MINIHOVERCRAFT – AN AMPHIBIAN ROBOT

NOORAKMAL IKRAM BIN AZIZAN

This thesis is submitted in partial fulfillment of the requirements for the award of a

degree in Bachelor of Electrical Engineering (Mechatronics)

Faculty of Electrical Engineering

Universiti Teknologi Malaysia

MAY 2008

iii

Special dedicated to

Azizan Bin Abdul Rahim, Noormah Bte Ahmad, sister, my special friend,

Azwani Bte Alias and friends who have encouraged, guided and inspired

me throughout my journal of education.

iv

ACKNOWLEDGEMENTS

First and foremost, I would like to take this opportunity to thank my supervisor,

the distinguished Professor Dr. Shamsudin Hj Mohd Amin, who has been there to give

me his utmost support, determinedly assisted me during the project, and unfailing

guidance from day one. His valuable advice and assistance have truly been instrumental

in the completion of my project.

My heartfelt appreciation also goes out to my parents, as well as the rest of my family,

for providing me with the love and encouragement throughout this while. They have

undoubtedly played very significant roles to ensure my constant well-being. I am

grateful to have love affection and care from all of my family members as well. Last but not least, I would like to extend my gratitude to all my course mates and

friends who have helped me in one way or another, by sharing their ideas and opinions,

by showing their care and concern. Their views and tips are useful definitely. My fellow

friends should also be recognized for their continuous support and encouragement.

Thank you.

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ABSTRACT

In recent years, robots technologies have been developed rapidly in most

countries. Robot is a device used to replace humans in doing tasks or work especially in

hostile environment. Robotics are always related to automation which defined as the

process of following a predetermined sequence of operations with little or no human

intervention using specialized equipment and devices that control and perform the

particular tasks. The progress on robotics, computer technology, sensors and perception

systems has produced great advances in the field of hovercraft. This project, entitled

MiniHovercraft – An Amphibian Robot, is mainly about designing and fabricating a

mobile model hovercraft which is operated autonomously. Firstly, the hovercraft will be

designed after prior research and review of its principles of operation. This project is to

create a hovercraft which is can move on land and water respectively. The lift and

propulsion of the model hovercraft will be provided by electric-powered motors. The lift

propeller will direct air downward onto the ground generating an air cushion beneath the

craft while the thrust propellers will enable the craft to move forward. This hovercraft

can go forward, right and left depend on the detection of Infra-Red (IR) sensors and give

the signal to the PIC which is act as a brain for this hovercraft to control the movement

of hovercraft. The objectives of this project are to design the MiniHovercraft which

includes a design of the physical structure, electronic circuit and control of the

hovercraft.

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ABSTRAK

Sejak kebelakangan ini, teknologi robotik telah dibangunkan dengan pesatnya di

kebanyakan negara. Robot adalah suatu alat yang digunakan untuk menggantikan

manusia dalam melakukan tugas atau kerja terutamanya di kawasan merbahaya. Robotik

sering dikaitkan dengan automasi yang ditafsirkan sebagai proses atau operasi yang

dilakukan tanpa atau sedikit penggunaan tenaga manusia. Ia lebih mengunakan peralatan

khas untuk mengawal tugas-tugas tertentu. Kemajuan di dalam bidang robotik, teknologi

komputer dan alat pengesan telah menghasilkan teknologi yang maju dalam bidang

hoverkraf. Projek ini yang bertajuk MiniHoverkraf – Robot Dua Permukaan (air dan

darat) adalah tentang merekacipta satu model hoverkraf yang bergerak secara kawalan

bebas atau bergerak sendiri. Pada mulanya, hoverkraf ini akan direka setelah

menjalankan penyelidikan tentang prinisip operasinya terlebih dahulu. Projek ini adalah

mencipta satu hoverkraf yang boleh bergerak di darat dan di permukaan air. Daya angkat

dan daya tujah model hoverkraf ini akan dibekalkan oleh motor elektrik. Kipas angkat

akan menumpukan angin ke bawah untuk menghasilkan satu kusyen udara di bawah

hoverkraf manakala kipas tujah akan membolehkan hoverkraf bergerak ke hadapan.

Hoverkraf ini boleh bergerak ke hadapan, kiri dan kanan bergantung kepada pengesanan

penderia Infra-Merah dan memberi isyarat ke PIC yang berfungsi sebagai otak kepada

hoverkraf untuk mengawal pergerakan hoverkraf. Tujuan projek ini adalah untuk

menghasilkan MiniHovercraft yang merangkumi rekabentuk mekanikal, litar elektronik

dan kawalan untuk hoverkraf.

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TABLE OF CONTENTS CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGMENTS iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF APPENDICES xiv

1 INTRODUCTION

1.1 Overview 1

1.2 Objectives 1

1.3 Scope of Work 2

2 LITERATURE REVIEW

2.1 Basics 4

2.2 History 5

2.3 Theory 6

2.4 Case Studies 10

2.4.1 Pierre Rouzeau 10

2.4.2 Kevin Jackson - Basic Hovercraft 11

2.4.3 Kevin Jackson - SR.N1 Model 12

2.4.4 Mike Porter – SR.N5 Model 13

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2.4.5 SEALEGS Amphibious Boat 13

2.4.6 Hovercraft and Ram-wing Craft 15

2.5 Summary 16

3 METHODOLOGY

3.1 Electrical and Electronic Design 19

3.1.1 MICROCHIP PIC16F877A Microcontroller 19

3.1.2 PIC Startup Kit-SK40A 22

3.1.3 Relays 24

3.1.4 Motor Driver 24

3.1.5 DC Motor 26

3.1.6 Power Supply 28

3.1.7 Infra-Red Sensors 28

3.2 Mechanical Structure and Design 31

3.2.1 Mechanical Design and Planning 31

3.2.2 Mechanical Parts and Specification 32

3.2.2.1 Polystyrene 32

3.2.2.2 Polymer Base 33

3.1.2.3 Lift Fan 34

3.1.2.4 Thrust Propeller 35

3.2.3 Structural and Layout 36

3.3 Operation of MiniHovercraft 39

3.3.1 Mechanical 39

3.3.2 Electronical 42

3.3.3 Flow Chart 43

3.4 Software Development 44

3.4.1 MikroC, mikroElektronik C compiler 44

3.4.2 How to write source code using MikroC 46

3.4.3 Load the source code using WinPic800 47

3.4.4 Load the source code using MPLAB IDE 48

3.4.4.1 PICC LITE 49

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3.4.4.2 Boot Loader 50

3.4.4.3 Compile the program 50

4 RESULTS

4.1 MiniHovercraft 55

4.2 Maneuver Test 56

4.2.1 Water Surface Test 56

4.2.2 Land Surface Test 57

4.3 Component and Circuitry Test 57

4.3.1 Infra-Red (IR) Sensor Circuit 57

4.3.2 Motor Driver Test 58

4.4 Final Structure of MiniHovercraft 59

5 CONCLUSION

5.1 Issues 63

5.2 Future Developments 63

REFERENCES 65

APPENDIX 66

x

LIST OF TABLES

TABLE

NO.

2.1

3.1

3.2

TITLE

SEALEGS Amphibious Boat criteria

PIC16F877A Device Features

Motor Specification

PAGE

15

20

27

xi

LIST OF FIGURES

FIGURE

NO.

