Report

INSTITUTE OF TECHNOLOGY TALLAGHT DUBLIN
Dept. of Mechanical Engineering
Third Year Project
Report Title: The Investigation of a DC Motor Position Control System through the
Design and Manufacture of a Wind Direction Analytic Display Unit
Supervisor: Ciaran Young
Name: John Arigho
Student Number: X00075278

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Table of Contents
INSTITUTE OF TECHNOLOGY TALLAGHT DUBLIN.........................................................................i
1. Introduction........................................................................................................................1
1.1 Project Description......................................................................................................1
1.1.1 Deliverables .........................................................................................................1
1.2 Project Scope...............................................................................................................1
1.2.1 Design Specification ............................................................................................2
1.2.2 Desired Additional Features ................................................................................2
1.2.3 Criteria of Excellence ..........................................................................................3
1.2.4 Safety ...................................................................................................................3
1.3 Justification .................................................................................................................4
1.4 Project Plan .................................................................................................................4
2. Investigation.......................................................................................................................5
2.1 Background .................................................................................................................5
2.1.1 DC Motor.............................................................................................................6
2.1.2 Control Units/Methods.........................................................................................6
2.1.3 Angle Sensors ....................................................................................................10
3. Concept Selection ............................................................................................................12
3.1 Aim............................................................................................................................12
3.2 Preliminary Concept Designs....................................................................................12
3.2.1 Concept 1. ..........................................................................................................12
3.2.2 Concept 2. ..........................................................................................................12
3.2.3 Concept 3. ..........................................................................................................13
3.3 Concept Selection......................................................................................................13
3.3.1 Criteria Identification.........................................................................................13
3.3.2 Peer Evaluation ..................................................................................................15

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3.3.3 Criteria Scoring Table........................................................................................15
4. Concept Development......................................................................................................16
4.1 Selected Concept Rework .........................................................................................16
4.2 Final Design ..............................................................................................................16
4.3 Material Analysis ......................................................................................................17
4.3.1 Frame Material/Shape Analysis.........................................................................17
4.3.2 3D Printer Filament Analysis.............................................................................19
4.4 Gear Chain Development..........................................................................................21
4.4.1 Gear Chain Design.............................................................................................21
4.4.2 Pitch Circle Diameter and Cog Shaft Alignment...............................................21
4.5 Encoder Development...............................................................................................22
4.5.1 Track-Pattern......................................................................................................22
4.6 Bill of Materials ........................................................................................................22
4.7 Requisition Sheet.......................................................................................................22
5. Manufacturing and Assembly..........................................................................................23
5.1 Introduction...............................................................................................................23
5.1.1 Health and safety considerations .......................................................................23
5.2 Assembly Breakdown ...............................................................................................24
5.3 Manufactured Components .......................................................................................25
5.3.1 Frame .................................................................................................................25
5.3.2 Cog housing .......................................................................................................26
5.3.3 Compass Rose....................................................................................................28
5.3.4 Motor position Indicator ....................................................................................28
5.3.5 Encoder Plate Alignment Shaft..........................................................................29
5.3.6 Idler Gear Shaft..................................................................................................30
5.3.7 Output Shaft.......................................................................................................31

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5.3.8 Incremental Encoder Position Plate...................................................................32
5.4 Acquired Components...............................................................................................34
5.4.1 Motor Gear.........................................................................................................34
5.4.2 Drive Gear..........................................................................................................34
5.4.3 Idler Gear ...........................................................................................................35
5.4.4 Optical Sensor....................................................................................................35
5.4.5 LED Bezel..........................................................................................................35
5.5 Final Assembly..........................................................................................................35
5.6 Exploded Part Assembley .........................................................................................35
5.7 Electronics and Wiring Manufacture ........................................................................36
5.7.1 Introduction........................................................................................................36
5.7.2 Manufacturing Process.......................................................................................36
5.7.3 Wiring Schematic...............................................................................................37
5.8 Final Manufactured Product......................................................................................37
6. Programming....................................................................................................................38
6.1 Introduction...............................................................................................................38
6.2 Programming Design Process ...................................................................................38
6.2.1 Control Loop......................................................................................................38
6.2.2 Flow Chart .........................................................................................................39
6.3 Programme Manufacture...........................................................................................40
6.3.1 Introduction........................................................................................................40
6.3.2 Digital inputs......................................................................................................40
6.3.3 Analogue Outputs ..............................................................................................41
6.3.4 If and Else Statements........................................................................................41
6.3.5 Input Pulse Counters..........................................................................................41
6.3.6 External Functions .............................................................................................42

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6.3.7 Serial Commands...............................................................................................42
6.3.8 While Loops.......................................................................................................43
7. Testing..............................................................................................................................44
7.1 Introduction...............................................................................................................44
7.2 Programme Testing ...................................................................................................44
7.3 Tailored PWM vs Resistance Test ............................................................................45
7.4 Specification Conformity Testing.............................................................................47
8. Discussion........................................................................................................................48
8.1 Manufacturing Difficulties........................................................................................48
8.1.1 Material Issues ...................................................................................................48
8.1.2 Dimensional Discrepancies of Rep Rap (3d-Printer).........................................50
8.1.3 Frame Bend Angle .............................................................................................50
8.1.4 Encoder Plate Alignment Shaft..........................................................................51
8.2 Programming Difficulties..........................................................................................51
8.2.1 Debugging..........................................................................................................51
8.2.2 Serial Communications......................................................................................51
8.3 Instrumentation and Control Issues...........................................................................52
8.3.1 Encoder Resolution............................................................................................52
8.3.2 Overshoot...........................................................................................................52
8.4 Additional Comments ...............................................................................................53
9. Conclusion .......................................................................................................................54
Appendix A – Project Plan ........................................................................................................a
Appendix B – Concept Sketches................................................................................................a
Concept 1. ..........................................................................................................................a
Concept 2. ..........................................................................................................................b
Concept 3. ..........................................................................................................................c

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Appendix C - Calculations.........................................................................................................d
a. Gearing Ratio Calculations.............................................................................................d
b. Pitch Circle Diameter and Cog Shaft Alignment Calculations....................................... f
Appendix D – Encoder Development........................................................................................g
a. Encoder Orientation........................................................................................................g
b. Output Waveform Sequence...........................................................................................g
c. Subsequent Input Signal Positions..................................................................................h
d. Input Signals Relevant to Compass Rose .......................................................................h
Appendix E – Bill of Materials...................................................................................................i
Appendix F – Requisition Sheet .................................................................................................j
Appendix G – Technical Drawings............................................................................................k
Appendix H – Final Assembly................................................................................................. cc
Appendix I – Exploded Part Assembly Model ........................................................................dd
Appendix J – Electrical Schematic .......................................................................................... ee
Appendix K – Final Manufactured Product..............................................................................ff
Appendix L – Flowchart ............................................................................................................ii
Appendix M – Programme.........................................................................................................jj
a. Final Programme.............................................................................................................jj
b. Testing Programme........................................................................................................rr
References..............................................................................................................................qqq

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1. Introduction
1.1 Project Description
The aim of this project is to design and manufacture a simple, cheap and accurate motor
position control system. To demonstrate this a wind direction analytic system will project the
8 positions of a compass rose (N, NE, E, SE, etc.) The mechanism will be powered by a DC
motor and regulated by a control element to move the motors position to the desired compass
direction. The desired angle will be set by the user and will be detected by an angle sensor. The
user will be able to control and command the mechanism either manually (by turning a turn
dial) or by using a computer interface, depending on the system. If using a computer interface,
the data from the micro-controller will be collected and displayed with the use of a computer
programme. The system will also need to adhere to European directive standards and any
additional criteria deemed necessary by the project supervisor/customer.
1.1.1 Deliverables
 Completed mechanism: A working mechanism that accurately and precisely responds
to commands given by the user or computer interface.
 A full working computer programme.
 Safety: Full risk assessment with any safety issues addressed and precautions put in
place as per European directives and any additional criteria deemed necessary by the
project supervisor.
 Full technical report.
 Project logbook.
 An interim design portfolio and presentation.
 Final poster and presentation.
1.2 Project Scope
The completed mechanism should be simple, accurate and very user friendly. It should
demonstrate the precise, automated, position control capacities of a DC motor. The ability of
the system depends on fitness of intended purpose i.e. moving the motor to the desired compass
position commanded. The controller will be programmed using a computer code and will
process commands given to the motor in relation to the motor’s current position. The motor’s

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location will be detected using a position sensor relevant to the motors shaft. The user will be
able to operate the device either manually, by turning a dial to the desired angle, or through
inputting information into a computer interface.
1.2.1 Design Specification
 Plug and play: The device is to be easily set up, very user friendly and need little to
no previous experience to operate, interact or read data/analysis with the user
interface.
 Geometry: The frame of the device should allow for easy, direct access to view all
internals of the system. The device is to be designed to sit neatly and comfortably
on a desktop.
 Portability: The device should be designed to be light, compact and easily handled
so that the finished product is easily transported.
 Cost: The cost of manufacturing should be <€23
 Capacity: The device should not need to be run off more than 24V DC. It should
have an angle range of 360 degrees and only needs to operate clockwise.
 Performance: The device should react immediately to commands, accurately
present the 8 cardinal points of a compass rose and incorporate high repeatability,
precision and durability of the system components. An unambiguous gauge display
should be included to read the angular location of the motor accurately. The data
collected from the device is to be displayed on a computer screen and should be
clearly visible, unambiguous and very comprehensible.
 Basic Data Analysis: The device should collect information and provide feedback
about the motors current position.
 Durability: High durability of components is necessary to allow high repeatability
of moving parts and other working components.
1.2.2 Desired Additional Features
 Input commands to be received from a computerized wind direction vane for analysis
of actual wind direction.
 A real time feedback/data collection feature to supply information from the device to
computer programme designed to facilitate the development graphs and another data
analysis tools to examine the trends, patterns and characteristics of wind direction.

