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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Improving Work Life Conditions via Portable Knowledge-Driven Recommender System</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>(Discussion Paper)</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Maurizio Atzori</string-name>
          <email>atzori@unica.it</email>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Alessandro Barenghi</string-name>
          <email>alessandro.barenghi@polimi.it</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Sara Comai</string-name>
          <email>sara.comai@polimi.it</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Mariagrazia Fugini</string-name>
          <email>mariagrazia.fugini@polimi.it</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Diego Marcia</string-name>
          <email>diego.marcia@unica.it</email>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Gerardo Pelosi</string-name>
          <email>gerardo.pelosi@polimi.it</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Manuela Sanguinetti</string-name>
          <email>manuela.sanguinetti@unica.it</email>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Vincenzo Scotti</string-name>
          <email>vincenzo.scotti@polimi.it</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Dipartimento di Elettronica Informazione e Bioingegneria (DEIB), Politecnico di Milano</institution>
          ,
          <addr-line>Via Ponzio 34/5 - Via Golgi 42, 20133, Milano (MI)</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>WorkingAge is a EU H2020 Project (lasting 2019-2022) aiming at promoting healthy habits in working environments to improve quality of life of workers. IoT sensors are used to detect environmental and workers conditions. Raw sensors data are then transformed into interventions in the form of reminders or recommendations communicated to the user through a mobile application. This paper describes the main issues of data management in the project: the knowledge-based DSS that has been developed to infer the recommendations for the users, which is based on a set of probabilistic rules and takes into account users' preferences to promote users' well being, and the design choices to guarantee data security and privacy.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;Recommender System</kwd>
        <kwd>Probabilistic Prolog</kwd>
        <kwd>Privacy</kwd>
        <kwd>Security</kwd>
        <kwd>Risk Management</kwd>
        <kwd>Quality of Life</kwd>
        <kwd>Decision Support System</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>This paper presents the overall approach and mid-term results of the WorkingAge (WA - Smart
Working environments for all Ages) Project, which focuses on the use of innovative Human
Computer Interaction methods, like augmented reality, virtual reality, gesture/voice recognition
and gaze tracking. The purpose is to measure the user’s health state at workplaces and provide
recommendations about possible corrections of damaging or harmful states. The large scale
introduction of social and technological innovation, such as e-health, mobile health, integrated
care or independent living, can improve the eficiency of health and well being systems. Remote
monitoring healthcare models, in particular those that include users actively in the design of</p>
      <sec id="sec-1-1">
        <title>Sensors data collection</title>
      </sec>
      <sec id="sec-1-2">
        <title>Sensors data processing</title>
      </sec>
      <sec id="sec-1-3">
        <title>Monitoring at work</title>
      </sec>
      <sec id="sec-1-4">
        <title>Edge computing units</title>
      </sec>
      <sec id="sec-1-5">
        <title>Raw data</title>
      </sec>
      <sec id="sec-1-6">
        <title>Raw data</title>
      </sec>
      <sec id="sec-1-7">
        <title>Processed data User Interface</title>
      </sec>
      <sec id="sec-1-8">
        <title>WAOW App</title>
        <p>with health
reccomendations
WORKINGAGE</p>
        <p>Mood
Incontrasttoyourindividual
assessment,thesensordata
detectedamediumstresslevel.Pay
atentiontoperceiveyourindividual
condition,concentrateonyour
individualsignsthathelpyouto
assessyourpersonalcondition
corectly
Gotit Seelater Omit</p>
      </sec>
      <sec id="sec-1-9">
        <title>Monitoring at home</title>
        <p>
          health care systems, have shown clear benefits [
          <xref ref-type="bibr" rid="ref1">1</xref>
          ] and are included in recent EU actions [
          <xref ref-type="bibr" rid="ref2">2</xref>
          ].
We rely on the general concepts of the WA approach presented in [
          <xref ref-type="bibr" rid="ref3 ref4">3, 4</xref>
          ]. In particular, these
papers describe the portion of the WA Tool that implements a Decision Support System (DSS)
developed in the project, and discuss privacy and security aspects. The WA Project aims at
creating a sustainable and scalable product that will empower users’ comfort by easing work
conditions and life, attenuating the impact of aging on their autonomy, health and well-being.
A key point is the adaptivity of the WA tool to the user profile. Active user engagement is a
focus, in order to ensure the match against user needs, safeguarding ethics, privacy, security
and regulatory aspects of work premises. In the proposed DSS, recommendations take into
account the efectiveness of previous advice on the monitored risks and the acceptance of the
user of the given advice. A big issue in creating such a tool is privacy, since personal data are
collected by several devices and elaborated to analyze the users features, observe wrong habits
and give suggestions to improve wellness. We will show how privacy and security have been
tackled in the project to face these issues.
