Sensorized Environment for Self-communication
Based on Observation of Daily Human Behavior
Yoshifumi Nishida1 , Toshio Hori1 , Takashi Suehiro1 and Shigeoki Hirai1
1Electrotechnical Laboratory
1-1-4 Umezono, Tsukuba, Ibaraki, 305-8568, Japan{ynishida, toshi, suehiro, hirai}@etl.go.jp
Abstract
This paper describes an intelligent environmental
system, SELF (Sensorized Environment for LiFe), thatenables a person to maintain his or her health through”self-communication.” The system externalizes a ”self”
by storing personal data such as physiological status,
analyzing it, and reporting useful information to assist the person in maintaining his or her health. To
establish the methodology to create such a system, thisstudy analyzes and re-deﬁnes the self as an object of
information processing. Self-communication is nothing but understanding ourselves objectively. It is noteasy to put into practice because it requires a visualized or numerized representation of oneself. As an
example of an externalized self, this study focused on
the physiological status of a person. The physiological status is obtained as follows: SELF observes the
person’s behavior with distributed sensors invisibly embedded in the daily environment, extracts physiologicalparameters from it, analyzes the parameters, and accumulates the results. The accumulated results are used
for reporting useful information to maintain the person’s health. The authors constructed a model room
for SELF consisted of a bed with pressure sensor array, a ceiling lighting dome with a microphone, anda washstand with a display. Fundamental results ofself-externalization using SELF are presented.

1

Introduction

Human beings can think about themselves. They
can understand their present condition and decide what
to do in the future based on the their present condition. However, like other abilities such as memory,
calculation, and vision, the ability of thinking about
oneself also has limits. It is diﬃcult for humans tounderstand their condition objectively because their
judgment depends largely on their feeling and knowledge. As an example, let us consider the status ofour physiological selves, namely the condition of ourhealth. Most people cannot notice a change in theircondition without a medical monitor.

It is not until a phenomenon is broken down andrepresented as objective data that a person can grasp
the phenomenon, ponder it, share it with other people
precisely, and discuss it with them. This is true of selfdata. Externalizing the self as objective data enables
the person to gain a deeper insight into himself or
herself.
This study addressed problems in an intelligent system which enables a person to understand himself or
herself objectively by externalizing the self as objective
data. Speciﬁcally, this study focused on the problems
for a method of externalizing the self from the person to the intelligent system in order to objectify theself, and a method for recombining his or her externalized self with the person to guarantee the person’s
accessibility to the externalized self.
To solve these problems, this study was based on
the following : Human behavior is communication media that enables the person to convey self-data naturally. A daily environment with sensors and computer is a new approach to deal with the person’s
daily behavior as an object of information processing.
Namely, an environmental computer with sensors can
automatically observe daily behavior, extract the selfdata from the observed behavior, and represent theresult.
Research on an environmental computer has beenreported. The concept of ubiquitous computing[1] waspresented and opened the way for research on supporting human activities in a daily environment withubiquitous computing devices. For example, the theDigitalDesk[2], Smart Room[3], Robotic Room[4], Intelligent Room[5], and Intelligent Space[6] have been
proposed. These research studies show the possibility of providing information at home input throughnatural human gestures without the use of keyboards,
mice, and other special input devices. In particular,
the Robotic Room provides not only information services but also mechanical services using robotic elements by understanding human natural behavior. An
invisible computer[7] symbolizes the direction of thesetechnologies. It is the concept of enabling a person
to concentrate on his or her activity itself by hiding
the computer and thus removing it from the person’s

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consciousness.
This paper describes the concept of self-communication which enables a person to understand himself
or herself objectively and continuously by observing
the person’s daily behavior with invisible computer
technology that analyzes and represents the observed
behavior, and reports useful information for ther person’s daily life. This paper also describes the method
for creating such a system and reports on a healthcare support system (SELF; Sensorized Environment
for LiFe) which was constructed to demonstrate theproposed concept.
This paper is organized as follows: The next section
describes the proposed concept of self-communication.
The authors identify the necessary functions for realizing the self-communication and describe the methodof realizing the functions. The eﬀectiveness of theself-communication system constructed by integratingthese functions is also discussed. In section 3, the authors report on the healthcare support system. Conclusions are presented in section 4.

