Influence Surfaces for Reconstructing Foot-Specific Ground Reaction Forces and Location from Dual-Contact Measurements on a Single Force Plate

Authors:
Preprint
Publisher website
Google Scholar
Abstract
Force plates are the gold standard for measuring ground reaction forces, but their reliance on equilibrium equations limits them to single-contact measurements. During the double support phase of walking, when both feet touch the ground simultaneously, conventional force plates yield only the combined force and center of pressure. The individual foot contributions cannot be separated. This paper applies influence surface theory to extend force plate analysis beyond equilibrium-based methods. Instead of evaluating global force and moment balances, influence surfaces characterize how loads at different positions contribute to structural responses at individual supports. This enables load identification for multiple simultaneous contacts, with the number of separable loads determined by the available sensor count.The influence surfaces are trained from walking data using Gaussian Process Regression, capturing the real plate behaviour without requiring finite element modelling. To reduce complexity, the inverse problem is addressed sequentially. First, load positions are estimated. Second, the horizontal force components are determined.The method is validated on a 2.5m x 1.0m force plate using static tests with known load positions and walking trials with synchronized instrumented insoles providing the load distribution. The results show that the approach successfully reconstructs positions and three-dimensional ground reaction forces for both contacts, generally achieving accuracy comparable to equilibrium-based single-contact measurements while preserving natural gait.

This publication has 18 references indexed in Scilit: