Uncertainty estimation in marker-based motion capture of the tennis serve
Year: 2025
Type: article
Abstract: Marker-based motion capture (MoCap) systems are widely used to analyse human movement. However, they are affected by measurement uncertainties, particularly marker placement errors (MPE) and soft tissue artefacts (STA). Here, we quantify the individual and combined effects of these two sources of uncertainty on joint angles and angular velocities in the case of the tennis serve. A Monte Carlo approach was used to simulate 3000 perturbed marker trajectories for each uncertainty source and their combination. We applied a random offset for MPE and a random displacement within a sphere for STA. The resulting joint kinematics were compared across all degrees of freedom. Confidence intervals (5–95%) and minimal detectable changes (MDC) were calculated for key biomechanical variables. Results showed that STA predominantly affected angular velocities, while MPE had a greater impact on joint angles. The combined simulation consistently produced the largest variability, with mean confidence intervals ranging from 2.2° to 26.9° in joint angle and from 31.3°.s-1 to 154.5°.s-1 in joint angular velocities. These findings highlight the importance of accounting for measurement uncertainty when interpreting biomechanical data and validating new motion analysis technologies. MDC values provide thresholds below which observed differences may be attributed to measurement error rather than true biomechanical changes.
Source: Journal of Biomechanics
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,650
OpenAlex ID: W4417184603