Three-dimensional spring-loaded inverted pendulum walking model considering human moving speed and frequency.

Abstract

The spring-loaded inverted pendulum (SLIP) model is an effective model to capture the essential dynamics during human walking and/or running. However, most of the existing three-dimensional (3D) SLIP model does not explicitly account for human moving speed and frequency. To address this knowledge gap, this paper develops a new SLIP model which includes roller foot, massless spring and concentrated mass. The governing equations-of-motion for SLIP model during its double support phase are derived. It is noted that in the current formulation, the motion of roller foot is prescribed so only the equations for the concentrated mass needs to be solved. In order to yield model parameters leading to a periodic walking gait, a constrained optimization problem is formulated and solved using gradient-based approach with a global search strategy. The optimization results show that when the attack angle ranges from 68° to 74° the 3D SLIP model can yield a periodic walking gait with walking speeds varying from 0.5 to 2.0 m/s, the predicted human walking data is also compared with published experimental data, finding reasonable accuracy.