Ambulatory Assessment of the Dynamic Margin of Stability Using an Inertial Sensor Network

Area of Science:

• Biomechanics
• Kinesiology
• Wearable Sensor Technology

Background:

• Loss of dynamic stability is a primary cause of falls, particularly in vulnerable populations.
• Assessing balance control and fall risk requires evaluating dynamic stability during activities of daily living (ADLs).
• The dynamic margin of stability (MOS) quantifies the body's center of mass relative to the base of support.

Purpose of the Study:

• To propose and validate a novel magneto-inertial measurement unit (MIMU)-based method for assessing dynamic margin of stability (MOS) during gait.
• To compare the accuracy of the MIMU-based MOS assessment with a traditional camera-based system.

Main Methods:

• Six healthy young adults walked on a treadmill at various speeds while equipped with MIMUs on their lower limbs and pelvis.
• Dynamic MOS was calculated using an inverse kinematics approach based on lower body displacement.
• Results were validated against a camera-based system, analyzing root mean square deviation (RMSD) and correlation coefficient (ρ).

Main Results:

• The MIMU-based method achieved a root mean square deviation (RMSD) of ≤1.80 cm and a correlation coefficient (ρ) of ≥0.85 across all tested walking velocities.
• These findings indicate high accuracy and strong agreement between the proposed MIMU method and the gold-standard camera system.

Conclusions:

• The proposed MIMU-based method demonstrates accuracy comparable to camera-based systems for assessing dynamic MOS during gait.
• This technology presents a practical and potentially more accessible strategy for evaluating stability during ADLs, even in non-laboratory settings.