automatic lawn mower project report

8/16/2019 automatic lawn mower project report

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DAV INSTITUTE OF ENGINEERING

AND

TECHNOLOGY

MAJOR PROJECT REPORT

ON

AUTOMATIC LAWM MOWERSUBMITTED IN PARTIAL FULFILLMENT OF REQUIREMENT FOR THE

AWARD OF DEGREE

INBACHELOR OF TECHNOLOGY

IN MECHANICAL ENGINEERING

By

Jaswinder Singh Sodhi Roll No. 524/12

Rishabh Sahejpal Roll No. 542/12

Shanker Goyal Roll No. 544/12

Sukhdeep Singh Brar Roll No. 548/12

Under the Guidance of

Mr. Gagandeep Singh


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ACKNOWLEDGEMENT

First we would like to offer our special thanks to our guide, Mr. Gagandeep Singh

for the help and guidance given throughout the preparation and conduction of this

project.

We would like to thank our teachers in the deptt. Of Mechanical Engineering,

DAVIET for their support and guidance given for the completetion of the project.

We would like to thank our families who has always support us over the years.Their encouragement and love were really important for us in completing this

project successfully.

Last but not least, we would express my appreciation to all our friends who

supported us whether direct or in directly on this project. Their help was so

meaningful and supportive.


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ABSTRACT

An automatic lawn mower is a device or robot that help human to cut grassautomatically. Due to rapid development, many robots have turn into an

autonomous robot. In this project, an automatic lawn mower is developed with

several features such as detection of lifting, rain falls, day and night. The

movement or the path of the automatic lawn mower is based on a path planning

technique. Sensors are used to provide feedback from outside world. For this lawn

mower, Arduino UNO microcontroller is utilized as the microcontroller. Everyaction of the lawn mower is monitored by the microcontroller with the help of the

sensor. Furthermore, CATIA as CAD software was used to design the structure of

the lawn mower.


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Table of Contents

CHAPTER TITLE PAGE

Acknowledgement 2

Abstract 3

Index 4

List of Tables 7

List of Figures 8

1. INTRODUCTION

1.1 Background 11

1.2 Problem Statement 13

1.3 Objective of Project 13

1.4 Expectation from the Device 131.5 Outline of Project 14

2. LITERATURE REVIEW

2.1 Introduction 16

2.2 Background Research 16

2.3 Existing Technology 18

2.4 Disadvantages of existing technology 21

2.5 Motor and Battery Selection 22

2.6 Components 23

2.6.1 DC Motor 23


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2.6.2 Ultrasonic Sensor 24

2.6.3 Arduino UNO 25

2.6.4 Cutter 26

2.6.5 Battery 27

2.6.6 Wheels 28

2.7 Path Planning 29

2.7.1 Path Recording 29

2.7.2 Offline Programming 29

2.7.3 Joint Trajectory Programming 302.8 Computer Aided Software 30

2.8.1 CATIA 30

2.8.2 Arduino 1.0.5 IDE 31

2.9 Different Designs 33

2.10 Working of Device 34

3 Methodology

3.1 Introduction 38

3.2 Hardware Implementatation 38

3.2.1 DC Motor 40

3.2.2 Motor Controller 42

3.2.3 Sensor 443.2.4 Battery 44

3.2.5 Wheels 45

3.3 Software Implementation 46


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3.3.1 Modeling in CATIA 46

3.3.2 Programming and Algorithm 47

3.4 Summary 49

4 Results

4.1 Introduction 52

4.2 3D Model 52

4.3 Performance Factors 59

5 Project Management5.1 Introduction 63

5.2 Bill of Material 63

6 Conclusion and Recommendations

6.1 Conclusion 66

6.2 Recommendations 66

6.3 Advantages 67

References 68

Sketch 70


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List of Tables

S.No Table Page No

2.1 Summary of Arduino Microcontroller board 26

2.2 Sample Arduino Library Code 52

5.1 Bill of Materials 63


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List of Figures

S.No Figure Page No

2.1 Robomow Lawn Mower 18

2.2 Criss Cross Pattern of Robomow 19

2.3 Random Cutting Pattern of Lawnbot 20

2.4 Pattern with st. path & semi circle curves 21

2.5 Motor Calculator 22

2.6 Battery Calculator 23

2.7 DC Motor 24

2.8 Ultrasonic Sensor Concept 24

2.9 Ultrasonic Sensor 25

2.10 Arduino UNO 26

2.11 Cutter 27

2.12 Battery 27

2.13 Wheels 282.14 CATIA Interface 31

2.15 User Interface of ARDUINO 32

3.1 Research Methodology Flow 38

3.3 DC Motor 40

3.4 Motor Controller Circuit diagram 40

3.5 B/D of Arduino UNO with Motor Controller 413.6 Ultrasonic Sensor 42

3.7 B/D of Ultrasonic Sensor with Arduino Uno 43

3.8 Battery 45

3.9 Wheel 46


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3.10 Arduino UNO 48

3.11 Circuit 49

4.1 Front View 52

4.2 Top View 534.3 Bottom View 54

4.4 Side View 55

4.5 Explode View 56

4.6 Assembly 56

4.7 Base Plate Dimensions 57

4.8 Front Wheel Dimensions 584.9 Back Wheel Dimensions 58

4.10 Path of Lawnmower 1 60

4.11 Graph 1 of grass cut 60

4.12 Path of Lawnmower 2 61

4.13 Graph 2 of grass cut 61


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Chapter 1

INTRODUCTION


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1.1 BackgroundA lawn mower is a machine that uses one or more revolving blades to cut a lawn to

