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XBEE IMPLEMENTATION ON MINI MULTI-ROBOT SYSTEM
Andi Adriansyah Yuliza
Department of Electrical Engineering, Faculty of Engineering, Universitas Mercu Buana
Jl. Meruya Selatan, Kembangan, Jakarta 11650
[email protected] [email protected]
ABSTRACT Wireless communications are now
growing very rapidly because it is very efficient to use. Wireless technology that is widely used at
close range is a device that can interface to the
other devices. Communication between robots is
the process of delivering informations to do
something useful task. Communication between
robots is an important component in the interaction
of the multiple robots. In multiple robot systems,
robot leader delivering orders to the follower robot
to complete a task that occurs coordination
between the robot forms of communication between
the robot wirelessly using XBee signals. This form of communication is in the form of a command to
the robot follower robot to follow the movement of
the robot leader. Advantages of communication
between the robots are efficient in completing the
task. With time quickly orders can be delivered in a
broadcast to the follower so that the job can be
completed simultaneously.
Key Word: Robot, Leader, follower,
communication, XBee, Microcontroller
1 INTRODUCTION
Wireless technology has been developing
very rapidly due to highly efficient wireless
communications. One of the wireless
communication technologies in great demand is
Wireless Local Area Network (WLAN). WLANs
are based on IEEE 802.11 standards that use has some advantageous, such as high capacity, wide
coverage and able to broadcast directly [1],[2],[3].
If the area used in wireless is not too
widely, a kind of wireless technology applied are
Wireless Personal Area Network known as WPAN.
WPAN is a network communication among devices
over wireless technologies. The reach of a WPAN
varies from a few centimeters to a few meters.
WPANs are widely used for communication
between sensors and electronic devices. There are
some technologies used in WPAN such as IrDA, Wireless USB, Bluetooth, Z-Wave and ZigBee.
Nowadays, ZigBee is applied in many
applications. ZigBee has a defined rate of 250 kbit/s, best suited for periodic or intermittent data
or a single signal transmission from a sensor or
input device. Applications include wireless light
switches, electrical meters with in-home-displays,
traffic management systems, and other consumer
and industrial equipment that requires short-range
wireless transfer of data at relatively low rates. The
technology defined by the ZigBee specification is
intended to be simpler and less expensive than
other WPANs, such as Bluetooth or Wi-Fi.
In another side, technology and application of robotic grow rapidly, in terms of reliability,
coverage ability and field applications. There are
several research themes were also developing, such
as sensor technology, motor technology, power
supply technology, telecommunications technology,
control technology and artificial intelligence
technology. The development of these technologies
support each other’s to robotic technology.
Therefore, investigations of robotic become
interesting area for researchers.
In this decade, there has been an important
variation in robotic research focus. Researchers are beginning to modify the direction of robotic
research, from investigation of a single robot
system to exploration of coordination of multi-
robot systems. Multi-robot system is a system of a
robot entities that work together to complete a
specific task [4],[5]. There are several advantageous
of the application of multi-robot systems.
Generally, the application of multi-robot system is
to produce a better system in order to solve the
problems of the system. With the multi-robot
system, the existing complex and difficult system can be performed using the robot with a cheap and
simple [6].
Therefore, this paper seeks to address
multiple robot communication system design. A
communication system design attempted as
possible compared to the existing ones. The focus
of the design is intended for communication
between the leader and the follower so that the
follower can follow the movement leaders. The
transmission medium used among the robots is a
wireless system using the XBee, Arduino
microcontroller where the mobile robot is able to
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perform bi-directional communication and
recognize the controller ID.
2 DESIGN AND IMPLEMENTATION
2.1. ZigBee and XBee
ZigBee is a specification of the
communication protocol low-power digital radios
based on the IEEE 802.15.4 specification in 2003
and Zigbee alliance with a maximum range of 100
meters. IEEE 802.15.4 specification is the basis for
the lower layers of the ZigBee MAC and PHY and
determine the standard 2.4 GHz radio that is used
in the world.
