Defining the angles’ range in ergonomics assessment using 3D cameras and surface EMG

Abstract

Work-related Musculoskeletal Disorders (WMSDs) are pathologies of great impact in the working population. The main risk factor in the onset of these diseases are the postures adopted and held by the workers or, in other words, the critical joint angles adopted by them during significant time periods. Large exposure periods usually occur in the workplace. The influence of the postures adopted at the workplace has been studied by several authors who have developed different methodologies for the corresponding risk assessment (e.g., OWAS, RULA, REBA, LUBA, PATH, etc.). There is also a European standard, the EN 1005-4:2005 that is applied to the evaluation of working postures and movements in relation to machinery. The main problem while using these methodologies is the difficulty of knowing the specific angle adopted at a given joint. Currently, this is not a problem since some new technology enables accurate position sensing of any body part. Nowadays, 3D cameras can recreate the specific body segment in the three planes of space with high accuracy by using passive markers that are placed in different anatomical references, allowing to obtain the speed, trajectory, and angles variation data. Additionally, through the use of surface electromyography (sEMG) it is also possible to obtain data about different muscle activation patterns. This paper intends to present a comparative analysis of the angles used by major research methodologies in the field of WMSDs. It tries to establish the reference ranges of angles with their corresponding score for a later ergonomics assessment. The idea is to use that reference with new technologies as 3D cameras and surface EMG, in order to accurately assess and score postures adopted in every workplace.