an even height. The blades may be powered either by hand; pushing the mower

forward to operate the mechanical blade(s), or may have an electric motor oran internal combustion engine to spin their blades. There are several types of

mowers, each suited to a particular scale and purpose. The smallest types are

pushed by a human user and are suitable for small residential lawns and gardens.

Riding mowers are larger than push mowers and are suitable for large lawns. The

largest multi-gang mowers are mounted to tractors and are designed for large

expanses of grass such as golf courses and municipal parks. But with advancementin technology and things being converted to mobile and automatic these days,

transition from traditional hand-guided or ride-on mowers to automatic electric

mowers is beginning to take place. In 2012, the growth of robotic lawn mower

sales was 15 times that of the traditional styles. It is predicted that if this growth

continues at this rate, automatic lawn mowers may even surpass the sales of

traditional lawn mowers in some places.

Automatic lawn mower is a machine that cut grass automatically. It can be stated

as a machine or robot that helps people to do cutting grass work. The automatic

lawn mower will do the cutting grass task with a preset setting by the user. Unlike

other robotic lawn mowers on the market, this design requires no perimeter wires

to maintain the robot within the lawn. Through an array of sensors, this robot will

not only stay on the lawn, it will avoid and detect objects and humans.

The concept of lawn mower started during the 19th century whereby the design of

grass cutter pulls by an animal such as cow or buffalo. This animal will pull the

grass cutter and the grass cutter will does its work cutting the grass along the way

the animal walk. Due to animal cannot work for a very long period, human start to


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reduce the usage of animal and building a machine. So various types of lawn

mower have been built over the course of time. Mostly theses have been manually

operated but corresponding to the advancing of technology, latest lawn mowers

work automatically. Sensor such as rain sensor, light sensor, ultrasonic sensor andinfrared sensor has widely been used nowadays to enable the lawn mower to be

more intelligent and work efficiently.

Automated lawn mowers have been made available to the general public for over

30 years but its widespread or public use on the other hand has been limited mainly

Due to the current costs of such devices. Existing technology sell at around £899

(INR 70000) or more (Lawn Mower Reviews, 2011) and considering the fact thatthe manual versions of these devices, the standard lawn mowers, sell at around £86

(INR 5000) (Lawn Mower Reviews, 2011). Although the cost of labor would need

to be added to that of the equipment, the latter is still a current viable and

affordable option for most consumers will benefit from.

The reason for robotic lawn mowers are an interesting area of research and work

because there are numerous real-world benefits of having a machine that

autonomously cuts grass, these include:

Aid elderly users or those with disabilities who are unable to fulfill this taskthemselves.

For users with a busy schedule and rarely find time to mow, etc. Working range is increased due to absence of main supply wires. It reduces human effort.

It is a device that can fit into just about everyone's lifestyle, therefore having a

device that costs less, whilst accomplishing the same task as the higher end models

is a great advantage in order to compete with the current market.


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1.2 Problem Statement

How can we develop an economic and friendly user automatic lawn mower?

1.3 Objective of Project

1. To build an economic automatic lawn mower.

2. To produce a user friendly automatic lawn mower.

3. To conduct and analyze the automatic lawn mower.

1.4 Expectations from the device

There are many desirable properties in this device some of which are listed as –

Should be capable of cutting the grass properly: The device should be able

to cut the grass properly as it the primary requirement of the machine. The grass

should be cut uniformly and cuts should be clean.

Should operate automatically: As the name suggests, the device should be

able to operate automatically. It shall use the sensors and microcontroller to

formulate its path and its required work.

Should be lightweight: It should be light in weight due to energy consumption

issues. Lighter is the device, lesser will be the energy required to run it and hence

more will be its efficiency.

Should work effectively in sensing the obstacles: As the device is required to

run without a human operator, it must be capable of sensing and avoiding the

obstacles in its path.


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1.5 Outline of Project

This report consists of six chapters. The first chapter introduces the project. The

background of the project is discussed. Besides that, it contains the objective and

scope of the project. Problem statement and outline of the project also mentioned

in this chapter.

Chapter Two, discusses the literature review and the related works. Some

components like sensors, micro controller etc is discussed in this chapter.

Methodology will be discussed in the Chapter Three. In this chapter, it will discuss

about the method on hardware implementation of this project. It will show how a

lawn mower will be fabricated out and also how to design the circuit connection of

the component used.

