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SELF-POWERED WIRELESS SENSOR NETWORK FRAMEWORK TO MONITOR BIN LEVEL 295
SELF-POWERED WIRELESS SENSOR NETWORK FRAMEWORK
TO MONITOR BIN LEVEL
S. R. Jino Ramson, Asst. Professor, Dr. D. Jackuline Moni, Professor,
A. Alfred Kirubaraj, Asst.Professor, S.Senith, Assistant Professor
Dept. of ECE, Karunya University, Coimbatore-641114, INDIA
jino@karunya.edu
ABSTRACT
Development of an application of Wireless Sensor Network (WSN) powered by solar energy
harvesting system to monitor the unfilled level of bins through central monitoring system is pre-
sented in this paper. The nodes called Solar Powered Wireless Monitoring Unit (SPWMU) are
installed in each and every bin and the sensor present in the SPWMU measures the unfilled
level of the bins and transmit the data to the Solar Powered Wireless Access Point Unit
(SPWAPU). The SPWAPU receives data from the SPWMU’s and sends the data to the central
monitoring station through a gateway and the level of the bins are monitored by using graphical
user interface. The difference between experimental data and manual data have been evalu-
ated, also battery charging time and life expectancy of SPWMU have been estimated. It is
found that battery takes 6.26 hours to get fully charged and the charge will long last for 27 days
17 hrs. Even in worse cases like rainy days, the unfilled level of bins can be monitored perfectly
without any interruption.
Keywords: Solar powered, Bin, Solid waste management, Remote monitoring, Wireless Sen-
sor Networks
INTRODUCTION
Wireless sensor Networks (WSNs) are highly promising
outfits in the field of remote monitoring [1]. Several monitor-
ing systems have been implemented by using WSN [2-3]
such as Solar Powered Aquatic environment monitoring [4],
On-board monitoring of Railway Freight Wagons [5], Cattle
health monitoring [6], monitoring an ozone sterilizer [7],
monitoring radioactive materials [8], smart medication sys-
tem [9] and so on. Solid waste management is one of the im-
portant applications of WSN. Solid waste management is the
process of collecting, shipping, treating and disposing of
waste material. Improper handling of solid waste leads to
unsanitary conditions and this can create environment pollu-
tion and diseases. The responsibilities of handling solid waste
present complex technical encounters. The critical issues in
handling solid wastes are, if solid wastes are scheduled to
collect in daily basis, in case if the bins are unfilled, then it is
wastage of time, fuel and manpower, and if the solid wastes
are scheduled to collect in weekly basis, in case if the bins
overflow, it spreads around the area, producing illness to the
peoples and pollutes the environment [10-12]. Remote moni-
toring system using wireless sensor networks resolve the
above said critical issues and provide a clean environment.
Several existing bin level monitoring systems have been im-
plemented by using Radio Frequency Identification (RFID)
technology [13] - [15]. It uses RFID, Global Positioning Sys-
tem (GPS), General Packet Radio Service (GPRS) and Geo-
graphic Information System (GIS) along with camera tech-
nologies. All these have been integrated and mounted in bins
and truck. Low cost cameras are mounted on the top of the
truck in order to catch images and the images are transmitted
from the truck to the designated server through GPRS con-
nectivity. Then the level of bins have been determined by
296 JOURNAL OF SOLID WASTE TECHNOLOGY AND MANAGEMENT VOLUME 43, NO. 4 NOVEMBER 2017
using image processing techniques. The crucial problems of
RFID technologies are, in order to measure bin level, the ve-
hicle has to move around and snap images of each bin, dead
areas and orientation problems, security concerns, ghost tags,
proximity issues, unread tags and vulnerable to damage easi-
ly. Wireless sensor network overcomes the above said issues.
Only two works have been reported so far by using WSN [3].
[16] and [17] presents bin level monitoring by using WSN. In
[16], the deployment of WSN is not clearly mentioned and no
practical results were provided, and [17] shows the deploy-
ment and evaluation of wireless links but the sensor nodes
run with battery power which will last long around 28 days
for 1000 mA*h batteries. Also, a computer is needed to send
data for remote monitoring. This paper presents a WSN
framework with solar energy harvesting which will overcome
the above-mentioned issues. The rest of this paper is orga-
nized as follows. Section 2 shows system description, Section
3 gives the results and discussion and the paper is concluded
in Section 4.