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

2.10

2.11

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

TITLE

General Parts of a Hovercraft

Basic Ground Effect Phenomenon

Plenum Chamber

Peripheral Jet Curtain

Components of Hover Height

Pierre Rouzeau’s Hovercraft

Basic Hovercraft

SR.N1 Model

SR.N5 Model

SEALEGS Product

Raw-wing Craft

Research Methodology flow chart

Pin Diagram for PIC16F877A Microcontroller

Block Diagram for PIC16F877A Microcontroller

Boot Loader

Schematic Diagram Microcontroller with Boot Loader

Songle SRD-06VDC-SL-C Relay

ULN 2803

Motor Driver Circuit

Mabuchi Motor RS-540RH/SH

PAGE

4

7

8

8

9

11

11

12

13

14

15

18

20

21

22

23

24

25

25

26

xii

3.10

3.11

3.12

3.13

3.14

3.15

3.16

3.17

3.18

3.19

3.20

3.21

3.22

3.23

3.24

3.25

3.26

3.27

3.28

3.29

3.30

3.31

3.32

3.33

3.34

3.35

3.36

3.37

3.38

3.39

3.40

Detail view of motor

9.6V AAA Battery Packs and 9V PP3 Batteries

IR sensor on two different surfaces

A Pair of Infra Red Sensor

Schematic Diagram for LM324

Circuit for LM324

Mechanical design planning

Extruded Polystyrene Board

Expanded Polystyrene Board

Floating Material

Polymer Base

Lift Fan

Thrust Propellers

Propeller side view

MiniHovercraft Plan View and Measurements

MiniHovercraft Plan Front and Measurements

MiniHovercraft Plan Side and Measurements

MiniHovercraft Trimetric View

MiniHovercraft Cross-section View

Forward Movement

Left Steering

Right Steering

Reverse Movement

Electronic Circuitry Block Diagram

Flow Chart of Program

MikroC IDE - Integrated Development Environment

Project Wizard GUI

WinPIC800

Desktop Programmer

MPLAB IDE Desktop Interface

Opening a new file to compose source codes

27

28

29

29

30

30

31

32

33

33

34

34

35

36

37

37

38

38

39

40

40

41

41

42

43

45

46

47

48

49

51

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3.41

3.42

3.43

3.44

3.45

3.46

3.47

4.1

4.2

4.3

4.4

4.5

4.6

4.7

4.8

4.9

Saving the source codes as C Source File

Creating a new project with MPLAB IDE

Adding the file saved as Source files

Open the added source file

Selecting “Build all” to compile the project

File successfully compiled

File failed to be compiled due to errors

Hovercraft on Water Surface

Hovercraft on Land Surface

Complete Infra-Red sensors circuit

Motor Driver Circuit

MiniHovercraft Front View

MiniHovercraft Top View

MiniHovercraft Rear View

MiniHovercraft Side View

MiniHovercraft Diagonal View

51

52

52

53

53

54

54

56

57

58

58

59

59

60

60

61

xiv

LIST OF APPENDICES

APPENDIX

A

TITLE

The Source Code of the MiniHovercraft – An Amphibian Robot in C Language

PAGE

66

1

CHAPTER 1

INTRODUCTION

1.1 Overview

This project involves the design and fabrication of a model mini hovercraft. The

model hovercraft is mobile and autonomous; hence its operation is controlled

autonomously. When Minihovercraft is in operation, it is lifted from the ground,

supported by a cushion of pressurized air. It then moves and maneuvers with an air

propulsion system. All of these are controlled with the implementation of onboard

electronic circuitry and use programming to control maneuvers of hovercraft.

1.2 Objectives

The main objective of this project is to build an amphibian robot which can

travel on the land and water. The vehicle can move on dual surface by using air thrust

concept. With this concept, the hovercraft can move either on land or water. The

important is to replace the hovercraft operated from control by radio controller to

autonomous control.

The hovercraft movements were up grade by using more thrust propellers,

sensors and motors. Otherwise, sensors which use in this project is for detect the

2

obstacle when the Minihovercraft maneuvers autonomous on the water. Motor driven are

uses for controlling the movement for right and turning of the hovercraft.

This encompasses the design and fabrication of the physical structure of the

model hovercraft. The design will be in accordance with the principles of operation of

hovercrafts, and also based on prior review and research. The physical fabrication will

involve the appropriate materials that have been chosen based on studies of other

models.

Furthermore, the final objective is to develop the software to be programmed into

the microcontroller. This will be the instructions that will be executed by the

microcontroller. The hovercraft uses the PIC Controller. This objective will be

concluding the designing of microcontroller system and programming of the

microcontroller system using C language to accomplish the task.

1.3 Scope of Work

This project has its own scopes of work and limitations. The propulsion of the

model hovercraft consists of two main parts, the lift and the thrust. The lift supply is

provided by a motor-driven propeller while the thrust supply consists of two-motor

driven propellers, which also double up as a means of steering the craft.

The hovercraft uses a PIC microcontroller as the main controller and a circuit for

sensors with Infra Red emitter and receiver to detect the obstacle. The PIC controller

controls all the activities of the Minihovercraft. The control circuitry will mainly consist

of the microcontroller. This project employs three DC Motors to move the

Minihovercraft.

3

The size of the model hovercraft will be approximately 40 centimetres by 30

centimetres by 15 centimetres. It is basically a scaled-down model of an actual

hovercraft, but nevertheless, will operate with the same physics principles.

4

CHAPTER 2

LITERATURE REVIEW

The following chapter documents the findings from the research of the theory

and concept of hovercrafts, as well as case studies of other models.

2.1 Basics

The hovercraft, or air cushion vehicle (ACV), is different from other more

conventional, terrestrial vehicles in that it requires no surface contact for traction and is

able to move freely over a variety of surfaces while supported continually on a self-

generated cushion of air. It is also different in that the rate of development of the

hovercraft has been outstandingly faster than that of any other mode of transportation.

Figure 2.1: General Parts of a Hovercraft

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2.2 History

The first recorded design for a vehicle which could be termed a hovercraft was in

1716 by Emanuel Swedenborg, a Swedish designer. His man-powered air cushion

platform resembled an upside-down boat with a cockpit in the centre and manually

operated oar-like scoops to push air under the vehicle on each downward stroke.

However, no vehicle was ever built as human effort could not have generated enough lift

for the needed air cushion.

In the 1870s, Sir John Isaac Thornycroft, a British engineer, built a number of

ground effect machine test models based on his idea of using air between the hull of a

boat and the water to reduce drag. Although he filed a number of patents involving air-

lubricated hulls in 1877, no practical applications were found.

In 1930s, Vladimir Levkov, a Soviet engineer, assembled about twenty

experimental air-cushion boats, which included fast attack crafts and high-speed torpedo

boats. The first prototype, codenamed L-1, had a very simple design which consisted of

two small wooden catamarans that were powered by three prop engines. Air cushion was

produced by the horizontally-placed engines. During successful tests, one of Levkov's

air-cushion crafts achieved a speed of 70 knots.

Charles J. Fletcher, an American, designed his "Glidemobile". The design

worked on the principle of trapping a constant airflow against a uniform surface, either

ground or water, generating about ten inches to two feet of lift to free it from the surface.

Control of the craft would be achieved by the measured release of air. Fletcher's work

was largely unknown because it was deemed to be classified by the United States

Department of War.

Colonel Melville W. Beardsley, an American aeronautical engineer, worked on a

number of unique ideas during the 1950s, which he patented. His company built craft

6

based on his designs at his Maryland base for the both government and commercial

applications. He later worked for the Navy on developing the hovercraft further for

military use.

Dr. W. Bertelsen, an American, built an early prototype of a hovercraft in 1959

called Aeromobile 35-B, and was photographed for Popular Science magazine riding the

vehicle over land and water in April on 1959.

