Magnetometer-Free, IMU-Based Foot Progression Angle Estimation for Real-Life Walking Conditions

Area of Science:

• Biomechanics
• Gait Analysis
• Wearable Technology

Background:

• Foot progression angle (FPA) is crucial for assessing diseases and rehabilitation.
• Existing magneto-IMU algorithms for FPA estimation suffer from magnetic distortion and inaccuracies during dynamic gait changes.

Purpose of the Study:

• To develop and validate a novel foot-worn IMU-based algorithm for accurate FPA estimation.
• To address limitations of previous methods, particularly in real-world walking conditions involving starts and turns.

Main Methods:

• A new IMU-based algorithm was developed using orientation estimation, acceleration transformation, and peak foot deceleration for FPA calculation.
• Twelve healthy subjects participated in two experiments validating the algorithm for continuous walking across various FPA patterns and for steps post-walking initiation and turns.

Main Results:

• The algorithm demonstrated high accuracy, closely matching marker-based systems with a mean absolute error of 3.1±1.3 degrees.
• Valid FPA estimations were achieved for all steps immediately following walking starts and turns.

Conclusions:

• The proposed IMU-based FPA algorithm provides reliable gait assessment, even in environments with magnetic interference.
• This technology enables accurate FPA measurement in real-life walking scenarios, including common transitions like starts, stops, and turns.