SYSTEM DESCRIPTION
Figure 1 portrays the WSN framework proposed in this
article. The proposed self-powered WSN framework mainly
consists of SPWMU, SPWAPU, Router, and Graphical User
Interface. The SPWMU is fitted in every bin, which measures
the unfilled level of bins and transmit the data to SPWAPU.
The SPWAPU collects all the data from the SPWMU’s and
sent the data to the central monitoring station or Municipal
Corporation through the wireless router. By using Graphical
User Interface, the unfilled level of every bins will be dis-
played accurately in a laptop or mobile. The description and
installation of SPWMU, SPWAPU, Router and Graphical
User Interface are discussed in this section.
SPWMU
SPWMU mainly consists of an ultrasonic sensor, an
eZ430-rf2500 end device board, batteries and solar panels.
The installation of SPWMU into the bin is shown in the Fig-
ure 2 and the block diagram of SPWMU is shown in the Fig-
ure 3. The sensor used in this remote monitoring system is an
ultrasonic sensor, which is fabricated into the bins to measure
the unfilled level. The sensor includes ultrasonic transmitter,
receiver and a control unit. It offers excellent non-contact
range detection with high accuracy and stable readings with a
range from 2 cm to 400 cm. It consists of 4 pins specifically,
trigger, echo, Vcc (5V) and Gnd. This sensor is directly con-
nected to the digital input/output lines of the MSP430F2274
microcontroller. A pulse of high (5V) with a time period of at
least 10 microseconds is applied to the trigger pin, this will
generate the sensor to transmit out 8 cycles of ultrasonic burst
at a frequency of 40 KHz. This ultrasonic burst hits the waste
which is present in the bin and reflected back. The echo pin is
set to high (5V), when the sensor detected ultrasonic from the
FIGURE 1
Scenario of Self-powered WSN framework
SELF-POWERED WIRELESS SENSOR NETWORK FRAMEWORK TO MONITOR BIN LEVEL 297
receiver. The unfilled level is calculated by using the simple
formula
Time
Unfilled level in centimeters = (1)
58
Where, Time is the width of echo pulse in microseconds [18].
The RF network end device board used in this remote
monitoring system is commercially available Texas Instru-
ment’s eZ430-rf2500 board, which mainly comprises an ul-
tra-low power consumption microcontroller (MSP430F2274)
and a radio device (CC2500). The microcontroller includes a
16-bit RISC (Reduced Instruction Set Computing) CPU, 16-
bit register10-bit A/D converter, data transfer controller
FIGURE 2
Implementation of SPWMU
FIGURE 3
Block diagram of SPWMU
298 JOURNAL OF SOLID WASTE TECHNOLOGY AND MANAGEMENT VOLUME 43, NO. 4 NOVEMBER 2017
(DTC), two general purpose operational amplifiers and 32
input/output pins. The digitally controlled oscillator (DCO)
which is present inside the controller is used to wake-up the
controller from low power modes to active modes in less than
1µs. The radio device CC2500 is a low-cost, low-power con-
suming 2.4GHz RF transceiver which is designed for low-
power consumption devices. This device is used to transmit
the data from SPWMU to SPWAPU. Once the SPWMU is
initialized, it searches for SPWAPU to connect. Upon discov-
ery of an SPWAPU, the SPWMU attempts a network link.
Once the link is successfully established, a message array is
created in SPWMU to store the unfilled level of bins. Now
the radio device in the SPWMU goes to ON state. SPWMU
waits for an acknowledgement (ACK) from the SPWAPU to
transmit the data. Once the ACK is received, the created mes-
sage buffer is divided into packets for data transmission.
SPWAPU receives all the packets from SPWMU through
polling method [19]. The microcontroller MSP430F2274 uses
SimpliciTI protocol to control the packet transmission from
SPWMU to SPWAPU. SPWAPU sends an ACK to SPWMU
to stop the transfer. On receiving the ACK, the radio device
CC2500 goes to OFF state. An unconditional loop at the end
of the program makes the flow to shift at point where the
unfilled level value is stored in the message buffer. The proc-
ess takes place in the SPWMU is stated in the Figure 4. Now,
the process of sending ACK, dividing message into packets is
repeated till the SPWPU is powered OFF [20].