In 1952, British inventor Christopher Cockerell, widely regarded as the father of

the modern-day hovercraft, worked with air lubrication with test craft. He then moved

on to the idea of a deeper air cushion. He used simple experiments involving a vacuum

cleaner motor and two cylindrical cans to create his unique peripheral jet system, the

recipe of his hovercraft invention, and was patented as the ‘hovercraft principle’. He

proved the functionality of the principle of a vehicle suspended on a cushion of air

which is ejected under pressure. This made the hovercraft easily mobile over most

surfaces as the air cushion would enable it to operate over soft mud, water, and marshes

and swamps as well as on firm ground. He designed a working model vehicle based on

his patent. In 1958, the National Research and Development Corporation paid for the

rights to his design and had an experimental vehicle built by Saunders-Roe, the SR.N1.

The craft, built to Cockerell's design, was launched in 1959 and made two crossings as

part of its public demonstrations. It proved its potential as a transport vehicle, first by

crossing the Solent and then by crossing the English Channel. The latter trip lasted two

hours and took place on the 50th anniversary of Louis Bleriot’s cross-Channel flight.

2.3 Theory

The ground effect phenomenon is the basic principle of operation found in

hovercrafts. According to Ahmad Luthfi B. Musa (2004), this is best explained by taking

a simple example of a circular disc. If a jet of air is directed downward onto the ground

7

through a hole in the disc, it will tend to rise. Two reasons are responsible for this.

Firstly, if the nozzle is attached to the disc, the jet of air has a reverse effect of its own

which forces both the nozzle and the plate away from the surface. Secondly, some of the

air hitting the ground bounces back against the disc and hence, creates additional lift in

the process. The second factor is called the ground effect phenomenon.

Figure 2.2: Basic Ground Effect Phenomenons Air cushion suspension systems can be divided into two; skirted and non-skirted.

This term refers to the way in which the ground effect phenomenon may be sustained, or

in other words, how the air cushion may be maintained beneath the hovercraft. The

functions of the air cushion include reducing friction between the craft and the ground,

acting as a spring suspension to reduce some of the vertical acceleration effects which

arise from traveling over uneven surfaces, and distributing the weight of the hovercraft

over almost its entire plan area.

Two of the basic non-skirted air cushion suspension systems are the plenum

chamber and the peripheral jet curtain. The former is the simplest of all systems. It is

essentially an inverted bowl into which air is pumped through an orifice at its top, and

then allowed to escape at the bottom edges in a ‘vena contracta’ type of flow. Unless the

gap at the periphery of the chamber is small, air will escape at a very high rate and

excessive power will be required in order to maintain the air cushion.

8

Figure 2.3: Plenum Chamber The peripheral jet system, also known as the momentum jet curtain, was

originally conceived by Christopher Cockerell. It is essentially a system whereby

pressurized air is ducted to a jet ring located at the periphery of the craft and directed

downward and inward to supply air to the underside of the craft; in so doing the air jet

also acts as a curtain which seals the air gap between the underside of the hovercraft and

the surface over which it is operating. The pressurized air causes the hovercraft to rise

until some height above the ground is reached when the air pressure within the cushion

is built up to the state where it is so much greater than atmospheric that the air curtain is

deflected outward and the contained air is able to escape.

Figure 2.4: Peripheral Jet Curtain The flexible skirt was introduced as it offered solutions to overcome existing

limitations. The skirt functions as a reinforcement of the air curtain as a means of

containing the air cushion. Additionally, it also seals the gap between the hovercraft and

an uneven riding surface so that the air cushion’s leakage would be reduced, thereby

resulting in the more efficient usage of lift power. Last but not least, the skirt enables the

9

hard structure of the hovercraft to be raised further above the surface so as to produce

sufficient obstacle clearance for practical use.

These aims are achieved by simply directing the downward air jet between two

fabric curtains so that the air curtain is formed at the hemline of the flexible material.

Thus, not only would the air cushion be more effectively contained, but the underside of

the hovercraft would be immediately raised to a height equal to the length of the skirt

plus the air curtain daylight clearance. Since the introduction of the skirt, various designs

have evolved, each with its own pros and cons. Among the types of hovercraft skirts are

trunked, convoluted, jetted, segmented, bag skirt with finger extensions and plenum

chamber skirts (Cross, Ian and O’ Flaherty, Coleman A., 1975).

The development of the flexible peripheral skirt has undoubtedly been of the

important milestones and advancements in the technological design of hovercrafts.

Skirts enable hovercrafts to negotiate huge obstacles on land and sea with great ease,

making it much more practical and commercially viable.

Figure 2.5: Components of Hover Height There are a few types of propulsion methods, depending on the type of the

hovercraft. Two of the common ones are air propellers and air jets. The aircraft-type

variable-pitch propellers have been the more popular choice for air-propeller driven

hovercraft throughout history. By varying the propeller pitch, the amount of thrust

10

provided is regulated. Immediately behind the propeller and placed in the propeller slip-

stream is the tail unit comprising twin fins with rudders for directional control. This

technique of maneuvering the hovercraft is widely used.

In the case of air jet-propelled hovercrafts, thrust air is directed rearward out of

two ports on either side of the hull through some small rudders set in the air stream of

each port. Also set in each of the two thrust ports, ahead of the rudders, is a reverse-

thrust bucket which is interconnected with flaps set in each of the fan ducts with

forward-facing openings. Directional and lateral control is achieved by manipulating the

rudders set in the jet air stream and by differential use of the reverse thrust and flap

system.

Among model hovercrafts however, the use of twin propellers for the thrust

supply and maneuvering is common. The velocity or spin directions of each of the

propellers are adjusted accordingly to produce varying jet air streams which will then

result in the directional control and maneuvering of the hovercraft.

2.4 Case Studies

2.4.1 Pierre Rouzeau

The hovercraft is a derivation of Sevtec and Vanguard hovercraft models from

Rouzeau, Pierre (2004). The physical frame of the hovercraft is made primarily of

plywood while kite fabric is used to make the skirt. For the thrust propulsion supply, an

8.4 V ferrite motor size 500 is used with an epicycloidal gear reducer ratio of 3.8:1. Its

unloaded speed is roughly 30000rpm and it is fitted with a 12” propeller. The lift is

provided by a 7.2 V Graupner speed gear 500 race motor fitted with a 4.7” fan and a

2.8:1 gear reducer. The unloaded speed of the motor is 8000rpm. One 2400 mAh, 8.4 V

7 elements nickel-cadmium battery common to both motors supplies the power to the

11

hovercraft. It is controlled with a programmable Graupner MC12 radio controller and

three servo motors, two for compartment opening and one for the rudders (Rouzeau,

Pierre, 2004). The size of this hovercraft is 92 cm by 50 cm by 46 cm and it weighs 2.5

kg.

Figure 2.6: Pierre Rouzeau’s Hovercraft

2.4.2 Kevin Jackson – Basic Hovercraft

Figure 2.7: Basic Hovercraft

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According to Jackson, Kevin (2003), the physical frame of the hovercraft is

made primarily of hard foam while a polythene sheet is used to make the skirt. The lift is

provided by a 12-18 V RS Components Electrovalue motor fitted with a 4” fan. One 12

V battery supplies the power to the hovercraft. The size of this hovercraft is 50 cm by 30

cm by 15 cm. This model is a very basic one which demonstrates the operating principle

of a hovercraft, and hence does not have a propulsion system nor any form of control.