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1.2.3 Criteria of Excellence
The system will be tested using the following criteria:
 Final level of control.
 Overall accuracy and precision.
 Final cost.
 Clear human machine interface.
 Feedback and data analysis capabilities.
1.2.4 Safety
In the interest of constructing safe working equipment in accordance with industry standards,
general engineering good practice and also trying establish an ethos of “safety first”
throughout, the European machine directive, European low voltage directive and also the
European general product safety directive were consulted via their equivalent harmonized
standards to insure conformance or exemption to the safety provisions supplied. *Note:
Compliance with harmonized standards results in automatic compliance with the respective
EU directive.
o It is stated in chapter 1, article 1.1 of DIRECTIVE 2006/42/EC OF THE EUROPEAN
PARLIAMENT AND OF THE COUNCIL of 17 May 2006 on machinery, and
amending Directive 95/16/EC (recast) that;
“The following are excluded from the scope of this Directive:
(k) Electrical and electronic products falling within the following areas, insofar as they
are covered by Council Directive 73/23/EEC of 19 February 1973 on the harmonisation
of the laws of Member States relating to electrical equipment designed for use within
certain voltage limits:
— Household appliances intended for domestic use, Audio and video equipment,
Information technology equipment, Ordinary office machinery, low-voltage switchgear
and control gear, Electric motors;” [1]
As this article exempts the product being constructed from the machine directive parameters
further research into other compulsory safety standards was under taken.
o It is stated in chapter article 1 of DIRECTIVE 2006/95/EC OF THE EUROPEAN
PARLIAMENT AND OF THE COUNCIL of 12 December 2006 on the harmonisation

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of the laws of Member States relating to electrical equipment designed for use within
certain voltage limits that;
“For the purposes of this Directive, ‘electrical equipment’ means any equipment
designed for use with a voltage rating of between 50 and 1 000 V for alternating current
and between 75 and 1500 V for direct current, other than the equipment and phenomena
listed in Annex II.” [2]
As stated in the design specification, it is required that the device being constructed constrain
to a voltage rating of < 25 volts and therefore is exempt from the parameters of this directive.
o It is stated in chapter 1, article 2(a) of Directive 2001/95/EC of the European
Parliament and of the Council of 3 December 2001 on general product safety that
the definition of a product is as follows:
“”product" shall mean any product - including in the context of providing a service -
which is intended for consumers or likely, under reasonably foreseeable conditions, to
be used by consumers even if not intended for them, and is supplied or made available,
whether for consideration or not, in the course of a commercial activity, and whether
new, used or reconditioned.”” [3]
Although the device being designed is not intended to be a commercial product it will in fact
be used by students of the college as a DC motor control demonstration unit so therefore it falls
into compliance with the definition of a product here and thus the general product safety
directive. So, in the interest of overall safe use of the project, the working temperature will be
kept below 60ºC, This will be achieved by restricting the level of current in the circuit by
limiting the power supply. Resistors will be used where necessary and all electrical wires, along
with the motors shaft safety concealed
1.3 Justification
The design, manufacture and overall production of this project will result in a device that can
be used as a teaching aid to demonstrate the position control capabilities that are possible with
the common DC motor.
1.4 Project Plan
Please view Appendix A Figure A-1 for project plan.

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2. Investigation
Figure 2-1 Image of a Feedback 33-100 USB mechanical servo position control unit. [4]
2.1 Background
Precision position control of a motor is a key factor incorporated into many industrial
operations such as robotic manipulators and conveyors while also lending itself to many
commercial devices such as auto focus of a digital camera and inkjet printers. [5]
Applications where accurate, precise and highly repeatable angular locations of a motor are
critical such as CNC machinery. Computer numerical control (CNC) systems such as
automated milling machines and lathes rely on co-ordinate motor position control to machine
work pieces according to exact specification input commands. [5]
High precision control is an extremely desirable characteristic for automated weapons systems
such as aircraft and anti-aircraft gun turrets with their main design ambitions geared towards
attaining rapid and precise responses to commands given. [6]
This chapter includes investigated information on the main components that make up a basic
motor position control system i.e. a motor, feedback element, and control unit.
Figure 2-2 – Basic Negative Feedback Control System

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2.1.1 DC Motor
The brushed DC motor is a tool used to convert electricity from a direct current to mechanical
work. [7] A stationary magnet with north and south poles about a commentator repel the
opposing and systematically changing magnetic polarity of the electrically charged motor
brushes. The brushes are fixed about an axel and begin to rotate as a result of the torque
produced by the electro-magnetic field. [8]
Putting current through a coil of wire creates an electro-magnetic field with the poles of the
magnetism dependant on the direction of current passing through it [9], the brushes are
connected to an individual winding which are wound identically in the same direction about
the armature. Depending on which side of the power connector (positive/negative) the brush is
in contact with as it rotates will dictate the direction of current flowing through these windings
and therefore determine the polarity of the brushes.
The spinning rotor is connected to an output shaft which supplies accessible mechanical
energy. [8]
Figure 2-3 Concept diagram of a basic DC motor. [10]
2.1.2 Control Units/Methods
This section includes researched examples of control units and methods that can be used
individually or in combination with each other to create different types control systems.

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1. Micro-controllers
A micro-controller is “essentially a simple computer with eyes and ears.” [11]. It is a tool used
to facilitate the communications and interactions of a computer with a dynamic physical
environment. It receives data through inputs (e.g. push buttons and sensors) and sends signals
to output hardware (e.g. motors, solenoids and digital displays). Examples of basic micro-
controllers are extremely common in everyday use i.e. printers, microwaves, alarm clocks and
anything else in a household that has buttons and a digital screen. [11]
Micro-controllers is a small embedded computer containing a CPU, RAM, ROM, EPROM and
I/O terminals and are designed to communicate with computer software (e.g. Processing,
LabVIEW, MATLAB) and output hardware straightforwardly when compared to a normal
desktop computer. This makes it possible to create complex electro-mechanical and data
analysis systems easily “For example, a microcontroller might regulate the operation of an
artificial heart or perform critical functions in an aircraft.” [12]
Arduino is a recommended choice of micro-controller platform for beginners. It would be
recommended over other physical computing platforms that facilitate a similar service of
simplified micro-controller use such as Parallax Basic Stamp and MIT's Handy board due to
the following advantages:
 Relatively inexpensive compared to other microcontroller platforms.
 Software isn’t limited to Windows and is compatible with several other computer
operating systems e.g. Linux and Mac.
 Easily programmed due to its simple programming environment.
 Official details of hardware and software is open source giving freedom to users to
build on and expand the programming language and circuit design as they progress.
 Compatible with other software i.e. LabVIEW and MATLAB. [11] [13] [14]
Figure 2-4 Arduino Uno Revision 3 Embedded Computing Platform. [15]

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2. Computer Programs - LabVIEW
LabVIEW (Laboratory Virtual Instrument Engineering Workbench) uses virtual
instrumentation that is specifically designed to ease the taking of measurements, analysis of
data, and presentation of results. It incorporates a graphical programming language “G” which
uses a pictorial icon user interface that makes it inherently easy-to-use as opposed to text-based
languages such as java. LabVIEW is a flexible and economic alternative to standard laboratory
instrument hardware as it is software based which allows the user to modify the instruments
functionality, virtually, to cope with the corresponding task at hand. [16] [17] [18]
Figure 2-5 Example of Structure and Sub VI: (a) Front Panel, (b) Block Diagram [19]

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3. Analogue Control
The implementation of closed-loop feedback circuit consisting of a set point potentiometer,
summing amplifier, power amplifier and a feedback potentiometer on the shaft of the motor
can be used control the position of a motor analogously. By changing the voltage at the set
point from 0v (e.g. +10v) it causes a voltage difference between it and the feedback
potentiometer (0v) of +10v at the summing amplified.
Figure 2-6 [20]
This signals to the summing amplifier to produce DC voltage that is amplified and inverted by
the power amplifier which allows current to the motor. The motor rotates clockwise with the
connecting feedback potentiometer, now providing an increasing negative feedback voltage
until an equal but opposite voltage value has been reached (-10v). At this point the voltage
difference between potentiometers is 0v again so the summing amplifier stops producing Dc
voltage and thus the motor stops.
Figure 2-7 [20]
The same is true but opposite for reversing the process. By aquiring a voltage difference via
lowering the the set point voltage the motor will rotate anticlockwise with feedback
potentionometer in pursuit of leveling the voltage variances at the summing amplifier. [20]