SPWAPU
Figure 5 shows the block diagram of SPWAPU. It con-
sists of a RF network access point board which is also an
eZ430-RF2500 target board, used in the receiver mode and a
simple link Wi-Fi device CC3200. The SPWAPU searches
for SPWMU device to receive data packets. When it detects a
SPWMU, it assigns a linkID. After assigning a linkID it es-
tablishes a connection for reception of the packets. A mes-
sage buffer is created in SPWAPU to store all the data re-
ceived from SPWMUs. SPWAPU process all the data packets
received through the channel. Once the process is completed
the connection with SPWMU for transmission of data packets
is terminated.
FIGURE 4
Flow chart of SPWMU
SELF-POWERED WIRELESS SENSOR NETWORK FRAMEWORK TO MONITOR BIN LEVEL 299
The process takes place in the SPWMU is stated in the
Figure 6. All the received data packets are processed in the
SPWAPU and are sent to CC3200 simple link Wi-Fi device
through an UART backchannel [18]. CC3200 module is a
wireless network processor from Texas Instruments that
shortens the implementation of internet connectivity and in-
FIGURE 5
Block diagram of SPWAPU
FIGURE 6
Flow chart of SPWAPU
300 JOURNAL OF SOLID WASTE TECHNOLOGY AND MANAGEMENT VOLUME 43, NO. 4 NOVEMBER 2017
tegrates a high-performance ARM cortex-M4 microcontrol-
ler, runs at 80 MHz. Once CC3200 is initialized, it will be
connected to router (TP-Link TL-MR3020 Wireless Router).
The values which were stored in CC3200 will be sent to the
monitoring station. An unconditional loop at the end of the
program makes the flow to move at point where the empty
level value is kept in the message buffer.
Graphical User Interface
The graphical user interface uses Microsoft C# program-
ming language based on .NET architecture which is shown in
the Figure 7. The SPWAPU’s are connected to remote moni-
toring station through client server TCP connection. CC3200
acts as client and remote monitoring PC acts as server. Once
the client socket is opened, PC will be connected with server
by means of IP and port number. Now the unfilled level will
be sent to the client. Once the values are sent, the client
socket will be closed. The process takes place in server side
which opens the socket, creates a TCP server, listens for con-
nection, accepts a connection, receives packets and closes the
socket.
RESULTS AND DISCUSSION
Experimental reading vs Manual data
An experiment has been conducted to evaluate the differ-
ence between experimental reading and manual data. The
unfilled level received from the sensors through wireless
router is continuously monitored using the graphical user
interface and the results obtained are displayed and discussed
in this section. One time every second, the sensor unfilled
level is received from the TCP connection and all the bins are
mapped to their sensor unfilled value. Considering the bin
levels and the maximum unfilled levels of the bins, the plat-
form maps each bin to a colour code depending on the level
to which the bin has been filled. The extreme value of the
bins used in this experiment is 59.6 cm. The threshold levels
used in this experiment is presented in the Table 1.
FIGURE 7
Screen shot of Graphical User Interface
TABLE 1
Threshold levels
UNFILLED LEVEL (cm)
FILLED AREA COLOUR
STATUS
Unfilled level=59.6
Green
Empty
Unfilled level >50
Green
Lightly Filled
15< Unfilled level <50
Orange
Partially filled
Unfilled level <15
Red
Almost full
SELF-POWERED WIRELESS SENSOR NETWORK FRAMEWORK TO MONITOR BIN LEVEL 301
The Main window of the program displays entire regions
representing the entire bins in the bin level remote monitoring
system. The colour of the home screen is mapped to the col-
our of the bin with the lowest unfilled level. Here the unfilled
value of bin 1 is 10.8cm which is less than 15 cm. Hence, if
any one of the bins is in the almost full or unfilled level<15
cm, the display on the home screen shows a red colour coded
building draws immediate attention to the status of the system
as almost full to the waste collector which is exposed in the
Figure 8.