Chapter Four discusses on the result of this project. It will show the performance of

the lawn mower. Several data collection from analyzing the performance was

located in this chapter.

Chapter Five discusses on the project management. In this section, the time line of

the project flow and the budget that needed for this project was listed out.

Last but not least, recommendation and conclusion is presented in the last chapter.

In this chapter several recommendation were pointed out in order for further

development of this project.


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Chapter 2

LITERATURE REVIEW


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2.1 Introduction

This chapter studies various fields that are used for development of an automatic

lawn mower. Components such as power motor, ultrasonic sensor, battery used in

this project are discussed. These include software such as CATIA and Arduino

1.0.5 IDE which are used for design and programming. Several techniques for

robot routing are also presented in this chapter.

2.2 Background Research

1. Design and Implementation of Autonomous Lawn Mower Robot Controller

This paper basically focuses on designing an automated lawn mower controller

which can use to mower the grass at lawns and playground. It used the concept of

„sense-act‟ whereby it does not fully depend on the workspace surrounding. The

automated lawn mower has the feature of detecting the grass. Besides that it has

GPS system which allocated the path for the robot movement. Other than that,

some sensor such as sonar sensor which use to detect obstacles, encoder to

calculate the distance the lawn mower travel together with the GPS system. [1]

2. Design and Implementation of a Control Algorithm for an autonomous

lawn mower

This paper discuss on the way of implementing GPS system for automated lawnmower path flow. Besides that it also stated there they used PID controller to

increase the performance of the motor speed which can provide better flow.

Besides that, their project also included encoder to calculate distance but their

encode was made by magnetic and hall sensor which placed around the wheel and


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2.3 Existing Technology

Some of the existing manufacturers of Robotic Lawn Mowers are: Friendly Robotics (USA) Husqvarna (Sweden) SN Eno (France) Technical Solutions (USA) Weed Eater (USA)

Fig 2.1: Robomow Lawn Mower

Existing automated lawn mowers each have a distinct working principle, forinstance the Robomow from Friendly Robotics requires the user to perform a

onetime set up where the garden perimeter is set. The perimeter is set using a

battery powered wire that is laid around the outer edges of the garden and any area

where the robot is not to cover. Special sensors inside Robomow enable the wires


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to be recognized and the robot is therefore kept within the designated area. The

Robot travels on the garden in a systematic criss-cross pattern, several times from

side to side to ensure that the entire area is covered and that the grass is cut from

different angles.

Fig 2.2: Criss-Cross Cutting pattern of Robomow (Friendly Robotics)

Other technologies work around a similar principal as the Robomow, in the sense

that it requires a perimeter wire to limit its cutting area. A difference between them

may be added features and the cutting pattern, for instance the LawnBott of the


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Husqvarna have a random operating principle in the sense that they do not follow

any specific cutting pattern.

Fig 2.3: Random Cutting pattern of LawnBott (Husqvarna)

Another type of cutting pattern involves matrix cutting. The lawn-mower search

pattern, one of the most widely used search patterns because of its simplicity and

guarantee of path continuity and smoothness. The pattern consists of two major

movements:

(1) Straight path(2) Semicircle path.

The pitch refers to the spacing between two consecutive straight paths.


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The two movements of the lawn-mower search have different purposes. While the

objective of straight path is to search/explore the area, the semicircle path is to

connect straight paths. Therefore, the overall path is planned such that

• Straight paths reduce as much uncertainty as possible• Semicircle paths satisfy the turning constraint of the vehicle.

Fig 2.4: Pattern with straight path and semi circular curves

2.4 Disadvantages of Existing Technology

The operation method of the Robomow although effective, is to a certain degree

inefficient and contributes to a quite costly end product. The main advantages of

their design include, virtually any size or shape of garden can be specified, it is

flexible and it can work without requiring the user intervention at any stage, can

operate at surface areas with slopes, these points can also constitute a

disadvantage. The system design has the following disadvantageous aspects:

The size and shape of the garden – as wires have to be placed in the


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garden area to be covered by the robot; the cost of the entire system may be

considerably higher depending on the size. In the case of many plants being

in the middle of the garden area, the setup can become cumbersome.

Damage or faults – the wires are set on the grass and although the company mentions the fact that they would typically be covered by grass and become

unnoticeable in a matter of 2 to 3 weeks and the wires are prone to damage.

The damage can be from any origin for example, pets can dig up and

damage the wire, over time due to weather it can wear off, amongst others.

A fault on the wire can provide incorrect information to the device and as

consequence the device will not work as expected.

2.5 Motor and Battery Selection

The selection of motor and battery are most important factors on the performance

and working of any robot as the motors are directly responsible for the movement

of the robot while the batteries are responsible for providing the energy required to

do every function. The most reliable solution for the selection these days is to the

use online calculators for determining the right battery and motor for the robot.

These calculators are very carefully managed and programmed and are very

reliable, being used by so many webs and people across the globe.