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2.1.3 Angle Sensors
1. Potentiometers
A Potentiometer, also known as a rheostat or a “pot” is a small electronic component that serves
as a variable voltage divider or variable resistor subject to which and how many terminals are
being used. This facilitates the manual adjustment of resistance being applied to current in a
circuit i.e. varying (Increasing or decreasing) the value of this resistance will control the
amount of current flowing in a circuit. [21] [22]
A sliding contactor, made up of a resistive element, is controlled manually by rotating a shaft
or dial and it connects the conductive and resistive strips together and depending on its position
will affect the resistance i.e. the more material the current must pass through, the higher the
resistance offered. Commonly used in electric circuits such as audio, digital and lighting
devices to control inputs e.g. a light dimmer or volume control on the radio or the television.
If coupled with the adaptation of more terminals on the shaft the potentiometer can also be used
as an on off switch for these devices e.g. turning the light dimmer all the way down will
eventually switch the light itself completely off.
A Potentiometer can also be used as a transducer for position identification of an external
mechanism e.g. A PlayStation controller or for musical instrumentation such as mixing decks
and effects pedals.
Its disadvantages are that it has limits on the rotations possible (standard pots are limited to less
than 360 degrees and even multi turn pots are limited to a certain number of rotations) and is
susceptible to corrosion of the sliding contact especially. [22] [23] [24]
Figure 2-8 Potentiometer Internals Diagram [25]

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2. Incremental Shaft Encoders
An encoder is an electro-mechanical device that converts linear or rotary displacement into
pulse signals. This type of encoder consists of a rotating disk, a light source, and a photo
detector (light sensor). The disk, which is mounted on the rotating shaft, has patterns of solid
and clear sectors systematically printed or cut into the disk. As the disk rotates, these patterns
dictate the light received by the photo detector, generating a digital or pulse signal output. (See
Figure 2-9).
An incremental encoder generates a pulse for each incremental step in its rotation. Although
the incremental encoder does not provide complete positioning alone, it can provide a high
resolution in the change of its displacement. To provide useful position information, the
encoder can be coupled with an external electronic counter to record each pulse. The counter
must also be referenced to a ‘home’ position of the encoder i.e. location where counter = 0.
This is generally achieved using an indexing position signal.
Higher detail patterns increase the resolution while increasing tracks will increase the
functionality of the encoder. For example, an incremental encoder with a single code track,
generates a pulse signal that can detect velocity and displacement. However, a two-channel
encoder can also detect direction by using two detectors and two code tracks offset from each
other to achieve this. [26]
Figure 2-9 – Working Principal of a Single Channel Incremental Encoder [27]

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3. Concept Selection
3.1 Aim
To design a well displayed wind direction analytic that shows the effectiveness and potential
positional capabilities of a DC motor coupled with a controller element.
3.2 Preliminary Concept Designs
Considering the researched information presented in chapter 2, three alternative concepts were
developed to meet the requirements specified. A basic development sketch was drawn up of
the finished solution for each individual concept. Their purpose is to illustrate and define each
concepts unique features and characteristics. These sketches are used as a visual aid and
considered a key factor in the concept materialization process. Each concept will be evaluated
and one will be chosen for further development.
3.2.1 Concept 1.
Digitally operated via Arduino
The frame of the device is manufactured from Aluminium and is in the form of a simple L-
bracket to house and easily display the internals. The motors speed and direction is controlled
by a Driver IC. It receives user defined location commands from an Arduino microcontroller.
An incremental encoder is used to detect the motors position and any relevant data is displayed
on a computer interface.
Please view appendix I figure I-1 for design sketch of concept 1.
3.2.2 Concept 2.
Digitally operated via computer programme
The frame of this device is identical to the design of that in concept 1. The motors speed and
direction is also controlled by a Driver IC with all user defined location commands being
dictated solely by a LABVIEW program. An incremental encoder is used to detect the motors
position and any relevant data is displayed on a computer interface.
Please view appendix I figure I-2 for design sketch of concept 2.

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3.2.3 Concept 3.
Analogue operated
The frame of this device is identical to the design of that in concept 1. The motors speed,
direction and location will all be operated by a series of components connected in a circuit.
User defined commands dictate the desired position and a potentiometer is used to detect the
motors position with any relevant data displayed on a computer interface. Please view appendix
I figure I-3 for design sketch of concept 3.
3.3 Concept Selection.
3.3.1 Criteria Identification
In order to create a scoring system to evaluate each concept a list of relevant criteria was
created. The needs and specification of the project were considered when identifying relevant
criteria. The following criteria were selected for the reasons outlined below.
Safety: A key aspect that should be considered in the construction of any equipment. Its
importance was weighted very heavily in the interest of the end user/consumer. Safety has been
taken very seriously through-out this project in keeping with industry standards and general
engineering good practice. Immediate safety issues that should be addressed relate to the use
of electricity which poses the biggest threat. Other prominent safety issues include the shape
of the projects frame i.e. sharp edges and corners, the weight i.e. if it falls, and the stability i.e.
will it fall. This was all considered as the main intention of the finished product is to be an
interaction device. Each concept is scored based on the likelihood and levels of possible injury
occurring Weighting: 10
Ease of Manufacture: Time is one of the most important factors in manufacturing and the
simplicity of the manufacturing processes needed will dictate what materials and
machinery/tools are to be used to manufacture it. It will also indicate the speed and level of
skill needed to produce required work pieces or if ordering in pre-manufacture parts is an
option. Each concept is scored based on the simplicity and time needed to be dedicated to the
physical manufacturing of the project, the availability of the materials needed and how easy it
is to acquire to pre-manufactured parts. Weighting: 6
Assembly Materials/Components: The simplicity and time needed to be dedicated to the
physical assembly of manufactured work pieces and components. Once again, time is a very

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important factor in producing any product and the assembly design will determine the skill
level needed and also the speed at which assembly can be completed. The assembly design is
also very important for the manufacturing process as it can reduce the likelihood of
encountering errors with a simple design. The size, type and amount of components is also
taken into account here. Each concept should be scored on the simplicity and time needed to
be dedicated to the physical attachment of manufactured work pieces/components to one
another. Weighting: 6
Ease of Circuit Construction: As stated before, time is invaluable in industry, therefore the
less time need to construct the electronic circuit and its components without losing
effectiveness, the better. Each concept should be scored on the simplicity and time needed to
be dedicated to the wiring of the electronic components and the general construction of the
electronic circuit. Weighting: 6
Portability: As mentioned in design specification, the device should be designed to be light,
compact and easily handled so that the finished product is easily transported. This was weighted
heavily as it would defeat the purpose of such a products existence otherwise. Each concept
should be scored on weight, size, shape and overall handle-ability. Weighting: 10
Cost: The idea of an engineer is to get the job done as cheaply as possible. With this in mind
and with a budget of €23, the cost criteria has been weighted heavily respectively. Each concept
should be scored on overall cost to manufacture the product. Weighting: 10
Ease of Programming: Weighted heavily due to lack of experience encountered in this
particular sector. Each concept should be scored on the amount of coding and its level of
difficulty necessary to accomplish the desired requirements. Weighting: 8
Angle Accuracy: As mentioned in design specification, the accuracy of the angular location
of the motor should be to the degree and with great precision. For this reason the criteria was
weighted heavily as it would defeat the purpose of such a products existence otherwise.
Weighting: 10
Angle Display: The accuracy of the angular location of the motor is only as good as the display
that it’s read off of. Creating an unambiguous gauge display is paramount when designing any
measurement device and especially for one to be used in the classroom as a learning device.
Although important an accurate compass rose is easily acquired and therefore the overall
weighting for this criteria was weighting lightly. Weighting: 4

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3.3.2 Peer Evaluation
To help eliminate designer bias towards the best selection of the above concepts, a peer
evaluation meeting was held. A group was forged of selected peers that currently or have
previously completed similar projects. Using equally qualified peers designing similar projects
was a benefit to the scoring process as the ability to fulfil the criteria via experience was a large
factor in some cases. A scoring table with weightings assigned to each individual criterion
depending on the gravity of its importance to the finished product was handed out to be filled
in (see Table 3-1). Each member allocated an individual score (1-10) respectively, depending
on how well it satisfied that criteria for each of the concepts above.
The scoring data was collected, averaged and the total of the results was calculated. The
concept with the highest overall score was chosen as the most feasible option.
3.3.3 Criteria Scoring Table
Criteria Weighting
Avg. Concept
1
Avg.
Concept 2
Avg.
Concept 3
Safety 10 9 9 9
Ease of Manufacture 6 9 9 9
Assembly of Materials/Components 6 8 9 7
Ease of Circuit Construction 6 8 9 6
Portability 10 10 10 10
Cost (10 = cheapest) 10 9 10 8
Ease of Programmability 8 8 5 9
Angle Accuracy 10 10 10 10
Angle Display 4 4 4 1
Avg. Overall Score 610 602 578
Table 3-1 – Criteria Scoring Table
The concept chosen via peer evaluation was concept design 1. The deciding factors came down
to the overall ease of programmability of the computer interface for which concept 2 suffered
greatly due to unfamiliarity of lab VIEW amongst peers, as well this was weighted heavily due
to limited experience in this sector; Also upon the comparison of the infinite rotational
capabilities associated with a shaft encoder, to the single/multi turn limitations of a
potentiometer present in concept 3, the shaft encoder was chosen as the more suitable method
of position detection for this application.

