Instrumentation & Measurement Magazine 23-4 - 38

◗◗ An App for the caregiver, who can access data on the
platform and receive notifications and alarms. Alarm
notifications sent to caregivers through text messages
(SMS) are also foreseen in the case of Wi-Fi connection
faults or electric grid blackouts.
In the following, a focus on the Fall Detector and the RFID
based User-Environment Interaction solutions is provided.

Fall Detector
To cope with the need to automatically detect falls in a fast and
reliable way, a solution already developed by the researchers
of the University of Catania has been adopted. The wearable
inertial device exploits a tri-axial accelerometer and dedicated
smart signal processing to detect and classify falls with respect
to other events of the daily activities. The classification methodology developed is based on the consideration that ADLs
are characterized by typical signatures in the acceleration magnitude evolution in time [11]. The classification algorithm
compares each new detected event with the signatures looking
for particular features. In particular, the approach developed
searches for the maximum value of the cross-correlations between the unknown event and the set of signatures identifying
the candidate class of events. A threshold-based methodology
is then used for the sake of classification. The performances
of the classification algorithm have been assessed by a set of
dedicated experiments. An average sensitivity of 87% and
an average specificity of 98% have been observed during the
classification task for fall events with respect to other daily
activities like sitting and going up and down the stairs [11].
When a fall event is detected, an alarm is then sent to the local server through Wi-Fi. A picture of the developed device is
shown in Fig. 3.

RFID System for User Activity Tracking
In order to gain information about environmental exploitation
and the user-environment interaction, Radio-Frequency Identification (RFID) based methodology has been implemented
[14]. In particular, the user is required to wear an RF tag reader
on his belt, as shown in Fig. 4a. The user module exploits the
compact high-performance UHF RFID M6E-MICRO module
by ThingMagic and a small (2.5 cm x 2.5 cm) ceramic antenna
to read small passive flexible RFID tags. The reader transmits
the detected tag IDentifier (ID) to a dedicated App running on
the smartphone through the Bluetooth communication protocol, which is then conveyed to the local server using the Wi-Fi
communication protocol.
Passive RFID tags have been placed on domestic appliances (refrigerator, cooking plate, coffee machine) and
furnishings (like the cupboard) and other specific objects like
food containers to gain different kinds of information such as
user habits or user-environment interaction, with the aim of
tracking the user's lifestyle and eventually detect deviations
which could be indicative of discomfort, uneasiness, or the deterioration of the quality of life of the user.
An analysis of the performance of the reader in terms of sensitivity and specificity while changing the reader distance and
38

Fig. 5. The user wearing the reader while opening the door of the cupboard
and the App interface with the indication provided.

the distance between tags has been presented in [14]. Obtained
results have permitted designers to optimize the size and power
consumption of the reader, as well as the inter-tag distance.
Another set of RFID tags has been positioned on door jambs
to monitor how much the user explores the environment as
well as the user mobility rate inside the house (Fig. 4b).
Additional examples of passive tags placed on different
objects in the PDS are shown in Fig. 4c-Fig. 4f. Finally, Fig. 5
shows the user wearing the reader while opening the door of
the cupboard as well as the App showing the identified action.

Conclusions
As it emerges from both the literature in the field of assistive
technology and considerations carried out through this paper, a lot of work has been dedicated to the development of
assistive solutions for AAL. However, many efforts are still
required to "bring assistive technology to end-users," by reducing costs, increasing reliability and ease-of-use. One of the
current trends is to re-consider the home environment, making it more suitable for frail people, by moving from Standard
Domotics to Assistive Domotics. In this sense, houses must be
rethought in order to fit the needs of weak users, assuring the
right comfort and promoting accessibility. This fosters the new

IEEE Instrumentation & Measurement Magazine

June 2020

Instrumentation & Measurement Magazine 23-4

Table of Contents for the Digital Edition of Instrumentation & Measurement Magazine 23-4