Three-Dimensional Walking Load Based on Bipedal Variable Damped Spring-Loaded Inverted Pendulum Model

To overcome the limitation of the traditional two-dimensional (2D) bipedal inverted pendulum model, which fails to account for lateral Ground Reaction Forces (GRFs) in human walking, this study proposes a novel three-dimensional (3D) walking load model based on a bipedal Variable-Damped Spring-Loaded Inverted Pendulum (VDSLIP) model. The equations of motion are derived using the Euler–Lagrange formalism. To validate the proposed model, ground reaction force data were collected from 25 human subjects using force plates, and the corresponding gait parameters were accurately identified through an intelligent optimization algorithm. A comparative analysis between the experimental measurements and the model’s inverse dynamic solutions revealed normalized maximum absolute errors ranging from 1.38% to 13.85%, thereby demonstrating the model’s accuracy and reliability. Additionally, the performance of the proposed 3D model was benchmarked against the conventional 2D inverted pendulum model, showing significantly improved fidelity in replicating walking loads. These findings offer new perspectives and robust methodologies for advancing biomechanical modeling and gait optimization research.