Biomedical Engineering Reference
In-Depth Information
corresponding bone points in several postures. With the soft
tissue artifacts being specific to both the subject and the task
analyzed, the relative positions between the bone points -
estimated by palpation - with regard to cutaneous markers
must be measured, at least, in the extreme postures of the
movement analyzed [CAP 97]. This approach is efficient, in a
clinical context, to analyze knee movements during walking
[STA 09] or even those of the scapula during elevation of the
arms [BRO 11].
Figure 4.3.
Double-calibration, modified according to [CAP 97]
Finally, a third approach involves using optimization
methods again to correct the trajectories of the cutaneous
markers. Two main types of optimization have been
proposed: segmental and global. Segmental optimizations
aim to independently correct the trajectories of markers
fixed to each body segment. Based on the assumption that
the motion of the whole set of markers is rigid, these
methods only cover the deformation of the cluster of
segmental markers [CHE 95, SOD 93]. Although joint
kinematics has been improved, recent studies [AND 12,
BAR 13a, DE 12, GRI 13] have shown that most of the errors
