automatic lawn mower project report

DAV INSTITUTE OF ENGINEERING AND TECHNOLOGY

MAJOR PROJECT REPORT ON

AUTOMATIC LAWM MOWER SUBMITTED IN PARTIAL FULFILLMENT OF REQUIREMENT FOR THE AWARD OF DEGREE IN BACHELOR 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 Page 1

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 grass automatically. 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. Every action 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

1.

TITLE

PAGE

Acknowledgement

2

Abstract

3

Index

4

List of Tables

7

List of Figures

8

INTRODUCTION

1.1

Background

11

1.2

Problem Statement

13

1.3

Objective of Project

13

1.4

Expectation from the Device

13

1.5

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 Page 4

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

30

2.8

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

44

3.2.4

Battery

44

3.2.5

Wheels

45

3.3

Software Implementation

46 Page 5

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 Management

5.1

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

Page 6

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

Page 7

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

28

2.14

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

3.6

Ultrasonic Sensor

3.7

B/D of Ultrasonic Sensor with Arduino Uno 43

3.8

Battery

45

3.9

Wheel

46

41

42

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3.10

Arduino UNO

48

3.11

Circuit

49

4.1

Front View

52

4.2

Top View

53

4.3

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

58

4.9

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 Background A 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 or an 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 advancement in 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 Page 11

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 and infrared 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 that the 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 task themselves.   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. Page 13

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. Page 14

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 lawn mower 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 Page 16

it calculate the number of magnetic field strength while moving which will convert the number of magnet to distance travelled. The lawn mower performance is being watch throughout the whole working process at the base station using wireless transmission. [2] 3. Modified Lawn Mower Search Pattern for Areas Comprised of Weighted Regions This paper discuses on the way the lawn mower move while it work. It used weightage spot or region to determine the correct way of path. With this technique, the lawn mower can find the most important place to cut the grass depending on the amount of weight comprised in order to cover the maximum area and also to minimize the time usage. The region with the most weight will be allocated first followed by the second weight and so on. This is some sort of guided path system whereby it move according to the weight given. With this technique, is able to achieve a good result on area coverage. [3]

4. Design and Modeling a Prototype of a Robotic Lawn Mower This paper discuss on how to develop a robotic lawn mower with several functions. It objective is to build a lawn mower that do not go out of workspace, do not leave any uncut area, able to avoid collision and the most important that is the robot must be cheap and affordable to everyone. Basically it used PIC microcontroller to perform the lawn mower working process or to run the lawn mower. [4] 5. Survey of Robotic Lawn Mowers This paper discusses different types of Robotic Lawn Mowers present in the market at present. It discusses different companies and their products and compares them with others.

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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, for instance 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 Page 18

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 Page 21

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 Page 22

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 motor and 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 Sensor Ultrasonic 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 Page 24

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 source needs 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 Page 26

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. Page 28

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 any movement 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 Page 29

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 final speed 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, is the 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 3D model 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 is good 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 Page 32

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, number of 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. Page 33

 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 in given 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 Page 34

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 and more 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. Page 35

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 in the 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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Chapter 3 METHODOLOGY

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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 Page 38

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 be included 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 Motor Specs Type : DC Gear Motor Voltage: 12 V Current: 300mA (max) Wattage: 3.6 W RPM: 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 and u4 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. Page 40

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 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. In this project, the ultrasonic sensor will be Page 42

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. Page 46

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 body and 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 Algorithm To 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 UNO Board: 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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The basic flow of the lawn mower is the lawn mower will start the cutting process according to the path has being calculate. Along the path, if there is obstacle in front of it, the lawn mower will find the other way to move to go around it and continue the cutting process. It will not hit the obstacle due to the present of the ultrasonic sensor.

Fig 3.11 Circuit

3.4 Summary This chapter discussed the method used to design an automatic lawn mower. Hardware such as DC motor, buzzer, LCD module, IR sensor, ultrasonic sensor, rain sensor and light sensor were used in this project. The circuit connection of Page 49

each component was discussed. The algorithm for the main program and sensors were discussed using flow chart.

Page 50

Chapter 4 RESULT

Page 51

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 Page 52

Fig 4.2: Top View Page 53

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 Page 58

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 power required 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 Page 60

Fig 4.12: Path 2 of Lawnmower

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Chapter 5 PROJECT MANAGEMENT

Page 62

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 Materials All prices are in INR (Indian National Rupee)

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Chapter 6 CONCLUSION AND RECOMMENDATION

6.1 Conclusion Page 65

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 Page 66

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 to absence of main supply wire.  It aids elderly users or those with disabilities who are unable to fulfill this task themselves.

References Page 67

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 Areas Comprised of Weighted Regions. American Control Conference. 9-13 July. 918923.

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   Page 68

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 pin int 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); } Page 70

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))