2.4.3 Kevin Jackson – SR.N1 Model

The model is constructed using balsa over a plywood frame (Jackson, Kevin,

2003). The ducts are 1/32 and 1/16 plywood. The ducts have full reverse and forward

flap valves in both thrust ducts each using a Futaba 148 servo. The radio has 7 channels

with 4 for the valves inside the ducts 1 for rudder control and 1 for throttle. The power

plant is an OS 40 LA with a rubber vibration mount at the base of the intake duct. Lift is

generated with a 3-blade 8 by 6 propeller. The OS 40 uses 15% nitro Omega fuel. The

muffler is the stock OS 40 type which vents into the base of the intake duct (Jackson,

Kevin, 2003). The needle valve is extended through the intake duct using a nylon rod

and the glow plug has an extender wire so it can be remotely powered.

Figure 2.8: SR.N1 Model

13

2.4.4 Mike Porter – SR.N5 Model

The model is approximately 73 cm by 43 cm. Both the lift and thrust propellers

are powered by an RS540 motor each. The lift power supply is a 6-cell nickel-cadmium

battery, while the thrust power supply is a 7-cell variation. The rudder, lift and thrust are

controlled using a three-channel radio control as shown in Porter, Mark (2006). The

frame is made from balsa and plywood while the skirt is polyester. Unlike most models,

this one does not have any holes in either the base of the craft or the inner wall of the

skirt to provide airflow to the cushion. This is because the material that is used is leaky

enough for air to seep through (Porter, Mark, 2006).

Figure 2.9: SR.N5 Model 2.4.5 SEALEGS Amphibious Boat

SEALEGS Amphibious boat has two rear marinised hydraulic wheel motors with

stainless steel hubs. It also specify that the vehicle land powered is by 4 stroke v-twin

14

cylinder air-cooled 16hp Honda in-board engine (mounted under center console)

electronic ignition and electric start. Figure 2.10 shows the product of SEALEGS

amphibious vehicle. Table 2.1 is showing SEALEGS Amphibious Boat criteria.

Figure 2.10: SEALEGS Product

Standard feature of SEALEGS amphibious vehicle product:

4mm aluminum hull (5083 Marine Grade)

Foam filled Aluminium D-Tube pontoon sections

Integral 80 liter (21 gal) fuel tank and gauge

Center console with seating for 3 adults

Storage in seat locker, outboard well locker & three deck lockers

Davit lifting points

Anti-slip deck tread

4180lph (1100gph) Automatic bilge pump

Navigation lights

Ski pole with 4 rod holders

Navman 4100SX depth sounder/fish finder

15

Table 2.1 SEALEGS Amphibious Boat criteria

Length Overall 5.6m (18ft 4")

Beam 2.4m (8ft")

Draft 0.41m (16")

Weight (dry) Dead rise 1050kg (2315lbs) (with 90HP 2-stroke outboard

Payload 21 degrees

Recommended HP 500kg (1100lbs) (6 adults)

Top Speeds Sea 60kph (37mph), Land 10kph(6mph)

2.4.6 Hovercraft and Ram-wing Craft in the 1960's and beyond

Figure 2.11: Raw-wing Craft

Ram-wing craft that show in Figure 2.11 were craft based on the principle of a

wing using the ground effect. They were first developed by American aerodynamicists

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in the early 1960's. In the global technological race that was going on during the 1960's

an amazing array of wing-in-ground effect vehicles were built the world over. The

Russians in particular explored this principle in a myriad of craft, like the Ekranoplan

and its infamous Caspian Sea Monster. Although few of the craft built got beyond the

experimental stage, they did show that a combination of airfoil and air-cushion

technology provided enough stationary hovering capability. This lift was then

transferred into forward speed.

Even though it was now possible to surpass the theoretical hover speed limit of around

320 kilometers per hour (200 mph), it became clear that the air cushion would not stay in

place above these speeds and another solution had to be found. The ram-wing craft did

prove beyond doubt that the air cushion principle was a practical one and had

advantages over wheels and other methods of transport in certain situations.

2.5 Summary

Besides the cases reviewed above, there are numerous hobbyists and enthusiasts

around the world who have built various kinds of model hovercrafts. Listing all of the

projects that have been reviewed throughout the course of this project would be

impossible due to space constraints. In short, they can be divided into electrical-powered

and fuel-powered motor-driven hovercrafts. Each of them is unique in terms of their

design and construction materials. However, it can be generally concluded that all of

them operate using the same basic mechanical principles. Thus, after assessing the

diverse techniques of hovercraft construction, a wide range of methods are employed in

the design and fabrication of the model hovercraft.

17

CHAPTER 3

METHODOLOGY

The following chapter discusses the methods and materials employed in the

design and fabrication of Minihovercraft, as well as its manner of operation.

Basically, this project is an interdisciplinary field that ranges in scope from the design of mechanical and electrical components. The mechanical and electrical components include mechanical frame and motor, while the electrical components consist of microcontroller, motor driver and IR sensor circuit.

In this design, the components can be classified into input, the process and the output. Figure 2.1 shows the research methodology flow chart for complete this project.

18

CONCEPTS AND IDEAS

LITURETURE STUDIES

MOTOR DRIVER AND SENSOR CIRCUIT

FABRICATE MECHANICAL STRUCTURE

COMBINATING MECHANICAL AND ELECTRICAL PART

SOFTWARE DEVELOPMENT

FINAL TESTING

FINAL REPORT

Figure 3.1: Research Methodology flow chart

NO

YES

19

3.1 Electrical and Electronic Design 3.1.1 MICROCHIP PIC16F877A Microcontroller

In this project, a PIC16F877A micro controller is chosen to be used as the brain

of the robot. The microcontroller is chosen because it provides more input and output ports and supports more functions. Besides that, free samples for the PIC microcontroller can be obtained from Microchip website which will help to reduce the cost of the project. The PIC16F877A micro controller will serve as the brain of the robot and controls the actions of the hovercraft. Input signals are sent to the microcontroller and the microcontroller will send instructions to control the robot to act accordingly after processing the input signals received (Smith, D.W., 2005).

Microchip PIC16F877A microcontroller runs at 20 MHz with 8 Kbytes of Flash memory and 256 bytes EEPROM. This type of microcontroller is selected because it has a large memory for programming.

PIC16F877A microcontroller has 5 ports at could be used as input or output.

Figure 3.2 shows the pin of PIC16F877A Microcontroller and figure 3.3 shows block

diagram for PIC16F877A microcontroller. Table 3.1 shows the PIC16F877A

microcontroller device features.

20

Figure 3.2: Pin Diagram for PIC16F877A Microcontroller

Table 3.1: PIC16F877A Device Features

21

Figure 3.3: Block Diagram for PIC16F877A Microcontroller

22

3.1.2 PIC Startup Kit - SK40A Input voltage: 7 - 30 V

Power Output: If user requires voltage directly from the power supply, user may extend

the voltage from this port.

Figure 3.4: Boot loader

Among the many features built into Microchip’s Enhanced FLASH Microcontroller, this device has the ability to change program memory to self-program. This useful feature has been deliberately included to give the user the ability to perform boot-loading operations. Device like the PIC16F877A is designed with a designated “boot block”, a small section of protect able program memory allocated specifically for boot load firmware. Once a program is ready and a hex file is generated, the boot loader will load the program into the microcontroller using the Universal Synchronous.

23

Asynchronous Receive Transmit (USART) module in the PIC is used to receive

data with hardware handshaking. In this project, CYTRON PIC Microcontroller Start-up

Kit (SK40A) is used as a boot loader to ease the process of loading program further save

development time and cost. The upload process is done using Hyper Terminal software

(available in all Microsoft Windows version).

