Real-time gait assessment utilizing a new way of accelerometry

Area of Science:

• Biomechanics
• Biomedical Engineering
• Wearable Technology

Background:

• Real-time body segment angle registration is crucial for artificial body position control systems.
• Traditional accelerometry methods for angle calculation suffer from integration drift, limiting their accuracy.

Purpose of the Study:

• To present a new method for real-time calculation of lower extremity angles using pairs of 1D accelerometers.
• To demonstrate the feasibility of calculating relative and absolute joint angles without integration.
• To assess the accuracy and potential applications of this method in artificial body control.

Main Methods:

• Utilized pairs of two one-dimensional accelerometers to capture motion data.
• Developed a method assuming rigid-body dynamics and simple hinge joints for angle calculation.
• Transformed relative angles to absolute angles during the stance phase of walking.
• Validated the method by calculating knee joint angles in a healthy subject during various activities.

Main Results:

• Successfully calculated relative lower extremity angles without integration, overcoming integration drift.
• Demonstrated stability and resolution during standing measurements.
• Identified shock (heel-strike) and skin movement as primary error sources, suggesting signal processing solutions.
• Achieved high accuracy in knee angle measurement, suitable for feedback control.

Conclusions:

• The proposed accelerometer-based method accurately calculates lower extremity angles in real-time.
• This technique offers a drift-free solution for body segment angle registration.
• The findings support the use of this method in feedback controllers for functional electrostimulation of the lower extremities.