title: Main component of soft tissue artifact of the upper-limbs with respect to different functional, daily life and sports movements.
abstract: Soft tissue artifact (STA) is the main source of error in kinematic estimation of human movements based on skin markers. Our objective was to determine the components of marker displacements that best describe STA of the shoulder and arm (i.e. clavicle, scapula and humerus). Four participants performed arm flexion and rotation, a daily-life and a sports movement. Three pins with reflective markers were inserted into the clavicle, scapula and humerus. In addition, up to seven skin markers were stuck on each segment. STA was described with a modal approach: individual marker displacements or marker-cluster (i.e. translations, rotations, homotheties and stretches) relative to the local segment coordinate system defined by markers secured to the pins. The modes were then ranked according to the percentage of total STA energy that they explained. Both individual skin marker displacements and marker-cluster geometrical transformations were task-, location-, segment- and subject-specific. However, 85% of the total STA energy was systematically explained by the rigid transformations (i.e. translations and rotations of the marker-cluster). In conclusion, large joint dislocations and limited efficiency of least squares bone pose estimators are expected for the computation of upper limb joint kinematics from skin markers. Future developments shall consider the rigid transformations of marker-clusters in the implementation of an STA model to reduce its effects on kinematics estimation.
authors: Université de Lyon, université Lyon 1, Laboratoire Interuniversitaire de Biologie de la motricité, Villeurbanne, France; Laboratoire de Simulation et Modélisation du Mouvement, Département de Kinésiologie, Université de Montréal, Montréal, QC, Canada. Electronic address: yoann.blache@univ-lyon1.fr.
authors: Y
authors: Y
authors: Blache
authors: IFSTTAR, LBMC, UMR_T9406, Bron, France; Université Lyon 1, Villeurbanne, France; Université de Lyon, Lyon, France.
authors: R
authors: R
authors: Dumas
authors: Karolinska Institute, Stockholm, Sweden.
authors: A
authors: A
authors: Lundberg
authors: Laboratoire de Simulation et Modélisation du Mouvement, Département de Kinésiologie, Université de Montréal, Montréal, QC, Canada; Centre de Recherche du Centre Hospitalier Universitaire Sainte-Justine, Montréal, QC, Canada.
authors: M
authors: M
authors: Begon
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D001132:Arm / Q000502:physiology*; D016477:Artifacts; D001696:Biomechanical Phenomena; D002968:Clavicle / Q000502:physiology; D006801:Humans; D006811:Humerus / Q000502:physiology; D016018:Least-Squares Analysis; D008297:Male; D009068:Movement / Q000502:physiology*; D012399:Rotation; D012540:Scapula / Q000502:physiology; D012782:Shoulder / Q000502:physiology*; D013177:Sports / Q000502:physiology
keywords: Cluster deformation; Deformation energy; Geometrical transformation; Shoulder complex; Skin marker