Fig 2.5: Motor Calculator


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Fig 2.6: Battery Calculator

2.6 Components

2.6.1 DC Motor

DC motor is a device that converts electrical form into mechanical form of energy.

There are many kind of DC motor such as DC motor, separately excited DC motorand self-excited DC motor. DC motor was powered by DC current. There are

various voltage input for DC motor and the common voltage input for DC motor

are 3V, 5V, 12V, and 24V. There are advantages for DC motor which are the DC

motor perform better than AC motor, and DC motor provide excellent of

controlling the speed.


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Fig 2.7: DC Motor

2.6.2 Ultrasonic SensorUltrasonic sensor is a sensor that uses ultrasonic sound to detect range or distance

of an object. This sensor can also act as a sensor to detect present or absent of an

object. Due to ultrasonic is in the form of sound, a sort of energy, it can be used to

calculate distance whereby the distance of the sound travel from the emitter to an

object and reflect back to the receiver. Sound wave travel at speed of 340m/s.

Figure 2.3 shows the ultrasonic sensor concept used to calculate the distance

Fig 2.8: Ultrasonic Sensor Concept


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Fig 2.9 Ultrasonic Sensor

2.6.3 Arduino UNO

Arduino UNO is a component on the shelf (COTS) circuit board which aims for

the helping people on their project. It is based on ATmega328 microcontroller.

Rather than making own circuit board from scratch, Arduino UNO provides a

sufficient circuit board which able to program and contain most of the necessary

pin function. Arduino UNO board consists of 14 input output pin whereby 6 of

them can be used as PWM output. Besides that it contains also 6 analog to digital

(ADC) pin. Basically, Arduino UNO operates at 5V and the input power sourceneeds to be a range of 7V to 12V.


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Table 2.1 Summary of Arduino UNO microcontroller board

Fig 2.10: Arduino Uno


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2.6.4 Cutter

This will be used for the primary function of the mower i.e. to cut the grass.

Depending on the design, more than one cutter can be used in synchronization as

well. Also cutters with different shape or number of blades can be used for the

purpose of getting the required cutting speed.

Fig 2.11: Cutters

2.6.5 Battery

It will provide the energy for the working of the robot. The battery of a two

wheelers will be able to provide enough power to drive the robot for its working or

independent multiple batteries can be used for better performance.

Fig 2.12: Battery


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2.6.6 Wheels

These will be required for the cause of the motion of the body of the robot. The

choice of the wheels largely depends on the shape and size of the grass. It will also

depend on the required ground clearance of the robot. As treads of the tires can

contribute significantly to the performance of the mower, great caution is needed

during the decision to choose the particular tires.

Fig 2.13 Wheel

2.7 Path Planning

Path planning is a term whereby describe the motion of a robot which is planed

accordingly. Sometime path planning also defined as motion planning as it main

function is to plan a robot motion. Many robot produce nowadays and this

technique still use by every industry that build robots. Path planning can be say as

the basic motion algorithms that allow the robot to move around at a specific

workspace with predefined path. With predefined path, the robot will not get lost

or go out of their workspace. With the guided path, the robot knows the way they

should go.


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There are several approaches that have being used for programming the path

planning of a robot.

1. Path Recording

2. Off-line path programming

3. Joint trajectory programming

Several important notes to be considered when design or program a robot path.

This is to ensure that the robot can be control easily.

a) Continuity of position, velocity and acceleration.

b) Precise control of motion

c) Mid-range motion

2.7.1 Path Recording

Path record is the basic and easy way of programming the robot path. It used the

technique whereby human will operate the robot and the robot simply record anymovement move by the human. It will record the path given and will play back the

path according to the record it hold. This technique was easy as the robot record

every coordinate of the movement and no need any programming skill for the user.

It is very simple but there are some problems whereby it need power the robot to

program and it is difficult to place robot which are big and heavy.

2.7.2 Off-line path programming

Off-line path programming is the technique of computerize programming without

power on any robot. Here the path will be programmed with the guide equation and

all the data will be gain from a specific table plot by the user. The computer will


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calculate the path according to the information and the robot to follow it. Behalf of

the computerize programming, this technique does not take into account of the

acceleration of the robot.

2.7.3 Joint trajectory programming

Join trajectory programming is the technique where all the joint of robot were

specified at a time into a computer control. This way the joint movement of a robot

is calculate through computer and faster than Cartesian method. This also does not

require any inverse kinematic calculation. Joint space description can be

programmed off line or teaching method. Through this method, the initial and finalspeed and acceleration can be specified and get the accurate results.

2.8 Computer Aided Software

Computer software will be used in this project to modeling and design of a robot.

There is much computer software and each of them has their own function. Human

used computer software to ease their design. With computer software, one can perform their task efficiently and fast. Below is the example of computer software:

a. CATIA

b. Arduino 1.0.5 IDE

2.8.1 CATIA

CATIA, stands for Computer Aided Three-dimensional Interactive Application, isthe most powerful Knowledge based and widely used CAD (computer aided

design) software of its kind in the world. CATIA has been created by Dassault

Systems of France and is marketed & technically supported worldwide by IBM.


