A Low Cost Motion Analysis System Based on RGB Cameras to Support Ergonomic Risk Assessment in Real Workplaces

Abstract

This paper introduces a motion analysis system based on a network of common RGB cameras, which provides the measurement of various angles considered for postural assessment, in order to facilitate the evaluation of the ergonomic indices commonly used for the determination of risk of musculoskeletal disorders of operators in manufacturing workplaces. To enable the tracking of operator postures during the performed tasks, the system exploits the multi person keypoints detection library “OpenPose”. The proposed system has been validated with a real industrial case study regarding a washing machine assembly line. Results suggest how the proposed system supports ergonomists in risk assessment of musculoskeletal disorders through the OCRA index.

Preliminary Validation of a Low-Cost Motion Analysis System Based on RGB Cameras to Support the Evaluation of Postural Risk Assessment

“…The motion analysis system based on RGB cameras (RGB-motion analysis system, RGB-MAS), here proposed, is conceptually based on that described in [18] and improves its features and functionalities as follows:…”

“…Several tools are available to automate the postural analysis process by calculating various risk indices, to make ergonomic assessment more efficient. They are currently embedded in the most widely used computer-aided design (CAD) packages (e.g., CATIA-DELMIA by Dassault Systèmes, Pro/ENGINEER by PTC Manikin or Tecnomatix/Jack by Siemens) and allow detailed human modeling based on digital human manikins, according to an analytical ergonomic perspective [18]. However, to perform realistic and reliable simulations, they require accurate information related to the kinematic of the worker's body (posture) [19].…”

“…It is an open-source software, based on Convolutional Neural Network (CNN) found in the OpenCV library [44] initially written in C++ and Caffe, and freely available for non-commercial use. Such a system does not seem to be significantly affected by occlusion problems, as it ensures body tracking even when several body joints and segments are temporarily occluded, so that only a portion of the body is framed in the video [18]. Several studies validated its accuracy by comparing one person's skeleton tracking results with those obtained from a Vicon system.…”

“…Many studies exploited OpenPose for several research purposes, including Ergonomics. In particular, several studies carried out both in a laboratory and in real life manufacturing environments, suggest that OpenPose is a helpful tool to support worker posture ergonomics assessment based on RULA, REBA, and OCRA [18,[46][47][48][49].…”

Creation of a UX index to design human tasks and workstations

“…Postural data can be extracted and analysed manually by experts or automatically, using a motion analysis system (e.g. (Altieri et al 2020)). Moreover, users are asked to fill in pre-questionnaires focusing on users' demographic data (i.e.…”