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4. Concept Development
4.1 Selected Concept Rework
The original design had seen the motor, face mounted, flush against the back of the aluminium
frame and held in place by a bracket. The motor shaft was to be slotted through a hole in the
face of the frame, thus exposing the shaft on the other side (see figure 4-1 below). This design
allowed the motor shaft to act as the output shaft directly which in theory seemed to be very
efficient and neat. Upon further investigation it was realised that having the motor shaft directly
controlling the output shaft would result in the short, sharp, twitchy movements of the motor
being translated directly to the pointer connected at the end of the output shaft.
It was also recognized that the motor would be rotating at a ratio of 1-1 and it would therefore
most likely be rotating in revolutions of < 1 at any time considering its application of displaying
the direction of wind. Bearing this in mind, it was decided that this set up would make it very
difficult to control the motors angle/position accuratly. The above information was relayed to
the customer/supervisor for consideration and it was declared that this area needed to be
redesigned suitably.
Figure 4-1 Original directly-mounted motor design
4.2 Final Design
A gear chain consisting of a series of interlinked cogs is to be placed between the motor and
the output shaft to lower the ratio at which the output shaft reacts to the motor (see figure 4-2
below). This solution would see the output shaft and therefore the pointer move more smoothly
upon the activation of the motor. The cogs of the gear chain would also provide a very suitable
medium to set up the encoder to measure the motors position/angle from.

17
This redesigned concept was presented to the customer/supervisor for review and approval and
was given the go ahead as a suitable solution to the problem encountered above.
Figure 4-2 – Sketch of Reworked Selected Concept
4.3 Material Analysis
4.3.1 Frame Material/Shape Analysis
The project has been designed as a desktop display unit. It will not be undergoing any great
structural stresses so materials chosen will be prioritized by cost effectiveness and ease of
machinability. In terms of strength and durability the frame of the device will only be expected
to house the internal components and to be capable of withstanding an impact from a fall from
< 1.5 metres. Considering the involvement of the Arduino PCB it would also benefit to find
the natural frequency of the frame upon impact to ensure that damage of the PCB via resonance
is avoided.
3mm Aluminium sheet metal was available to use from the college labs and would be ideal for
the frame material as it is widely used in industry as a relatively inexpensive and lightweight
metal. It is also easily machined allowing for the drilling of holes and fitting of brackets which
will save manufacturing time.
Material and structure analysis was undertaken to insure that the frame material chosen had the
required mechanical properties to fulfil specification and that its resonant frequency would not
affect the project electronics. As undertaking an overall impact test of an object falling from a
height would be extremely extensive and be far beyond the scope of this project it was proposed

18
that a simple drop test be conducted. A basic prototype model of the frame is to be constructed
from the 3mm aluminium sheet metal mentioned above and dropped several times from a
specified height. The destructive behaviour (if any) and natural frequency of the work piece is
be observed and recorded via high speed camera and accompanying software.
Figure 4-3 – High Speed Camera Image of Model Frame During Drop Test
Below is a table of results and relevant graphs taken from the drop test.
Drop Test # Orientation
Upon Landing
Velocity
(m/s)
Frequency
(Hz)
G-Force
Deceleration (G)
Damage Recorded
Drop # 1 @ 1.5 m Short Face 2 m/s 10 Hz 154.4 G None
Drop # 2 @ 1.5 m Bend
Corner/Side
2.1 m/s 16 Hz 200 G Small Surface
Blemish
Drop # 3 @1.5 m Long Face 2.1 m/s 15 Hz 154.7 G None
Table 4-1 – Drop Test Results
Figure 4-4–Velocity Time Graph of Drop 2 Figure 4-5–G Force Vs Time Graph for Drop 2
0 20 40 60 80 100 [ms]
-4
-2
0
2
[m/s] XT Diagram (drop2_C001S0001) T=0.0 ms
0 50 100 150 200 250 [ms]
-100
0
100
[g] XT Diagram (drop2_C001S0001) T=224.0 ms

19
Upon examination of the damage results above it can be said that the 3mm aluminium sheet
metal is of sufficient strength to resist the forces applied during the drop test. Considering this
and its overall machinability it can be said that it is suitable material to be used in manufacture
of the projects frame.
Upon comparison of the frequencies experienced during the drop test to that of the researched
resonant frequencies found of a PCB of similar dimensions (810 Hz) [29]. It can also be said
that it is unlikely that the material of this size and shape will resonate at a frequency that will
endanger any of the electronic components involved in the Arduino board if dropped from the
tested height.
Ethics:
Aluminium is the most abundant metal in the world and 3rd
most common element in the world
therefore stocks are plentiful. Primarily mined in China and Brazil, it provides countless jobs
across these countries. Its production is a very young process that is just over a century old and
due to the heavy necessity of heating and electrical current needed in the production process,
aluminium costs is seven times more per tonne produced then that of steel. A great effort has
been untaken to make the process more environmentally friendly and reduce the energy used
in the process with a decrease from 28,000 KWh – 13,000KWh per tonne produced. Although
its production is energy taxing it boasts an extremely high recyclability rate with two thirds of
aluminium produced remaining in use. Aluminium also indirectly reduces petroleum
consumption as its most common alternative is high strength plastics. [30] [31]
Considering all the information above it was agreed that for this projects purpose’s aluminium
was a practical and ethically acceptable option thus, a comparison to alternative materials was
not necessitated.
4.3.2 3D Printer Filament Analysis
ABS (Acrylonitrile butadiene styrene) is a petroleum based thermoplastic and is the preferred
filament to use when printing parts with engineering applications in mind. This is due to its
more ductile nature when hardened which will therefore facilitate machining better than its
more brittle counterpart PLA which can splinter or sometimes crack if the proper care is not
taken. Although with PLA it is possible to create more accurate components, the inaccuracies
in the 3D printer supplied make those improvements in accuracy negligible. ABS requires a
heated under table for which to print on as it is in its nature to bend upon contact with a cold

20
surface and unfortunately the only 3D printer made available in the college labs does not have
a heated under table so therefore PLA is made the material of choice unless it is found
structurally unsound and in which case an effort will need to be made to externally source a 3d
printer with a heated bed. [32] [33]
PLA (Polylactic Acid) is a plant based thermoplastic and provided this material facilitates
general machining (drilling of holes etc.) and the use of adhesives it could potentially save a
lot of manufacturing time and overall project costs by making the option of 3D printing several
parts of the device available e.g. the cog housing, Encoder plate, Indicator and Compass Rose.
Further Research into PLA shows that it does take well to adhesives such as super glue even
when not sanded smooth. In terms of mechanical properties there seems to be a lot of deviations
in the recorded values, in particular with strength and stiffness values depending on a list of
many factors ranging from infill orientation to colour. Colour has a significant effect on both
factors with stiffness ranging from 2.77 GPa – 2.55 GPa and strength ranging from 105MPa –
54MPa [34]. As for the machinability PLA has a low thermal deformation temperature of 65°C
which could bring about warping of the work piece during machining of the material [35].
Although the information researched above indicates that PLA is averse to machining, several
online accounts showed projects involving simple machining such has drilling screw holes and
filing which is the extent of the intended machining for this material. [36] [37]
Ethics:
A commonly used biodegradable plastic made from corn starch or sugar cane as opposed to
fossil fuels. Left to its own devices it can take up 1000 years to decompose and also will release
methane, a lead contributor to global warming, if the correct methods are used it is eco-friendly
in its creation and its disposition i.e. incinerated or recycled correctly will avoid the release
toxic fumes unlike its petroleum based counterparts. Its production promotes the use of
genetically modified corn as it adds to the already massive demand for ethanol and food which
in turn has a negative effect on the environment and also human health. It also promotes 3d
printing which is 50-100 times more energy consuming the injection moulding of a part of the
same weight. 3d-printing in itself is a worry as it becomes an easily accessible manufacturing
process for the general public i.e. 3d printed weaponry. PLA is bio compatible and as a result
is a massive beneficiary for medical and surgical application. It can be degraded and absorbed
by the human body so it is possible to be used as medical plates and screws to be surgically
inserted.

