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Mobile phone is a very useful invention. Today all the people are using mobile phones for their convenient the mobile phone is a very good technology for communication. Having mobile phone is a great advantage for communicating with friends and families from anywhere to all over in the world. By calling or sending messages from mobile phone we can easily able to connect with others without electricity.
Now a day's SMS (short message service) is the most useful application. Today 80% of mobile phone users are using this data application. But the visually impaired people cannot able to use this application.
In this project the visually impaired people can read message using mobile phone, and also this system help the blind people to send acknowledgment for the current incoming messages .This will be implemented by interfacing the Braille system with mobile phone.
Louise Braille is the father of Braille system. This system is a worldwide system; with the help of this system, all the blind peoples for reading and writing like a normal people.
It was invented by Louise Braille (1809-1852), who was blind and become a teacher of the blind. Braille is the system to write and read the words by touch for the visually impaired people. Old days the Braille system is used only for the reading purpose. Now only the system convert to use both read and write.
It consist of patterns of arranging dots in array manner and all the dots all arranged in 3x2 configuration. Each cell represents a particular letter or symbol and the combination of Braille cells mention the words or sentences.
There are number of different versions of Braille:
Grade 1 is consists of 26 letters of standard alphabets and punctuations. This is first starting system for the blind people.
Grade 2 is also consists of 26 letters standard alphabet and punctuation. Also this grade has the contractions. Braille page cannot fit into printout page. So using contractions we match the Braille and take printout pages.
Grade 3 is mainly used for personal letters, diaries and also literature. This type of shorthand written is mostly used for the message applications.
Braille code is the world first binary encoding scheme to represent the letters in the writing system.
The system is invented by in two parts:
In the French language, character encoding is used for mapping characters in the form of six dots. By raising the dots they can identify their characters.
Braille alphabet (English Braille American edition)
Braille Alphabet Card (grade one)
Braille punctuation signs
Today different Braille codes are used to mention the different languages by six bit cells. Because of the six-dot Braille cell only have 63 combinations. In this diagram, some same oriented character omitted based on their context. So only the characters are not mapping to each other letters.
The main objective of this project is blind or partially blind people can understand the messages and give acknowledgment for particular message using mobile as normal people.
Braille technology is making of revolution among the visually impaired people. This Braille technology allows blind people to do many things like writing, browsing the internet, typing Braille and printing in text document, typing in chat, downloading files, music, using electronic mail and for reading documents. It is also useful for blind students for completing their assignments like a normal student.
Braille is most useful technology for the blind people in communication world. In the existing system message application dose not complete for blind people. In message application the visually impaired people only can able to read the message in on the tactile surface of the display. But the quality of the system is not good because the blind people not able to identify the text exactly
In this system the message received from the GSM modem. Every single incoming message is indicated by external vibration motor using vibration. The every single message collecting in the arm board, will be display in these formats (LCD display, Braille board and voice output) by pressing key number"1" in the control unit.
Fig 1 Block diagram of message application using Braille system
Here LCD is used for all except blind people, but output message from the audio is used for blind and dumb people only. Both Braille output and audio output can be used by the blind people. The incoming message which is not important for the user can be deleted by using control unit (key no: 3).
The user can reply the current message by using input voice from microphone (mic). After completing voice record the voice input convert into text automatically in the ARM board. Before sending that reply text message is check the spell by using Braille board when pressing the key "6" in control unit. Finally the message is sent through the GSM modem by press the key "9".
V. CONTROL UNIT
This system is mainly developed for mobile application. By using this system the blind people could read and write message by Braille module. So only we are implemented all these system functions in to one control unit is called keypad.
Control unit have 12 keys (0 to 9, # and *) for controlling the entire system. Each key have specific function in that unit. Blind people, every time when pressing a key, the indication of key which pressed that will be indicated in loud speaker.
Functions of control unit:
1. Ready to read
3. Delete current message
4. Reply for current message
5. Voice record, Voice record complete
6. Check text
8. Re-voice record
9. Send message
*. Temperature indication
0. Time indication
#. Date indication
Vibration: It is first function of this project, If any new message is comes into the mobile, the indication of new message to start vibrating using mini vibration motor.
