A generalized 3D inverted pendulum model to represent human normal walking

This paper compares different inverted pendulum models to represent the stance phase of human normal walking. We have developed a model which takes into account the mechanism of the foot during the single support phase, by defining a pivot point under the ground level. Similarly to other models, the pivot point as well as the rod length remain constant during the complete single support phase. Lowering the position of the pivot point allows reducing the vertical amplitude of the center of mass (CoM) trajectory and therefore approaching the real CoM trajectory. We have measured the whole body kinematics of a representative healthy male subject and set a reference CoM trajectory based on multi-body modeling of the human body (16 segments). Then, we have determined a common mathematical definition of two inverted pendulum models extended in the three dimensional space: the classical IP-3D and our GIP-3D model.