21
Considering all of the above, the customer/supervisor was consulted and it decided that PLA
would be a practical and ethically acceptable material to be used for the following components:
 Cog Housing – largest, most robust part after frame
 Compass Rose – design intricacies would make this difficult to machine from metal.
 Indicator – no machining necessary
NOTE: All other materials used in this structure were sourced from the college laboratory and
selected on the basis of availability, cost and ease of machinability.
4.4 Gear Chain Development
4.4.1 Gear Chain Design
A set a four cogs and a DC motor was scavenged from a gearing chain in a desktop CD drive.
Through a set of calculations the most practical cog combination was chosen to be used in
project gear chain (See Appendix C-a for gearing ratio calculations). The calculated gear chain
will consist of a motor cog directly coupled to a chosen output cog.
The motor cog was attached to the motor shaft and the output cog was then aligned in the
proposed calculated orientation. It was then quickly realized that the distance between the
centre holes of the cogs would not allow enough clearance for a shaft to surpass the motor. The
impedance of the motor would obstruct the depth of the rear fixture hole in the cog housing
and therefore it was decided an idler cog was to be placed in between the motor cog and output
cog. The idler cog had a greater diameter and therefore gave itself enough clearance to be fixed
without impedance from the motor. The idler cog also allows for extension of the gearing chain
while still maintaining the originally calculated gearing ratios.
4.4.2 Pitch Circle Diameter and Cog Shaft Alignment
Upon settling on a gearing chain it was of utmost importance to ensure that the shaft holes to
the cogs in the cog housing were to be positioned exactly so that the cogs would mate correctly.
Too loose, the cogs would slip and too tight, the cogs will wear. This precise mating position
is known as the pitch circle diameter (PCD). In an attempt to ensure the highest accuracy
possible the optical profile projector was used to take measurements of the cogs. These high
accuracy measurements will be used in the following calculations to determine the exact PCD
for each of the cogs. (See Appendix C-b for PCD and shaft alignment calculations)

22
4.5 Encoder Development
4.5.1 Track-Pattern
Given that there are eight possible compass rose points at exactly 45° from one another and
that each position was to be manipulated from the motor at a ratio of 2:1, it was determined
that that motor would need to turn 90° to produce a 45° movement at the motor shaft.
Therefore it can be said that the encoder plate will need four points at exact 90° about the
central axis as a result i.e. track 1. This presented a problem in that only four points could exist
on the encoder where eight positions were needed. Considering this, the addition of a second
track was introduced i.e. track 2. This track would consist of a single point offset from track 1
to detect the point of a full 360° rotation. (Please see appendix D Figure D-1 to view encoder
orientation graph).
As a result the existence of a 4:1 ratio between the encoder tracks was presented. (Please see
appendix D Figure D-2 to view output waveform sequence).
The theory is as follows,
 The first four positions should be detected upon the first rotation of the encoder and
send input signals via an optical sensor
 A full rotation should then be detected and send an input signal via a separate optical
sensor
 The second four positions should then be detected upon the second rotation of the
encoder and send input signals via an optical sensor
 Reset and Repeat upon the detection of the second full rotation.
(Please see appendix D Table D-1 to view subsequent input signal positions and Figure D-3 to
view and input signals relevant to compass rose).
4.6 Bill of Materials
(Please view Appendix E Figure E-1).
4.7 Requisition Sheet
(Please view Appendix F Figure F-1).

23
5. Manufacturing and Assembly
5.1 Introduction
The project overview and final design was presented to the supervisor/customer for review.
Upon acceptance the assembly was cleared for manufacture.
In the following sections the steps taken to manufacture the wind direction analytic will be
outlined in detail.
5.1.1 Health and safety considerations
The use of aluminium and presence of other design features in the assembly of this structure
necessitated the use of high power machine tools for cutting metal and finishing processes.
All machining processes were undertaken in the college machining laboratory under the safety
rules provided and under the supervision of the lab technician.
For the band-saw, lathe, and pillar drill, the lab technician provided training in how to safely
use and setup the machines, after which the student used them alone.
Some of the operations performed on the milling machine were more difficult demanding
extensive accuracy.
For this reason the manufacturing lab technician provided assistance on necessary operations.
This is normal practice as in industry as manual milling machines are often only used by highly
skilled fitter/turners who have completed apprenticeship training.

24
5.2 Assembly Breakdown
Figure 5-1 – Assembly Breakdown of Components

25
5.3 Manufactured Components
5.3.1 Frame
Manufacturing Process Conditions
Marking Out
Figure 5-2 - CAD Model of Frame
Mark outline on 3mm Aluminium sheet,
Mark desired position of bend as per CAD
drawings.
Mark hole positions via centre punch as per Cad
drawings
Cutting (Band-Saw) Equip: Aluminium Blade,
Clamp to rig,
Set descent speed,
Coolant on,
Adjust work piece accordingly after each cut.
De-Burring File down burrs on corners and edges,
Smooth using emery paper.
Drilling- Centre Shaft Hole (Milling Machine) Equip: ⌀6mm Drill Bit
Set spindle speed: 1167 RPM
Drill Centre Hole
Drilling – Offset LED Hole (Milling Machine) Equip: ⌀4.5mm Drill Bit
Set spindle speed: 1594 RPM
Drill LED Hole - ⌀4.5mm
Bending (Manual Bender) Position component and align accordingly,
Bend to desired angle as per CAD drawing,
Remove and measure angle,
Re-bend if necessary
(Please view Appendix G figure 1 for CAD part drawing).

26
5.3.2 Cog housing
3D-Printing (Rep-Rap)
Figure 5-3 – CAD Model of Cog Housing
Create CAD model, Convert to STL file, Select
fill, definition and tolerances, select material
(PLA), print, remove scaffolding
Drilling (Milling Machine) (Motor Shaft Hole) Equip: drill bit (⌀2.5mm),
Work Piece Orientation: Horizontal, Step
facing up, Addition of fitted support block in
the gap to prevent bending/damage to work
piece.
Set Speed: 2653 RPM,
Zero Z-axis on work piece
Zero X-axis on work piece
Zero Y-axis on work piece
Drill motor shaft hole as specified in CAD
drawings.
Neglect counter sink of shat hole and the two
additional offset motor fixture holes (See
Discussion)
Drilling (Milling Machine) (Idler Shaft Hole) Equip: centre drill bit (⌀2mm),
facing down, Addition of fitted support block
in the gap to prevent bending/damage to
work piece.
Drill pilot hole as specified in CAD drawings.
Equip: drill bit (⌀6mm),

27
Drill idler shaft hole as specified in CAD
drawings.
Neglect above housing fixture hole (See
Discussion)
Drilling (Milling Machine) (Output Shaft Hole) Equip: centre drill bit (⌀2mm),
facing down, Addition of fitted support block
in the gap to prevent bending/damage to
work piece.
Drill pilot hole as specified in CAD drawings.
Increase diameter of output shaft hole as
specified in CAD drawings.
Increase diameter of output shaft hole on
face of work piece as specified in CAD
drawings.
Neglect below housing fixture hole (See
Discussion)

28
5.3.3 Compass Rose
Figure 5-4 – CAD Model of Compass Rose
Create CAD assembly model, Convert to STL
file, Select fill, definition and tolerances, select
material (PLA), print, remove scaffolding
Drilling (Pillar Drill) (Motor Shaft Hole) Equip: drill bit (⌀2.5mm),
Work Piece Orientation: Face up
Line up work piece
Clamp to rig
Drill motor shaft hole as specified in CAD
drawings.
(Please view Appendix G figure 3,4,5 for CAD part drawing).
5.3.4 Motor position Indicator
Figure 5-5 – CAD Model of Position
Indicator
Create CAD model, Convert to STL file, Select
fill, definition and tolerances, select material
(PLA), print, remove scaffolding

29
5.3.5 Encoder Plate Alignment Shaft
Facing off (Lathe)
Figure 5-6- CAD Model of Alignment Shaft
Equip: Cutting Tool,
Set Speed: 1150 RPM ,
Face off ⌀6mm Aluminium rod,
Zero X-axis,
Turning (Lathe) Zero Y-axis,
Incrementally turn down external diameter to
specified dimension.
Initially increments of ⌀1mm per cut,
Finally increments of ⌀0.2mm for the last five
cuts.
Cut length as per specification in CAD
drawing
Parting off (Lathe) Equip: Parting Tool,
Zero X-axis,
Take into account width of the tool (3mm),
Part off work piece at required length as per
CAD drawings.
Smooth using emery paper.

30
5.3.6 Idler Gear Shaft
Facing off (Lathe)
Figure 5-7 – CAD Model of Idler Gear Shaft
Zero X-axis
Turning (Lathe) Zero Y-axis,
cuts.
Cut length as per specification in CAD
drawing
Zero X-axis,
CAD drawings.
Smooth using emery paper..

31
5.3.7 Output Shaft
Facing off (Lathe)
Figure 5-8 – CAD Model of Output Shaft
Zero X-axis
Turning – larger Diameter Section (Lathe) Zero Y-axis,
cuts.
Cut length as per full length of work piece
specification in CAD drawing
Turning – Smaller Diameter Step Down Section
(Lathe)
cuts.
Cut length as per section length specification in
CAD drawing
Zero X-axis,
CAD drawings.
Smooth using emery paper..

