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Instrumented Ergonomic Risk Assessment Using Wearable Technology and Marker-less Optical Sensor
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- Author / Creator
- Humadi, Ahmed
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Work-related musculoskeletal disorders (WMDs) are reported as the primary category of non-fatal work-related diseases in the industrial environment that affect joints, ligaments, tendons, and muscles. The contributing factors to the WMDs could be awkward postures adopted by workers, forceful exertions, repetitive motions, vibration, and psychological and environmental factors. Various assessment methods based on the kinematics and kinetics of the body were proposed for preventing WMDs. Self-report methods, including questionnaires, checklist, and interviews, are used for this purpose, based on a subjective report of the individuals about their behavior, symptoms, and attitude. Although the self-report methods have low cost and cover a wide range of samples, personal reporting has drawbacks originating from the individuals’ inaccurate perception of the WMDs factors exposure. Additionally, self-report methods could have low validity and reliability compared to other methods. At the same time, the observational methods were proposed for evaluating and reducing the WMDs factors. The previous studies showed that inter-observer reliability is the major shortcoming of these methods. Besides, accurate and reliable advanced observational methods such as marker-based systems are challenging to use in real workplaces. Therefore, a reliable system based on marker-less motion trackers or wearable technologies combined with an observational method is required for evaluating postures and movements, causing WMDs and overcome the shortcomings mentioned above.
The objective of this thesis is to investigate the accuracy and reliability of using a marker-less motion tracker and a wearable technology against a gold-standard marker-based system combined with an observational ergonomic method for different manual material handling tasks.
To this end, eleven able-bodied individuals participated in two manual material handling tasks while their motion was recorded by a marker-based system (reference), marker-less motion tracker (Microsoft Kinect), and a system of inertial measurement units (IMUs). Then, joint angles were calculated and inserted into an observational risk assessment tool: Rapid Upper Limb Assessment (RULA). The calculated joint angles and the associated RULA scores obtained by the marker-less motion and IMU-based systems were compared against a marker-based system (reference) using the proportion agreement index (Po), Cohen’s Kappa coefficient (κ) for RULA scores, and root mean square error (RMSE) for joint angles. Also, the intra-class correlation coefficient (ICC) was used to assess inter-participant reliability for each system. The IMU-based system showed “moderate” to a “substantial” agreement with the marker-based system in most of the tested manual handling tasks with the median of κ > 0.6, according to Landis and Koch scale. Also, it showed an “excellent” agreement in the RULA scores median between participants for most of the manual handling tested tasks (ICC > 0.75). While the reference marker-based system showed an “excellent” agreement for all manual handling tested tasks (ICC > 0.75) in the RULA scores median between participants, according to Cicchetti guidelines for interpretation of ICC.
On the other hand, the marker-less system showed “fair” to a “moderate” agreement with the median of κ < 0.4 and κ > 0.41 with the maker-based system over the same scale, affected by both self-occlusion and object occlusion. In addition, the ICC showed “fair” to an excellent agreement in the RULA scores median, between participants for the tested manual handling tasks (ICC < 0.59) and (ICC > 0.75), according to the same guidelines for interpretation of ICC. -
- Graduation date
- Fall 2020
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.