Design And Construction Of A Digital Weight Balance

This paper presents the design of an efficient, accurate and inexpensive microcontroller based weighing scale which can be used in all weight measuring operations. A digital weighing scale widely uses a load cell (resistive strain gauge) to measure weight. It converts pressure into appropriate voltage levels. This voltage level is filtered and converted into digital data in the microcontroller which is then displayed on a 16*2 LCD. The prime goal of this project is to provide high precision, low cost and user friendly functionalities.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

CHAPTER ONE

• INTRODUCTION
• BACKGROUND OF THE PROJECT
• AIM AND OBJECTIVE OF THE PROJECT
• PURPOSE OF THE PROJECT
• APPLICATION OF THE PROJECT
• SIGNIFICANCE OF THE PROJECT
• LIMITATION OF THE PROJECT
• METHODOLOGY
• PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

• REVIEW OF THE STUDY
• HISTORICAL BACKGROUND OF SCALE
• DIFFERENT KINDS OF SCALE
• HISTORY OF THE BALANCE SCALE

CHAPTER THREE

METHODOLOGY

• SYSTEM BLOCK DIAGRAM
• SYSTEM CIRCUIT DIAGRAM
• COMPONENTS REQUIRED
• CIRCUIT EXPLANATION
• CIRCUIT DIAGRAM
• WORKING EXPLANATION
• PROGRAMMING EXPLANATION
• DESCRIPTION OF LCD DISPLAY
• POWER SUPPLY UNIT

CHAPTER FOUR

4.0      TEST AND RESULT ANALYSIS

• CONSTRUCTION PROCEDURE AND TESTING ANALYSIS
• CASING AND PACKAGING
• ASSEMBLING OF SECTIONS
• TESTING OF SYSTEM OPERATION
• INSTALLATION OF THE COMPLETED DESIGN
• RESULTS AND DISCUSSION

CHAPTER FIVE

• CONCLUSION
• RECOMMENDATION
• REFERENCES

CHAPTER ONE

1.0                                                        INTRODUCTION

1.1                                        BACKGROUND OF THE STUDENT

Weighing balance is device to measure mass. Spring balance or spring scale calculate mass by first measuring weight by balancing the force due to gravity against the force on a spring, whereas a balance or pair of scales using a balance beam compares masses by balancing the weight due to the mass of an object against the weight of one or more known masses. Some of them can be calibrated to read in units of force (weight) such as newtons instead of units of mass such as kilograms. The balance or pair of scales using a traditional balance beam to compare masses may read correctly for mass even if moved to a place with a different non-zero gravitational field strength. Also the spring balances that are designed with reading of weight (force) in mind, would read correctly for weight in a different non-zero gravitational field strength.

A digital weight scale is one of the most precise digital instruments. It uses force sensors to measure the load offered by an object. Weigh scales are used in a multitude of applications ranging from point of sales terminals to industrial measurement equipment.

The most common method for implementing weigh scale designs uses a resistive load cell configured as wheat stone bridge.

However, the sensor interface is complex due to precision requirements. In the load cells, the signal levels are low and the effect of noise is prominent. This work discusses how to measure this signal accurately to meet the requirements of precision measurement for weighing scales. It will discuss the different parameters of a load cell and their contribution to its inaccuracies. A weighing scale system is not just about the analog front end (AFE) for high accuracy measurement. It also needs many other things like a clear user interface and boost circuitry to deal with low battery conditions. Also, in some weighing scales, some kind of communication protocol may be needed to communicate with a host controller. Other considerations include managing cost and integrating a weighing scale design to implement all the features mentioned above.

1.2                                                   AIM OF THE PROJECT

The aim of this work is to design a digital display device that displays the weight of an object digitally via LCD. Digital weight balance gives the accurate measurement of an item or the people. The work is built around arduino, Load Cell and HX711 Weight Sensor Module.

1.3                                             OBJECTIVE OF THE PROJECT

At the end of this work, the student involved will be able:

1. To construct a portable device that displays the weight of an object.
2. To know the connection and operating principle of LCD
3. To know the connection and operating principle of arduino

1.4                                              PURPOSE OF THE PROJECT

The purpose of this work is to have an easy and accurate means of measuring the weight of an object. Using this device is quick and easy to learn – simple, intuitive system reduces training/operation time.

1.5                                          APPLICATION OF THE PROJECT

Digital Weight balance has several applications. It is used all over the world for many purposes. In many places like shops, industries, airport, jewelry, courier office, and scientific laboratories use these weighing machines.

1.6                                         SIGNIFICANCE OF THE PROJECT

Some of the important uses are listed out here.

1.Identity: There are several weighing machines that exist to weigh the mass or quantity of an item. The beam and the pivot used in the machine is the simple form of machine.

In olden days the weighing machines were using analog method to calculate weight. These weighing machines do not give the exact measurement of weight. Now a days the digital weighing balance used commonly by all.

2.Commercial Use: First use of weighing machines is to measure the weight of products in commercial transactions. The restaurants and shops use the machine to weigh the food items.

Weighing items is very necessary to calculate the price of the item. So the exact quantity has to be measured. It is used in various industries and offices.

Courier office and airports also use the weighing machines to measure the quantity of the goods.  Floor weighing scales are used in the veterinary hospitals to check the weight of the animal. It can even weigh large animals.

3. Health: Weighing scales are used to measure the weight of the body. It helps you to maintain a good diet and will keep you healthy. Weighing machines can help you to deduct whether you are overweight or underweight. The BMI can also be calculated by this weighing scale. Hence the weighing scales are very much useful in tracking your health. Check your weight daily so that you can able to maintain the diet.

If you try to lose weight, then measuring your weight will be the perfect choice. Measuring your weight daily will motivate you to do exercise regularly. It also will help you to maintain a good diet and stay healthy.

4. Science: The chemical and scientific laboratories use the weighing machines to measure the solutions. To make a concentrated solution you have to weigh the water and the solution in grams.

Only then the result of the solution will be perfect. Weighing machines will help you to get the equation for the solution. The labs use the machines for the accurate measurement of the solution.

Digital weight balance gives the accurate measurement of an item or the people.

1.7                                           LIMITATION OF THE PROJECT

This device was built using Arduino and Load cells, having capacity of measuring upto 40kg. This limit can be further increased by using the Load cell of higher capacity.