32
5.3.8 Incremental Encoder Position Plate
Drilling (Lathe)
Figure 5-9 – CAD Model Position Plate
Equip: Tailstock drill bit (⌀2mm),
Zero X-axis
Drill exact centre hole 20mm deep,
(See Additional Information)
Facing off (Lathe) Equip: Cutting Tool,
Zero X-axis
Zero X-axis,
Parted off work piece at length 30mm.
Drilling (Milling Machine) Equip: drill bit (⌀2mm),
Work Piece Orientation: Vertical
Zero Z-axis
Zero X-axis via centre hole
Zero Y-axis via centre hole
Drill holes as specified in CAD drawings at depth
30mm (See Additional Information)
Drilling (Milling Machine) Equip: Slot-drill bit (⌀2mm),
Work Piece Orientation: Horizontal
Zero Z-axis
Zero X-axis via Shim (for exact position)
Zero Y-axis zeroed via Shim (for exact position)

33
Drill 2mm slot as and where specified in CAD
drawing. Length of cut @ 20mm
Turning (Lathe) Equip: Cutting Tool,
X-axis zeroed
Y-axis zeroed,
Turn down external diameter to specification
incrementally at ⌀1mm per cut initially and finally at
⌀0.2mm for the last 5 cuts. Cut length @ 20mm
Zero X-axis,
Part off work piece at required length as per CAD
drawings.
Repeat this cut twice more.
Additional
Information
Considering the level of accuracy needed to ensure exact manipulation of the motor
position and also the time estimated to make this delicate component, it was decided
to part off are larger segment of original rod to aid gripping in the milling machine
vice. Along with this all drilled holes and slots were also increase in length to allow
for multiple components to be made at once with extras to be used as spares.
5.3.9 Output Shaft Spacer
Cutting (Hack-Saw)
Figure 5-10 – CAD Model of Motor Gear
⌀ 6mm inner diameter tubing cut to
specification as per CAD Drawings

34
5.3.10 Extruded Outer Track Pattern Piece
Cutting (Hack-Saw)
Create CAD assembly model, Convert to STL
file, Select fill, definition and tolerances, select
material (PLA), print, remove scaffolding
5.4 Acquired Components
5.4.1 Motor Gear
Acquisition Process Conditions
Scavenged
CD-Drive
5.4.2 Drive Gear
Scavenged
Figure 5-12 – CAD Model of Drive Gear
CD Drive

35
5.4.3 Idler Gear
Scavenged
Figure 5-13– CAD Model of Idler Gear
CD Drive
5.4.4 Optical Sensor
Scavenged
Figure 5-14 – CAD Model of Optical Sensor
Electronics Laboratory
5.4.5 LED Bezel
External Purchase
Figure 5-15– CAD Model of LED Bezel
External Purchase (See Requisition Sheet)
5.5 Final Assembly
5.6 Exploded Part Assembley
(Please view appendix I figure I-1 for exploded part assembly model).

36
5.7 Electronics and Wiring Manufacture
5.7.1 Introduction
After the physical components were manufactured and assembled, it was now necessary to
construct an electrical control circuit to allow for automation of the project. The electronics
will also provide communicative information to the Arduino and allow for interactions with a
dynamic physical environment.
Given that the author had little previous experience in circuit design this was a less intuitive
aspect of the project than the mechanical design.
5.7.2 Manufacturing Process
1. Arduino
To determine how to operate the Arduino PCB properly the Arduino.cc website was consulted
where operation information and board schematics were discovered.
The Arduino is powered by USB connection and the PCB ports supply connection points for
external inputs and outputs [38]
2. Motor Control
To determine how to control the motor properly the Arduino.cc website was consulted to
provide information on the basic wiring of a motor to an Arduino.
It was discovered that an Arduino can only supply up to 50 milliamps of current which is too
low for driving most motors [38]. Upon this realization it was determined that a driver chip and
an external power supply would have to be sourced and included in the circuit design.
A 9 Volt battery was obtained to be used as the external power supply.
The chip sourced was an L293d H-Bridge motor driver chip from ST electronics. Technical
files were downloaded for the chip, and Arduino specific online tutorials were consulted to
provide information on how to properly wire the L293d driver chip to an Arduino and thus the
motor. [39]
3. Optical Sensors
To determine how to incorporate the optical sensors into the circuit the Arduino.cc website was
consulted to provide information on the wiring of external inputs.

37
The technical file for optical sensor was also downloaded for reference and it was discovered
that the current in the circuit was higher than the operating current stated. [41]
Upon this realisation it was determined that a resistor would need to be incorporated in series
for each optical sensor for safe operation.
This problem was presented to the electronics lab technician who advised the use of a 220Ω
resistors for each of the optical sensors
4. LED
To determine how to incorporate an LED into the circuit the Arduino.cc website was consulted
to provide information on the wiring of LED’s.
The technical file for LED was also downloaded for reference and it was discovered that the
current in the circuit was higher than the operating current stated. [42]
Upon this realisation it was determined that a resistor would need to be incorporated in series
with the LED for safe operation. This problem was presented to the electronics lab technician
who advised the use of a 220Ω resistor.
5. Wiring
The majority of electrical connections in this project were made using a solder-less bread board
and solid cored prototyping wire however, some of the components acquired used copper cored
wire from production. In this case the copper cored wire was connected to solid core
prototyping wire via crimped connection sleeves. This was necessary as alone copper cored
wire was too flexible to connect to the solder-less bread board.
Upon gathering sufficient information a draft circuit diagram was produced using Fritzing, a
free open source software programme for electronic prototyping and PCB design. The electrical
circuit was presented to the supervisor/customer who cleared the design for production. [43]
5.7.3 Wiring Schematic
(Please View Appendix J for Fritzing Wiring Schematic of Wind Analytic System).
5.8 Final Manufactured Product
(Please View Appendix G for Final Manufactured Product).

38
6. Programming
6.1 Introduction
The Arduino platform provides an integrated development environment (IDE) based on
Processing. The initial objective was to use this platform as the medium to programme the
system. Additionally it is desired to use MATLAB programming language for data analysis
features if time was available.
6.2 Programming Design Process
The programming process was one of the most difficult aspects of the project as the author had
no previous experience of programming microcontrollers.
Fortunately there exists extensive first and third party support for the Arduino platform in the
form of free tutorials, books and forums which were consulted extensively.
The difficultly with the project in question was that it was impossible to find any tutorials for
a similar project. This was mainly due to the incorporation of a bespoke incremental encoder
present in this project. Researched projects generally included servo motors and commercially
produced encoder set ups.
As a result the programming research took the form of examining specific elements of various
codes and tutorials that were necessary for the final programme such as
 Motor control
 Reading of digital inputs
 Configuration of pulse counters
 Application of “if and else” statements, while loops, external functions, pulse width
modulations and serial communications
 Writing analogue outputs.
These aspects will be discussed in the following headings.
6.2.1 Control Loop
To achieve the desired objectives it was determined that the final programme would need to
incorporate closed loop control. Therefore the system would constantly be checking the motors
current position using a negative feedback loop via the encoder.

39
Figure 6-1– Basic System Operation Control Loop
6.2.2 Flow Chart
(Please view Appendix L Figure L-1 Programme Flowchart).
The next process used in the development of a working programme is to build a flowchart that
gives a good overall description of the system operation.
Due to the nature of the incremental encoder, its functionality is dependant of on a system of
counters and is not able to give absolute positioning.
As a result the encoder needs to be referenced to a home position i.e. North where, counter1 =
1 via an indexing program.
The outer track of the encoder has only one pattern and due to the 2:1 gearing ratio, it will be
detected twice (at North and South) by the system per revolution of the output shaft.
The indexing programme activates the motor until the outer pattern is detected. Upon detection,
the user will be asked to confirm the North location.
If the resulting position is South, the programme is to be reset and repeated. Through the
process of elimination the motor will position itself to North.
Upon North confirmation the programme will be able to execute accurate position commands
relevant to this home position.
As the motor rotates the encoder will produce a unique input signal combination for each of
the eight cardinal compass rose (See encoder pattern development section and appendix D).
The objective of the position loop programme is to bring about equilibrium between the desired
combination and the current motor position combination.
It achieves this by activating the motor and cyclying through the position combinations until
the current and desired position are equal. At this point the motor will stop.

40
6.3 Programme Manufacture
(Please view Appendix M-a for Final Programme).
6.3.1 Introduction
A functional approach was taken in the construction of the programme which was applied as
follows:
 Identification of functions that the software is expected to perform
 Creation of input data based on the function's specifications
 Determination of output based on the function's specifications
 Execution of the test case
 Comparison of actual and expected outputs
 Pass/Fail Comparison to functional requirements as per customer specification.
 Resolve if necessary (See testing)
Below is an insight into the majority of the functions and statements that were combined
together in the construction of the programme.
6.3.2 Digital inputs
Given that the project required the use of optical sensors, it was essential that the programme
was given the ability to read the digital pulse inputs from this component. Upon consolation of
the Arduino.cc website it was discovered that digital signals are relatively simple in their
configuration this device produces signals in binary form i.e. HIGH or LOW. It was found that
it would be sufficient for the Arduino to read the value of the sensors by connecting the output
signal wire of the components to one of digitalRead input pins of the Arduino. This digital
reading could then be assigned to a variable e.g.
quadRead, NSRead
These variables were then used in a selection of functions and statements to control the motor
behaviour according to its current position.

