ABSTRACT
There have been significant development in the
field of measurement and instrumentation in recent times. Now, it encompasses
almost all the areas of science and Technology. Even in our day-to-day life,
instrumentation is indispensable.
An automobile driver needs on instrument panel
to facilitate him in driving the vehicle properly.
A speed measuring transducer is a device which
measures the speed of a rotating shaft or object in revolution per second. This
project entails how the speed of a rotating device (Electric Motor) can be
measured in the laboratory in other to improve the teaching and learning of the
course instrumentation and measurement.
TABLE OF CONTENTS
Title page i
Certification ii
Dedication iii
Acknowledgement iv
Abstract v
Table of Content vi
CHAPTER ONE
1.1
Introduction 1
1.2
General Background of the Project 2
1.3
System Configuration 3
1.4
Transducer 4
1.5 Electrical Transducer 5
1.6 Classification 6
1.7 Basic Requirement of a Transducer 7
1.8 Input-Output Devices and Displays 8
1.9 Basic Characteristic of Measuring Devices 9
1.10 Relevance of the Project 9
CHAPTER TWO: LITERATURE REVIEW 12
2.1 Electronic Speedometer 15
2.2 Centrifugal Force 17
2.3 Mechanical Speedometer 18
2.4 Quartz Electric Speedometer 18
2.5 Inductor Speedometer 18
2.6 Transducers 21
CHAPTER THREE:
Statement of
Problem/Design Problem 22
CHAPTER FOUR
Method of Solution
(Design Procedure) 23
4.1 Smoothing Capacitor 25
4.2 Power Supply Amplifier Unit 26
4.3 The Amplifier Stage 30
4.4 Heat Sink Fundamental 41
4.5 The Display Stage 45
CHAPTER FIVE: Discussion of Results
5.1 Result Achieved 49
5.2 Conversion from Revolution per seconds to
Kilometer
per hour 50
CHAPTER SIX
6.1 Limitations 52
6.2 Suggestions for Future works 52
6.3 Conclusion 52
6.4 Recommendation 53
References 54
CHAPTER ONE
1.1 Introduction
The art of measurement is a wide discipline in
both engineering and science, encompassing the areas of detection, acquisition,
control and analysis of data. It involves the precise measurement and recording
of a physical, chemical, mechanical, electrical or an optical parameter and
plays a vital role in every branch of scientific research and industrial
processes interacting basically with control systems, process instrumentation,
and data reduction.
Recent advances in electronics, physics,
material sciences, and other branches of science and technology have resulted
in the development of many sophisticated and high precision measuring devices
and systems, catering to varied measurement problems in such disciplines as
aeronautics, science and technology, space, medicine, oceanography and industry
in general.
Measurement provides us with a means of
describing natural phenomena in quantitative terms. As a fundamental principle
of science, Lord Kelvin stated “when you can measure what you are speaking
about and express them in numbers, you know something about it and when you
cannot measure, it or where you cannot express in number; your knowledge is of
a meager and unsatisfactory kind. It may be the beginning of knowledge but you
have scarcely in you thought advanced to the stage of science”. In order to
make constructive use of the quantitative information obtained from the
experiment conducted, there must be a means of measuring and controlling the
relevant properties precisely. The reliability of control is directly related
to the reliability of measurement. This means that the control and regulation
of industrial systems and process depend on accurate measurement. It would not
be going too far to state that a variable must be measured accurately to be
controlled.
1.2 General Background of the Project
Before the advent of speedometer (speed
measuring transducer), people embarked on long journeys, without necessary
consideration on the speed at which they move, to cover the required distance
needed. Scientist and Engineers have mastered the measurements of distance,
from fractions of a millimeter to thousands of kilometers and they can measure
time with same degree of accuracy.
A combination of the two gives us a further
important measurement called speed. Speed is the distance traveled by an object
in a certain time. Measurement of speed, are given by the device named
according to the vehicle, in which they are found.
