# Comparative assessment of heel rise detection for consistent gait phase separation

## TL;DR

This paper compares different methods for detecting heel rise during walking to improve gait analysis accuracy.

## Contribution

The study introduces and validates novel IMU-based methods that closely match high-accuracy motion capture techniques for heel rise detection.

## Key findings

- Heel marker's vertical acceleration and jerk-based methods show high agreement with visual detection.
- IMU-based methods offer a cost-effective alternative with accuracy comparable to motion capture systems.
- Subtle heel motion variations after mid-stance contribute to detection variability across individuals.

## Abstract

Accurate identification of gait events is crucial to reliable gait analysis. Heel rise, a key event marking the transition from mid-stance to terminal stance, poses challenges in precise detection due to its gradual nature. This leads to variability in accuracy across studies utilizing diverse measuring techniques.

How do different HR detection methods compare when assessed against the underlying heel motion pattern and visual detection across varying speed, footwear conditions, and individuals?

Leveraging data from over 10,000 strides in diverse scenarios with 15 healthy subjects, we evaluated methods based on measurements from optical motion capture (OMC), force plates, and shank-mounted inertial measurement units (IMUs). The evaluation of these methods included an assessment of their precision and consistency with the heel marker's motion pattern and agreement with visually detected heel rise.

OMC-based heel rise detection methods, utilizing the heel marker's vertical acceleration and jerk, consistently identified the same point in the heel motion pattern, outperforming velocity-based methods and our new position-based method resembling traditional footswitch-based heel rise detection. Variability in velocity and position-based methods derives from subtle heel rise variations after mid-stance, exhibiting individual differences. Our proposed IMU-based methods show promise by closely matching OMC-based accuracy.

The results have significant implications for gait analysis, providing insights into heel rise event detection's complexities. Accurate HR identification is crucial for gait phase separation, and our findings, especially with the robust heel marker's jerk-based method, enhance precision and consistency across walking conditions. Moreover, our successful development and validation of IMU-based algorithm offer cost-effective and mobile alternative for HR detection, expanding their potential use in comprehensive gait analysis.

•We assess motion capture, force plate, and IMU data to identify the most precise heel rise detection method.•Subtle rising of the heel before the actual lift-off causes variability in heel rise detection.•Heel marker's acceleration and jerk-based methods are in high agreement with visual detection.•Novel IMU-based methods closely mirror the performance of acceleration and jerk-based methods.•The proposed methods improve heel rise detection accuracy for gait analysis.

We assess motion capture, force plate, and IMU data to identify the most precise heel rise detection method.

Subtle rising of the heel before the actual lift-off causes variability in heel rise detection.

Heel marker's acceleration and jerk-based methods are in high agreement with visual detection.

Novel IMU-based methods closely mirror the performance of acceleration and jerk-based methods.

The proposed methods improve heel rise detection accuracy for gait analysis.