Static Precision of Instrumented Pointers for Anatomical Landmark Calibration in CAST-Like Motion Analysis...

Area of Science:

• Biomechanics
• Motion Analysis
• Human Movement Science

Background:

• Calibrated Anatomical Systems Technique (CAST) is crucial for motion analysis.
• Inconsistent landmark calibration causes errors in joint angle calculations.
• Variations in intra- and inter-examiner accuracy are significant issues.

Purpose of the Study:

• To characterize and minimize factors causing inconsistent landmark calibration in motion analysis.
• To examine and optimize the performance of instrumented pointers for landmark calibration.
• To address the lack of complete characterization of instrumented pointer precision.

Main Methods:

• Investigated four different instrumented pointers with an optical OptiTrack motion capture system.
• Measured pointer tip location variability at three distinct locations within the capture volume.
• Assessed pointer precision across different orientations at each location.

Main Results:

• Stationary markers show <0.06 mm variation (95% confidence).
• Stationary pointer tip variation is approximately 0.2 mm.
• Variations can double if markers are too close for system resolution; pointer geometry has minimal impact.

Conclusions:

• Static precision of motion capture systems is excellent due to technological advancements.
• Improving tracking robustness may have minimal impact on overall pointer precision.
• Current instrumented pointer precision is adequate for most motion analysis applications.