Development of a mobile, cost-effective and easy to use inertial motion capture system for monitoring in rehabilitation applications

Nana Schlage,Edwin Naroska,Andreas Kitzig,Gudrun Stockmanns

doi:10.1515/cdbme-2021-2149

Nana Schlage, Edwin Naroska + Show 2 more

Open Access

https://doi.org/10.1515/cdbme-2021-2149

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Abstract

Abstract Many people are familiar with the feeling of instability, pain, or subsidence in the knee joint after a knee injury. There are many different methods for examining the knee, such as the drawer test or the Lachman test [1], before and after surgery. While these tests can be used in short term and provide useful results, motion capture systems can be used as an alternative measurement method, almost as a substitute in longer term. These include marker-based or mechanica l systems, which achieve good measurement results but are expensive and inflexible. For this reason, this paper presents a mobile, easy-to-use motion and easy expandable capture system using a low-cost IMU-based development system. The modular design of the system allows it to be adapted to each body region with simple adjustments. However, the present work focuses on applications for capturing human motion sequences and deriving three joint angles of the lower extremities to detect malposition.

Highlights

In addition to conventional examinations [1], a common procedure for examining movement patterns, e.g., after a lower limb injury, is the use of motion capture (MoCap) systems [2, 3, 4]
Most systems are very expensive or require further expertise / support to use them [2], for example in attaching the markers to the body. To avoid these drawbacks and still be able to use a valid reference system, this paper presents a prototype of an easyto-use and expandable variation of a motion capture system, implemented with a low-cost IMU-based development system
The modular design of the system allows it to be adapted to each body region with simple adjustments

Summary

Introduction

In addition to conventional examinations (palpation and movement tests, radiographs or CT/MRI) [1], a common procedure for examining movement patterns, e.g., after a lower limb injury, is the use of motion capture (MoCap) systems (e.g., marker-based camera system) [2, 3, 4]. An advantage of such systems is that they achieve good measurement and diagnostic results and are widely accepted [2]. On the other hand, are their limitations in terms of the number of subjects that can be captured concurrently, in terms of the type of movements

System overview

System operation

Angle calculation

Stickman model

Evaluation and results

Conclusion and outlook