41
6.3.3 Analogue Outputs
Similar set up to digital inputs only the signal is sent as opposed to received. In this case the
enable pin of the driver chip was connected to a specific analogWrite input pin of the Arduino
and then assigned a variable as discussed before. E.g.
on.
This variable was again used in a selection of statements and functions to control the enable
pin which in turn controlled the actuation of the motor.
Upon activation this pin will generate a steady, square wave, Duty cycle output dependant on
the specified frequency e.g.
analogWrite(motor, 85);
This is known as pulse width modulations (PWM) and in this case allows for speed control of
the motor.
6.3.4 If and Else Statements
Basic conditional statements discovered during research. They are used together and separately
in the programme to decide between two courses of action or whether to do something at a
specific point such as stopping the motor upon the detection of the desired cardinal position
e.g.
if ((buttonPushCounter1 == PCB1) && (buttonPushCounter2 ==
PCB2)) {
digitalWrite(motor, LOW);
6.3.5 Input Pulse Counters
Given the nature of the incremental encoder discussed previously, a counter system for each
track of the encoder was required to be put in place. A “pushbutton state change” tutorial was
found to be useful and a variation of this was used to create a system to detect any change in
the digital input signals (from HIGH to LOW or vice versa) e.g.
Buttonstate1, Buttonstate2,
This system also recorded how many times this state change happened e.g.
buttonPushCounter1, buttonPushCounter2.

42
Combining this with a counter reset function of specific values for each of the digital inputs
produced by the optical sensors e.g.
if (buttonPushCounter1 > 2) buttonPushCounter1 =1;
The basis was now formed for which the system could begin to relate a desired position to that
of its current position.
6.3.6 External Functions
Each cardinal position on the compass rose had a unique counter combination to define its
position but other than this, the code required to achieve this position was identical.
Upon consultation of relevant forums0 the division of code into external functions was
recommended for repeatable tasks
This method allows a section of code that performs a defined task to be created e.g.
void Move()
It then returns to the area of code from which the function was "called" e.g.
void loop().
6.3.7 Serial Commands
Considering the project was required to at least react to user commands input from a computer
keyboard, it was essential that the programme incorporated a human machine interface.
Upon consultation of the arduino.cc website it was found that a serial monitor window exists
in the Arduino software development environment.
Continued research discovered that a certain function will open communications between the
computer and the programme e.g.
(Serial.available() > 0)
Next the data transmission rate between the computer and the serial monitor must be set e.g.
Serial.begin(9600);
With this a variable must be constructed to allow for the serial inputs to be read but the
programme e.g.

43
ByteReceived = Serial.read();
Sufficiently in place it should would be possible to see functions called in response to signals
received from the serial monitor e.g.
if (ByteReceived == '1') { // Point North
PCB1=1;
PCB2=1;
Move(); )
6.3.8 While Loops
The project required that the programme constantly checked the motor current position so that
the system was able to react instantaneously to the detection of the desired cardinal position.
Upon consultation of the arduinop.cc forum it was recommend that a while loop be used.
The while loop can be thought of as a repeating if statement that will loop continuously, and
infinitely, until the expression inside the loop becomes a specified Boolean condition (TRUE
or FALSE).
A variable was made to denote that the motor was not in the desired position e.g.
boolean moveMOTOR =false;
The position detection code was placed inside the while loop e.g.
while (!moveMOTOR)
With the result that, as the desired position or moveMOTOR, was FALSE, the motor would
rotate and continue to do so while the programme continually checked the current position of
the motor.
This loop will continue to be repeated until the desired position was detected and thus specified
as TRUE e.g.
moveMOTOR=true;
At this point the motor will stop and the programme will await the user’s next serial command.

44
7. Testing
7.1 Introduction
The following headings define the testing processes undertaken throughout this project.
7.2 Programme Testing
Assessment of the programme came in the form of functional testing which was applied as
follows:
 Identify and Diagnose the Problem
 Determine the Root Cause(s) of the Problem
 Research and Develop Alternative Solutions
 Select most Suitable Solution
 Implement the Solution
 Evaluate the Outcome
This was an extremely lengthy process as a substantial programme code had been produced to
achieve the desired functions specified.
To aid the designer in the testing process trouble shooting techniques were incorporated
throughout the manufacture of the programme.
This was achieved by integrating LED’s and serial monitor output prompts at critical points in
the code. E.g.
if (buttonState2 ==HIGH && lastButtonState2 ==LOW) {
buttonPushCounter2++; // if the state has changed, increment the counter
digitalWrite(ledPin2,LOW); // Turn on LED every time the counter is incremented
Serial.print(" button2 pushes: "); // Display encoder hole detection (HIGH or LOW)

45
Serial.println(buttonPushCounter2); }//Display encoder hole detection count
As a result this created a feedback system through which it was possible to monitor the
programmes activities and therefore it acted as a reference platform during the debugging
process.
In relation to the detection and recording of encoder input signals, this was found to be a
particularly helpful method in the differentiation between the root of a problem to be either
physical or interfacial.
7.3 Tailored PWM vs Resistance Test
(Please view Appendix M-b for Testing Programme).
The extensive and lengthy programme test process had a negative effect on some of the less
durable mechanical components present in the device. As a result the mechanism experienced
poor mating of the cogs in the gear chain and increased frictional factors about the output shaft.
This is discussed in detail in the following section but in summary the output shaft would now
encounter different levels of resistance for each of the 8 cardinal rose positions. Consequently
the indicator would experience either sticking or overshooting depending on the level of
resistance met. In an attempt to prove that it was in fact purely slight mechanical resistances
and frictional factors preventing the smooth operation of the device, a test programme was
constructed. This programme incorporated eight specific PWM duty cycles that were tailored
to the resistance met at each position allowing sufficient motor power in each case. E.g.
if (ByteReceived == '2') { // Point NE
PCB1=1;
PCB2=2;
Move2(); }
void Move2() {
moveMOTOR=false; //motor on
analogWrite(motor, 85); // bespoke PWM tailored to resistance
Serial.println(" motor ON ");
while (!moveMOTOR) // Code identical to original code from here on

46
The objective of this test was to prove that any resistances met in transition could be overcome
given enough power from the motor and thus demonstrate that overall the project was a success.
The limitations of this programme restricted the movement of the motor to a successive routine
(i.e. North, North-East, East, South-East, etc.)
Below is a table of the test results.
Transition PWM PASS FAIL
N - NE 82 
NE - E 85 
E- SE 80 
SE - S 80 
S - SW 65 
SW - W 105 
W - NW 85 
NW - N 85 
Index (North Calibration) 92 
Table 7-1 - Results from Tailored PWM vs Resistance Test
It was realised that this programme could have been adapted to cycle clockwise through each
point in a stop and start manner applying the tailored PWM’s in each case and stopping upon
the desired position. This realisation was in the latter stages of the project time frame and will
be noted in the recommendations/possible solutions.
It can be seen in the table of results above that in every case it was made possible to overcome
the resistance encountered and therefore it can be said that increased performance was possible
provided either a specialized programme based on the test programme discussed in this section
was introduced or ideally, undertaking the replacement of any faulting components.

47
7.4 Specification Conformity Testing
Below is a pass/fail examination of overall project conformity to original design specifications.
Specification Comments PASS FAIL
Plug and Play Project simply needs to be connected to a computer via the USB connection provided. Upon connection, the IDE
programme is opened, USB port and board type selected, serial monitor opened, and North position calibrated. User
is presented with instructions and can now request desired cardinal rose positions. Collected data is displayed on the
computer screen in a clear, unambiguous manner via the serial monitor.


Geometry Neat, steady desktop orientation with all internals displayed for viewing. 
Portability Net weight: 405g therefore easily transported by hand. 
Cost Total cost: €1.85 therefore < €23 Budget 
Capacity Product runs on a combination the 3.3V produced by the PCB and the 9V external battery.
Potential Angle range of 360° with infinite rotational capabilities in the clockwise direction


Performance Mechanism responds instantaneously and has the capacity to fulfil the accuracy and precision specifications but is
held back by issues outlined in the discussion


Basic Data Analysis System collects, records and displays current position information 
Durability Poor durability of the materials/components directly effecting mechanical functions and friction factors therefore
reducing repeatability of intended processes to zero. (See Discussion)

Table 7-2 - Pass/Fail Examination Table

48
8. Discussion
After the final programme was developed and any outstanding mechanical problems fixed to a
realistic degree the system performed reasonably close to expectations. Upon receiving
instruction via the human-computer interface the device the reacted and moved to the
corresponding desired position. However throughout the project a number of unforeseen
problems arose which caused significant performance constraints particularly in relation to
mechanical and frictional factors.
8.1 Manufacturing Difficulties
8.1.1 Material Issues
Wearing action on the output cog and also the decay of the PLA used in the manufacture of the
cog housing presented a great deal of problems throughout the project. In this section these
problems will be discussed.
1. Lack of Machinability
A low deformation temperature and brittle nature was experienced in preliminary attempts to
drill the PLA. Warping, cracking and melting of the material was common. A range of spindle
speeds were examined with in some cases the material liquefied and re-hardened on the drill
bit rendering the tool useless.
Solution
As a result it was decided that only compulsory holes were to be drilled i.e. shaft holes.
Therefore all fixture holes present in the original design of the cog housing were to be
neglected. In each case an engineering adhesive was to be used instead.
2. Shaft parallelism Issues
A low wear resistance of the PLA used to construct the cog housing was experienced. As
specified the output shaft was free to rotate in full contact with the PLA. During the testing
process a growing offset in the parallelism between the output and idler shaft was noticed. The
source of the problem was due to erosion present in the rear output shaft housing. As a result
the rear side of the shaft was sitting slightly lower than the front side (which is supported by
the frame metal, reducing wear).