As technology advances, there is a need for a
device to measure the speed covered by travelers making use of vehicles and
speed of any rotating shaft in science and engineering. A device known as
speedometer does this measurement. Now, motor cars have varies electrically
operated indicating instruments on the dashboard or instrument panel. These indicating
devices range from the temperature indicator, fuel indicator, oil pressure
indicator to the speed indicator. The purpose of having these indicating
devices is to keep the driver informed about the operating conditions of the
car.
1.3 System Configuration
A generalized measurement system comprises the
following elements, as shown in fig 1.1.
a. The transducer which converts the measured (measured quantity,
property or condition) into a usable electric output.
b. The signal conditioner which converts the transducer output
into an electrical quantity suitable for control recording and/or display.
c. The display or readout devices which display the required
information about the measured generally in engineering units.
d. The
electrical power supply which provides the required excitation to the
transducer and the necessary electrical power to the signal conditioners and
display devices.
1.4 Transducer
A transducer is defined as a device capable of
being actuated by an energizing input from one or more transmission media, and
in turn, generating a related signal to one or more transmission systems or
media. It provides a usable output in response to a specific input measured
which may be a physical or mechanical quantity, property or condition.
Actually, the energy in one form of information, transmission system or
physical state is transferred to that of another system or state. The
responding device may be mechanical, electrical, magnetic, optical, chemical,
acoustic thermal, nuclear, or a combination of any two or more of these.
Automation in motion control application is
only possible if the controller section receives information about conditions
in the manufacturing or scientific process. There conditions include
displacement, position, speed, and acceleration. The devices capable of
monitoring these conditions are called transducers. The transducer performs the
measurement of the condition and produces a feedback that provides information
on the result. Some transducers produce an analog output signal while other
produces a digital output signal.
1.5 Electrical
Transducer
An electrical transducer is a sensing device
by which a physical, mechanical, or optimal quantity to be measured is
transformed directly, with a suitable mechanism, into an electrical voltage or current
proportional o the input measured. The input versus output energy relationship
takes a definite reproductive function. The output to and the output to time
behaviour is predictable to a known degree of accuracy, sensitivity and
response, within the specified environmental conditions. The significant
parameters which dictate the transducer capability are linearly, repeatability,
resolution, and reliability.
The main advances of an electrical transducer
may be summarized as follows:
a. The
electrical output can be amplified to any desired level.
b. The
output can be indicated and recorded remotely at a distance from the sensing
medium. Further, more than one indicator can be actuated simultaneously.
c. The
output can be modified to meet the requirements of the indicating or
controlling equipment. The signal magnitude can be related in terms of the
voltage or current. The analog signal information can be converted into a
digital format for display, print-out or on-line computation.
Since the output can be modified, modulated,
or amplified at will, output signal can be easily adapted for recording on any
suitable multichannel recording oscillograph which can cater to a number of
electrical transducers simultaneously.
d. The
signals can be conditioned or mixed to obtain any combination with outputs of
similar transducers or control signals as in an air data computer or adaptive
control systems. A typical example is the Mach number measurement with two
measurands.
e. The
size and shape of the transducer can be suitably designed to achieve the
optimum weight and volume.
f. The
contour design and dimensions can be so chosen as not to disturb the measured
phenomena, as in the case of turbulence measurements. In certain cases the size
can be made extremely small, thereby increasing the natural frequency to a high
value. An example is the miniature piezoelectric pick-up employed for vibration
measurements.
1.6 Classification
All electrical transducers are broadly
classified under two categories, viz, active and passive transducers. Active
transducers are self-generating devices, operating under energy conversion
principles. They generate an equivalent electrical output signal, e.g. from
pressure to charge or from temperature to electrical potential, without any
external energizing source. Passive transducers operate under energy
controlling principles. They depend upon the change in the electrical parameter
(resistance, inductance or capacitance) whose excitation or operation requires
secondary electrical energy from an external source. A typical example is the
case of the strain gauge excited by a dc voltage source or differential
transformer energized by a carrier wave signal.
