Design And Construction Of A Microcontroller Based Stadiometer

ABSTRACT

The project is aimed at designing a portable electronic device for human height measurement with the use of a microcontroller and ultrasonic transducers. Ultrasonic transducers use ultrasound wave having frequency being greater than the upper limit of human hearing. The ultrasonic transducer is controlled by the PIC16F877A to generate ultrasound wave to be emitted through the transmitter, and the pulse is reflected off an object and the echo received by the receiver, derive the time travelled, calculate the distance, and then calculate the height which is then displayed on the Liquid Crystal Display. The use of the ultrasound wave finds it application in several sectors such as in the medical, industrial and security, electronic and navigational sectors.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

CHAPTER ONE

INTRODUCTION

1.1      BACKGROUND OF THE PROJECT

• PROBLEM STATEMENT
• SIGNIFICANCE OF THE PROJECT
• AIM AND OBJECTIVES OF THE PROJECT
• SCOPE OF THE PROJECT
• LIMITATION OF THE PROJECT
• PURPOSE OF THE PROJECT
• DEFINITION OF TERMS
• PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

2.1      OVERVIEW OF THE STUDY

2.2      PHYSICAL GROWTH INDICATIONS

2.3     HEIGHT MEASURING EQUIPMENT

2.4     TECHNIQUES FOR HEIGHT ASSESSMENT

2.5      THE IMPORTANCE OF HEIGHT ASSESSMENT

2.6     STADIOMETER MEASUREMENT PROCEDURE

CHAPTER THREE

METHODOLOGY

• SYSTEM BLOCK DIAGRAM
• BASIC OVERVIEW OF THE UNIT
• CIRCUIT DIAGRAM
• CIRCUIT DESCRIPTION
• SOFTWARE DESCRIPTION
• POWER SUPPLY UNIT
• COMPONENTS USED

CHAPTER FOUR

TEST AND RESULT ANALYSIS

4.2     RESULT AND DISCUSSION

CHAPTER FIVE

• CONCLUSION
• RECOMMENDATION

REFERENCES

CHAPTER ONE

INTRODUCTION

1.1       Background Information

Measuring has been important ever since man settled from his nomadic lifestyle, need for measuring processes has always been a part of his regular day to day activities; while cooking in the kitchen, while reading, while playing games (football, tennis etc), while moving around a measurable distance is covered over time. All this processes stated entails one form of measurement or the other.

Measurement is a process that involves the comparison of a measured quantity with a specific unit; it is therefore necessary to know the highest possible accuracy. In a more engineering perspective, measurement is a way of quantifying physical quantities like length, weight, force, pressure etc. These quantities are mostly used in scientific climes, and are required to be as accurate as possible (Roman, 2011). In a layman’s view, height could be defined has a vertical distance.

There have always been an observed need for the measurement of distance and height in several fields, from engineering, surveying, architecture, military operations, airplanes and many others to name a few.  There are diverse devices so far developed and commercially available for the measurement of distance, but less concentration on the height measurement.

With advancement in technological approaches and the increasing trend for simplicity, effectiveness and accuracy included in the design of technological equipments, there has been an observed significant shift from the development of analogue to digital devices. The digital distance measuring tool so far developed as been a critical technological tool mostly referred to as range finders and finds a great application in various fields requiring distance measurement. But we still have significant lack in commercial availability of height measuring devices (digital to be specific).

Height measurement in process control and other industrial applications have been achieved using various physical parameters for measurement, and they include the use of sight, pressure, electrical, sound and radiation properties for measuring. The evolution from more analogue process of measurement in the form of sight instruments, to the use of pressure, electrical parameters in form of resistance and capacitance type, to the application of sonic waves, to the use radiation there is has been a significant shift in techniques and technologies involved in developing several of this devices, which has brought about the digitalization of the height measuring instruments.

The use of sonic and radar technologies in the design and construction of distance and height measuring tools are common and have proven over time to be more effective and of  higher accuracy ratio level. Although, both approach have their limitations in application, example of which is the inherent limitation of ultrasonic wave. Sound (ultrasonic) waves are a form of mechanical energy that uses the atmosphere to propagate, hence changes in chemical make-up of the atmosphere causes variation in the speed of sound, which causes a typical error (Thomas, 2002).

On the face of it, ultrasound (ultrasonic) device has many of the same advantages that a LASER meter device enjoys – one-person / one-handed operation, no need to access the target personally, etc. However ultrasound is intrinsically less accurate, because sound is far more difficult to focus than laser light. Accuracy is typically several centimetres, compared with a few millimetres for laser. And in some conditions, the ultrasound accuracy can be much poorer than the ‘typical’ values.