2

Self-communication based on Human
Daily Behavior

2.1

Concept of Self-communication System

This section describes the drawbacks in thinking
about ourselves to clarify what we need to compensate
for by externalizing ourselves. In this study a ”self” isdeﬁned as a representation which we can use for analyzing ourselves (self-analysis), evaluating ourselves(self-evaluation), improving ourselves (self-improvement)
and realizing desirable conditions for ourselves (selffulﬁllment).
The drawbacks in thiking about ourselves are shownas follows.
Drawbacks in thinking about ourselves
1. Uncontrollability
When and where a person should access and remember self-data and how important this task
is cannot be controlled. Such a task tends to be
uncertain and contingent.
2. Subjectivity
Self-data is not based on objectivity. It tends tobe subjective and inaccurate.
3. Knowledge dependency
Self-data is generated only by the knowledge system the person has. No matter how importanta signal is, the signal may be processed inadequately or ignored as being insigniﬁcant if theperson has limited knowledge.

Self Externalized
to Environment

Human3) Useful report2) Humanobjectification

1) Soft interaction
by daily behavior

Fig. 1: Concept of self-communication system
Based on our analysis, we propose a concept of”self-communication.”
Self-communication is communication via an intelligent environmental system which can 1) externalize
the self from the person to the system by observing
the person’s daily behavior in order to objectify theself, and 2) recombine the externalized self with theperson to guarantee the person’s accessibility to theself based on the person’s daily behavior.
Figure 1 shows a conceptual diagram of a self-communication system we propose. The system consists ofthe functions of 1) soft interaction by human daily behavior, 2) human objectiﬁcation, and 3) useful report.
Each function is described in detail in the following.
Soft interaction by human daily behavior In
view of interaction, we describe the appropriate interaction for self-communication. Interaction can be
categorized into hard interaction and soft interaction.
Hard interaction puts an emphasis on the quick response of the system. Conventional computers areused only for hard interaction. Hard interaction isappropriate for a task where we process data which
already exists. Let us consider preparing documents.
As long as we use the computer, while sitting at thecomputer, we don’t have to walk around to gather
necessary information. However, conversely a computer where the input/output devices and processors
are concentrated in one place requires us to be nearit. It is not suitable for dealing with typical events inour daily lives because most people’s daily lives don’t
occur near the computer nor around the computer,much less on the computer.
On the other hand, soft interaction puts an emphasis on the sustainable usage of the system over along term. To this end, daily behavior is utilized as
information media.
Daily behavior has the following features. 1) Timeregularity; the behavior tends to occur regularly be-

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cause of the physiological needs of the body. 2) Spatial
regularity; the behavior also tends to occur in special
places where the necessary tools are located because
the tools cannot be moved freely. Figure 2 shows anexample of some daily behaviors. This daily behavior
loop consists of waking up in the morning, going toa washstand to make up or wash the face, and goingto a bed to sleep at night. Thus there are daily behavior loops in our daily lives because of time-space
regularities.
Taking such features of daily behavior into consideration, by embedding sensors into the furnishings
necessary for daily behavior and observing the behavior with the embedded sensors, we can have the system
input self-data periodically. Similarly, by embedding
output devices into tools or furniture, we can have thesystem provide some information to the person naturally when he or she uses the furniture. The function of soft interaction through daily behavior enables
the sustainable usage of the system over a long term
because the input/output of the system is integrated
with daily behavior and that there is no concept ofoperation or working space.
In terms of the drawbacks in thinking about ourselves, the function of soft interaction by human daily
behavior compensates for drawback (1) controllability.
Since output devices are installed in places where theperson is conscious of information, the person can get
the information certainly and periodically.

