Inertial Measurement Unit-Based Estimation of Foot Trajectory for Clinical Gait Analysis.

Koyu Hori,Yufeng Mao,Yumi Ono,Yuki Hirobe,Hiroyuki Sawada,Hiroki Ora,Yoshihiro Miyake,Satoshi Orimo,Akira Inaba

doi:10.3389/fphys.2019.01530

Koyu Hori, Yufeng Mao + Show 7 more

Open Access

https://doi.org/10.3389/fphys.2019.01530

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Abstract

Gait analysis is used widely in clinical practice to evaluate abnormal gait caused by disease. Conventionally, medical professionals use motion capture systems or make visual observations to evaluate a patient's gait. Recent biomedical engineering studies have proposed easy-to-use gait analysis methods employing wearable sensors with inertial measurement units (IMUs). IMUs placed on the shanks just above the ankles allow for long-term gait monitoring because the participant can walk with or without shoes during the analysis. To the knowledge of the authors, no IMU-based gait analysis method has been reported that estimates stride length, gait speed, stride duration, stance duration, and swing duration simultaneously. In the present study, we tested a proposed gait analysis method that uses IMUs attached on the shanks to estimate foot trajectory and temporal gait parameters. Our proposed method comprises two steps: stepwise dissociation of continuous gait data into multiple steps and three-dimensional trajectory estimation from data obtained from accelerometers and gyroscopes. We evaluated this proposed method by analyzing the gait of 19 able-bodied participants (mean age 23.9 years, 9 men and 10 women). Wearable sensors were attached on the participants' shanks, and we measured three-axis acceleration and three-axis angular velocity with the sensors to estimate foot trajectory during walking. We compared gait parameters estimated from the foot trajectory obtained with the proposed method and those measured with a motion capture system. Mean accuracy (± standard deviation) was 0.054 ± 0.031 m for stride length, 0.034 ± 0.039 m/s for gait speed, 0.002 ± 0.020 s for stride duration, 0.000 ± 0.017 s for stance duration, and 0.002 ± 0.024 s for swing duration. These results suggest that the proposed method is suitable for gait analysis, whereas there is a room for improvement of its accuracy and further development of this IMU-based gait analysis method will enable us to use such systems for clinical gait analysis.

Highlights

Analysis of abnormal gait can provide important information about diseases and injuries
We propose a novel gait analysis method for clinical purposes that uses inertial measurement units (IMUs) attached on the shanks to estimate foot trajectory and to obtain estimated clinical gait parameters
To evaluate the proposed method, the shank trajectory and clinical gait parameters calculated by our proposed method were compared with those collected by the motion capture system

Summary

Introduction

Analysis of abnormal gait can provide important information about diseases and injuries. Clinical gait analysis is performed mostly by health-care providers using visual observation (Krebs et al, 1985). This method is the most readily accessible means of gait analysis available to health-care providers (Barker et al, 2006), it is a subjective and qualitative method that is inadequate for assessing changes in gait features during ongoing treatment interventions. Motion capture systems are used in clinical research for gait analysis (Mcginley et al, 2009) and scientific research (Lieberman et al, 2010). Because the special equipment needed for motion capture is expensive and requires a large space, few medical institutions can use these systems for clinical gait analysis (Barker et al, 2006)

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