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CATIA is software the function to create a 3D model CAD system. CATIA is a

simple tool that has many features to create a virtual 3D model. It can use to edit

3D model. Besides 3D model, it can also perform 2D model design where it is

usually use in engineering drawing where it can show the dimension of the 3Dmodel or in other word show the details of the 3D model in term of dimension.

In CATIA software, it contain some basic feature such as “Pad”, “Pocket”,

“Constrain”, “ Dimension”, and “Offset”. These features are easy to use.

Through this software it contains a feature called “Assembly Module ”. In this

assembly feature, several parts can be combined to together. Using assembly isgood while designing any 3D model. Due to it is assemble of parts, editing of some

parts can be made easily and no need to redraw the whole parts compare to

drawing whole structure in one part.

Fig 2.14: CATIA Interface


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2.8.2 Arduino 1.0.5 IDE

Arduino 1.0.5 IDE is a software to program the Arduino UNO. This software is an

open source and can download from the web for free. Arduino 1.0.5 IDE have their

own programming library which is simple and user-friendly. All the coding is

given as well as example. With the existing of library, the user does not need to

have a great knowledge on c programming to write Arduino program. Table 2.2

shows the sample of Arduino library code which used for programming

microcontroller.

Table 2.2 Sample Arduino library code

Figure 2.15 User Interface of Arduino 1.0.5 IDE


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2.9 Different designs

There are various designs of the Automatic Lawn Mower possible depending of

different factors. These factors include source of energy, mode of control, numberof grass cutters, type of sensors etc. These are discussed in brief as –

Type of energy source: There can be two different designs depending upon

the source of power used. First is using conventional battery. A rechargeable

battery will provide power to drive the motors for the motion of the mower

i.e. motion of the wheels and the motion of the grass cutter. Second choice is

to use power of solar energy to drive the mower. For this a solar panel will

be required and setup to convert that energy gathered to be converted into

usable form and magnitude. The choice of the mode of energy will be

affected by the factors like difficulties in producing required power by using

solar panel, added weight of solar panel, difficulties of integrating solar

panel into the circuit and cost factors.

Mode of control: Depending upon this, again two different designs can be

made. First is use of sensors to control the motion of the mower. Mower will

make use of sensors like Proximity Sensor, Ultrasonic Sensor etc to detect

the presence of the physical obstacles and with help of micro controller, path

of the mower can be determined. The second option is to use a remote

control to drive and control the mower remotely. This can be achieved by

integrating the R/C into the electronic circuit of the mower. The choice of

The mode of control will be affected by the factors like difficulty of

integrating R/C into the electronic circuit, the range of the radio control and

the cost factors.


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Number of cutters: The number of the cutters to be used can also result into

different type of designs of the mower. The use of multiple cutters can be

there. It can result in increase of the cutting speed or amount of grass cut ingiven time but it has limitations like increased cost factor, increase in energy

demands, and increase in the physical dimensions of the mower to

accommodate the extra number of cutters.

Type of sensors used: The designs dependent on this factor will result into

Contact type mower and Non Contact type mower. In Contact type mower, there will be micro switches used that will come into physical

contact with the external obstacle and then change the path of the mower

accordingly. While in Non Contact type mower, sensors like Ultrasonic or

Proximity sensors will be used to detect the presence and distance of the

obstacle and determine the path of the mower accordingly with help of the

microcontroller.

These are some of the different type of designs which can be implemented

while deciding upon the final design of the mower. This depends upon the

factors like energy/power requirements, ease or difficulty of integrating a

component into the electronic circuit, weight and physical aspect of the mower,

cost factors etc.

2.10 Working of the device

In general, a robot lawn mower can operate in three distinct modes: remote control,

teach control and automatic operation. For remote control operation, the human

commands must be executed in the mobile lawn mower. Also, sensory information


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such as motor speed, blade status, tactile information and an image of the local

environment can be transmitted to the operator to provide a "telepresence" in

which the operator senses enough information about the environment to perform

the proper action. The general telepresence concept is still being researched andmore information is needed in some situations. In teach mode, the storage capacity

of the microcomputer is used to store command and encoder information so that

repetitive operations can be performed. In some operations, the use of a given

home position for calibration may provide enough accuracy for simple repetitive

operations. In the general case, an absolute global positioning system such as the

target update method for navigation is required to provide accurate teach programming or automatic operation. With this capability, full region filling

algorithms may be implemented for lawn mowing.

The working of the device is all dependent on the electronic circuitry that is to be

designed.

1. Capturing the environment data: It involves the collection of data

regarding the obstacles present in the course of the cutting of grass,obstacles present in the path of the device. It is to be done with the help

of various sensors that are to b used in the device.

2. Processing the data: It involves processing the data collected by the

sensors with help of a central unit. The central unit to be used in this

device is a micro-controller.

