Article

Despite the widespread use of Magnetic and Inertial Measurement Units (MIMUs) for
movement reconstruction, only a few studies have tackled issues related to their
accuracy. It has been proved that their performance decreases over a period of
use since calibration parameters become no longer effective. Good practice rules
recommend to assess, prior to any experimental session, the instrumental errors
associated to the relevant measures. Aim of this study was to provide a practical
and reproducible spot check for assessing the performance of MIMUs in terms of
consistency in determining their orientation with respect to a common
(inter-MIMUs consistency, IC) and invariant (self-MIMU consistency, SC) global
frame. IC was assessed by verifying the hypothesis that the orientation of 9
MIMUs aligned to each other on a rigid Plexiglas plank coincided at any
orientation of the plank. SC was assessed separately by verifying differences
between measured and imposed known rotations imparted to each MIMU. The
orientation of MIMUs relative to the global frame was expressed in terms of
quaternion. IC test showed that MIMUs defined their orientation differently. This
difference was not constant but varied according to the plank's orientation. The
least consistent MIMU showed discrepancy up to 5.7 degrees . SC test confirmed
the same MIMU as that affected by the highest inaccuracy (8.4 degrees ), whereas
it revealed errors within limits (1 degrees ) in correspondence to other MIMUs. A
tool has been proposed that allows the users to be aware of the errors that may
be expected when using MIMUs for the estimate of absolute and relative segments
kinematics.
CI - Copyright (c) 2010 Elsevier B.V. All rights reserved.

Langue : ANGLAIS