title: Shoulder kinematics and spatial pattern of trapezius electromyographic activity in real and virtual environments.
abstract: The design of an industrial workstation tends to include ergonomic assessment steps based on a digital mock-up and a virtual reality setup. Lack of interaction and system fidelity is often reported as a main issue in such virtual reality applications. This limitation is a crucial issue as thorough ergonomic analysis is required for an investigation of the biomechanics. In the current study, we investigated the biomechanical responses of the shoulder joint in a simulated assembly task for comparison with the biomechanical responses in virtual environments. Sixteen male healthy novice subjects performed the task on three different platforms: real (RE), virtual (VE), and virtual environment with force feedback (VEF) with low and high precision demands. The subjects repeated the task 12 times (i.e., 12 cycles). High density electromyography from the upper trapezius and rotation angles of the shoulder joint were recorded and split into the cycles. The angular trajectories and velocity profiles of the shoulder joint angles over a cycle were computed in 3D. The inter-subject similarity in terms of normalized mutual information on kinematics and electromyography was investigated. Compared with RE the task in VE and VEF was characterized by lower kinematic maxima. The inter-subject similarity in RE compared with intra-subject similarity across the platforms was lower in terms of movement trajectories and greater in terms of trapezius muscle activation. The precision demand resulted in lower inter- and intra-subject similarity across platforms. The proposed approach identifies biomechanical differences in the shoulder joint in both VE and VEF compared with the RE platform, but these differences are less marked in VE mostly due to technical limitations of co-localizing the force feedback system in the VEF platform.
authors.affiliation: Laboratory for Ergonomics and Work-related Disorders, Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7 D-3, 9220, Aalborg East, Denmark.
authors.forename: Afshin
authors.initials: A
authors.lastname: Samani
authors.affiliation: Centre de Recherche des Ecoles de Coëtquidan, Ecoles Militaires de Saint-Cyr Coëtquidan, 56 381, Guer, France; MimeTIC, IRISA/INRIA Centre de Bretagne, Campus de Beaulieu, 35042, Rennes, France.
authors.forename: Charles
authors.initials: C
authors.lastname: Pontonnier
authors.affiliation: MimeTIC, IRISA/INRIA Centre de Bretagne, Campus de Beaulieu, 35042, Rennes, France; ENS Rennes, Campus de Ker Lann, 35170, Bruz, France.
authors.forename: Georges
authors.initials: G
authors.lastname: Dumont
authors.affiliation: Laboratory for Ergonomics and Work-related Disorders, Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7 D-3, 9220, Aalborg East, Denmark.
authors.forename: Pascal
authors.initials: P
authors.lastname: Madeleine
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D004576:Electromyography / Q000379:methods; D004777:Environment; D006804:Ergonomics / Q000379:methods; D006801:Humans; D008297:Male; D012782:Shoulder / Q000502:physiology*; D012785:Shoulder Joint / Q000502:physiology*; D000066908:Simulation Training; D064171:Superficial Back Muscles / Q000502:physiology*; D013647:Task Performance and Analysis; D014584:User-Computer Interface