largely on feelings and tends to be inaccurate. Inaccurate data prevent us from examining it by comparing
it with other data or past data. Therefore, our insight
into ourselves is limited considerably. To go beyond
the limits, we must objectify ourselves based on constant criteria.
Objective data based on constant criteria enables
us to perceive our diﬀerences compared with othersand diﬀerences compared with our past condition precisely and to use the objective data in order to evaluate and improve ourselves. Moreover, if the objective
data is extracted as scientiﬁc variables, we can utilize
the knowledge of that science to amplify our ability tointerpret the data.

Useful report To make the generated objective data
signiﬁcant to the person, the system must extract signiﬁcant facts and report them. Let us consider thephysiological self again. When the person shares theself-data with a doctor, the doctor wants to know thephysiological parameters of the self-data. On the other
hand, the person wants to understand the self-data
more intelligibly and focuses on only any changes fromthe past condition of the self in daily life. This function enables the person to know what he or she needs
to know and what he or she wants to know.

2.2

Daily Behavior Loop

Fig. 2: Human daily behavior

Human objectiﬁcation The function of human objectiﬁcation compensates for drawback (2) subjectivity, and drawback (3) knowledge dependency.
Without any criteria, a person’s judgment depends

Realization Scheme for Self-communication System

Figure 3 depicts a scheme of the self-communication
system. The system consists of 1) a sensorized environment for soft interaction, 2) a human model for human objectiﬁcation, and 3) a part for creating a usefulreport. In this study, sensorization means making theroom itself a sensor for inputting human daily behavior by embedding sensors into the room invisibly tokeep the room’s appearance natural. The data ﬂows
in the system as follows: In the sensorized environment, the system observes the human’s daily behavior
and sends the observed data to the human model. The
human model consists of an environmental model, ahuman behavior model, and a human scientiﬁc model.
The environmental model is used for observing humanbehavior with the environmental sensors. The humanbehavior model is used for extracting objective variables from the observed behavior data. The humanscientiﬁc model consists of knowledge to extract meaning from the fundamental data which is extracted by
the human behavior model. If this knowledge is already available, we can create the human scientiﬁcmodel using the knowledge. Finally, the system creates a report by analyzing the self-data and informs
the person using the sensorized environment.

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the input of data with certainty because theinput and output of human behavior datais performed utilizing human daily behavior which is repeated accompanying daily
life activity irrespective of the system’s existence.

Share with others(if needed)g) reporting useful information
to human intelligiblyf) extracting change in self condition(b) Automatism of data update
Since regular periodic input of human behavior data is guaranteed, the data the system processes and reports to us are guaranteed to be the latest.

e) human scientific knowledge
to extract meaning if possibled) human behavior model
to extract objective variables
for scientific usage
sensor output

Externalization

2) Human objectificationc) environment model
to observe human behavior
by sensorized environment

1) Soft interaction by daily behaviorb) sensorization of environment
invisible devices

human daily
behaviora) daily behavior loop

Fig. 3: Scheme of self-communication system

2.3

Advantages of Self-communication System

The advantages of using the self-communication system compared with thinking about ourselves without the self-communication system are 1), 2) and 3)(a), and the advantages compared with a conventional
computing system, which has only the capability forthe hard interaction, are 3) (a) and (b).
1. Objectivity of data
By externalizing the self as objective representation based on constant criteria such as scientiﬁcfacts, we can refer to the self-data objectively,
recognize change in the self-data, and improveourselves by evaluating the change.
2. Ampliﬁcation of interpretation capability
Even if we lack the necessary knowledge, the system can extract an important meaning from ourdata using a human model for human objectiﬁcation.
3. Sustainability of system usage(a) Certainty of data input/output
The function of soft interaction guarantees