3. Actions: It involves the actions the micro-controller will take after

processing the data acquired. It will be based on the programming done

into the micro-controller and the pre fed instructions. The actions involve

mainly the motion control of the device.


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The working of the device also depends on 4 main mechanisms. The main

mechanisms to be used are –

Collision Detection Mechanism: This is to deal with the obstacles present inthe path of device. This is to be achieved with the help of sensors or micros

witches. The difference between the two is that whereas in case of collision

detection sensor, there will be no physical contact with the obstacle, it will not be

the same if micro switches are to be used. In case of micro switches, there will be

collision with the obstacles and then the device will turn away from it.

Grass Cutting Mechanism: As this is basically a lawn mower, so this is the

important part of the device. This mechanism is to be used to cut the grass, which

is the primary function of the lawn mower. It is to be achieved with help of a grass

cutter and a motor to run this cutter. The number of cutters can be more than one

depending on the design of the mower. Also the motion of the cutter can be

controlled with help of timer as to when to switch it off.


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3.1 Introduction

This chapter discusses the method use to design an automatic lawn mower. There

several steps taken to complete the task. Before starting to build a robot, many

initial steps have taken such as research on automatic lawn mower which is

discuses in Chapter 2.

Fig 3.1: Research Methodology Flow

This chapter will be separated into two sections:

Hardware Implementation Software Implementation


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Hardware part includes the sensors, motors, wheels that are used in the project

while the software part includes the modeling in CATIA and the programming in

Arduino environment.

3.2 Hardware Implementation

In this section, the hardware selection will be discussed. The hardware that will beincluded in this project is DC motor, ultrasonic sensor, battery, wheels, chassis etc.

3.2.1 DC motor

Figure 3.3 shows the motor that will be used in constructing automated lawn

mower. It can operate at a range of 12V to 24V. It has higher torque which made it

easier. DC motor is a device that converts electrical form into mechanical form of

energy. There are many kind of DC motor such as DC motor, separately excited

DC motor and self-excited DC motor. DC motor will be powered by DC current.


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Fig 3.3: DC MotorSpecs

Type : DC Gear MotorVoltage: 12 VCurrent: 300mA (max)Wattage: 3.6 WRPM: 200 for wheels

1000 for cutter

3.2.2 Motor Controller

This motor controller has the ability to control the direction of the motor. The

component used to build this controller are 5V relay, transistor 9013, power

transistor and 10 k Ω resistor. Figure 3.5 shows the motor controller circuit

diagram which function to control the motor direction of motor and also the PWM

of the motor. The input signal for this system is u1, u2, u3 and u4 which use to

control motor direction. Whereas the bottom of the circuit is the PWM input signal

which use to control the motor speed. For clockwise rotation, the input pin u1 andu4 will be set to high and the u2 and u3 pin set as low. On the other hand. For

anticlockwise direction, pin u2 and u3 will set as to high and pin u1 and u4 will set

as low. Setting high to the transistor will activate the transistor whereas setting low

will deactivate the transistor.


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Fig 3.4: Motor controller circuit diagram


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Figure 3.5: Block diagram of Arduino with motor controller

Figure 3.5 shows the connection between Arduino UNO pin with motor controller

pin. The ground of Arduino and motor controller are common ground. The pin

from the Arduino will send signal to the controller.Specs

Type: L293D Motor Drive IC

Voltage: 5V DC

Arduino support

3.2.3 Sensor

Ultrasonic sensor is a sensor that uses ultrasonic sound to detect range or distanceof an object. This sensor can also act as a sensor to detect present or absent of an

object. Due to ultrasonic is in the form of sound, a sort of energy, it can be used to

calculate distance whereby the distance of the sound travel from the emitter to an

object and reflect back to the receiver. In this project, the ultrasonic sensor will be


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used to detect obstacle which will prevent the lawn mower to knock any obstacle.

Figure 3.8 show the sensor that will be used. Figure 3.9 shows the connection

between an ultrasonic sensor and Arduino UNO microcontroller .

Fig 3.6: Ultrasonic Sensor


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Fig 3.7: Block diagram of Ultrasonic sensor with Arduino UNO

Specs

Name: HC-SR04 Ultrasonic sensor

Voltage: 5V

Range: 2cm-200 cm

Precision: 5mm

3.2.4 Battery

It will provide the energy for the working of the robot. The battery of a two

wheelers will be able to provide enough power to drive the robot for its working or

independent multiple batteries can be used for better performance. Two 6V

batteries were attached in series to provide the required 12V.


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Fig 3.8 Battery

Specs

Use: Powering the components

Nos: 2

Type: Li- Ion Rechargeable

Voltage: 6V DC, Total 12V

3.2.5 Wheels

These will be required for the cause of the motion of the body of the robot. The

choice of the wheels largely depends on the shape and size of the grass. As treads

of the tires can contribute significantly to the performance of the mower, great

caution is needed during the decision to choose the particular tires.


