Developing an Intelligent Waste Sorting System with Robotic Arm : A Step towards Green Environment

Abstract

Waste management as well as sorting is a very crucial task to make the environment green and to ensure better (re)use of the resources. Bangladesh, because of its high density population, is facing enormous challenges to manage huge amount of wastes produced every day. So the purpose of this paper is to use the advancement of Information and Communication technology (ICT) to improve the waste management system and make lives better by providing a smarter way for waste sorting and management. In this paper, an intelligent system was proposed and developed for automatically sorting the waste to be used in context of Bangladesh. A light weighted experiment was carried out to evaluate the system performance. The experiment replicated with 11 objects (waste) of different size and types. The experimental results showed that the proposed system was reliable and achieved about 82% accuracy for the categorization of different kinds of waste.

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International Conference on Innovation in Engineering and Technology (ICIET) 27-29 December, 2018
Developing an Intelligent Waste Sorting System
with Robotic Arm : A Step towards Green
Environment
Sadia Zahin Diya1, Rifat Ara Proma2, Muhammad Nazrul Islam, Tasmiah Tamzid Anannya,
Abdullah Al Mamun, Rizvi Arefeen, Saifullah Al Mamun, Ihtiaz Ishmam Rahman, Md Fazle Rabbi
Department of Computer Science and Engineering
Military Institute of Science and Technology
Mirpur Cantonment, Dhaka -1216, Bangladesh
Email: 1sadiazahin@yahoo.com; 2proma.ayuzawa96@gmail.com
Abstract—Waste management as well as sorting is a very
crucial task to make the environment green and to ensure
better (re)use of the resources. Bangladesh, because of its high
density population, is facing enormous challenges to manage huge
amount of wastes produced every day. So the purpose of this
paper is to use the advancement of Information and Communica-
tion technology (ICT) to improve the waste management system
and make lives better by providing a smarter way for waste
sorting and management. In this paper, an intelligent system was
proposed and developed for automatically sorting the waste to be
used in context of Bangladesh. A light weighted experiment was
carried out to evaluate the system performance. The experiment
replicated with 11 objects (waste) of different size and types.
The experimental results showed that the proposed system was
reliable and achieved about 82% accuracy for the categorization
of different kinds of waste.
Keywords—Waste sorting, sensor, robotic arm, automation,
green environment
I. INTRODUCTION
Waste materials can be classified in different categories
based on their re-usable functionality [1], that includes, (a)
recyclable waste like paper, metal, plastic, glass, cardboard
are used to recycle and reuse; (b) organic waste are used to
make compost for agriculture; and c) non-disposable waste are
not reusable and need to be buried as these are harmful for
the environment. To ensure the better use of these resources,
to promote the cost-effective production and cultivation, and
finally to make the environment green, it is utmost important
to categories and manage the wastes in to different category.
Waste sorting contributes to recycling and saving energy.
The Aluminum Association [2] estimates that the energy saved
in recycling a single aluminum can, could be used to power a
television for 3 hours. Creating new plastic from raw materials
requires ten times more energy than the energy needed for
recycling plastic [3], [4]. Environmental Protection Agency
[5] estimates that producing a paper product from recycled
paper requires only 60 percent of the energy required to create
one from fresh wood pulp. Energy Administration Information
[6] reports that recycling a ton of paper can save 17 trees.
However, due to lack of any efficient way of sorting the waste,
most of the recyclable products are wasted. This turns out to
be very harmful for the environment in the long run.
However, in context of Bangladesh, a huge amount of waste
materials are generated every day due to its high population
density that have a population of approximately 163 million
people [7]. To manage these huge waste materials properly,
no effective and innovative means are used. Everyday a vast
portion of effort and resource of Dhaka City Corporation is
invested for properly collecting and processing waste. More-
over, sorting these wastes in to different kind of wastes are
crucial challenge to green the environment of Bangladesh; as
because, waste materials that are dumped in the landfill creates
bio-gas that mainly contains methane gas (CH4) which is
approximately 30 times more overpowering as a heat-trapping
gas than Carbon dioxide (CO2) [1], [8]. It is also harmful
for the water body that are around the landfill. Again, waste
generation in Bangladesh is increasing vigorously and it is
expected to reach 47, 064 tonnes per day by 2025. The total
waste collection rate in major cities of Bangladesh such as
Dhaka is only 37% [9]. Which is much less than what it
should be. Such poor management system can cause health
hazard and major damage to the environment. In Bangladesh,
thus a system of sorting waste materials to reuse or recycle
may help to save a lot of space, person-effort, air-pollution,
land-pollution, and money; which in turn may lead Bangladesh
to move a step forward towards making greener environment.
Therefore, the objective of this project is to develop an efficient
automatic system to sort out different kinds of waste to make
the environment greener.
The other sections of this paper are organized as follows.978-1-5386-5229-9/18/$31.00 © 2018 IEEE