3
3.1

Healthcare Support by Self–communication
Healthcare Support

Healthcare is an issue of communication between
a person and his or her physiological system. The
viewpoint of communication with the self is important.
It is necessary for the person to maintain his or her
health by grasping the physiological self objectively
and continuously by communicating with the person’s
physiological self.
Sleep is one of the most familiar problems for mostpeople. Respiratory disorders during sleep, including
sleep apnea syndrome and snoring, prevent the personfrom gaining the beneﬁts of proper sleep. Becausesuch disorders cause increased respiratory work andhypoventilation1 , which create various adverse eﬀects
on sleep and daytime activities.
From this perspective, of the many functions a healthcare support system should have, this study focuses on
the SELF healthcare support system with its functionof monitoring of the respiratory system’s condition,
storing and analyzing it, and reporting useful information to the person.

3.2

System Architecture of SELF

Figure 4 outlines the architecture of SELF in termsof soft interaction by daily behavior, human objectiﬁcation, and useful report. SELF consists of 1) a
sensorized environment for the soft interaction, 2)ahuman physiological model for human objectiﬁcation,and 3) a part for creating a useful report. The data
ﬂows in SELF as follows: In the sensorized environment, SELF observes daily human behavior and sends
the observed data to the human model. The humanmodel consists of an environmental model, a humanphysical model, and a human physiological model. Finally, SELF creates a report using the physiological
data of the person and informs the person using thesensorized environment.
1 A state in which tidal volume is small and a person has ashortage of oxygen.

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Useful reportCreate useful report
Extract change of physiological condition

Human objectification
Physiological model

Extract upper physiologicalvariables based on knowledge

Physical model

Extract fundamental physiologicalvariables

Environmental model

Observe daily behavior
using sensorized environment

Fig. 6: Photograph of bed room
Soft interaction by daily behavior
Sensorized environment

Target daily behavior

1) Pressure sensor bed
2) Ceiling dome microphone
3) Washstand display

sleep
wash facemake upFig. 4: Architecture of SELF

3.3

Soft Interaction: Sensorized Environment

a bed-shaped touch sensor. A microphone is embedded into a lighting ﬁxture. A display is embedded into
a washstand. Figure 6 shows the photograph of theconstructed bed room.
In SELF, soft interaction is realized as follows: 1)
SELF observes a person using the pressure sensor bed
and the ceiling dome microphone when he or she goesto bed and sleeps, 2) SELF reports useful information
to the person using the washstand display when he or
she goes to the washstand to wash his or her face ormake up after waking up.
These devices are explained in detail in the followings.

3.3.1
Camera set behind
two-way mirror
Directional microphoneby ceiling dome

Em
be
dd
ed

in

m
oo

Embe
dde
di
nr
o

om

r

ed in room
bedd
Em

3.3.2
Em be

Washstand display

d d e d in roo m

Pressure sensor bed

Fig. 5: Sensorization
The room is sensorized as shown in Fig. 5. A
keyboard, which is a kind of touch sensor, becomes

Pressure Sensor Bed

The pressure sensor bed consists of a pressure distribution sensor array, a controller, and a bed[8, 9].
Figure 7 shows a photograph of the bed. Figure 8
shows an example of output from the pressure sensor
bed. The pressure distribution sensor has 210 Force
Sensing Resistors (FSRs) which are set at 7[cm] intervals. An FSR is a thin ﬁlm sensor made from piezoresistive polymer. The sampling frequency of the pressure image is 20 [Hz]. The measuring range of eachpressure sensor is 0 to 1[kg]. The pressure sensor bed
is used for monitoring the breath curve, oxygen desaturation, posture, and body movement. These parameters will be explained later.

