Visually impaired people find it extremely difficult to acquire basic and vital information necessary for their living. Therefore, they are at a very high risk of being socially excluded as a result of poor access to information. In recent years, several attempts have been made in improving the communication methods for visually impaired people which involve tactile sensation such as finger Braille, manual alphabets and the print on palm method and several other electronic devices. But, there are some problems which arise in such methods such as lack of privacy and lack of compatibility to computer environment. This paper describes a low cost Braille hand glove for blind people using slot sensors and vibration motors with the help of which they can read and write e- mails, text messages and read e-books. This glove allows the person to type characters based on different Braille combination using six slot sensors. The vibration in six different positions of the glove which matches to the Braille code allows them to read characters.
Step 1: List of componenets
The electronic circuitry of the hand glove comprises of the following components and modules
1. Slot sensors
2 Vibration motors
3. Vibration motor driver IC DRV1117
4. Comparator IC LM324
5. AVR Micro controller development board (ATMEGA 8)
6. CC 2500 Trans receiver (Radio Frequency module)
7. Power supplies
8. Woollen gloves
9 . 6 Variable potentiometers
Step 2: Mounting vibration motors on the Glove
A total of six vibration motors are used in the project. the vibration motors are placed on the five fingers and palm as shown in the figure.
Step 3: Mounting slot sensors on the Glove
Place the slot sensors on the glove as shown in the figure.
The circuit for slot sensors is as shown in the figure.
Step 4: Connecting vibration motors to DRV117
All the vibration motors are connected to the vibration motor driver IC DRV1117 for voltage conversion.
Step 5: Connecting slot sensors to comparator IC
The output of the slot sensors is analog hence to digitize the output we connect it to comparator IC LM324. We use 6 variable potentiometers in a voltage divider circuit.
Step 6: Atmega 8 microcontroller development board
We use an atmega 8 development board for processing .
We developed an ASCII to braille conversion algorithm which we fed in the controller, vice versa we also developed a braille to ASCII conversion algorithm. Therefore effective two way communication can be established.
Step 7: CC 2500 Trans receiver (Radio Frequency module)
The CC 2500 Trans receiver module is used for transmitting data wirelessly from the PC to the hand glove and vice versa. This wireless module has a range of up to 100 meters. This makes the hand glove portable, comfortable to use and eliminates the use of unnecessary wires and cables for interfacing the hand glove to the PC. The module consists of two parts, one is the transmitter and the other is the receiver. Both the transmitter and the receiver can be interchanged. This module transmits characters in the form of its American Standard Code for Information Interchange (ASCII) values.
Step 8: Power supplies
Power supply used in the circuit is a 9V DC battery. The microcontroller development board requires an operating voltage of 3.3 Volts and other electronic circuits involving different ICs like the comparator IC and the motor driver IC require a voltage of about 5 Volts. Therefore, we have designed voltage regulator circuits using some passive components and special voltage regulator ICs.
Figure shows the circuit diagram of a 5 Volt voltage regulator circuit. The IC used here is the LM7805 5 Volts, 3 pin voltage regulator. This is a low power, low cost IC.
Step 9: Software Implementation
The Integrated Development Environment (IDE) used for the proposed system is AVR Studio for compiling and running the code on the ATmega8 development board. The conversion code for converting Braille to text and vice versa is written in Embedded C. The boot loader flashing tool used for burning the code on the development board is HID boot flash as shown in Figure. The HyperTerminal used for displaying the text is the FLASH MAGIC terminal with the help of which the RF module can transmit the text data in the form of its American Standard Code for Information Interchange (ASCII) values. This terminal displays the text to be read/written using the hand glove. This HyperTerminal is linked with Graphical User Interface which enables the user to link the text read/written to the internet.
Figure shows the Graphical User Interface which is developed using MATLAB for reading as well as writing text online. This is linked to web pages and internet. The Graphical User Interface can also be made by using Code Composer Studio but using MATLAB is very easy and convenient