        </p>
        <p>The paper is organized as follows: Section 2 describes the issues related to data privacy and
security that impacted the WA architecture. Section 3 describes the DSS we developed to infer
recommendations for the users. Finally, Section 4 concludes the paper and outlines future work.</p>
      </sec>
    </sec>
    <sec id="sec-2">
      <title>2. Data Privacy and Security</title>
      <p>The success of the WA approach requires to collect a significant amount of personal information
from diferent sensors both at work (through cameras, microphones, environmental sensors,
etc.) and possibly also at home (through a smart band and a body scale), to provide a fitting set
of suggestions to the WA tool user, as outlined in Fig.1. For example, if the camera detects a
wrong posture, the worker receives an alert to change his/her position or a tip about a suggested
physical exercise. In designing the solution in WA, we built on the considerable computing</p>
      <sec id="sec-2-1">
        <title>Teleworker WA network</title>
        <p>WAOW user
smartphone
Wifi
Router
WAOW user
smartphone
WAOW user
smartphone
Wifi
Router</p>
      </sec>
      <sec id="sec-2-2">
        <title>WA partner</title>
        <p>Remote
maintenance
endpoint</p>
        <p>WA VPN
Bastion Host
Wifi
Router
Wifi
Router</p>
      </sec>
      <sec id="sec-2-3">
        <title>WA Edge Cloud network</title>
      </sec>
      <sec id="sec-2-4">
        <title>BrainSigns private cloud backup</title>
        <p>Encrypted
Backup
Server</p>
        <p>WA</p>
        <p>Sensor</p>
        <p>WA Edge
cloud servers
Secure network perimeter</p>
        <p>Encrypted and authenticated VPNs
power available in modern mobile devices to shift the phase of data aggregation and user
profiling entirely on a device which is owned by the user herself. This approach was guided
by the provisions of the EU Regulation 2016/679, General Data Protection Regulation (GDPR),
which states two fundamental principles: i) minimality of data retention and ii) security by
design. Following the minimality of data retention approach led us to design a system where
the raw data collected from the sensors, such as audio/video recordings, are processed as soon
as possible by a set of dedicated machines on premise (i.e., the edge computing units in Figure
1). This early processing stage allows us to extract the relevant features from the collected
data and prevent the long term storage of raw sensor datasets. Only data from the smart band
and body scale that do not need preprocessing are directly sent to the mobile device. Instead,
the dedicated set of processing machines supplies the DSS of the WA tool with small and
highly informative pieces of data, allowing the decision support agent to be run on the mobile
phone of the user. The security by design principle was embodied in the WA network and data
processing infrastructure design mapping the legal basis for data treatment provided by the
user consent onto cryptographically enforced access control. The first step in this sense is to
provide a network infrastructure where data confidentiality is provided with respect to external
adversaries. Figure 2 illustrates the WA network structure, highlighting its secure perimeter.
We chose to employ well-established secure network standards for the WA edge cloud network,
located on premise at the firms which host our test experiments. The network is formed by
an IEEE 802.11n Wi-Fi network, employing the WPA2 key agreement and data encryption
standard to provide the desired security guarantees. Extending the network to of-site locations
to allow WA users to work from home, a highly desirable feature in an evolving work scenario,
was performed by means of VPN tunnels relying on the standard Transport Layer Security
(TLS) v1.3 secure transport protocol. The edge cloud network is thus extended via a remote
VPN endpoint embedded in the WiFi router providing the teleworker WA network. The VPN
endpoint connects to the WA VPN bastion host present in the WA edge cloud network placed
in the hosting firm premises, allowing the sensing equipment present in the teleworker WA
network to securely send the recorded data to the WA edge cloud servers. Finally the WA
edge cloud network perimeter is extended, by means of VPN links, also to the WA partner
workstations, which may be in need of performing maintenance on the WA edge cloud servers,
and to a remote encrypted backup server, maintained by the partner BrainSigns. The latter
provides of-site backups of encrypted data bundles, sent to it by both the edge cloud servers
and the user smartphones. Having ensured data confidentiality and endpoint authentication
for the entities connected to the WA edge cloud network, we complete the enforcement of the
access control to the data by means of the standard OpenPGP hybrid encryption, combined
with an appropriate certificate management. Each edge cloud server and each smartphone
are endowed with a dedicated OpenPGP certificate, containing an RSA keypair and a textual
identity. While the textual identity of the edge cloud servers is their common name, the identity
of the smartphones is a Universally Unique IDentifier (UUID) version 4, i.e., a 128-bit wide
random unique identifier. The WA sensors communicate with the WA edge cloud server which
is in charge of performing the data processing to extract high level features either by means of a
dedicated TLS connection, if a continuous data stream is required, or send asynchronously data
bundles encrypting them with the public key corresponding to the server certificate. The WA
edge cloud server in turn will send the processed data to the WA user smartphone encrypting
them with the public key contained in the OpenPGP certificate bound to it. This approach
efectively ensures that the consent provided by the user, which allows each specific partner to
process a subset of the collected data is mapped onto the technically enforced impossibility of
accessing data for which the private key required to decrypt them is not available. In addition, it
is possible to provide fault resilience in terms of an of-site encrypted backup simply by storing
the encrypted messages exchanged within the WA edge cloud network, with no further action.
