence, or gait speed) can be a function of only roll factor. The range of roll factor is 1.4 to 1.7. The vertical excursion of COM and the angular motion of ankle joint are strongly related to roll factor. Thus, roll factor, which reflects foot function in walk, can be a useful parameter to evaluate walking state. The new rocker-based inverted pendulum walk model is appropriate to the soft wearable walking assistive suit.