A Wearable and Modular Inertial Unit for Measuring Limb Movements and Balance Control Abilities

Measuring human movement has many useful
applications ranging from fall risk assessment, quantifying sports
exercise, studying people habits, and monitoring the elderly. Here,
we present a versatile, wearable device based on a 9-degrees-of-
freedom inertial measurement unit conceived for providing objec-
tive measurements of trunk or limb movements for the assessment
of motor and balance control abilities. The proposed device
measures linear accelerations, angular velocities, and heading
and can be configured to either wirelessly transmit the raw or
preprocessed data to a computer for online use, e.g., visualization
or further processing, or to store the acquired data locally for
long-term monitoring during free movement. Furthermore, the
device can work in either single sensor or multiple sensors
configuration, to simultaneously record several body parts for
monitoring full body kinematics. Here, we compare body sway
and trunk kinematic data computed based on our sensor with
those based on the data from a force platform and a marker-
based motion tracker, respectively, during the evaluation of both
static and dynamic exercises drawn from clinical balance scales.
Results from these experiments on two populations of healthy
subjects are encouraging and suggest that the proposed device
can effectively be used for measuring limb movements and to
assess balance control abilities.