SK40A have onboard voltage regulator, 7805 which will provide stable 5V

output to PIC and other application. Therefore, user may extend the 5V from SK40A kit

external used, no extra voltage is necessary. However, the maximum current of this

regulator is only1A. Once power is connected to Power Input, Power ON LED will light

up. If the LED does not light after power is connected, it might be caused by wrong

polarity of power or no power from battery. SK40A is ready with a protection diode to

avoid damage to circuit if the Power Input polarity is connected wrongly. Figure 3.4

shows the complete boot loader and Figure 3.5 shows the schematic diagram for

microcontroller with boot loader.

Figure 3.5: Schematic Diagram for Microcontroller with Boot Loader

24

3.1.3 Relays A relay is an electrical switch that opens and closes under the control of another

electrical circuit (Hewes, John, 2007). The purpose of implementing the usage of relays

in this case is to electrically isolate the low-current microcontroller circuit from high-

current circuit which actuates the motors. The four relays used in this circuit are the

Songle SRD-06VDC-SL-C. This is a single pole double throw (SPDT) relay with a

nominal coil voltage and current of 6 volts and 71.4 miliamperes respectively.

Figure 3.6: Songle SRD-06VDC-SL-C Relay

3.1.4 Motor Driver

Motor cannot connect directly to microcontroller. Motor is a high current consumptions device. If both of them connected, most likely the microcontroller will get damage. For protection from damage, motor driver is used. Motor driver circuit is the circuit used to control the rotation direction of DC motor. For this project, 2 devices are used in motor driver, ULN 2803 and relay that be design in motor driver circuit. 1 ULN 2803 and 4 relay 6Vdc is used in this motor driver and used for control the output from PIC Microcontroller. Figure 3.7 shows the pin-outs of ULN 2803. The reason using ULN 2803 in motor driver is because relays is used in the motor driver circuit. 1 ULN 2803 can control up to 8 relays. 1 transistor can control 1 relay. ULN 2803 has eight NPN Darlington connected transistor. 1 relay control 1 direction of motor. For 2 motor and 4 directions, 4 relays were used for the motor driver. Figure 3.8 shows the schematic diagram for motor driver circuit.

25

Figure 3.7: ULN 2803

Figure 3.8: Motor Driver Circuit

26

3.1.5 DC Motor

DC motors are simple two-lead, electrically controlled devices that come with a

rotary shaft on which wheels, gears, propellers can be mounted. DC motors generate a considerable amount of revolutions per minute (rpm’s) for their size and can be made to rotate clockwise or counterclockwise by reversing the polarity. At low speeds, DC motors provide little torque and minimal position control, making them obsolete for function like position-control applications.

DC motors are available in many different shapes and sizes. Most DC motors provide rotational speeds anywhere between 3000 and 8000 rpm at a specific operating voltage typically set between 1.5 and 24 volt. The operating voltage provided by the manufacturer specifies the voltage for which the motor will runs most efficient. Another specification given to DC motors is the torque rating. This represents the amount of force the motor can exert on a load. A motor with a high torque rating will exert a larger force on a load placed tangential to its rotational arm than a motor with a lower torque rating.

Figure 3.9 shows a Mabuchi RS–540RH/SH Motor that used for the

MiniHovercraft. The application of motor is for the propeller movement. The motor is installed with a propeller. The operating voltage is 4.5V – 9.6V and produce speed range around 11600 rpm with no load at 860mA. The output range is 5.0W-90W (approx) and motor weight is 160g. The detail motor specification is given in table 3.2 and Figure 3.10 shows the detail view of motor.

Figure 3.9: Mabuchi Motor RS-540RH/SH

27

Table 3.2: Motor Specification

Figure 3.10: Detail view of motor

28

3.1.6 Power Supply

The low-current power supply is provided by three 9-volt PP3 batteries for the

control circuitry. The high-current power supply which drives the motors is provided by

a separate set of batteries. Two 6-cell 9.6-volt 650mAh nickel-metal hydride (NiMH)

AAA batteries pack powers the lift fan, while another similar battery pack powers both

the thrust propellers. This ensures that adequate current is provided for all the motors to

run at high speed. Unlike nickel-cadmium (NiCad) batteries, NiMH batteries do not use

heavy metals that may have toxic effects. In addition, they can store up to 50% more

power than NiCad batteries and do not suffer from memory effects.

Figure 3.11: 9.6V AAA Battery Packs and 9V PP3 Batteries

3.1.7 Infra-Red Sensors Infra-Red (IR) is the typical light source used as a sensor in robot to sense

opaque object. The basic principle of IR sensor is based on an IR emitter and an IR

receiver. IR emitter will emit infrared continuously when power source is provided.

Since there is no source of power for IR receiver, it would not emit any obstacle.

It will only receive infrared if there is any. Generally IR emitter and IR receiver will be

attached side by side, and point to a reflective surface.

29

Figure 3.12: IR sensor on two different surfaces

When the IR receiver receives infrared, it will generate voltage at its pin. The

generated voltage is in the range from 0V to 5V depends on the intensity of infrared it

received. The voltage will drop to zero if there is no infrared received. Error will occur

when the microcontroller is unable to recognize value other than 0V and 5V.

This is due to, if the infrared reflected is less, the receiver would probably

produce a 2V or 3V and microcontroller is unable to deal with these analog values.

Thus, a comparator (LM324) is needed to solve this error. By using this LM324, the

output voltage from IR receiver will be compared with an input voltage through a

variable resistor, and the corresponding digital output will be feed to the microcontroller.

Figure 3.12: A Pair of Infra Red Sensor

30

As indicated before, three pairs of IR sensors are used to be mounted on

MiniHovercraft. Where three pairs integrated with relevant circuit is used for forward,

left and right position detector function. The output from LM324 connected to PIC

microcontroller at port RD7, RD5 and RD4. These pins where initialized as input from

IR sensor.

Figure 3.14: Schematic Diagram for LM324

Figure 3.15: Circuit for LM324

31

3.2 Mechanical Structure and Design 3.2.1 Mechanical Design and Planning This section discusses the mechanical design. The mechanical design is a critical design phase in the development. Without an accurate and details design, there are possibilities that the expected movement cannot be reached by the vehicle. This design was upgrade from Ahmad Luthfi B. Musa (2004) design.

The vehicle consists of two DC Motors and single Servo Motor. The propeller is designed by using the DC motor for clarify the air thrust to move the MiniHovercraft. Figure 3.16 shows the flow of design development and planning.

START

Literature Review

Material Selection

Building Hardware

Testing

Error

END

Figure 3.16: Mechanical design planning

NO

YES

32

3.2.2 Mechanical Parts and Specification 3.2.2.1 Polystyrene

Polystyrene is a polymer made from the monomer styrene, a liquid hydrocarbon

that is commercially manufactured from petroleum by the chemical industry. At room

temperature, polystyrene is normally a solid thermoplastic, but can be melted at higher

temperature for molding or extrusion, then resolidified. Styrene is an aromatic monomer,

and polystyrene is an aromatic polymer. Extruded polystyrene, or more commonly

known by its trademark Styrofoam, is used to fabricate most of the physical structure of

MiniHovercraft. The industrial-grade polystyrene board is light yet durable; making it an

excellent choice for this task. It is also easily shaped, using very simple tools, such as

hot-wire cutter which is used in this project. Additionally, expanded polystyrene, a less

dense variant, is also used in the fabrication of certain parts, namely the motor mounts.

