Objective

The objective of this project is to provide an electronic device for local navigation tasks of the blind so that it may assist the blind person to move around without collision, compensating for the defects of visual function and improving the quality of life of the visually impaired.

Introduction

Blind people are those who suffer from diseases or accidental injuries that cause blindness. Blind people are divided into congenital blind people and acquired blind people. According to estimates by the World Health Organization (WHO), there are between 40 to 45 million blind people worldwide and the number is still increasing alarmingly. Blind people rely on hearing environmental cues for key tasks such as awareness, orientation, mobility and safety. A representative example is when trying to cross a street intersection all alone they stand still listening to the environment and will not cross until the traffic light sequence is fully understood.  There is a dire need for assistive devices for blind people so that they may enjoy their lives.

Wearable devices are devices that allow a hand free interaction or at least minimize the use of hands when using the device. This is done by wearing the device on the body such as head-mounted devices, wristbands, vests, belts, shoes etc. these devices are light weighted and can be carried by the user. In this project, a small, wearable, lightweight device is designed to help the impaired ones to be alert of the obstacles or hurdles in the path. The device has a  set of sensors that detect the object in the path and makes the person aware of the object by emitting sound through a buzzer. A specific range is set so when the objects come in this range, the person is made alert.

Components of a wearable sensor for blind people

The components used in this project to create wearable sensor device for blind people are,

• Arduino
• Buzzer
• Switch
• Battery
• Jumper wires

Ultra-sonic sensor (HC-SR04)

It is the device that measures the distance of the target object by emitting the sound waves by piezoelectric effect and converting the reflected sound waves into electric signals. Ultra-sonic waves travel faster than normal audible sound waves. Its range is 2-400cm and has a frequency of 40kHz. It consists of two components. A transmitter and receiver. The transmitter emits the sound waves and the receiver encounters the sound after it has travelled to and from the target. The circuitry in the sensor measures the time it takes between the emission of sound by transmitter to its contact with receiver.

The distance is calculated by following relation.

D = T×C

Where,

                 D = distance

                T = Time

                C = Speed of sound (343m/s)

Piezo-electric Buzzer

Piezoelectric buzzers are sound components that generate a monotone. Its working principle is piezoelectric effect. It is the effect where certain crystal change their shape when electricity is applied.

Arduino Nano

Different microcontrollers can be used to operate the ultrasonic sensor. For this project, we selected Arduino nano because of its small size, cost-effectiveness and breadboard-friendly features. It works with a Mini-B USB cable instead of a standard one. It has14 digital pins, 8 analogue Pins, 2 Reset Pins & 6 Power Pins. Arduino Nano comes with a crystal oscillator of frequency 16KHz 

Circuit Diagram

Procedure to build wearable sensor for blind people at your own

• First of all, check that all the components are working properly and accurately.
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• Connect the components according to the circuit diagram.
• Adjust the circuit on the glasses or wristband suitably.
• Supply the circuit with a 9V battery. 
• Compile the program on Arduino IDE software and then upload it to the Arduino board. Before uploading the program, make sure that the components are connected correctly and according to the circuit diagram.
• The range of device can be varied according to the requirement by changing the value of the range in program.

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Literature view

• Designing this project was an awesome experience as the aim behind it was the curiosity to do something for blind people. Some issues and problems were also faced by us while designing it.
• The component selection was a difficult task. As we were unfamiliar with the components, their functionality and of course, their prices as many proceeded projects were designed at a high price which becomes difficult for an ordinary person to buy. We opted for Arduino nano instead of Arduino mini because Arduino mini does not have a programming port and need FTDI so it becomes costly because of that we selected Arduino nano. A problem was also faced while assembling the components as the final molded form was to be such that it may assist the person in wearing it easily.  
• A vibrator can also be used in addition to a buzzer so it may also assist deaf people.
• The band wrist was made of cloth so it becomes easy to wear.
• We generated two projects. The main aim for this was to increase the precision for the detection of an obstacle. Glasses will detect for longer distances and alert the user. The band will have a shorter range which can help users to move to an accurate and specific place. 
• The cost per project is about Rs 1200 ($7) which is much less than previously designed projects.

General comparison

Conclusion

This device detects an object in its path within a specific range. The transmitter of sensor transmits the US signals which after striking the object their path, are received by the receiver. The distance is calculated by the circuitry in the sensor and as a result, the buzzer produces sound as the object comes in the range. The intensity of the sound produced, increases as the objects comes nearer. Furthermore, we added a vibrator so that it may also assist the people who have hearing problems or to support them in the noisy environment. Using a sensor for an auditory function will also assist in hearing for deaf people. This project is designed at an affordable price and has more features than most previously designed projects. Further modification in it will make it more advantageous in future and hopefully, it will improve the lives of blind people.