Indeed, only the entity in possession of the appropriate private key will be able to decrypt the
backed-up data bundle. The WA smartphones also profit from the availability of the remote
backup facility, storing on it a full backup of the DSS-derived user profile, encrypted with their
own public key, and copy of the private key symmetrically encrypted under an emergency
password derived key. This strategy allows the user, in case of theft or loss of the smartphone
itself, to securely retrieve the backup simply providing the emergency password to a new
smartphone where the WA app has been installed.</p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3. Decision Support System</title>
      <p>The architecture of the system described in the previous section requires to adopt a hybrid
data-driven/expert-driven approach to process the sensors data: for each type of sensor, raw
data are processed with data-driven approaches based on Natural Language Processing (NLP),
stochastic models, or Machine Learning (ML) to generate high-level information to be sent to
the smartphone application. For example, from the video recording the posture is estimated
Data-driven approach</p>
      <p>Expert-driven approach
High-level
information
Classifier</p>
      <p>Trained
model</p>
      <p>Advice
DSS</p>
      <p>Worker
Rule
updater Feedback</p>
      <p>
        Ontology Facts Rules
Sensors
and a low/medium/high risk is computed. On the smartphone, a Decision Support System
processes the high-level information to generate recommendations for the final users, based
on an expert-driven approach. Figure 2 depicts the data processing flow. For coping with this
“mismatch” between the data-driven classifiers and the model-driven DSS, we chose to adopt
the ProbLog language [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ], a probabilistic reasoning engine that allows not only inference of
certainly-true facts (according to the usual declarative models), but also derives the level of
confidence for the specific inferred fact.
3.1. Ontology
To determine the recommendation for the user, the DSS analyses the high-level information
received from the sensors and described according to an Ontology, including eight main entities:
Worker is the core of the ontology, due to our user-centered design;
Profile holds the personal information about the worker (e.g., age, gender, etc.);
Task describes the job performed by the user (e.g., manager, clerk, etc.);
Sensor describes the High-level information collected about the worker (e.g., the sitting body
posture risk can be low, medium or high; the facial expression can be positive, neutral or
negative, etc.);
Smart Goal and Goal State represent what the WA tool suggests (e.g., a physical activity)
and its degree of completion (goal reached or not);
Advice is the suggestion or feedback that provided to the worker (e.g., "Change pose" or "The
current heartbeat is 150");
Feedback represents the attitude of the worker towards a piece of advice (e.g., the user accepts
or rejects the advice).
      </p>
      <p>
        Even though the user is the core of the Ontology, the DSS strongly depends on data coming
from the sensors, classified into:
Body Sensors include wearable bio-metric devices (to gather ECG and GSR), cameras (to
gather body postures, facial expressions and eye movements) and microphones (to collect
voice recordings);
Environmental Sensors gather data about temperature, humidity, CO2 concentration, noise
level etc.;
Other Sensors include questionnaires that are periodically administered to understand
workers current state.
3.2. Reasoning engine
The DSS developed for this project belongs to the class of knowledge-based DSSes [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ] and has
been implemented through an expert-driven approach. An expert defined a priori the rules we
encoded in our engine. In our use case, the rules describe the intervention strategy, which is the
set of recommendations to give to the workers. The whole DSS is based on stochastic-aware
Rules and Facts. We employed fact  to state something about the worker or environment
and we associated  with a truthfulness probability  (we see such probability value as a
reliability index of  ). In the same way, we associated rule ℛ with a reliability index ℛ.
We used a probabilistic representation to handle the uncertainty about the modelled system
(including users and environment). The edge server computes the High-level information
through probabilistic models and associates the predicted values with probabilities. To model
this uncertainty within the DSS, we employed ProbLog [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ]. ProbLog is a variant of ProLog, a
declarative language and an inference engine, augmented with probabilistic descriptive and
inference capabilities.
      </p>
      <p>Hereafter we reported an example of code written with ProbLog.
1 1.0::time(morning).
2 0.7::state(user,stressed).
3
4 0.9::candidate_suggestion(take_a_short_pause)
5 :- time(morning), state(user, stressed).