The development of LASER (Light Amplification by Stimulated Emission of Radiation) is a further improvement on the radar technology approach. It has been effectively applied in the area of distance measurement based on various principles which are; the time of flight principle, triangulation principle and the phase modulated time of flight principle (Acuity Schmitt Industries, Inc, 2017).

In present time, acoustic and optical technologies are expanding into literally all areas of modern life, in telecommunications, in microelectronics, storage media and microprocessors optical techniques are been applied in their production.  In Medicine also, the use of both acoustic and optical techniques have significantly increased, for both diagnosis and therapy. In production engineering, laser techniques are systematically gaining ground in metrology and manufacturing where high productivity, flexibility and quality are the key advantages of both technology (Navendu, 2014).

1.2       Problem Statement

Measurement of height parameters have been a recurring activity in sciences, engineering, surveying, architecture, building construction technologies etc, the measured parameter include; Human, various material or substance (mainly solid) heights.

The availability of more analogue instruments like the meter rule, tapes and chains for measurement process in building activities, surveying and other engineering fields makes the process of measuring height a more tedious activity, hence the need for  a more effective and stress free approach is been required in carrying out this activities.

While advanced technologies in terms of sonic and radar techniques application has proved to be significantly effective and quite accurate, our in ability to determine or manipulate environmental obstruction to the operation of this devices based on working principles are major problems.

1.3       Significance of Project

The development of a digital height measurement tool will provide a device that will aid in the quick and accurate measurement of heights while carrying out measuring activities in engineering, architecture, surveying, building construction and many other fields.

The devices been a digital device will ensure that better accuracy and precision is achieved and the application of human power in measuring processes will be reduced considerably.

This project would also appreciate height has a vertical distance.

1.4       Aims and Objectives

The aims of this project are numerous and include the following;

ü  To create a device that is able to effectively measure the human height and height for forms of solid materials or objects, such as a pile of brick blocks, a building etc.

ü  It also aims at eradicating the issue of time lag in measurement processes that involves the measurement of height, particularly when using analogue device, thereby increasing productivity and efficiency in areas it would be deployed for use.

ü  The focus of this project would also be to ensure that the device developed has more accuracy, with minimal error ratio.

1.5    Scope of Project

The theory on which this project is intended to be based is the time of flight principle as applied in ultrasonic, radar and laser technologies for distance measurement. Time of flight principle involves the calculation of the time taken for a beam of light or ultrasonic wave as the case maybe to travel from the source point to a target point and then back again. Making use of elementary physics relationship between the velocity of light and total time taken to travel back and forth, in calculating the distance covered.

The idea is to make use of an ultrasonic module (a device that consists of an ultrasonic transmitter and receiver), from which the sonic beam of sound from the device transmitter would be directed at a targeted object at the distance to measured, and then reflected back at the receiver and consequently the time of travel from the transmitter to the receiver is been taken and calculated to calculate the distance travelled by the sonic wave.

1.6    Limitation of Project

Time of flight principle is a easily applied in the development of distance range finder, due to fact that the sound wave or light beam is easily reflected has the target is in a horizontal plane, unlike distance range finders, it’s difficult to have an obstruction to reflect the vertically projected sound wave or light emitted by the ultrasonic transmitter or laser diode has the case may be.

Due to device height the maximum range of  measurement was reduced to a little below is feet, which makes the device to be limited to the calculation of those that shorter in height and smaller children.

As a result of inability to influence environment factors that causes little interference to the propagated sound waves, the noticed variation in measured values could not be avoided.

Despite the best method used, it is still impossible to develop devices that are completely free of small variations caused by errors which must be guided against or their effects corrected or brought to the barest minimal.

1.7                                     Purpose of the project

The main purpose of building this device is to ensure to ensure correct and uniform measurement of adult height.

1.8       Definition of Terms

Ultrasonic: Ultrasonic is generally referred to as a high pitch that is inaudible to humans. It has frequency is above the 20 KHz, which is the maximum frequency audible to humans.

L-I Curve: This is the Light Intensity-Current Characteristic graph which characterizes the emission properties of the laser as it shows the current required to maintain a certain light intensity (power).

Piezoelectricity: This the electrical signal produced by mechanical pressure on crystals (mostly quartz crystals).

1.9                                   Project Organisation

The work is organized as follows: chapter one discuses the introductory part of the work,   chapter two presents the literature review of the study,  chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.