A Telecare System on Smart Watches that Communicate with Wireless

Bio Sensors

Akio Sashima, Mitsuru Kawamoto and Koichi Kurumatani

Human Informatics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST),

2-3-26 Aomi, Koto-ku, Tokyo, 135-0064, Japan

Keywords:

Telecare System, Wireless Bio-sensor, Wristwatch-type Device, Smart Watch, Peer-to-peer, Tactile Interface.

Abstract:

In this paper, we propose a prototype of telecare system by using wristwatch-type devices, so called smart

watches. In the prototype system, the smart watch receives physiological data of a user, such as heart beats

and body movements, by communicating with a wireless bio-sensor worn by the user. The smart watch sends

the physiological data to the other users’ smart watches connected to the Internet. The sensed data are shared

among family members in a peer-to-peer manner so as to remotely monitor the physical health status of the

other members. We have designed a user interface which visually shows the remote user’s current body posture

and enables the others to tactilely feel his/her heart beats. We describe the overview of this prototype system

and its user interface implemented with the smart watches. We show experimental results of communication

performances of the system.

1 INTRODUCTION

Recently, wristwatch-type information devices, so

called “smart watches”, have drawn attention of in-

dustrial and research communities. In general, the

wristwatch-type information device is regarded as a

peripheral device of smartphone because it is a small

sensing device attached with the user’s wrist to sense

her/his activity and shows alerts of the connected

smartphone, such as when a mail is received. How-

ever, some of them can be used as stand alone devices

which do not need to work with smartphones because

they have wireless communication modules, such as

Wi-Fi and LTE (4G), to independently communicate

with other devices on the Internet.

In addition, as a user interface device, wristwatch-

type devices have distinguished features from the

smartphones. For example, a feature is intimacy of

the devices: they are attached with the users wrists

and stay close with the users at all times; they can

directly provide tactile information for the users by

using their vibration. By utilizing this feature, we

can create a new service that directly and successively

provides the telecare information with care givers. An

example of such intimate service is “Mediated social

touch,” (Haans and IJsselsteijn, 2006). It is an impor-

tant issue in teleacare researches how we can mediate

social touch and tactile information between family

members.

In this paper, we describe a prototype of peer-to-

peer telecare system by using wristwatch-type infor-

mation devices instead of smartphones. The system

is implemented with small wireless bio-sensors and

wristwatch-type devices. Physiological information

of a service user, such as electrocardiogram and body

movements, are sensed by the bio-sensor and shared

with the others’ devices in a peer-to-peer manner. Uti-

lizing the above features of wristwatch-type device,

we have developed a user interface which visually

shows the remote user’s current body movements and

enables the others to tactilely feel his/her heart beats.

The user interface has been designed to realize intu-

itive communication in family members. First, we de-

scribe overview of the system and its user interface.

Then experimental results to investigate its communi-

cation performances are shown.

2 BACKGROUND

Mobile sensor devices have been used in telecare

services to remotely monitor statuses of older per-

sons who live alone (Lin, 2012)(Triantafyllidis et al.,

2015)(Sashima et al., 2008). The services provide

their health and activity statuses, which are obtained

by the wearable devices, for their trustworthy persons

Sashima A., Kawamoto M. and Kurumatani K.

A Telecare System on Smart Watches that Communicate with Wireless Bio Sensors.

DOI: 10.5220/0006248404290434

In Proceedings of the 10th International Joint Conference on Biomedical Engineering Systems and Technologies (BIOSTEC 2017), pages 429-434

ISBN: 978-989-758-213-4

429

Internet

(Wi-Fi)

Connection

Management

Server

• Connection

Management

Smart Watch

Sender

Smart Watch

Receiver

Sensor Data

Internet

(Wi-Fi)

Connection

Data

Internet

（

Wi-Fi)

Connection

Data

• Cared person

Ex. elderly person

• Care giver

Ex. family member

Wireless

Bio-Sensor

Figure 1: Overview of telecare service for elderly person.

who take care about them, such as caregivers, family

members, doctors, by using smart phones.

So far, in order to implement such telecare ser-

vices, most of them have been built based on server-

client communication model; all of sensing data of

the older person are sent to a central data server and

the server manages and provides the data of the users.

However, the approach has a drawback to start up and

maintain a practical service in reality. It is about man-

agement costs of the physiological sensing data in a

central data server; the management costs rise as in-

creasing personal health data in the server because it

requires careful handling.

In order to prevent the management issue aris-

ing from the server-client model, we have proposed

peer-to-peer communication model (P2P communi-

cation model) for telecare services (Sashima and Ku-

rumatani, 2016). The P2P communication model as-

sumes that the smartphones of the users directly com-

municate with each other in a peer-to-peer manner.

