A Three-Dimensional Mass-Spring Walking Model Could Describe the Ground Reaction Forces

The oscillatory behavior of the center of mass (CoM) and the ground reaction forces (GRFs) of walking people can be successfully explained by a 2D spring-loaded inverted pendulum (SLIP) model. However, the application of the 2D model is just restricted to a two-dimensional plane as the model fails to take the GRFs in the lateral direction into consideration. In this article, we simulated the gait cycle with a nonlinear dynamic model—a three-dimensional bipedal walking model—that compensated for defects in the 2D model. An experiment was conducted to compare the simulation results with the experimental data, which revealed that the experimental data of the ground reaction forces were in good agreement with the results of numerical simulation. A correlation analysis was also conducted between several initial dynamic parameters of the model. Through an examination of the impact of 3D dynamic parameters on the peaks of GRFs in three directions, we found that the 3D parameters had a major effect on the lateral GRFs. These findings demonstrate that the characteristics of human walking can be interpreted from a simple spring-damper system.