Assessment of task ergonomics with an upper limb wearable device

Upper Limb Work-related Musculo Skeletal Disorders (ULWMSD) are constantly increasing every year in developed countries. It is estimated that in Italy, in 2007 ULWMSD were the 41,6% of all the work-related pathologies. In this context, the importance to correctly diagnose and treat this kind of pathology is growing. Traditionally the assessment is done using pen-and-paper observational techniques in which movements are manually classified, labelled and compared integrating the results with subjective questionnaires given to the monitored subjects. The main problem with those traditional methods is the lack of objective assessment regarding the motion and the forces exerted, which are inferred by subjects inquiry and the body posture, manually extracted from video tapes. In this context we propose a novel wired system for assessing the muscular effort and posture of the human upper limb for ULWMSDs diagnosis in ecologic environment. The system is composed of inertial units to reconstruct the upper limb posture and EMG sensors to assess the muscle effort. The upper limb is considered as a kinematic chain comprising three degrees of freedom (DoFs) for the shoulder, two DoFs for the elbow and two DoFs for the wrist, while forearm flexor muscles are monitored through EMG. We propose a preliminary validation of the system testing it for assessing posture and muscle effort of a check-out operator during everyday real-life operations.