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Fig 3.9 Wheel

Specs

Use: Movement of Robot

Nos: 4

Diameter : 10 cm

Width : 4 cm

Shaft Hole: 6mm

3.3 Software Implementation

The software that will be used in this project are CATIA and Arduino 1.0.5 IDE.

CATIA will be used for designing the 3D model of the lawn mower. The Arduino

1.0.5 IDE will be used to program the microcontroller.

3.3.1 Modeling Design in CATIA

CATIA is a tool to design any 3D model electronically. In designing, it will need

two segments when drawing. The first is the CATIA parts and the CATIA

assembly. At first several part of the lawn mower was drawn. After that, all the

part will be combine or assemble together to form a full lawn mower.


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In CATIA, several techniques will be used such as pad, shell, pocket, fillet, mirror

pattern . A rectangular base forms the basis of the drawing. From this several parts

will be cut to form the desire pattern. Several hole also made to indicate the screw

position. There are three part will be drawn which are two back wheel the bodyand two front wheel. After finished drawing, the part will combine together using

CATIA assembly feature to assemble the parts drawn. Tuning and refinement will

be made at the end of drawing to prevent any error occur. Refining such as

increase or decrease the dimension of the part due to some obstacle.

3.3.2 Programming and AlgorithmTo enable a robot to move or operate, a microcontroller is needed in order to allow

the robot to function by itself. Arduino UNO will be used as the microcontroller

for this project. The movement and the path of the lawn mower will be program

into the microcontroller and it will also being control from several sensor input to

enhance the flow.


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Fig 3.10: Arduino Uno

Specs

Name: Arduino UNOBoard: atMEGA328

Pins: Digital I/O 14

Analog Pins 6

Voltage: 5V

Clock Speed: 16 MHz

An algorithm needs to be developing to ensure the microcontroller can perform

desire output depending on the input. Figure 3.9 shows the algorithm for the main

program process. The flow chart will then turn into c programming and compiled

into the Arduino UNO using Arduino 1.0.5 IDE complier.


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each component was discussed. The algorithm for the main program and sensors

were discussed using flow chart.


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Chapter 4

RESULT


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4.1 Introduction

This chapter presents the model of the automatic lawn mower developed in this project.

4.2 Model and Actual

Computer software is to be used in projects to modeling and design of a robot.

There is much computer software and each of them has their own function. Human

used computer software to ease their design. With computer software, one can

perform their task efficiently and fast. CATIA has been used for the modeling of

the project. Different views of the model are:

Fig. 4.1: Front View


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Fig 4.2: Top View


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Fig 4.3: Bottom View


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Fig 4.4 Side View


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Fig 4.5: Exploded View

Fig 4.6: Assembly


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Fig 4.7: Base Plate dimensions


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Fig 4.8: Front Wheel Dimensions

Fig 4.9: Back Wheel Dimensions


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4.3 Performance Factors

The device has to be evaluated on some factors to find out its working efficiency or

if it is convenient or not practically. Some of the factors are: Cutting Time : It is one of the basic and most important factors as how

much time does the device take to cut the required or pre set area of the

garden. As time is the most valuable resource these days, this factor

becomes most important in determining the usability of the device.

Cut grass condition: Whether the cut made to the grass is clean or not and

if the grass cut is uniform or not are two very important factors in

determining the usage of the device as the desired outcomes are uniform

cutting and clean cutting of the grass.

Human and obstacle detection and avoiding: Since the device is to be

made automatic, this factor is important as it is directly related with the

cutting time. If the device avoids the obstacles frequently and easily, it will

reduce the cutting time and the entire work will be done in lesser time. Also

it will help in saving the energy required.

Cutting Pattern: Cutting pattern is an important part because if the mower

does a crisscross pattern, it will cross same area of grass more than once

resulting in the more time taken for cutting and hence more energy

consumed.

Power requirements: Power requirements are easily one of the most

important factors in deciding the efficiency of the device. The powerrequired will decide the cutting time for required area and also the cutting

area in given period of time.


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Fig 4.10: Path 1 of Lawnmower

Fig 4.11: Graph of grass cut


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Fig 4.12: Path 2 of Lawnmower


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Chapter 5

PROJECT MANAGEMENT


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5.1 Introduction

Project management is to allow all project goals to be achieved under specific time

frame. Such goal are organizing, controlling, and planning the projects flow. The

primary constraints faced during conducting this project were research time,

research budget, research time and human resources. Below is the Gantt chart

which clearly shows the flow of timeline management for this project.

Next, cost estimation on component used for this project is done to ensure that a

minimum budget project cost. Several market surveys have been done to achieve

this requirement.