XBee is a brand that supports a variety of communication protocols including ZigBee
802.15.4 and WiFi. Figure Xbee module is shown
in Figure 1.
Figure 1. XBee Module
The ZigBee protocol is using same
standard with the Bluetooth standard. Any
manufacturer’s device that fully supports the
ZigBee standard can communicate with any other company’s ZigBee device. So just as your Motorola
Bluetooth headset can communicate with your
Apple iPhone, a CentralLite ZigBee light switch
can communicate with a Black & Decker door
lock. Architecture ZigBee protocol shown in Figure
2.
ZigBee is widely used in the market for
ZigBee has many advantages, such as [7]:
• Reach 1 meter - 100 meter.
• ISM (Industrial, Scientific and Medical) radio bands: 2.4 GHz, 868 MHz and 915
MHz.
• Low power consumption.
• CSMA-CA channel access.
• Large networks (65,000 nodes)
• Highly secure (AES encryption)
• Network topology star, mesh and mutual support various applications.
• Interoperability across the world with other products
• Co-existence with other wireless media (eg, WLAN, Bluetooth, cellular).
Figure 2. ZigBee Architecture
The process of sending and receiving data on
ZigBee. Using standard ZigBee network to transmit
data specified by IEEE 802.15.4:
• Request data means the data transmission
• Data Confirm means the knowledge of the data request
• Data Indication means receiving data
2.2. System Design
The system is designed as shown in Figure 3.
Figure 3. Block Diagram System Designed
The leader robot consists of an Arduino [8]
microcontroller as the center of all the systems, and
manages all activities of the input/output system. Sensor system which uses ultrasonic sensors
functions as sensors obstacle in order that the robot
can move well. Motion system using a DC motor
driven with L298 Shield with maximum current
2A. Communication systems use Xbee Module
with DFduino as connections between Xbee Shield
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and the Arduino microcontroller. This
communication function for communication
between leader robot and follower robots. As for
the follower robots not have a sensor system. The
movement of the follower robot just follows the leader robot by receiving commands via Xbee
modules.
2.3. Forms of Robot Communication
Leader robot sends request signal to the
robot and follower robot and the follower robot
transmit acknowledgment signals and handshaking
occurs, and then the leader robot send command,
so that follower robot follow orders. So the
follower robots will follow all movements of the
leader robot. Form of communication robot leader
and follower robots is shown in Figure 4.
Figure 4. Form of
Figure 4. Form of communication between leader and follower
robots
3 RESULTS
Overall system is made with a pair of shields
according to function. Arduino is located at the
very bottom and the motor shield L 298 is on
arduino after the XBee shield and XBee module
are on the top right on the XBee Shield. The
compilers of a series or robot are obtained. Its shown in Figure 5 as a series when it is released
from the composition of robot and Figure 6-7 is the
overall picture of the system.
Figure 5. The series of robots that have not been installed
Figure 6. The series Robot
Figure 7. The entire system
At this signal measurement spectrum
analyzer are set according to the specifications of the XBee signal with a frequency range of 2.4 GHz
marker around 2419.25 GHz and a frequency range
between 2400 and 2440 MHz spectrum and level of
-100 dBm. Transmitter signal form the leader is
shown in Figure 8.
Figure 8. Transmitter signal form the leader
From the results of measurements of the spectrum
analyzer are shown in transmitter signal power
level leader, it is Maximum -81 dBM and -97.4
dBM. The interaction between the leader and the
follower is shown in the Figure 9.
Communication system
XBee Module
Leader
Robot Folllower
Robot
Communication system
XBee Module
Request
Acknowledment
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Figure 9. Forms signaling interactions between
Table 1 are the results of measurements of transmit
power (power level) signal transmitter XBee leader
based on the distance traveled.