The sensing data are directly sent to a smartphone of

a caregiver not going through a central data server so

that the management cost is less.

In this paper we apply the P2P communication

model to a telecare system on wristwatch-type de-

vices. We have implemented a prototype of telecare

system based on the P2P communication model and

evaluated the validity of the system. In addition, we

propose a user interface that ﬁts for wristwatch-type

devices.

3 TELECARE SERVICE MODELS

We propose two service models using the peer-to-peer

telecare system implemented on wristwatch-type de-

vices;one is for elderly person is shown in the ﬁgure

1; the other is for family members is shown in the

ﬁgure 2.

Internet

(Wi-Fi)

Connection

Management

Server

• Connection

Management

Smart Watch

Sensor Data

Internet

(Wi-Fi)

Connection

Data

Connection

Data

• Family Member

Wireless

Bio-Sensor

Internet

（

Wi-Fi)

Wireless

Bio-Sensor

Figure 2: Overview of P2P telecare service for family mem-

bers.

3.1 Telecare Service for Elderly Person

In “telecare service for elderly person” model, we as-

sume that the service consists of a wireless bio-sensor,

a connection management server, a wristwatch-type

device of sensed user and a wristwatch-type device

of remote user. The service user, who wears a

wristwatch-type device and a wireless bio-sensor, is

an elderly person living in the nursing care facilities

which has Wi-FI access points. The other remote

users are care givers (e.g., family member, medical

staffs). The bio-sensor senses the user’s physiological

data, such as electrocardiograph data, and wirelessly

sends the data to the his or her wristwatch-type de-

vice. The data which represents the user’s physical

status are sent to the other remote wristwatch-type de-

vices connected to the Internet. The network address

of the remote devices, which is used for establishing

a communication channel among devices, are sent by

the connection management server. Hence, it is pos-

sible to share the latest physical status of the user by

using the wristwatch-type device.

3.2 P2P Telecare Service for Family

Members

In “P2P telecare service for family members” model,

we assume that the service consists of a connection

management server, two wireless bio-sensors, and

two wristwatch-type devices. Each service user has a

wristwatch-type device and a bio-sensor. This model

is a symmetrical telecare service model for family

members; each member can be take care of other

members. The difference between “telecare service

for elderly person” model and this model is that the

data ﬂows in both directions between the wristwatch-

type devices.

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4 IMPLEMENTATION

4.1 System Components

The system consists of the following components.

4.1.1 Wireless Bio-sensor Device

A wireless bio-sensor device is shown at the left side

in Figure 3. The sensor device is attached to a user’s

chest by sticking electrodes with a peel-off sticker.

The device consists of 5 kinds of sensors (electro-

cardiograph, 3-axis accelerometer, barometer, ther-

mometer, hygrometer), a lithium ion battery, and a

Bluetooth

module which communicates with a smart

watch. In the prototype, the device continuously

senses electrocardiographic data and 3-axes acceler-

ation data of the user and wirelessly sends the data to

the smart watch.

4.1.2 Wristwatch-type Information Device

(Smart Watch)

We have implemented the system on the Android

Wear smart watches

. The wristwatch-type informa-

tion device is shown at the right side in Figure 3. It

commutates with a connection management server to

know the network address of remote user’s device. By

knowing the latest address of the device, it relays the

physiological data obtained by the bio-sensor to the

remote user’s device in a peer-to-peer manner. Us-

ing a graphical user interface of the system, the other

user can know the his or her physical status visually.

We can conﬁgure the system settings e.g., specifying

a opponent service user, by the user interface. The

system can inform the user’s status by control the in-

ner vibrator. In this research, we use the vibrator to

provide remote user’s heart beats.

4.1.3 Connection Management Server

A connection management server stores the network

address (IP address and port number) of each user’s

smart watch, and dynamically updates them when the

smart watch connects from a different network envi-

ronment.

The network address of wristwatch-type informa-

tion device is dynamically changed according to its

network environments. To enable two devices com-

municate with each other, the network address of the

peer is required.

https://www.bluetooth.com/

https://www.android.com/wear/

Figure 3: Wireless bio-sensor (left) and wristwatch-type in-

formation device (right).

To solve this issue, we have introduced a connec-

tion management server in the system. A connec-

tion management server stores the network address of

each user’s watch devices, and updates them when the

device starts to connect to the server. It also tells the

updated address to other devices. By knowing the lat-

est address, the devices can communicate each other

even if the addresses are dynamically changed.

Notice that the server does not handle sensing data

but just initiates the communication of users.

4.2 Communication

The current wristwatch-type devices have Wi-Fi com-

munication facilities and directly communicate with

the other devices using Internet Protocols, such as

UDP. We use the communication facilities to imple-

ment the telecare system that can send and receive

UDP packets between the devices.

