In studies of human movement, inertial sensors
(accelerometers and gyroscopes) are gaining attention as a
promising alternative to laboratory-constrained video capture
systems. Kinematics of various body parts and joints can be
quantified by attaching inertial sensors at points of interest and
integrating the observed acceleration and angular velocity signals.
It is broadly accepted that this measurement procedure is significantly
influenced by cumulative errors arising from sensor noise,
non-linearities, asymmetries, sensitivity variations and bias drifts.
In addition, it is also known that linear acceleration superimposed
to the gravity acceleration introduces errors when calculating tilt
angles. Recently, newer techniques using sensor fusion methods
have shown error reduction in orientation measurements, but
require additional hardware and consume more energy.
In this paper, we assess the accuracy of a low-power wireless
inertial system (ViMove) that measures Low Back (lumbar spine)
orientation in three dimensions. The system consists of two
inertial units (sensor), with each sensor containing one tri-axis
accelerometer and one single-axis gyroscope. We investigate the
accuracy of 1D, 2D and 3D simultaneous movements by means of
root mean square error (RMSE) computed in comparison with
NDI Optotrak, an optical tracking system.