1.7 Basic
Requirement of a Transducer
A transducer is normally designed to sense a
specific measurand or to respond only a particular measured. A complete
knowledge of the electrical and mechanical characteristic of the transducer is
great importance while choosing a transducer for a particular application.
Often, it is deemed essential to get details of these characteristics during
the selection of instrument for the experiment concerned. The basic
requirements are:
a. Ruggedness: Ability to withstand overloads, with safety
stops for overload protection.
b. Linearity: Ability to reproduce input-output
characteristics symmetrically and linearly.
c. Repeatability: Ability to reproduce the output signal
exactly when the same measurand is applied repeatedly under same environmental
conditions.
d. Convenient instrumentation: Sufficiently high analog
signal with high signal to noise ratio; digital output preferred in many cases.
e. High stability and reliability: Minimum error in
measurement, unaffected by temperature, vibration and other environmental
variations.
f. Good dynamic response: Output is faithful to input
when taken as a function of time. The effect is analyzed as the frequency
response.
g. Excellent mechanical characteristics that can affect the
performance in static, quasi-static, and dynamic states.
1.8 Input-Output
Devices and Displays
All instrumentation systems have to process
either a display that a human operator can real out from and interpret, or an
output device that enables the transfer of information from the instrumentation
system to a general purpose or dedicated computer. Input – Output device are of
various forms depending on such factors as speed, (i) types of record required,
and type of system to which data is fed (ii) the type of data via analog or
digital.
An analogue output display is adapted for this
project because it can theoretically display an infinite number of speeds,
accuracy, it can be clearly seen in the strong sunlight or other bright light
and also it does not take away sense of change in speed. Analogue output
display is adequate for the design.
1.9 Basic
Characteristic of Measuring Devices
The function of a measuring device is to sense
or detect a parameter encounter in an industrial process or in scientific
research, such as pressure, temperature, on, resistance, voltage, current, and
power.
The measuring device must be capable of
faithfully and accurately deterring any changes that occur in the measured
parameter. For control purposes, the measuring instrument either generates a
warning signal to indicate the need for a manual change or activates a central
device automatically.
1.10 Relevance
of the Project
A speed measuring transducer (speedometer)
design and construction is targeted at providing one of the major experiments
in the control or measurement and instrumentation laboratory.
It is also aim at measuring the speed of
electric motor and motor vehicles with an analog read out or display because of
the limitations in digital speedometer. For example, while an analog
speedometer can theoretically display an infinite number of speeds, a digital
speedometer can only display speeds in whole numbers.
Other limitations of digital speedometer
includes
·
They took away the sense of change in speed that provided by an
analog speedometer.
·
They were hard to see in the strong sunlight or other bright
light.
·
They were expensive to repair in the event of malfunction.
As a result of these issues, digital
instrument panels were phased out of vehicles throughout the 1990s. And have
been replaced with traditional analog gauges in most vehicles, including those
from luxury divisions.
Objectives
The design and construction of a speed
measuring transducer is aimed at laboratory display of how a speedometer and
other speed measuring devices work.
Methodology
The project design involves four stages as
designated in the block diagram shown in fig 1.1
The measured parameter is the rotating device
whose speed is to be measured. With the aid of a pulley, the mechanical
rotation is transferred into the rotation of the motor of a dynamo which
produces electrical impulse. The impulse generated is then amplified by a well
designed amplifier circuit whose output is being display by a speed dial
calibrated to read in revolution per minutes.
ORGANISATION OF THE REPORT
The write up comprises
·
Chapter one is the introductory chapter and made up of the
background information, the purpose and scope of the work.
·
Chapter two is the literature review, review existing, types of
speedometer. The reviews are there to establish relevant knowledge in the
subject matter under consideration.
·
Chapter three contains the problems statement of design problem.
·
Chapter four contains the method of solution. It discusses how the
problem stated in chapter three is solved.
·
Chapter five gives the results
·
Chapter six this contains suggestions for future works and
conclusion, limitation and recommendations.
·
References indicate the sources of information used in the
write-ups.
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