(1)
(2)</p>
      <p>Listing 1: Rules and advice example.</p>
      <p>Lines 1 and 2 contains two facts: the former states the it is morning with a 100% reliability
(certainty), the latter states that the user is stressed with a 70% of confidence. Lines 4 and 5
represent a rule: it suggests to take_a_short_pause with a 90% of reliability. The probability
of displaying advice  is given by:
 = ℛ ·
∏︁  .
∈ℛ
while, for instance, the probability to show the advice take_a_short_pause is:
 = ℛ · time(morning) · state(user,stressed) = 0.9 · 1 · 0.7 = 0.63 .</p>
      <p>
        ProbLog is available as a Python package; as such, it can not run directly in an Android
environment. To cope with this issue we adopted Chaquopy1, a Python interpreter for Android,
and we developed a wrapper around the whole DSS, to ofer the main functionalities through
Java. In this way the WA App that represents the user interface can easily interact with the DSS.
3.3. Rule adaptation
For the scope of this project, we have defined two rule adaptation strategies, to adapt the
probabilities of the recommendations on the basis of user preferences and system efectiveness.
The former adaptation is referred to as short-term, the latter as long-term adaptation. For both
long- and short-term rules adaptation, we relied on a simple, yet efective technique: the
Exponentially Weighted Moving Average (EWMA) [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ]. We set the initial probability of a rule ℛ
to a value of 1 at time  = 0; then, at a given time step  ≥ 1, the chosen adaptation strategy
updates the rule probability (reliability in this case), with the EWMA strategy. Short-term
adaptation is achieved through user feedback on the recommendations (e.g., the user is (not)
going to apply the suggested advice). We paired each ℛ with a feedback log fℛ ∈ 1. This
feedback log is a sequence of Boolean values representing whether the -th time ℛ was triggered
(with  ∈ [1, ] ∈ N) the user accepted (fℛ, = 1) or rejected (fℛ, = 0) the advice. Each user
has his own feedback log within her/his WA App. Given a feedback log fℛ, we computed the
short-term update of probability ℛ as prescribed by Equation (3)
 ( ) =   · ∑︀=1 fℛ, + (1 −  ) ·  ( − 1) .
      </p>
      <p>ℛ  ℛ
Long-term adaptation is achieved though the measures of efectiveness of the WA tool. In
particular, we considered a subset  of such measures, so that by the end the of a time period
∆  each measure  ∈  reports an improvement. In this context, we derived the efectiveness
of rule ℛ as the correlation (during ∆ ) between the number of times advice , generated
by rule ℛ, collected a positive feedback and the subset of measures ℛ ⊆  such that the
Pearson’s correlation test between ℛ and  ∈ ℛ results in a -value ≤ 0.05. On this premise,
we defined with  the set of rules in the DSS and with  ℛ,ℛ the average correlation between
ℛ and its set of measures ℛ. Thus, we computed the long-term update of probability ℛ at
time  ≥ 1 as prescribed by Equation (4)
 ℛ( ) =   · max ℛ,ℛ′ℛ,ℛ′ + (1 −  ) ·  ℛ( − 1)
ℛ′∈
(3)
(4)
In Equations (3) and (4), the parameters   ∈ (0, 1] and   ∈ (0, 1] are the learning factors, the
parameters that control the updates. Higher values of   and   make the update system rely
more on “newer” information in the update, instead of the previous one; lower values have the
opposite efect.</p>
    </sec>
    <sec id="sec-4">
      <title>4. Conclusion and Future Work</title>
      <p>In this paper, we have presented the WA Tool based on the collection of sensors data and a DSS
for the generation of recommendations to improve the quality of life of workers. The WA Tool
is conceived to analyze the users’ health and behavior at work (or, possibly, telework and smart
working) and outside work, assisting with reminders and risks avoidance recommendations.
Currently, we are continuing the research stream presented here by designing a platform to
define safe working environments for human-robots teams (HRTs) for collaborative embodied
(physical) AI. Current work has the aim of keeping people away from unsafe and unhealthy jobs
in HRTs and engaging and empowering workers, regardless of their gender, age or background.
This platform will enable a strong ‘prevention through design’ approach that integrates human
factors and worker-centred design. The adaptive solutions proposed by the WA project are
currently analyzing three diferent real working settings and living environments, by
experimenting the profile of around 90 workers &gt; 50 years old, from the one side, and the working
place requirements from the other side. We are currently defining which information has to be
collected and stored to improve and increase Robot capabilities and interactions with humans.</p>
    </sec>
    <sec id="sec-5">
      <title>Acknowledgments</title>
      <p>This work has been supported by the European Union’s Horizon 2020 research and
innovation programme under grant agreement No. 826232, project WorkingAge (Smart Working
environments for all Ages)</p>
    </sec>
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