4.2.1 Communication Protocol

We adopt a protocol which has been proposed for fast

communications of mobile devices (Sashima and Ku-

rumatani, 2016). Figure 4 shows an outline of the

protocol. It is a right-weight protocol, which does

not have a mechanism to handle lost packets, so as

to be suitable for the limited computational resources

of wristwatch-type devices. In addition, as it does not

wait to receive acknowledge packets, it can immedi-

ately send the packet that represents the latest user

status. However, as losing packets is a weak point

of this protocol, we describe experimental results of

communication performances of the system in a later

section.

To establish a communication channel between a

wristwatch-type information device in a private net-

work and the device in the outside of the network, we

apply the NAT traversal technique (Ford et al., 2005)

that enable peer to peer communications over a NAT

router.

A Telecare System on Smart Watches that Communicate with Wireless Bio Sensors

431

Sender Server Receiver

Log on

ACK

Telling the peer logs on

Telling the peer’s UDP

socket address.

ACK

Data Request

ACK

Sending Data

Log off

ACK

Start

End

Sending Data

Go to Start

Telling the peer logs off

Start

Repeat

Figure 4: Overview of the communication protocol

(Sashima and Kurumatani, 2016).

4.3 Data Representation

To share the sensing data between the devices in the

service, the data has two data representations for the

service models: a) “raw data representation” which

includes raw sensing data and b) “abstract data repre-

sentation” which includes the data analyzed at a wrist-

watch device connecting to wireless bio-sensor.

4.3.1 Raw Data Representation

This representation includes raw data obtained by the

bio-sensor for the application that requires to know

detailed data of the sensed user. We assume that typ-

ical usage of this representation is for medical ap-

plications, such as remote monitoring of electrocar-

diograph. Thus the communication is one way from

a sensed user to a care giver, such as medical staff.

This raw representation data is synchronously sent at

a constant sensing interval. For example, if the sam-

pling period of the sensor is 5 msec, the data is sent at

each 5 msec interval.

4.3.2 Abstract Data Representation

two way communication assumed in “P2P telecare

service for family members” requires more compu-

tational power for handling trafﬁcs. We have devel-

oped the abstract representation to reduce the trafﬁcs

in the two way communication. The representation

includes an abstract data summarized by a data se-

quence of raw sensing data: a “posture” data of the

abstract representation is derived by analyzing a se-

quence of 3-axes acceleration data; and a “heart beat”

data is derived by analyzing a sequence of electrocar-

diographic data. In addition, the abstract represen-

tation data is asynchronously sent when the system

detects a change of the status. For example, the data

is sent as soon as possible when the posture of the

user is changed. Hence, using this representation, the

amount of trafﬁc data becomes 10–100 times smaller

than using the raw data representation in our proto-

type system.

4.4 User Interface

The wristwatch type device is tactilely attached with

the user’s wrist and stay close with the user at all

times. To utilize the features of the device, we have

designed a user interface which directly and succes-

sively provide telecare service to the user. The user in-

terface visually shows the users’ current body move-

ments and enables the user to tactilely feel other user’s

heart beats.

4.4.1 Graphical User Interface for Showing

User’s Status

Because the wristwatch-type device has a small dis-

play, we have designed a simple graphical user inter-

face showing the status of the remote user. Figure 5

shows display images of the user interface. In the ﬁg-

ure, each image shows a physical status of the remote

user. Currently, the system classiﬁes the following 6

statuses: standing, moving, laying-up, laying-down,

walking, unclassiﬁed. The system automatically clas-

siﬁes the status based on the 3-axis acceleration data

obtained by a wireless bio-sensor. The sampling rate

of the data is 100 Hz. For the classiﬁcation, we have

used a rule-based algorithm using predeﬁned thresh-

old values.

To share the classiﬁcation with the raw data repre-

sentations, the devices share the raw acceleration data

and do the classiﬁcation based on the data indepen-

dently. Because the classiﬁcation process is done by

each device, the analysis results can be slightly differ-

ent between the devices.

To share the classiﬁcation with the abstract data

representations, the devices connected to the bio-

sensor analyses the raw acceleration data and send the

abstract posture data to other devices. Because the

classiﬁcation process is done by a device, the same

analysis results are shared by the devices.

4.4.2 Tactile User Interface for Feeling Heart

Beats

Based on electrocardiographic data obtained by the

wireless bio-sensor, the system automatically detects

the pase of heart beats of sensed user. To detect

the pase of heart beats, the system monitors peak lo-

cations of the R-wave by calculating differentiation

values of the electrocardiographic data, and detect

sharply changing points as the peaks of the R-wave.