The work focusing to waste sorting and management are
presented in section II. The conceptual design of the proposed
system is discussed in section III. Section IV presents how the
system was implemented followed by discussion on system
evaluation. Discussion and concluding remarks are presented
in section VI.
II. RE LATE D WOR KS
This section briefly summarizes the work related to waste
sorting and management. In 2016, Williams & Bentil [10]
introduced and implemented an automatic waste management
sorting unit using micro-controller. In this design they suc-
cessfully sorted organic and inorganic waste materials. To do
this they used gas sensor which sent data to micro-controller
and using this data garbage was differentiated and used in
a recycling plant later on. Another work was conducted by
Elfasakhany et al. [11] on an autonomous system capable of
sorting common recyclable materials, namely ferrous and non-
ferrous metals, plastic and glass into distinct waste containers.
A micro-controller combined the interfaces of all the system
components using programming to control all the system
actions.
Authors presented the results of a survey in their paper
which showed three alternative methods to sort wastes from
building construction site were presented in [12]. Construction
wastes typically consists materials like timber, plaster, iron,
cement, plastics etc. Thus, such system will not be useful
for detecting daily household wastes which includes a large
amount of organic materials. Lukka et al. [13] in 2014,
presented a recycler called ZenRobotics Recycler. This robot
could pick up wastes from construction and demolition (CND)
sites and put it on a conveyor belt. It could sort between wood,
stone and metal without any human sorter through machine
learning.
Paulraj et al. [14] proposed an algorithm to detect waste
material from an image (captured by thermal imaging camera).
A robot was also developed which was equipped with a
thermal imaging camera, a proximity sensor and a 5-DOF
robotic arm. In another work [15], visual features were used
as sorting criteria. In such case, optical sensor and laser beam
were used to detect materials based on their shapes, colors
and textures and mechanical methods to perform sorting.
A technology based on optical identification of fluorescence
signature was developed by Ahmad [16] in his work. The
system was capable of tracing and identifying different kinds
of plastic materials using three commercial tracers. However
sorting any other kind of material was out of its scope.
Chahine & Ghazal [17] designed and developed an auto-
mated waste sorting system with the use of an inductive prox-
imity sensor, a capacitive proximity sensor and a photelectic
sensor. Ang et al. [18] developed automated waste sorter in
2013, which had a mobile robot delivery system. The system
included a line follower robot which could pick up waste and
drop it on a trash can. The system was successful in collecting
the garbage with more than 80% accuracy.
Another system was developed by Russel et al. [19] which
could sort metal, paper, plastics and glass. For sorting metal
and glass conventional sensors were used and for sorting paper
and plastics a sensor using LASER and LDR was developed.
A weight sensor and counter was also there to find out the
amount of sorted materials.
In summary, though a number of system has been developed
for waste sorting or management but these are costly, required
high skill to operate and maintain, focused to specific kind
of waste, and developed mainly for developed countries. In
Bangladesh, no such technology is available to sort the huge
amount of waste cost-effectively, efficiently and effectively.
Even though studies have been conducted in Bangladesh con-
text, there is still no practical implementation. This research
thus aiming to developing an automatic waste management
system considering the economical and contextual situation of
Bangladesh.
III. CONCEPTUAL DESIGN
A conceptual design to develop an intelligent automated
waste sorting system is discussed here. The proposed system
would have a number of features to overcome the limitations of
existing system used in Bangladesh. The features may include
the following:
1) Developing a robotic arm that will pick up garbage from
garbage bin and then put it on a conveyor belt. This part
of the system will let people not to touch garbage by
their hand.
2) The system will be capable to sort different types of
wastes in different baskets basing on their type.
3) A mechanism which will be used to differentiate among
different types of waste materials namely plastic,organic
and metal objects.
4) The system will also include a database that keeps track
of different types of materials that have been detected in
a period of time. This database will help to keep track of
how many items are segregated. This data can be useful
in recycling.
5) Apart from this, a mobile app will be developed to
operate the robotic arm easily and remotely.
A flow diagram to represent how the system may work is
showed in Figure 1. The system will start using a mobile app
that will trigger robotic arm to pick garbage from a container
and put it on the detection system to identify its type. The
sensors in the detection system will detect the object. Then
the objects will be classified between metal, plastic, organic
and others based on the sensors output. Depending on the type,
a rotating surface will rotate and bring the appropriate bucket
in front of the conveyor belt. After that, the object will be
dropped in its respective container at the end of the conveyor
belt.
IV. IMPLEMENTATION
The proposed conceptual design as discussed in earlier sec-
tion is materialized as depicted in Fig 2. The brief description
of developing each module are presented below:

Fig. 1. Flow chart of the proposed system
The system includes a robotic arm which is operated by
a mobile app. The structure of the robotic arm is made of
stainless steel. The joints of the arm functions with the help
of servo motor. The mobile app is basically an android app.
Java programming language was used to develop the app. This
allows to operate the servo motor of the arm, using a Bluetooth
module. The robotic arm is showed in Fig 3 and the user
interface of mobile app is showed in Fig 4. The mobile app
is created using MIT App Inventor and it supports android
version 2.1 and above.
The detection module includes three sensors- inductive,
voltage and IR (Infrared Ray) sensor to detect and differentiate
between different waste materials. The inductive sensor is ba-
sically a proximity sensor which detects only metallic objects.
It’s working principle is dependent on a coil and oscillator.
An electromagnetic field is created in the near surroundings
of the sensing surface by the coil and oscillator. A metallic
object in the operating area reduces the oscillation amplitude.
The rise or fall of such oscillation is identified by a threshold
Fig. 2. Block diagram of the proposed intelligent waste sorting system
Fig. 3. Robotic Arm
circuit that changes the output of the sensor. From the rise
or fall of the oscillation amplitude that is measures against a
threshold, the output of the sensor is determined. Thus with
the help of this sensor all the metallic objects are separated.
Differentiation between plastic and organic objects was done
by voltage sensor. Two aluminium foil strips were used to
provide voltage to the object as showed in Fig 5. The input
portion of inductive sensor was in between two foil strips so
that the object touches all of them together. As it is known that

