Estimation of Ground Reaction Forces from Kinematic Data during Locomotion

TL;DR

This work tackles the practical limitation of force plates in clinical gait assessment by proposing a force-plate-free method to estimate ground reaction forces (GRFs) from marker-based kinematics. It reconstructs the whole-body centre of mass (CoM) using a sixteen-segment model and derives GRFs from body accelerations, subsequently decomposing them into bilateral components via a minimization-based approach that resolves double-stance ambiguity. The method is validated by comparing CoM trajectories to Visual3D benchmarks and by demonstrating close alignment between kinematic GRFs and force-plate measurements, including the ability to monitor left-right loading continuously across multiple strides. The approach is compatible with markerless systems and scalable across settings, offering a practical, clinically relevant pathway to integrate kinetic analysis without dedicated force plates; further validation in pathological populations is needed to confirm broad applicability.

Abstract

Ground reaction forces (GRFs) provide fundamental insight into human gait mechanics and are widely used to assess joint loading, limb symmetry, balance control, and motor function. Despite their clinical relevance, the use of GRF remains underutilised in clinical workflows due to the practical limitations of force plate systems. In this work, we present a force-plate-free approach for estimating GRFs using only marker-based motion capture data. This kinematics only method to estimate and decompose GRF makes it well suited for widespread clinical depolyment. By using kinematics from sixteen body segments, we estimate the centre of mass (CoM) and compute GRFs, which are subsequently decomposed into individual components through a minimization-based approach. Through this framework, we can identify gait stance phases and provide access to clinically meaningful kinetic measures without a dedicated force plate system. Experimental results demonstrate the viability of CoM and GRF estimation based solely on kinematic data, supporting force-plate-free gait analysis.

Figures (6)

• Figure 1: During the Double-Stance phase of typical locomotion pattern, an ambiguity arises as to the individual contribution of GRF.
• Figure 2: Gait events detected using the sacrum-based kinematic method proposed by Zeni et al. Zeni2008 and validated against Visual3D results. HS and TO events for the left (top) and right (bottom) feet were identified from foot kinematics relative to the sacrum during gait.
• Figure 3: a) Comparison of estimated CoM trajectories between the custom sixteen segment model (Solid Line) and Visual3D benchmark (Dashed Line) for one representative participant. b) Planar trajectories of the center of mass and both feet during walking, with stance phases identified from vertical foot position.
• Figure 4: Filtered marker-based and force-plate GRFs for a representative participant. The vertical GRF during stance exhibits the characteristic double-peaked M-shaped profile, with peaks corresponding to loading response and push-off, and the intermediate region representing mid-stance and pre-swing phases.
• Figure 5: Decomposition of the total ground reaction force into discrete left and right foot GRF components based on Eq. \ref{['bilateralForce']} for all four participants, which computes individual GRFs from measured CoM during double support phase.

Theorems & Definitions (1)

• Remark 1