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432

Figure 5: Graphical user interface of the prototype system. Each image shows a physical status of a remote user: standing

(left), moving (center), laying up (right). HR ﬁeld shows the pase of heart beats of the user.

The sampling rate of the data is 200 Hz. It calculates

“beats per minute (BPM),” which stands for the pase

of heart beats. The BPM is based on the latest R-R

period, and shown at the heart rate (HR) ﬁeld in the

graphical user interface (see Figure 5).

To share the pase of heart beats with the ab-

stract data representations, the device is connected

to a wireless bio-sensor. It detects an R-peak from

the electrocardiographic data and repeatedly sends a

packet to remote user’s wristwatch device. We call

the packet corresponding to the detected R-peaks R-

peak packet. When the remote user’s device receives

the R-peak packet from sensed user’s device, it imme-

diately vibrates for a short time (30 msec). Hence, it

vibrates in synchronism with the heart beat of sensed

user so as to others can tactilely feel his/her heart beat

by the vibrations. Strictly speaking, as there are de-

lay times to receive the R-peak packets and the times

ﬂuctuate with network conditions, others can tactilely

feel ”his/her heart beat like pattern” by the vibrations.

To share the pase of heart beats with the raw data

representations, the devices sends the raw electrocar-

diographic data to the other users. The others calcu-

late the BPM based on the raw data independently.

5 EVALUATIONS

We have experimentally evaluated communication

performances by measuring the packet loss and end-

to-end delays of the prototype system.

The experimental network environments are a Wi-

Fi network (LAN) in our laboratory. We have mea-

sured the communication performance of two devices

which connect to the same Wi-Fi access point that

might be used by the other users. To prevent the ef-

fects of the sleep mode of the devices, we have ap-

plied power to USB ports of them.

We have evaluated communication performance

in the following two conditions assuming the differ-

ent service models: one-way communication used

for “telecare service for elderly person,” and two-

way communication used for “P2P telecare service

for family members.” For the above two conditions,

we have compared the performance between the ab-

stract data representation and raw data representation.

We have analyzed the performance based on the data

recorded by each device in each condition. We have

used the data recorded within ten minutes from the

starting time of the communication.

5.1 Packet Losses

Experimental results about packet losses between the

wristwatch-type devices are shown in Table 1. Total

samples means a total number of the data sent by the

devices. The “condition” column of Table 1 shows

combinations of communication styles and data rep-

resentations. For example “Two Way/Raw” stands

for two way communication with raw data represen-

tation. Using the abstract representation, the total

numbers of data became small in this experiment be-

cause the data is sent asynchronously when the user

changed his or her posture.

While many packets were lost by using the raw

representation especially in the two way communica-

tion, few packets were lost by using the abstract rep-

resentation. Because the wristwatch-type device has

limited computational resources, the abstract repre-

sentation with asynchronous communication is more

suitable for the prototype than the raw representation.

5.2 End-to-end Delay

We have measured delay times of the communication

in the conditions. The results are shown in Figure 6.

Before the experiments clocks of the devices are syn-

chronized based on a clock of the connection server.

The average delay time of “Two Way/Raw” condition

is omitted in the graph because it took for a long time

A Telecare System on Smart Watches that Communicate with Wireless Bio Sensors

433

Table 1: Experimental results of packet losses.

condition total

samples

lost

samples

loss

rate

(%)

One Way/Raw 180000 677 0.4

One Way/Abstract 870 0 0

Two Way/Raw 360000 149845 41.6

Two Way/Abstract 3267 4 0.1

100

150

200

250

300

350

One Way/Raw One Way/Abstract Two Way/Abstract

One Way/Raw

One Way/Abstract

Two Way/Abstract

Time

(msec)

Figure 6: End-to-end delay times (msec).

(over 30sec). Average delay times of the other con-

ditions are under 200 msec. Although more careful

investigations are required in various network condi-

tions, we believe that the result shows the feasibility

of the telecare services by using wristwatch-type de-

vices.

6 CONCLUSIONS

We have described a prototype of peer-to-peer tele-

care system by using wristwatch-type information de-

vices not using smartphones. Physiological informa-

tion of service user, such as electrocardiogram and

body movements, sensed by the wireless bio-sensor

are shared among the service users’ wristwatch-type

information devices in a peer-to-peer manner. To re-

alize intuitive communication between family mem-

bers, we have developed a user interface which visu-

ally shows the sensed user’s current body movement

and enables the others to tactilely feel his or her heart

beats. We believe that the system opens up a new de-

sign space in which all users in a social group can take

care of each others at the same time.

ACKNOWLEDGEMENTS

This work was supported in part by JSPS KAKENHI

Grant Number 26330125.

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