The body of the hovercraft is where all the other electric and electronic components are

mounted on.

Figure 3.17: Extruded Polystyrene Board

33

Figure 3.18: Expanded Polystyrene Board

Figure 3.19: Floating Material 3.2.2.2 Polymer Base

Polymer base is a thermoplastic commodity made by the chemical industry.

Polymer consists of long chains of the monomer ethylene. It is light, flexible and also

airtight, which makes it suitable for the construction of MiniHovercraft’s skirt. The skirt

is a strip of material that wraps around the edge of the hovercraft and inflates when air is

forced into it. It contains the air cushion while providing ground clearance. A polymer

base is cut according to design and used to make the skirt of hovercraft.

35cm

12cm

3cm

34

Figure 3.20: Polymer Base

3.2.2.3 Lift fan

The lift fan is responsible for forcing air under the craft to create a cushion,

causing it to hover. For this purpose, a high-speed direct current motor driving a 6-blade

ducted fan measuring 5 centimetres in diameter is used. The voltage applied to this

motor is 9.6 volts, while the current drawn by it is approximately 3 amperes.

Figure 3.21: Lift Fan

35

3.2.2.4 Thrust Propeller

The thrust propellers’ function is to generate propulsion to make the hovercraft

move forward, and with proper control, they can also steer the hovercraft accordingly.

The thrust motor and propellers for MiniHovercraft are sourced from that of a model

airplane. Each of the propellers measure 11 centimetres in diameter and have 2 blades

each. The voltage applied to both motors is 9.6 volts, while the combined current drawn

by them is approximately 3.2 amperes.

Propeller is a device which transmits power by converting it into thrust for

propulsion of a vehicle such as an aircraft, ship or submarine through a fluid such as water or air by rotating two or more twisted blades about a central shaft in a manner analogous to rotating a screw through a solid. The blades of a propeller act as rotating wings and produce force through application of both Bernoulli's principle and Newton's third law. The design had been modified to obtain a powerful energy to move the hovercraft forward. A pair of white propeller has been modified to increase the air thrust pressure.

Figure 3.22 show the complete propeller design and Figure 3.23 shows the

propeller illustration in side view.

Figure 3.22: Thrust Propeller

36

Figure 3.23: Propeller side view

3.2.3 Structural and Layout

The structural design of this hovercraft is based on the research and review of the

mechanical and physics principles of operation of hovercrafts in general. Several

prototypes were planned and fabricated before settling on the current design. After

thorough experimentation with a wide variety of shapes and sizes, as well as making

ongoing modifications to improve the performance of the model hovercraft throughout

the course of the project, the final design proves to be the ultimate one in terms of speed

and stability.

The structure of MiniHovercraft divides by three parts and a mount for the thrust

propellers. The first and second part is for fabricate the skirting are joined together with

thrust propeller at the back of the body on this part. Inside the both of skirt are

polystyrene block which are the strengthen part for floating the hovercraft. The third

parts are the main body for MiniHovercraft has a hole measuring five centimetres in

diameter directly beneath the lift fan. This is for facilitating the air outtake from under

hovercraft. The mounts for the thrust propellers are fixed on the upper at the back,

slightly towards the rear of hovercraft. Dual-circular structure acts as a protective casing

for the propellers.

37

For the fabrication of the skirt, a strip of polymer sheet 15 centimetres in width is

used. The length of the sheet is sufficient to surround the perimeter of the first and

second part of hovercraft. The polymer sheet is then stapled and taped to the both part of

MiniHovercraft, thus creating an airtight skirt which will function as a cushion.

Figure 3.24: MiniHovercraft Plan View and Measurements

Figure 3.25: MiniHovercraft Front View and Measurements

30cm

40cm

11cm

14cm

4cm

15cm

5cm

38

Figure 3.26: MiniHovercraft Side View and Measurements

Figure 3.27: MiniHovercraft Trimetric View

40cm

6cm4cm

20cm

15cm

Thrust Propeller

Air Cushion

2nd Part

3rd Part

1st Part

Electronic Circuit

Lift Fan

39

3.3 Operation of MiniHovercraft 3.3.2 Mechanical

The sketch below is a simple illustration of the cross-section of MiniHovercraft.

The direction of the air flow generated by the lift fan is downwards and outwards

through the base of the skirt. Air is forced into both the plenum chamber and the skirt.

The outer part of the skirt is attached to the top platform while the inner part is joined to

the bottom one. This design forms a ring of air around the perimeter of MiniHovercraft

to contain the air within the plenum chamber and lowers the rate at which the air

escapes.

Figure 3.27: MiniHovercraft Cross-section View

The following is a drawing of the rear view of MiniHovercraft, and a depiction

of how the hovercraft is maneuvered. When both of the propellers are spinning

clockwise, forward thrust is generated and hovercraft moves to the front.

40

Figure 3.29: Forward Movement When the right propeller spins clockwise, forward thrust is generated on the right

side of MiniHovercraft, steering it to the left.

Figure 3.30: Left Steering

41

When the left propeller spins clockwise, forward thrust is generated on the left

side of MiniHovercraft, steering it to the right.

Figure 3.31: Right Steering When both of the propellers spin anti-clockwise, backward thrust is generated

and MiniHovercraft goes backward.

Figure 3.32: Reverse Movement

42

3.3.3 Electronical

The following is a block diagram which illustrates briefly how the electronic

circuitry controls MiniHovercraft.

Figure 3.33: Electronic Circuitry Block Diagram

Outputs from LM324 were connected to PIC microcontroller at port RD7, RD5

and RD4. These pins initialized as input from IR sensor. For normal movement, no

sensors were detected the obstacle and the hovercraft move forward. The positions of

sensor on hovercraft are left side (RD7), front side (RD5), and right side (RD4)

When sensor detect obstacle on front, port RD5 is give the output logically high

and move backward and delay 3 second. After delay, the hovercraft move right side.

After that, when sensor detect obstacle at left side, port RD7 give the output logically

high and the hovercraft turn right. Otherwise, the sensor detect obstacle at right side,

port RD4 will be logically high, and then the hovercraft moves left side. The

microcontroller is programmed to maneuver MiniHovercraft by detection of three

sensors.

Output ports RD0 and RD1 control the relay for the left thrust motor, while

output ports RD2 and RD3 do the same for the right one. The pair of relays for each

motor is connected in such a way that depending on which one of them is turned on, the

Microcontroller

Relays

Right Thrust Propeller Left Thrust Propeller

Infra-Red Sensors (IR receiver & emitter)

43

motor is capable of spinning both clockwise and anti-clockwise. However, when both of

the relays in the same pair are turned on or off together, there will be no actuation of the

motors.

When no sensors detect obstacle, RD0 and RD2 will be logically high while RD1

and RD3 will be logically low, activating the relays to spin both thrust propellers

clockwise, thus moving MiniHovercraft forward. For a logically high RD4 for sensor at

right side, RD2 will be logically high while RD0, RD1 and RD3 will be logically low,

resulting in only the right thrust propeller spinning clockwise, thus steering hovercraft to

the left. Similarly, a logically high RD7 for sensor at left side results in RD0 being

logically high while the rest being logically low, causing the left thrust propeller to spin

clockwise and steer MiniHovercraft to the right. Finally, if sensors detect at the front a

logically high for port RD5, port RD1 and RD3 will be logically high while RD0 and

RD2 will be logically low, activating the relays to spin both thrust propellers anti-

clockwise, thus moving MiniHovercraft backward.

