title: A markerless estimation of the ankle-foot complex 2D kinematics during stance.
abstract: A markerless technique is proposed and applied to estimate the two-dimensional joint kinematics of the shank and foot complex during the stance phase. Image sequences were acquired with a single camera from three healthy subjects while walking barefoot and with socks. Automatic segmentation of the shank and foot was performed to isolate the moving body from the background. A multi-rigid body model for the shank and foot complex, with the relevant segment anatomical axes, was defined and an image cross-correlation technique was applied to detect the anatomical axes locations throughout the movement. The proposed markerless technique was validated by acquiring the same trials also with a stereophotogrammetric marker-based system and a simple marker set. Differences in the joint kinematics estimates obtained with the two techniques fall in most cases within the intra-subject variability showing that, in selected applications, the markerless technique may replace more expensive and more experimental time demanding marker-based techniques.
authors.affiliation: Biomedical Sciences Department, University of Sassari, Sassari, Italy. esurer@uniss.it
authors.forename: Elif
authors.initials: E
authors.lastname: Surer
authors.forename: Andrea
authors.initials: A
authors.lastname: Cereatti
authors.forename: Enrico
authors.initials: E
authors.lastname: Grosso
authors.forename: Ugo
authors.initials: U
authors.lastname: Della Croce
mesh_terms: D000328:Adult; D000843:Ankle Joint / Q000502:physiology*; D001696:Biomechanical Phenomena; D005260:Female; D005528:Foot / Q000502:physiology*; D006801:Humans; D008297:Male; D008954:Models, Biological; D010780:Photogrammetry; D014741:Video Recording; D016138:Walking / Q000502:physiology*