Influence of IMU position and orientation placement errors on ground reaction force estimation

Area of Science:

• Biomechanics
• Wearable Technology
• Sensor Fusion

Background:

• Wearable inertial measurement units (IMUs) offer potential for estimating ground reaction forces (GRF) outside laboratory settings.
• The impact of sensor placement errors on GRF estimation accuracy remains insufficiently understood.

Purpose of the Study:

• To investigate the influence of IMU position and orientation placement errors on GRF estimation accuracy.
• To quantify the impact of single and simultaneous sensor misplacements on GRF estimation.

Main Methods:

• Simulated 1848 combinations of position (±100 mm) and orientation (±25°) errors across eight body segments.
• Utilized kinematic data from twelve healthy subjects during walking trials.
• Employed three machine learning algorithms to estimate GRF under various error conditions.

Main Results:

• Position errors reduced VGRF, MLGRF, and APGRF accuracy by up to 4.9%, 6.0%, and 4.3% respectively when all eight IMUs were misplaced.
• Orientation errors reduced VGRF, MLGRF, and APGRF accuracy by up to 20.8%, 23.4%, and 12.3% respectively for all eight simultaneously misplaced IMUs.
• Orientation errors had a more substantial impact on GRF estimation accuracy than position errors.

Conclusions:

• IMU sensor misplacement, particularly orientation errors, significantly degrades GRF estimation accuracy.
• Implementing measures to mitigate or account for placement errors is essential for reliable wearable IMU-based GRF estimation.
• Findings highlight the sensitivity of GRF estimation to sensor positioning in wearable systems.