Ceiling Dome Microphone

The authors invented the ceiling dome microphonewhich consists of a ceiling dome, a lighting ﬁxture,
and a omnidirectional microphone. Figure 9 shows aphotograph of the ceiling dome microphone. This device has two functions: indirect lighting and gatheringsound. The ceiling dome is used to reﬂect both lightand sound. A microphone is set at the focal pointof the reﬂector. The device enables detection not only
snoring sounds but also normal breathing sounds withhigh sensitivity while keeping the room’s appearance
natural. It is positioned above the bed. The gain ob-

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ceiling dome
microphone

900mm

Fig. 7: Pressure sensor bed

Fig. 9: Ceiling Dome Microphone40
theoretical value

Gain [dB]30
20
measured value

10
0
2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

-10
-20
-30

Frequency [Hz]Fig. 10: Gain obtained by ceiling dome microphonetained by the ceiling dome ranges from -18 to 31 [dB]depending on the frequency of the sound. Figure 10
shows the gain obtained by the ceiling dome. The gain
is maintained at more than 20[dB] for high frequency
sounds of more than 6[kHz]. Since the frequency ofnormal breathing sounds ranges from 5 to 15 [kHz],
this device can be used to detect breathing sounds,
i.e., air ﬂow at the mouth and nose. The diameterof the dome is 900[mm]. Figure 11 shows an exampleof breathing sounds detection using the ﬁlter and theceiling dome microphone. Room’s background noise
includes such noises as those of an air conditioner anda computer. The ﬁgure shows that both the inhalation and exhalation component of the breath cycle aredetected quite clearly.

Integral of Power Spectrum
from 5 to 15 [kHz]Fig. 8: Example of output of pressure sensor bed
exhalation soundone breath

inhalation soundbreathing sound

0

10

20

30

Time [s]40
room noise

Fig. 11: Detection of normal breathing sounds byceiling dome microphone

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3.3.3

Washstand Display
two-way mirror

The washstand display consists of cameras, a monitor, and a two-way mirror. It can reﬂect the person’s
face while superimposing health information aroundthe face. It can also zoom in on a part of the face.
It works not only as an excellent mirror but also as adisplay of the healthcare support system. Figure 12
shows a prototype of the washstand display. Figure
13 explains its structure. Currently the prototype has
only the mirror part of the washstand. Other parts of
the washstand will be added later.

Camera22inch Display

Fig. 13: Structure of washstand display
Physiological Layer
Sleep Apnea Syndrome Model
If AI>5 then Sleep Apnea Syndrome
else Normal Breath

Apnea Model

Description of
upper variables based on
fundamental variables

Air flow < threshold
Body movement < threshold
Oxygen desaturation model
Analysis of Cheyne-Stokes-like breathing

Air flow < threshold
Body movement > threshold

Physical Layer

Breath curve

PostureAir flow at mouth/nose
Position
Snore
Body movement

Extraction of
fundamental physiologicalvariables from sensor data

Breathing model
Same phase sum method

Posture model

Breath frequency modelSensorized Environment
Sensorized bed

Sensorized
Ceiling

Fig. 12: Prototype of washstand display
Fig. 14: Human model for understanding physiological meaning

3.4
3.4.1

Human Objectiﬁcation: Human Physiological Model
Human model

The human model maps human daily behavior intoa physiological meaning space. Figure 14 shows thehuman model we created. It consists of a physicaland physiological layer hierarchy. The physical layer
infers fundamental physiological values (e.g., breath
curve and air ﬂow at mouth/nose) from sensor signals,
and the physiological layer consists of a description ofphysiological knowledge and infers upper physiologicalvalues (e.g., values relating to apnea, Cheyne-Stokeslike breathing, and oxygen desaturation in blood) fromthe fundamental physiological values based on the physiological knowledge. Details on the physiological values the human model can infer are described in thefollowing. Note that all physiological values are obtained by unrestricted monitoring.