Fig. 4. User interface of the mobile application
plastic is non- conductive element, no voltage will be passed
through it. That is why, output of the voltage sensor will be
zero. On the other hand organic objects are conductive. So
voltage will pass through it and output of the voltage sensor
will be a non zero value. The IR sensor is used to detect
the presence of any object on the detection system. When the
output of this sensor is high, the system starts detecting the
object type.
Fig. 5. Sensors used in the system
Conveyor belt and the garbage bins are the last module of
this system. Fig 6 shows the implemented conveyor belt. With
the help of two gears and a DC motor, rotation of the conveyor
belt was achieved in a downward motion. This allowed to
transfer the waste material in a bin depending on its type.
A servo motor was attached to a circular surface containing
different colored containers. Basing on the type of material, the
circular surface rotated and placed a specific colored container
Fig. 6. Conveyor belt
at the end of the conveyor belt allowing the waste to fall in it.
Along with this the total count of different types of elements
were saved in a text file. This file was written from the serial
output of the Arduino Uno. Whenever an item was detected
it was updated in the text file showing the latest amount of a
specific type of element.
V. SYS TE M EVALUATI ON
The developed system was evaluated in an academic en-
vironment at Software Engineering laboratory of authors’
institute. To evaluate the effectiveness and efficiency of the
system, 11 types of items(waste) of different dimensions were
passed through the system for sorting into different types. The
outcomes are presented in Table 1. The results showed that 9
out of 11 items were detected accurately, i.e. the accuracy of
that system was 81.8%. The results also showed that when
given an object that was mixed with two or more elements,
the detection was not accurate. Also in case of voltage sensor,
sometimes for metal detection, it did not give correct results,
which was not observed with the inductive sensor as it gave
only 1 or 0 as output.
The output of the voltage sensor is showed in Fig 7. In
case of organic materials, the voltage sensor output fluctuates,
for reading 1, it was 3.39 volts and for reading 2 it was 2.01
volts, reading 3 it was 1.32 volts and so on. But for plastic
and metal, the output curve was almost constant around 5.00
and 0.00 volts respectively. However, preference was given to
the inductive sensor while detecting metal objects.
VI. DISCUSSION AND CONCLUSION
In this paper, an intelligent waste sorting system is designed
and developed to segregate three different types of materials.
Whenever an object is put on the detection unit the IR sensor
detects the presence and readings of inductive sensor and
voltage sensor are considered. This reduces the possibility
of unnecessary rotation of the servo motor which rotates the
bucket carrier disc. As sensors are sensitive, it is possible
for them to give a value even when there is no object to be
identified. The robotic arm moves in such a pattern so that

TABLE I
OUTCOME OF THE EVALUATION STUDY
Item No Object Type Dimension(cm2)Voltage Sensor(Volts) Inductive Sensor IR Sensor Detected Type Success
1 Aluminium Foil Metal 6x6 4.91 1 1 Metal Yes
2 Watermelon Organic 6x1.5 3.39 0 1 Organic Yes
3 Bottle Cap Plastic 5x5 0.00 0 1 Plastic Yes
4 KeyRing Metal 3.5x3.5 5.01 1 1 Metal Yes
5 KeyRing Plastic 3.5x5.6 0.06 0 1 Plastic Yes
6 Badge(Metal and Plastic) Mixed 5.8x5.8 0.99 1 1 Metal No
7 Apple Organic 5x1.2 2.01 0 1 Organic Yes
8 Leaf Organic 6x3.2 1.32 0 1 Organic Yes
9 Coin Metal 2x2 5.09 1 1 Metal Yes
10 Cucumber Organic 2x1 0.99 0 1 Plastic No
11 Container Plastic 5x4 0.00 0 1 Plastic Yes
Fig. 7. Voltage sensor output
there is enough time to finish detecting the waste material and
also place the appropriate bucket in front of the conveyor belt.
All the time delays have been taken under consideration and
the system is designed accordingly.
Compared to other systems, this proposed system is made
up of less equipment and it is cost effective. Only three sensors
are used for the detection part - voltage sensor, IR sensor
and inductive sensor. None of these sensors are too expensive
which makes the detection process effective at a low cost. The
system also differs in the sense that it has a robotic arm to pick
up and drop the waste materials. This arm has the option to be
operated automatically and simultaneously it can be controlled
by a mobile app. None of the existing systems have mobile
app to control the functionality of the waste sorting system
remotely.
The research has a few limitations as well and future work
may focus to alleviate this limitations. Firstly, a high fidelity
prototype of the proposed system was developed and tested
only in an academic environment, thus future work may pursue
to develop the concrete version of the system and assess its
performance in a real environment with a large amount of
waste. Secondly, we were not able to compare our system in
terms of power, voltage or any other related metrics practically
with any other existing system. This is something we wish to
do in the future. Thirdly, the proposed system can screen and
detect only one item at a time. So there lies scope for future
improvement in this regard as well. Finally, the system can
segregate three types of elements at present, thus feature to
detect more types of waste can be included to improve the
overall performance and efficiency.
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