The region image which is shown in the Figure 9 also
serves as a progress bar that shows the average level of all the
bins on the system. When the user clicks main window, a
new window is displayed which shows a number of regions,
each mapped to each region under the bin level monitoring
system which contains bins fitted with the application sen-
sors. Each region icon is colour coded to show the level of
their constituent bin with the lowest unfilled level. In Figure
10, the colour code of region labelled as region 1 is red, since
the unfilled level value of bin 1 is 10.8 cm. Regions labelled
as region 2 and region 3 are orange colour since the unfilled
level values of the sensors are greater than 15 cm and region
labelled as region 3 is green in colour because all the unfilled
level values of the sensors are above 50 cm. Therefore, if all
the bins under a region are in the safer level, the colour of
region icon will be green. If anyone of the bins is nearly filled
status, the colour code of the building will instantly change to
red colour. The region icons also serve as a progress bar dis-
playing the average value of bins that are under the specific
region. When the user clicks a region icon, the application
opens up another window that displays all the bins that are
under the specific region. The bins show the exact level of
their sensor inputs and are also colour coded according to its
unfilled level values of the sensor. When the user soars his
mouse over bin 1 of the bins, the deployed system displays a
label that shows present unfilled value as 10.8 cm. In this
way, the waste collector can monitor the level of each bin
from a remote central station using the bin level monitoring
system. From the graphical user interface, the readings of bin
1 is noted at different levels and equated with the manual data
is shown in the Figure 11. Figure 11 clearly shows the
difference between the manual data and the automated system
readings. The difference between the experimental and
manual data ranges from 0.2 cm to 0.9 cm, since the surface
level of waste present in the bins.
Energy Requirement
The total energy required for SPWMU in sleep mode and
active mode for 24 hours is calculated as 17.3009 watt-hour.
The battery which is used to power up the SPWMU is Came-
lion Nickel Cadmium of 1000 mAh, 1.2 Volts x 4 numbers
and the size of the solar panel which is used to charge up the
FIGURE 8
The graphical user interface displaying overall levels of bin
FIGURE 9
The graphical user interface displaying overall status
of each region
FIGURE 10
The graphical user interface displaying status
of each bin in region 1
302 JOURNAL OF SOLID WASTE TECHNOLOGY AND MANAGEMENT VOLUME 43, NO. 4 NOVEMBER 2017
battery is 2 Watts. An experiment was conducted to find the
battery charging time, and it is plotted in the Figure 12. From
the figure 12, it is found that the total time taken to charge the
battery is 6.26 hours (11.40 am to 6.06 pm) and the maximum
current produced by the solar panel is 310 mA and the maxi-
mum voltage is 6.19 Volts.
Figure 13 shows the power supplied by the solar panel for
different instants of time. From the figure 13, it is observed
that the maximum power of 1.8662 watts is supplied by the
solar panel. Once the battery is fully charged (charging time-
6.26 hours), according to the calculation of life expectancy
[17], the charge will long last for 27 days 17 hrs. Even in
worse cases like rainy days, the unfilled level of bins can be
monitored perfectly without any interruption.
WSN performance, Wireless Link Quality,
Maximum distance data transmission
The metrics related to WSN performance such as maxi-
mum throughput, packet error rate, delay, and metrics related
to wireless link quality such as Received Signal Strength In-
FIGURE 11
Experiment data versus Manual data
FIGURE 12
Battery charging current versus Time
SELF-POWERED WIRELESS SENSOR NETWORK FRAMEWORK TO MONITOR BIN LEVEL 303
dicator (RSSI) and Link Quality Indicator (LQI) have been
analysed in [17]. From the experiment, it is observed that
Packet Delivery Ratio (PDR) values lies between 98.12 to
99.24 for RSSI values from -87 to -73decibels (dBm). Also, it
is observed that PDR lies between 98.12 and 99.24 for Link
Quality Indicator 223 and 237.The metrices RSSI and LQI
clearly proves that excellent link (PDR more than 98%)
which can be achieved when RSSI value is -87 dBm and the
LQI value is 223. The excellent link quality between
SPWMU and SPWAPU is achieved (PDR=99.24) when the
RSSI value becomes -73dBm and LQI value becomes 237.
Also, the maximum distance of data transmission between
SPWMU and SPWAPU is found as 27 meters of diameter
[17]. From the experiment, it is found that additional area of
more than 27 meters of diameter needs additional installation
of SPWAPU results in the movement of bins in bigger envi-
ronment.
CONCLUSION
An application of Wireless Sensor Networks to monitor
the unfilled level of bins through a remote central monitoring
system has been designed and studied. Two important ex-
periments have been carried out in this solid waste bin level
remote monitoring system. Firstly, the remote monitoring
system has been deployed and evaluated the difference be-
tween system reading and manual reading, which is found to
be 0.2 cm to 0.9 cm due to surface level of waste present in
the bin. Secondly, battery charging time and life expectancy
of SPWMU have been calculated and the battering charging
time found as 6.26 hours and observed that the charge will
long last for 27 days 17 hours. Even in worse cases like rainy
days, the unfilled level of bins can be monitored perfectly
without any interruption.
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