Some Aspects of Heel Strike Impact Dynamics in the Stability of Bipedal Locomotion

Heel impact contributes to the stability of bipedal locomotion: the change of trajectory induced at heel strike has a stabilizing effect, and the phase–space volume contraction to which heel strike contributes is a necessary condition for stability. For a given passive walker, there is a slope limit to obtain stable limit cycles. However, this limit can be surpassed if extra dissipation is introduced. This stabilizing mechanism can be used or be present in bipedal locomotion. In this paper, it is proposed that heel strike can be accommodated to absorb more or less energy, and then that it is used as a regulation or control mechanism in bipedal locomotion. From a biomechanical point of view, dissipation through heel impact is the most efficient way to lose energy, any other way requires an active participation of muscles. This signifies the importance of the proposed regulation mechanism. In this work, some of the control possibilities of heel impact are briefly analyzed related to the energetics in order to claim its role and importance as a control mechanism in bipedal locomotion. This study can be valuable in several areas, for example, in control, prosthetics, shoe design, and generally in further understanding of bipedal locomotion.