3.4.2

Physiological values detected using
human model

1. Posture, body movement
Posture is recognized by analyzing pressure sensor signals based on a posture model. Body
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pressure sensor output[8].
2. Breath curve
Breath curve is calculated by the ”same phasesum method” which is a method for appropriately summing the control oﬀset considering thephase diﬀerence in the output change in the pressure sensor[8].
3. Oxygen desaturation in blood
Oxygen desaturation is detected by detecting
Cheyne-Stokes-like breathing from the calculated
breath curve. The principle is that Cheyne-Stokeslike breathing occurs with high probability whenoxygen desaturation appears. This method can
detect only the frequency of oxygen desaturation, not absolute values of oxygen desaturation[10].
4. Air ﬂow at mouth and nose
Air ﬂow at the mouth and nose is detected using
the ceiling dome microphone.
5. Apnea
Apnea is identiﬁed when air ﬂow does not occur
for more than 10 minutes.

3.5

Fig. 15: Example of daily output of washstand display

Useful Report

Figure 15 is an example of a useful report displayedon the washstand display. The report consists of weekly
and daily information on the changes in health condition and is expressed with bar graphs and text. Changes
to be notiﬁed to the person are determined based on
the average condition of the person and of other people. For the basis of information on the average condition of people, we used a medical textbook.
Figure 16 shows an example of a report for a doctor.
If the person wants to share the health data with adoctor, the report is output in a format we deﬁned byasking several doctors.

4

Conclusion

This paper proposed the concept of ”self-communication” via an intelligent environmental system which
can 1) externalize the self from a person to the system
by observing the person’s daily behavior in order toobjectify the self and 2) recombine the externalized
self with the person in order to guarantee the person’s
accessibility to the self based on the person’s daily
behavior.
This study clariﬁed the method for realizing selfcommunication. Self-communication consists of 1) softinteraction by daily behavior, 2) human objectiﬁcation, and 3) useful report. Personal data is acquired
through the soft interaction and is stored. By humanobjectiﬁcation, the personal data is mapped into objective data. The objective data is reported to theperson intelligibly using the soft interaction again.

Fig. 16: Example of report for doctor.

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The advantages of self-communication are a) objectivity of data, b) ampliﬁcation of interpretation capability, and c) sustainability of system usage. This
paper also reported on an application system of selfcommunication to healthcare support called SELF (Sensorized Environment for LiFe). SELF stores the physiological condition of the person, analyzes it, and reports useful information to help the person maintainhis or her health based on the person’s daily behavior.
The SELF sensorized environment consists of a bed
with a pressure sensor array, a ceiling dome lighting
ﬁxture with a microphone, and a washstand with adisplay. The fundamental results of the functions of
SELF were presented.

Acknowledgments[8] Y. Nishida, M. Takeda, T. Mori, H. Mizoguchi, T.
Sato, ”Monitoring Patient Respiration and Posture Using Human Symbiosis System,” Proc. of
the 1997 IEEE/RSJ International Conference onIntellingent Robot and Systems, Vol. 2, pp. 405406, 1997
[9] T. Harada, T. Mori, Y. Nishida, T. Yoshimi, T
Sato:”Body Parts Positions and Posture Estimation System Based on Pressure Distribution Image,” Proc. of the 1999 IEEE International Conference on Robotics & Automation, pp. 968-975,
1999[10] Y. Nishida, T. Suehiro, S. Hirai, ”Estimationof Oxygen Desaturation by Analyzing Breath
Curve,” Journal of Robotics and Mechatronics,
Vol. 11, No. 6, pp483-489, 1999

We would like to thank Prof. Tetsuo Ishii, Prof.
Mikiko Takayama, and Ms. Takumi Yamazaki of Tokyo
Women’s Medical University for teaching us physiological variables a doctor needs and for cooperatingin the experiments. We wish to express our thanks
to Assistant Prof. Soichiro Miyazaki, Mr. Yoshiaki
Itasaka, and Toshihiko Tanaka of Akita University for
their useful suggestions on diagnosis. We also thank
Mr. Tomohisa Yoshimi of Denso Corporation for constructing the clinical system. This study was fundedin part by a Grant-in-Aid from The Fluidity Promotion Research System of the Science and Technology
Agency of Japan.

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