49
Recommended Follow on Solution
The incorporation a washer made from a suitable material to surround the rotating shaft which
would decrease any erosion greatly. Alternatively the complete replacement of PLA as the cog
housing material to that of a more suitable material e.g. Aluminium.
3. Lateral Cog Misalignment
Due to the low wear resistance of PLA more erosion problems involving the output shaft were
encountered. As the output shaft was rotated it began to erode the back wall of the shaft
housing. This was most likely exaggerated due to the aid of gravity considering the declining
angle the shaft was positioned at. As the shaft wore into the PLA of the cog housing it began
to misalign the out but and idler cog respectively.
Solution
Originally the position indicator was going to be placed flat against the face of the output shaft
protruding from the face of the frame. A redesign of the indicator (seen in CAD drawings) was
developed to double up as a spacer to hold the lateral position of the output shaft in place from
the front of the device as opposed to the shaft housing at the rear of the device.
4. Post Manufacture Deformation of PLA
As a result of low deformation temperature of PLA the cog housing began to bend and misshape
slightly both during the manufacturing process and as well after. Left to sit in a small closed
area subjected to sunlight, such as a car, the PLA will continue to distort. This deformation has
a significant effect on component dimension and positioning of feature as previously discussed
The complete replacement of PLA as the cog housing material to that of a more suitable
material e.g. Aluminium
5. Wear of Output Cog
Even though the optical profile projector was used to comprehensively measure the dimension
of the cogs and relevant calculations made with these results to produce accurate pitch circle
diameters for ideal mating distances, the output shaft was seen to mate too tightly. Given the
range and magnitude of sources of error mentioned above it can be said that this misalignment
was significantly affected by the distortion of the cog housing for a variety of reason mentioned.

50
As a result the teeth of the output cog began to wear and decay, producing poor traction and
sometimes slippage in the transition of the motors position to the output shaft.
The complete replacement of PLA as the cog housing material to that of a material with more
suitable mechanical properties e.g. Aluminium
8.1.2 Dimensional Discrepancies of Rep Rap (3d-Printer)
Position dimensions of features i.e. holes, provided in CAD drawings are, in general,
referenced from an edge of the component. Therefore any feature position dimensions present
in a CAD drawing are only relevant if the component is produced as specified. Unfortunately
the Rep Rap is not capable of reproducing exact manipulations of desired components.
Deviations from specification of up to 3mm were experienced. This was a particular problem
in the production of the cog housing considering the exact positioning needed its accompanying
shafts.
Solution
A full body measurement analysis of the component was undertaken. All hole positions were
recalculated in relation to the new dimensions supplied and were drilled accordingly.
8.1.3 Frame Bend Angle
The manual bender used was limited to a bend of 90°. The required angle of bend needed in
the frame was 115°.
Solution
The frame was bent to a maximum of 90° in the manual bended. And wooden reference block
with a chamfer cut to the exact specified angle of 115° was manufactured via the band saw.
The reference block was placed inside the frame with the chamfer at the back of the frames
face. Both pieces were secured in a vice and a rubber mallet was used to initiate remaining
bend until the back face of the frame was flush with the reference block. Note: A discrepancy
of 0.5° was presented at the end of this process.

51
8.1.4 Encoder Plate Alignment Shaft
Considering the minute scale of the part and the high level of accuracy needed to ensure its
axis was concentric with that of the motor shaft, it was very difficult to manufacture this
component on the lathe. Unavoidable oscillations and bending due to naturally occurring
imbalances combined with the force of the cutting tool on the work piece resulted in decay of
the part during machining.
Solution
0.1mm increments were employed for the final 10 cuts and a parting off length of 10mm
opposed to the required 4mm was undertaken. The desired length of the work piece was
accomplished by a delicate filing process.
8.2 Programming Difficulties
As previously mentioned the author has had no programming experience prior to undertaking
this project. Naturally, this presented many obstacles in the construction of the programme
which will be discussed in the following section.
8.2.1 Debugging
Difficulties in the overall process of identification and diagnosis of problems present in the
program.
Solution
Trouble shooting techniques were incorporated throughout the manufacture of the programme.
Please review the previous programme testing section for a more detailed definition of this
process.
8.2.2 Serial Communications
As previously mentioned, research found that by applying a certain function e.g.
(Serial.available() > 0) in the Arduino development environment, typed communications
between the computer and the programme would be possible i.e. functions could be called in
response to signals received from the serial monitor. However it was discovered that the serial
monitor could only work with ASCII characters rather than raw input strings. This meant that
the Arduino programme could only receive and process single digit figures at the serial

52
monitor. Given that the initial desirable was that the user could input a position such as “NE”,
this was a problem.
Solution
Consultation of relevant programming lectures confirmed that multi character serial inputs
would be possible by linking the Arduino with a high level programming language such as
PHP or Python. Considering this it was determined that this was outside the scope of the
project. Instead, for the purpose of this project, each position was allocated a signal digit
number of 1–8 accordingly.
8.3 Instrumentation and Control Issues
8.3.1 Encoder Resolution
The accuracy of the encoder mainly depends on the resolution of the track patterns. Considering
that the track patterns were made by drilling holes, slots and attaching extrusions to the encoder
plate it can be said that although each pattern was accurately placed, they were of significant
size in relation to the diameter of the plate itself. Inevitably using a plate of this size would
always slightly negatively affect the instruments resolution given the implementation of
reasonable engineering techniques.
Solution
Ideally a servo motor would be used instead of the encoder in general but upon investigation it
was found that it was not financially feasible to afford this component. The purchase of a
commercially produced encoder set up would have also been a very accurate solution but again
financial restriction would not allow this. To evolve the current encoder system into a more
accurate one, a great increase in the diameter of the rotating plate would be the initial step.
8.3.2 Overshoot
As previously discussed tailored PWM signals could have been used to overcome frictional
factors within the system. Unfortunately as a result of using some of the higher frequency
PWM’s the motor would overshoot its intended position.
Solution:
The implementation of a PID controller would be an ideal resolution to overcome this problem.

53
Alternatively, the addition of a motor reversal code could be incorporated with the intention
that upon overshoot the motor would rotate in the reverse direction until the desired position
was detected.
8.4 Additional Comments
Follow on objectives for this project would be to incorporate the desired additional features
mentioned in the scope of this project:
 The ability to receive and process input commands via Wi-Fi from a computerized wind
direction vane for analysis of actual wind direction.
 A real time feedback/data collection feature to supply information from the device to a
computer programme designed to facilitate the development of graphs and another data
analysis tools to examine the nature, characteristics, trends and patterns of wind
direction.

54
9. Conclusion
Although, there were certain frictional and mechanical factors that became prominent during
the testing process, the overall workings of the mechanism proved to be a feasible and therefore
the project, overall, was completed to the desired specifications of the customer/supervisor.
The wind direction analytic produced as a result of this project now provides the mechanical
engineering department with a learning platform to teach robotic first principles, Arduino
programming and control theory.
Overall was this a constructive experience as it helped further the authors understanding of
modern engineering fundamentals. The technical skills which were involved and consequently
improved in undertaking this project are as follows:
 CAD design,
 Machining, metal
 working, plastic moulding,
 material property analysis,
 electronic component design
 Programming fundamentals.
The author also improved profession soft skills that have become extremely important in
present-day engineering. The professional soft skills which were involved and consequently
improved in undertaking this project are as follows:
 Communicative abilities were improved in attempts to unambiguously discuss the
various problems that presented themselves.
 The authors paper based communicative skills were progressed in the production of
this report in an attempt to concisely express information about the project.
 The author’s compromise skills were also enhanced for the following reasons:
o Lab times had to be booked in advance with the various lab technicians.
o Waiting to be attend to by supervisor at supervisory group meetings.
o Booking to meeting with various lectures to discuss their area of expertise
relevant to the project.
 The author’s skills of research were also improved greatly. Given that there wasn’t an
exact example of the project, the author had to divide up the project to research
elements into relevant segments such as possible motors, angle sensors, and

55
controllers, then determining how to combine the obtained knowledge and focus it
into productive applications.
 The author’s time management abilities were greatly tested between sharing
workshop space and machines and also with pressure of meeting the plentiful,
compulsory, deadline present throughout the duration of the project.
In conclusion, considering what was learned in the process of completing this project and the
conformity of the end product to desired specifications, it can said that overall this project was
a success.

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