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5 IMPLEMENTATION
We finished the complete system architecture
structure involving all the components discussed in
this paper. The first prototype consists of three
Xsens MTw sensors, one gateway platform (a laptop
with an Xsens Awinda base station), one secure
database, one server with Liferay, Matlab and
custom-built portlets. Each data processing
component described earlier has been implemented,
but with a basic setting for processing data from
three MTw sensors. A demonstrational setup of the
sensors is shown in Figure 10.
Three MTw sensors are placed on the upper arm,
lower arm and trunk of the body. For
demonstrational purposes of the system, the
following measurement was performed. One subject
simulated a repetitive reaching motion of a stroke
patient’s non-affected arm for 10 seconds followed
by simulating the motion of the affected arm for 10
seconds. There was a 5 seconds rest period in
between.
During the first 10 seconds, the subject stands up
straight and does not move the trunk while reaching
for an object. During the last 10 seconds, the subject
utilizes the trunk to compensate for the decrease in
elbow flexion and elbow/shoulder coupling
(Dewald, 1995) to reach for an object.
Figure 10: MTw sensor placement.
The home gateway captures the measurement data,
stores the data in an EDF file and uploads the file to
the database if an internet connection is detected. If
an end-user (for example, a clinician) presses the
“analyze” button on the web portal (within a portlet),
the portlet retrieves the data from the database.
Subsequently, the data is processed according to the
data processing flow. In this demo, the
biomechanical model calculates the following:
elbow angle, shoulder abduction, hand-sternum
distance and trunk orientation. The activity
recognition functions detect the two types of
movement (the reaching movements of the non-
affected and affected arm) and the results are
visualized as graphs on the web-portal. The result of
one measurement is shown in Figure 9. During the
use of the affected arm, there is a decrease in elbow
flexion and an increase in trunk flexion while
reaching multiple times for an object.
6 CONCLUSIONS AND FUTURE
WORK
The INTERACTION project aims to develop and
validate an unobtrusive and modular system for
objectively monitoring the daily life activities of
upper and lower extremity motor function in stroke
patients. The system’s complete architecture was
developed according to the requirements identified
at the beginning of the project. The architecture,
including all its components, was validated by using
three Xsens MTw sensors in a short measurement,
during which we simulated a Stroke patient’s
reaching motion of the affected and non-affected
arm. In the first prototype of the architecture system,
we included a biomechanical model in combination
with activity recognition functions to compute
several clinical outcome measures, which are then
shown on a web-portal.
Extension of the architecture to a full on body
sensing system is a feasible task, as all components
are designed for that purpose. The system will be
extended to incorporate the full number of sensors
and each component needs to be updated
accordingly. The gateway software will be
transferred to a Smartphone and the Xsens Awinda
base station will be replaced by an Xsens dongle
connected to this Smartphone. Furthermore, the
portal’s MVC structure has been designed for
extensions and provides a flexible coding
environment for Engineers by the inclusion of a
Matlab-Java bridge.
In this project, we have identified an extensive
list of potential clinical outcome measures. The list
of clinical outcome measures given in this paper is
an example of what the INTERACTION system will
deliver. We are now in the process, together with
clinicians and engineers, to make a final selection of
the clinical outcome measures to be implemented by
the system. Finally, both the sensing system and
web-portal have to be evaluated before starting
clinical trials.
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