IMU-based joint angle measurement for gait analysis.

Area of Science:

• Biomechanics and Human Motion Analysis
• Sensor Technology and Signal Processing
• Rehabilitation Engineering

Background:

• Accurate joint angle calculation is essential for human motion analysis, but challenges arise from the human body's irregular geometry.
• Existing methods often rely on assumptions about sensor orientation or magnetic fields, limiting their applicability.
• Inertial Measurement Units (IMUs) offer a portable solution but require robust algorithms for precise biomechanical data extraction.

Purpose of the Study:

• To develop and validate novel methods for joint axis identification and angle measurement using IMU data.
• To address the challenge of sensor mounting orientation variability on non-rigid body segments.
• To provide an alternative to magnetic-based or optical motion capture systems for human motion analysis.

Main Methods:

• Development of new algorithms for joint axis and position identification using gyroscope and accelerometer data.
• Implementation of flexion/extension joint angle measurement techniques independent of magnetic field interference.
• Validation through gait trials of a transfemoral amputee, comparing IMU-based results with optical 3D motion capture data using anatomical landmarks.

Main Results:

• Root mean square errors for knee flexion/extension angles were below 1° for the prosthesis and approximately 3° for the residual limb.
• Ankle plantar/dorsiflexion measurements showed deviations of about 1°.
• The proposed IMU-based methods demonstrated high accuracy comparable to optical systems.

Conclusions:

• The novel IMU-based methods provide accurate joint angle calculations for human motion analysis, even on irregular body segments.
• The reliance solely on gyroscopes and accelerometers overcomes limitations associated with magnetic field dependency.
• These techniques offer a promising, non-invasive approach for applications in biomechanics and rehabilitation.