concrete applications/services as well as to different
business models (Foster et al., 2008).
Virtual environments based on scalable service
models appear at the moment as a high competitive
solution that, under the assumption of always con-
nected devices and relatively high bandwidth, could
be the most realistic and effective approach in order
to enable complex services on mobile devices.
In this paper, an architecture aimed to provide a
mobile solution to the distribution of services needed
by assistive technologies based on the Cloud Comput-
ing paradigm is presented.
The paper is structured in three main parts: first
an overview at the most relevant aspects of assistive
technologies, than a brief analysis of main advantages
of cloud technologies and finally a ”big picture” of the
proposed infrastructure are proposed.
2 ASSISTIVE TECHNOLOGIES
ICTs are commonly used to empower impaired peo-
ple in their daily life. In this way, the concept of as-
sistive technologies is defined (S et al., 2009). As-
sistive technologies are solutions to provide disabled
people with assistive, adaptive and rehabilitative de-
vices. These framework promotes the independence
by enabling people to perform common tasks that are
not able to perform by themselves of had a great dif-
ficulty to accomplish them.
To achievethis, Assistive Technologies, must, first
of all, be able to gather all the information available
about the user that will be the projection of the user
on the system. This is the concept of context (Preuve-
neers, 2010). In this framework, context can be de-
fined as any information that can be used to explain
the situation that is relevant to the interaction between
the users and the application. In this approach, the
key is to automatically determine whether observed
behavioral cues share a common cause - for exam-
ple, whether the mouth movements and audio signals
complement to indicate an active known or unknown
speaker (how, who, where) and whether his or her fo-
cus of attention is another person or a computer (what,
why).
The Context data can be gathered not only from
the user directly but also from the ambient. Existing
localization techniques will be combined (fused) with
information coming from the vision sensors in order
to track a person inside an apartment or any other
equipped enviroment. A person in the line of sight
of a vision sensor is located with great precision: one
knows in which room he/she is, even in which part
of the room, given the angle of the camera. A Wire-
less Sensor Network localization algorithm can use
this information as a starting point for tracking some-
one in places out of the sight of any vision sensor.
When the subject enters the field of sight of a visual
device again, the information is dispatched and used
to correct an eventual error of the radio-based local-
ization algorithm. This scheme will follow a mobile
device-centred approach.
An assistive application must not only gather
the information of the context but also be aware of
them and react to specific situations. This is the
mission of Context-Awareness systems (Preuveneers,
2010). Context-awareness is a very important aspect
of the emerging pervasive and autonomic computing
paradigm. The efficient management of contextual
information requires detailed and thorough modeling
along with specific processing and inference capabil-
ities. Mobile nodes that know more about the user
context are able to function efficiently and transpar-
ently adapt to the current user situation. Data fu-
sion combines the information originating from dif-
ferent sources. It is one of the primary elements of
modern tracking techniques. Its objective is to maxi-
mize the useful informationand make it more reliable,
obtain more efficient data and information represen-
tation, and detect higher-order relationships between
different data types.
Interactive and affective behavior may involve and
modulate all human communicativesignals: facial ex-
pression, speech, vocal intonation, body posture and
gestures, hand gesticulation, non-linguistic vocal out-
bursts, such as laughter and sighs, and physiological
reactions, like heartbeat and clamminess. Sensing and
analysis of all these modalities have improved signif-
icantly in the recent years. Vision-based technologies
for facial features, head, hand and body tracking have
advanced significantly with sequential state estima-
tion approaches, as for example Kalman (Chui and
Chen, 1987) and particle filtering, which reduced the
sensitivity of the detection and tracking schemes to
occlusion, clutter, and changes in illumination.
Recent advent of non-intrusive sensors and wear-
able computers, which promise less invasive physi-
ological sensing, opened up possibilities for includ-
ing tactile modality into automatic analyzers of hu-
man behavior. However, virtually all technologies for
sensing and analysis of different human communica-
tive modalities and for detection and tracking of hu-
man behavioral cues have been trained and tested us-
ing audio and/or video recordingsof posed, controlled
displays. Hence, these technologies, like the ones de-
veloped in FP6 AMI and CHIL projects (explained
below), are, in principle, inapplicable for sensing,
tracking, and analysis of human behavioural cues oc-
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