3.3.3 Flow Chart

Figure 3.34: Flow Chart of Program

START

RD5=0

RD5=1

RD7=1

RD4=1

No

No

No

No

Yes

Yes

Yes

Yes

RD0=RD2=1 RD1=RD3=0

RD0=RD3=1 RB1=RB2=0

RD0=1 RD1=RD2=RD3=0

RD2=1 RD0=RD1=RD3=0

Delay 0.5s Forward

Delay 0.5s Right

Delay 3s Backward

Delay 0.5s Left

44

3.4 Software Development In the beginning, the idea was to use assembly language to write the program source

code for my MiniHovercraft. But later, due to industries requirement, which are

implementing a more sophisticated language, which is C language of course. Besides, C

language proves not only being user friendly but faster source codes writing as well. For

this project, in order to download the .hex file, software is choose two programming

software named WinPIC800 and MPLAB IDE.

3.4.1 MikroC, mikroElektronika C compiler MikroC is a powerful, feature rich development tool for PIC micros. It is designed to

provide the programmer with the easiest possible solution for developing applications

for embedded systems, without compromising performance or control. MikroC provides

a successful match featuring highly advanced IDE, ANSI compliant compiler, broad set

of hardware libraries, comprehensive documentation, and plenty of ready-to-run

examples. Below are some of the features that offered by MikroC which helps to

develop and deploy complex applications in a faster manner:

• Write C source code using the built-in Code Editor ( Code and Parameter

Assistants, Syntax Highlighting, Auto Correct, Code Templates, and more )

• Use the included mikroC libraries to dramatically speed up the development:

data acquisition, memory, displays, conversions, communications

• Monitor program structure, variables, and functions in the Code Explorer.

• Generate commented, human-readable assembly, and standard HEX compatible

with all programmers.

• Inspect program flow and debug executable logic with the integrated Debugger.

45

• Get detailed reports and graphs: RAM and ROM map, code statistics, assembly

listing, calling tree, and etc

• Provided plenty of examples to expand, develop, and use as building bricks in

projects.

Figure 3.35: MikroC IDE - Integrated Development Environment

46

3.4.2 How to write source codes using MikroC? Programming using MikroC is just a simple. Once the MikroC program is launched, the

New Project tab should be clicked and a Project Wizard GUI will appear as in Figure

3.36.

Figure 3.36: Project Wizard GUI

In this GUI the PIC device that is going to be used is selected, the clock

frequency is set and the appropriate device flags are chosen. Once done a window shall

appear, and the C language source code writing can be started. If there are any troubles

or problem should occur, the user friendly help functions will always be handy. It can

47

even provide effective solutions for some algorithm through the examples given. Once

done, the Build Project tab is clicked in order to generate a .hex file or machine codes.

Error with messages will appear whenever MikroC had detected any faults in coding

together will suggests some solutions.

3.4.3 Load the source code using WinPic800 Once the .hex file is successfully generated, it will later be downloaded into the

PIC16F877A. In order to download the .hex file, software named WinPIC800 is used to

together with hardware, Desktop Programmer. The Desktop Programmer is connected to

the PC by using the Serial Port Interfacing. Figure 3.37 and Figure 3.38 show the

capture screen of the WinPIC800 software and Desktop Programmer hardware

respectively.

Figure 3.37: WinPIC800

48

Figure 3.38: Desktop Programmer

3.4.4 Load the source code using MPLAB IDE

MPLAB Integrated Development Environment (IDE) is a comprehensive editor, project manager and design desktop for application development of embedded designs using Microchip microcontroller. MPLAB IDE runs as a 32-bit application MS Windows® is easy to use and include a host of free software components for fast application development and super-charged debugging.

MPLAB IDE also served as a single, unified graphical user interface for

additional Microchip and third party software and hardware development tools. This software is used t assemble the program written using assembly language to create the machine code (HEX file). The application also provides the ability to create and edit the source code using the built in editor. Figure 3.39 shows MPLAB IDE Desktop Interface.

49

Figure 3.39: MPLAB IDE Desktop Interface 3.4.4.1 PICC LITE

PICC LITE is an ANSI C compiler that supports selected microchip. PIC16F877A is one of the devices supported by it. Therefore, it can be used to compile the source codes written for PIC16F877A. However, there is a size limit for the PIC16F77A micro controller using PICC LITE. The codes written can only be of 2048 words to the maximum.

50

3.4.4.2 Boot Loader

As mentioned earlier, boot loader is a program used to load the user’s program into the microcontroller easily. Before using the boot loader, it needs to be ensured that the boot code is already programmed into the microcontroller.

The first step of boot loading process is testing on pin RB0. Then, it will receive hex file using USART and hardware handshaking. Next data error checking is applied before writing the code to program memory. After the code successfully loaded into the microcontroller, the program waits for reset and then starts user code running. 3.4.4.3 Compile the program

The following steps briefly outlined the procedures to compile a program using MPLAB IDE.

i) Run MPLAB IDE

ii) Open a new file to write source codes (see Figure 3.40)

51

Figure 3.40: Opening a new file to compose source codes.

iii) Save the file as C Source Files (see Figure 3.41)

Figure 3.41: Saving the source codes as C Source File.

52

iv) Create a new project (Figure 3.42)

Figure 3.42: Creating a new project with MPLAB IDE.

v) Add the file previously saved to Source files (see Figure 3.43).

Figure 3.43: Adding the file saved as Source files.

53

vi) Open the source file added (see Figure 3.44).

Figure 3.44: Open the added source file

vii) Then go to ‘Project’ and select ‘Build All’ (see Figure 3.45).

Figure 3.45: Selecting “Build all” to compile the project.

54

viii) Observe if the file is successfully compiled (see Figure 3.46). If the

file is successfully compiled, a hex file will be generated. The hex file

is then loaded into the PIC microcontroller with the PIC programmer.

Figure 3.46: File successfully compiled.

ix) If there is an error (see Figure 3.47), correct the errors and build the

file again until it is successfully compiled.

Figure 3.47: File failed to be compiled due to errors

55

CHAPTER 4

RESULTS

The final accomplishments and results of the project shall be explained in this

chapter. This chapter discusses on the result, analysis and problems that are encountered

throughout the completion of MiniHovercraft-An Amphibian Robot. After the

development and completion of the hovercraft, it will then be evaluated in order to

measure the effectiveness and to ensure whether it had met the outlined objectives

successfully.

4.1 MiniHovercraft The model hovercraft, christened ‘Minihovercraft’, was successfully constructed

using raw materials and items of various sources. The project met its objective of being

a functional mobile model hovercraft that could be maneuvered autonomously.

MiniHovercraft can successfully travel on land and water, and this was determined after

carrying out experiments which returned positive results. Its hover height is

approximately 10 centimetres, calculated from the clearance between the third part body

and the ground. Its speed is roughly 10 kilometers per hour.

The maneuver of MiniHovercraft is autonomous controlled by using an infra-red

sensors and programming. MiniHovercraft can detect the obstacle and moves to other

56

way by using the infra-red sensors. The thrust propellers’ spin directions accordingly

from motor driver circuit. MiniHovercraft is able to go forward and reverse, as well as

steer left and right. It is responsive and relatively fast, considering its small size. The

hovercraft is able to perform their movement successfully on the land and water surface.

4.2 Maneuver Test 4.2.1 Water Surface Test

The hovercraft has been tested on water surface. The amphibian hovercraft can

move forward, right and left. The target for this test is to navigate the vehicle forward on

the water surface. Figure 4.1 shows the MiniHovercraft move on water surface. It proves

the hovercraft can travel on water surface.