5.2 Bill of Material

S.No Component Nos Price Per Part Total Price

1. Wheel Motors 4 500 2000

2. Cutter Motor 1 1000 1000

3. Micro-controller 1 2500 2500

4. Wheels 4 125 500

5. Breadboard 1 200 200

6. Ultrasonic Sensor 1 300 300

7. Battery 2 800 1600

8. Base Plate 1 500 500

9. Motor Controller 1 250 250


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S.No Parts Nos Price Per Part Total Price

10 Wires and Accessories ----- ----- 750

Total 9600

Table 5.1 Bill of MaterialsAll prices are in INR (Indian National Rupee)


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Chapter 6

CONCLUSION ANDRECOMMENDATION

6.1 Conclusion


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An automatic lawn mower with several features has been proposed. Several related

works has been studied in order to gain idea on how to build an automatic lawn

mower. Most research is on the robot path planning using variety technique. All

the technique used are mainly aim for the shortest path, consume less energy.Besides that, 2D and 3D model have been designed according to the specification

required such as circuit placement and sensor placement. The structure was user

friendly and economic which were achieving the objective.

6.2 Recommendation

The performance of this machine is slightly away from the desired requirement.Therefore some recommendation has been list out for future improvement.

Hardware improvement

The design of the machine may undergo some changes such as larger the cutting

blade so that the diameter is almost the same size of the width of the machine. The

increase of the diameter of the blade making larger area will be cover when cutting

operation is done. Special wheel can be applied such as wheel with some thorn

which will grip the grass stronger to prevent slipping occur. Higher torque motor

would be recommended so that it can help to maintain the machine to move at

slower speed and overcome friction between the machine and grass surface.

Software improvement

This system need more advance software to perform more accurate. GPS system

may apply on this project so that it can gain more accurate position for path

planning. Controller such Artificial Intelligent (AI) can also apply so that it have


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the ability to make decision whether the grass need to be cut or memorize which

part no need to cut and continue to next area.

6.3 Advantages

As an automatic device, this lawn mower has many advantages, some of which

are:

It reduces human effort. It has simpler design than most commercial mowers. This type of mower is cheaper than commercial mowers.

It has wider range more than conventional mechanical mowers due toabsence of main supply wire.

It aids elderly users or those with disabilities who are unable to fulfill this

task themselves.

References


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1. M. Wasif (2011). Design and Implementation of Autonomous Lawn-Mower

Robot Controller. 2011 7th International Conference. 5-6 September. Emerging

Technologies (ICET), 1-5.

2. Smith, J., S. Campbell, and J. Morton. (2005). Design and Implementation of a

Control Algorithm for an Autonomous Lawn Mower. Circuits and Systems. 7 – 10

August. Midwest Symposium, 456-459.

3. Ousingsawat, J. and M.G. Earl. Modified Lawn-Mower Search Pattern for AreasComprised of Weighted Regions. American Control Conference . 9-13 July. 918-

923.

4. Mohammad Baloch, T. and K. Timothy Thien Ching. (2008). Design and

modelling a prototype of a robotic lawn mower. Information Technology ,.

International Symposium. 25-28 August. 1-5.

5. Hicks, R.B. and Hall, E. A Survey of Robot Lawn Mowers. SPIE Intelligent

Robotics and Computer Vision Confrence.

6. http://spt06.chez-alice.fr/01/accueil.htm

7. http://www.robomow.com/robomow/howitworks/

8. http://en.wikipedia.org/wiki/Robotic_lawn_mower


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9. https://technubes.files.wordpress.com/2012/08/automated-garden-sweeper-

report-docx.pdf

10. http://www.open-electronics.org/a-robotic-lawn-mowers-powered-by-solar-

energy-with-an-arduino-heart/


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Sketch

#include "Ultrasonic.h"

Ultrasonic ultrasonic(12,13);//echo and trigger pinint s1=2;

int mc=7;int m00=8;int m01=9;int m10=10;int m11=11;int ss1=1;

int k=0,oo=0;

void setup(){ pinMode(s1,INPUT);

pinMode(mc,OUTPUT); pinMode(m00,OUTPUT);

pinMode(m01,OUTPUT); pinMode(m10,OUTPUT); pinMode(m11,OUTPUT);

}

void loop(){

ss1 = digitalRead(s1);// high=1, low =0

if(ss1==0){k++;delay(2000);

}


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if(k==1 && (ultrasonic.Ranging(CM))>30){

digitalWrite(m00,1);//forward

digitalWrite(m01,0);digitalWrite(m10,1);digitalWrite(m11,0);digitalWrite(mc,1);

}if(k==2||k==0){

digitalWrite(m00,0);digitalWrite(m01,0);digitalWrite(m10,0);digitalWrite(m11,0);digitalWrite(mc,0);k=0;}if(k==1 && oo==0 && (ultrasonic.Ranging(CM))


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delay(200);digitalWrite(m00,0);digitalWrite(m01,0);digitalWrite(m10,0);

digitalWrite(m11,0);delay(500);

digitalWrite(m00,1);digitalWrite(m01,0);digitalWrite(m10,0);digitalWrite(m11,1);delay(1000);oo++;}if(k==1 && oo==1 && (ultrasonic.Ranging(CM))


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delay(500);

digitalWrite(m00,0);digitalWrite(m01,1);

digitalWrite(m10,1);digitalWrite(m11,0);delay(1000);oo=0;}}

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