ABSTRACT
Distance measurement plays a vital role in engineering,
science and business. The distance is always measured between two points.
Generally distance measurement is possible only by making contact with the
target whose distance is to be measured, but this project discusses the
measurement of distance by digital measuring instrument. This is done by
providing a circular object (wheel) of about one meter in circumference. Here
the distance is calculated by the number of revolution or circulation of the
wheel multiplied by the total circumference of the wheel. This device also
makes the use of microcontroller for calculating the distance and displaying it
on a seven segment display. The digital measuring distance instrument can
measure a distance up to 1000 meter. The result obtained from practical
distance measurement showed that compared to the use of tape rule, this digital
distance measuring instrument is faster and easier. However it has higher error
rate since fraction of revolutions are not detected. It is recommended that
improvement of the efficiency of this device be made by employing a software
that can directly convert number of revolutions to distance.
CHAPTER ONE
INTRODUCTION
1.0 BACKGROUND
TO THE STUDY
Taking of measurements has been
necessary since human beings first began trading with their neighbors. In addition
to trading, early societies also needed to be able to measure to perform many
other tasks. When people turned from leading a nomadic life to settling in one
place, other measurements such as measurement of land and building materials
became important (Crease, 2011). Our knowledge about early measurement comes
from historians and archaeologists, leading us to realize that although the
roots of many of the early units of measurement were the same, actual values
and their application differed from country to country. As our societies become
increasingly technology oriented, the quality of measurements has improved over
time because of the need for higher measurement accuracy in many fields.
A measuring instrument is a
device for measuring a physical quantity. In the physical sciences, quality
assurance and engineering, measurement is the activity of obtaining and
comparing physical quantities of real-world objects and events (Kirch and
Wilhelm,2008). Established standard objects and events are used as units, and
the process of measurement gives a number relating the item under study and the
referenced unit of measurement (Kirch and Wilhelm, 2008). Measuring
instruments, and formal test methods which define the instrument’s use, they
are the means by which these relations of numbers are obtained. All measuring
instruments are subject to varying degrees of instrument error and measurement
uncertainty (Creased, 2011).
There are two main types of the measuring instruments:
analogue and digital. The analogue instruments indicate the magnitude of the
quantity in the form of the pointer movement. One has to learn reading such
instruments since there are certain markings on the scale. They usually
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indicate the values in the
whole numbers, though one can get the readings up to one or two decimal places
also. The readings taken in decimals places may not always be entirely correct,
since some human error is always involved in reading. (B.H. engineers, 2012).
The digital measuring instruments indicate the values of the quantity in
digital format that is in numbers, which can be read easily. One doesn’t needs
any prior training to read these instruments since they indicate the values
directly in the numerical form. They can give the readings in one or more
decimal places. Since there is no human error involved in reading these
instruments they are more accurate than the analogue measuring instruments.
(B.H. engineers, 2012)
In the construction field,
electronic measuring devices are still not widely used due to the high cost of
this equipment. Hence there is need to develop designs for accurate measuring
device with low cost. Nowadays, measuring distance is considered tedious task
in construction field or indoor measuring activities because this task is made
by using measuring tape in which at least 2 persons are needed to measure
between two distances. Besides, it does not have a perfect accuracy due to
parallax and in some cases, presence of some obstacles such as trees hamper
linear measurements in the field.
Improvement had been done where some products have infrared
light emitters and receivers to determine an object’s distance. Other devices
have laser-based systems which have improved accuracy and precision. Presently,
the detection techniques of laser, radar, and infrared ray have been widely
applied in the aspect of obstruction detection and distance measurement. Due to
high cost of design and use of laser and radar based measuring instruments,
they are not commonly employed. For infrared sensor, the range of the distance
that can be measured is very short with only a range of 4-30cm (Crease, 2011).
Therefore, a design that can enhance speedy and accurate measurement of
distance at low cost is necessary.
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1.1 AIM AND
OBJECTIVES
The
aim of this project is to design and construct a suitable electronic digital
distance measuring device. To achieve this aim the following objectives are
set;
a) To design an
electronic measuring device using AT89S52 microcontroller.
b) To write
appropriate program for the microcontroller.
c) To construct
and test the designed device.
1.2 SIGNIFICANCE
OF STUDY
This study became important
owing to the reoccurring issues resulting from the linear measurements in
construction fields, agricultural land use and surveying industries. Although,
there are distance measuring devices like tapes, they could measure short
distances and require two persons thereby wasting manpower. This digital
distance measuring device becomes important owing to the fact that it eliminates
the reflection problem in infrared based measuring instrument and takes care of
the human error due to parallax. It is also cost effectively as it requires
only one person to carry out the measurement.
1.3 SCOPE AND
LIMITATION OF STUDY
Several measuring instruments are in existence presently.
These instruments can measure quantities such as time, weight, current and so
on. However the scope of this work is limited to the design of instrument that
can measure distance. More so, there exist circular distances which are also
measured using variety of instruments. But the type of distance considered in
this project is linear distance involving length, width and height of objects.
Nevertheless this instrument can only be used to measure distances with flat
and smooth surfaces.