Figure 4.1: Hovercraft on Water Surface

57

4.2.2 Land Surface Test

For this part, the hovercraft was tested on land surface to check the movement.

After testing, the hovercraft can move left, right and forward. Figure 4.2 shows the

MiniHovercraft move forward.

Figure 4.2: Hovercraft on land surface 4.3 Component and Circuitry Test 4.3.1 Infra-Red (IR) Sensor Circuit

For this part, the IR Sensor circuit functions are use to control movement of

hovercraft by detect the obstacle. That component can control the hovercraft movement

without any wire. It also can control the hovercraft autonomously for a long distance

area. The range for the sensors are about 15 – 20 centimetres. Figure 4.3 shows the

complete Infra-Red sensors circuit.

58

Figure 4.3: Complete Infra-Red sensors circuit.

4.3.2 Motor Driver Test

The motor driver is tested after complete designed the electronic part. Figure 4.4

shows the complete circuit of motor driver. By connected Infra-Red sensors to PIC

microcontroller, motor driver is fully functioning by examining the output of relay. The

output range must be 4.5V – 9.6V.

Figure 4.4: Motor Driver Circuit

59

4.4 Final Structure of MiniHovercraft

The completed hovercraft is taken from multiple angles as shown in Figure 4.5,

so that a perfect front view can be seen and understood.

Figure 4.5: MiniHovercraft Front View

Figure 4.6: MiniHovercraft Top View

60

Figure 4.7: MiniHovercraft Rear View

Figure 4.8: MiniHovercraft Side View

61

Figure 4.9: MiniHovercraft Diagonal View

62

CHAPTER 5

CONCLUSION

The model of the hovercraft project has been a resounding success as

MiniHovercraft is fully functional according to its work scope. This amphibious vehicle

can travel on both land and water surface. The hovercraft is operated and maneuvered

autonomous control by using programming and Infra-Red sensors.

This hovercraft project discusses about the development of the MiniHovercraft-

An Amphibian Robot that used three DC motor and three pairs of sensors. This project

is implemented using PIC16F788A which was programmed using the C language to

control the hovercraft. The hovercraft was successfully built and tested. MiniHovercraft

can move on land and water surface to forward, backward, left and right side of

direction.

Through the development of the project, many skills have been acquired. The skills acquired are programming, circuit design and interfacing hardware and software. As a conclusion, this project is successfully designed, implemented and this hovercraft can be reconstructed with some modification to improve the abilities and to provide benefits in future.

63

5.1 Issues This project has not been without any challenges, which are predominant in the

undertaking of such an assignment. The initial lift supply, which was a two-bladed

propeller similar to the current thrust propeller, was inadequate to provide the necessary

down force to direct the air into the plenum chamber and out from under the hovercraft’s

skirt. It was not efficient and its design was not optimal for such a task. However, this

issue was resolved with the usage of a smaller yet more powerful ducted fan.

Widening the lower deck hole will increase the air outtake from the base of the

hovercraft. This will also increase the hover height and the speed of the hovercraft as

there is less friction between the skirt and the ground. However, its stability is

compromised as the air that is pushed out does not always distribute evenly along the

perimeter of the hovercraft, thus risking a lopsided air cushion. As such, the size and

placement of the hole or holes must be just nice to support the hovercraft’s total weight.

The material of the skirt could be improved to a more durable yet flexible one,

had it not been for the difficulty in sourcing a more favourable material. Skirt

construction in actual hovercrafts can be quite complicated, which required an in-depth

theoretical knowledge and technical expertise to fabricate. With a better-constructed

skirt, the airflow and efficiency of the air cushion system could be enhanced.

5.2 Future Developments

Although MiniHovercraft - An Amphibian Robot was successfully developed

and met the objectives, however it is found that this hovercraft can still be improved by implementing some modifications

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It is hoped that through the rather comprehensive description of this autonomous

model hovercraft project, there will be advancements made based on the working design

of MiniHovercraft. Certain features that could be added include better control of

maneuver and speed, obstacle avoidance and so forth. Since the relevant research and

experiments have already been completed in order to develop a fully functional

amphibious mobile model hovercraft, more attention could be given to improving the

performance, speed and intelligence of future hovercraft models to make them more

versatile and agile.

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REFERENCES 1. Ahmad Luthfi B. Musa (2004), Designing A Hovering Robot, Universiti

Teknologi Malaysia, Bachelor’s Degree Project.

2. Cross, Ian and O’ Flaherty, Coleman A. (1975), Introduction to Hovercraft and

Hoverports, London, Pitman Publishing.

3. Hewes, John (2007), Relays,

http://www.kpsec.freeuk.com/components/relay.htm

4. Jackson, Kevin (2003), Build Your Own Model Hovercraft,

http://members.aol.com/modelhov2/index.html

5. Olshove, Alex (2006), The Hovercraft Homepage,

http://www.olshove.com/HoverHome/

6. Porter, Mark (2006), Model Hovercraft, http://www.model-hovercraft.com/

7. Rouzeau, Pierre (2004), RC Hovercraft Model,

http://www.aeroglisseur.com/index_e.htm

8. Sheldon, Ryan (2005), Computer Control: Relays and Computer Controlled

Switching, http://www.controlanything.com/Merchant2/merchant.mvc?Screen=

CTGY&Store_Code=NCD&Category_Code=RelayIntro

9. Smith, D.W. (2005), PIC in Practice, London, Newnes Press.

10. Society Of Robots , Robot Tutorial,

http://www.societyofrobots.com/robot_tutorial.shtml

11. University of Alabama at Birmingham – School of Engineering, EGR 100 –

Hovercraft Design Project,

http://www.eng.uab.edu/me/faculty/amcclain/hovercrafts.html

12. Wikipedia, Hovercraft, http://en.wikipedia.org/wiki/Hovercraft

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APPENDIX A

THE SOURCE CODE OF THE MINIHOVERCRAFT – AN AMPHIBIAN ROBOT IN C LANGUAGE

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#define IR1 PORTD.F7 #define IR2 PORTD.F5 #define IR3 PORTD.F4 #define motorL_a PORTD.F0 #define motorL_b PORTD.F1 #define motorR_a PORTD.F2 #define motorR_b PORTD.F3 #define pwmL CCPR1L #define pwmR CCPR2L void PWM_la(void); void forward(void); void left(void); void right(void); void backward(void); void main() { TRISD = 0b11110000; TRISB = 0x00; PWM_la(); while(1) { if(IR1==0 && IR2==0 && IR3==0) {forward();} else if(IR1==0 &&IR2==0 && IR3==1) {left();} else if(IR1==1 && IR2==0 && IR3==0) {right();} else if(IR1==0 && IR2==1 && IR3==0) {backward(); delay_ms(3000); right();} } } void PWM_la(void) { PR2 = 255; CCPR1L = 0; CCPR1H = 0; CCPR2L = 0;

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CCPR2H = 0; CCP1CON = 0b00111100; CCP2CON = 0b00111100; TRISC = 0x00; T2CON = 0b00000100; } void forward(void) { motorL_a = 0; motorL_b = 1; pwmL = 255; motorR_a = 0; motorR_b = 1; pwmR = 255; } void left(void) { motorL_a = 0; motorL_b = 1; pwmL = 100; motorR_a = 0; motorR_b = 1; pwmR = 245; } void right(void) { motorL_a = 0; motorL_b = 1; pwmL = 245; motorR_a = 0; motorR_b = 1; pwmR = 100; } void backward(void) { motorL_a = 1; motorL_b = 0; motorR_a = 1; motorR_b = 0; pwmL=245; pwmR=245; }

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