Table 1 The results of measurements of the signal power level
Xbee
Distance (meter) Power Level (dBm)
1 -80
2 -80
3 -82
4 -90,4
5 -86,9
6 -91,9
7 -91,4
8 -86,8
9 -90,3
10 -89,5
12 -99,1
Average -88,02
From Table 2 it can be explained that the farther the
distance, the smaller the signal power level. From
the results of measuring the power level can be
displayed in graphical form as shown in Figure 10.
This measurement is performed in the space in the
Lab.Tehnik Electro VII.
Figure 10. Graphics power level XBee transmitter signal
Based on the graph it can be concluded that the
further the distance, the smaller the power level. It
means that the distance also affects the
communication between the robot so it will affect
system performance.
Based on some experiments it can be said
that the leader and the follower robots can communicate with a maximum distance of 11
meters. Robots are not the connected at a distance
of 12 meters because of the low power level that is
-99.1 dBm. Based on the specifications XBee is
shows the minimum receiver sensitivity -92 dBm
so that if the price is less than -92 dBm, the signal
can not be captured by the XBee receiver on the
follower.
Another experiments measuring time
required to make communication between the
leader and the follower so that everything started to move. It aims to determine the speed of the robot
performance in receiving orders and execute it.
Table 2. Results of measuring the communication
time leader and follower
Experiment Duration process the
communication
between the follower
and leader
1 11
2 10
3 11
4 11
5 12
6 13
7 15
8 13
9 15
10 15
average 12,5
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From the measurement results in Table 2 that the
communication between the leader and the follower
robots takes 12.5 seconds. These measurements do
not take up the position between the leader and
follower robots. The experiments were conducted to
determine the performance of signal XBee outdoor
and environmental influences on the robot XBee
signal. The experiments were done at the of
Electrical Technical of Mercu Buana University.
These test results are shown outdoors on a Table 3.
Table 3. Test results XBee communication outdoors.
From the results of Table 3 it can be said that the
ability to capture the signal from the transmitter
transceiver is only up to 5 meters and more than worth the transceiver is not able to capture the
signal.
4 CONCLUSIONS
Robot communication system designed
able to work well in indoor and outdoor as well. Based on experiments results it can be concluded
that the experimental signal indoors can be
connected properly to a distance of 12 meters. The
average power level of the signal up to a distance of
12 meters is -88.02 dBm. The average time need to
make communications between leader and follower
robot is 12.5 seconds. Unfortunately, in outdoor
experiments transmitter receiver can catch the
signal well only up to 5 meters.
REFERENCES
[1] Labiod, H, Afifi, H. And De Santis, C. (2007).
WiFiTM, BluetoothTM, ZigBeeTM, And WimaxTM,
Netherlands, Springer.
[2] Stalling, W. (2005). Wireless Communications
And Network, 2nd Ed., USA: Pearson
Education, Inc.
[3] Garg, Vijay K. (2007), Wireless
Communications And Networking, USA: Elsevier Inc.
[4] Parker, Lynee E. (2002). Current Research in
Multi Robot System. Paper presented at The
Seventh International Symposium on Artificial
Life and Robotics, Oita, Japan.
[5] Parker, Lynne E.(2008), Distributed
Intelligence: Overview of the Field and its
Application in Multi-Robot Systems, Journal Of
Physical Agents, Vol. 2, No. 1, March 2008.
[6] Mataric Gerkey, And Brian P. (2001).
Principled Communication fo Dynamic Multi-
Robot Task Allocation, In Experimental Robotics VII, LNCIS 271D. Rus and S. Singh,
editors, pages 353-362. Springer-Verlag Berlin
Heidelberg.
[7] Gislason, Drew ( 2008 ). Zigbee Wireless
Networking, USA: Elsevier Inc
[8] Simon, Monk (2010). 30 Arduino Projects for
the Evil Genius. United States of America: Mc
Graw-Hill.
experiments distance between
leader and
follower robot
(meter)
Status
1 1 connected
2 2 connected
3 3 connected
4 4 connected
5 5 connected
6 6 no
7 7 no
8 8 no
9 9 no
10 10 no
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