Ready to read: After vibrating, we can read that message by using press the key "1". These command to create a task into the controller for reading new message to convert "text message in to voice" and delivered in to loud speaker. This process is called Speech synthesis. The message also indicated in LCD display and Braille board.
Reread: The blind may cannot read the message clearly the first time, press the key "2" then the that current message again indicated in three format.
Delete the current message: If that current reading message is not important message, want to delete that message then press the key "3". The current message is deleted from the inbox.
Reply for current message: Want to reply for that current reading message, press the key "4". This is indicating to the controller for ready to record the voice for acknowledgment.
Voice record: After indicating the ready to voice record, press the key "5" to start recording the voice from the microphone input.
Voice record complete: Want to complete the recoding voice input, again by pressing the key "5" in control unit. Here the voice recording process complete, then start the process of the voice converting into text. This is the starting process of the speech recognition. This task is to initiate the speech recognition in the controller, after converting speech into text, then the text stored in the controller un till Waiting for spell check before sending message.
Check text: The stored text message is checking by using Braille board when pressing the key "6". Here the each character of the message display in the Braille board also delivered in the loud speaker and LCD display.
Recheck: If the checking the text is not compatible for the blind people, then recheck the text by pressing the key "7".
Re-voice record: If the text is not correct or any spelling mistake is there means, want to re voice record for correcting the message by pressing the key "8". Then above all the process re-do before sending message.
Send message: The text message is correct after checking spell then press the key "9". The message sent to the particular recipient.
Temperature indication: The blind people can see the weather and temperature of the environment. When pressing the key "*" the temperature of the current day to delivered in loud speaker.
Time indication: When press the key "0", current time will be delivered in the loud speaker also display in LCD.
Date indication: When press the key "#", date of the current day will be delivered in the loud speaker also display in LCD.
Braille system works in two type of mechanism:
Using an electro-mechanical technique the Braille display is raising dots through holes in a flat surface for displaying Braille characters.
The second mechanism, which is using piezoelectric effect to raises the dots when a voltage applied to it. The crystal connected to the lever, which raises the dots. This mechanism is high cost compare to electro mechanical display.
VI. ELECTRO MECHANICAL MECHANISM
A flapper has high mechanical stability, low actuating voltage, and low price compared piezoelectric mechanism. Each Braille cell has modular unit, called Braille cell module. It consists of six flappers to drive the Braille dots.
A . Flapper actuator:
The flapper works based on the theorem of electromagnetic principle. Inside the enamelled coil there is fixed iron core; flapper actuator acting as a rotatable armature. The enamelled coil is constructed in helix shape and it carries electric current and produces the magnetic field lines. The enamelled coil increases the magnetic field. The pole of iron core is acting as a strong magnetic field. And it attracts the armature for control the Braille pin. This mechanism of flapper acting principle shows in figure 2. Here a yoke is used to fit the iron core and to increase the magnetic field. An armature attractive by iron core and pushes the Braille pin upward. An armature clip has limited degree of freedom (DOF) of armature in one direction.
Fig .2 Flapper actuators and Braille cell mechanism.
Braille pins and flappers are depends on the number of Braille dot's. The flapper has two opposite operations in this technique. One is no current passes through the enamel coil and no magnetic force is created to attract the armature. Second condition is the enamel carrying current, the current passes through the enamel coil, and the armature is attracted by upwards because of lever mechanism. The point e2 in armature is clipped by armature clip and that armature rotate in z-axis because of DOF. Point e3 is lifted to contact Braille pin when the point e1 attracted to iron core. Finally Braille pin pushes upwards.
The angle between e1e2 and e2e3 can change because of vertical stroke at point e3. e2e3 is an horizontal position, when the flapper is not carrying current and that time small changes in angle between vertical line and e1e2.
The angle R can be estimated easily when the stoke move upwards and reach 0.7mm. This specific length ratio is to declare the upward stroke of Braille pin to three time of the air gap between the armature and iron core. The small space of air gap in the flapper will be used by this design to provide a large stoke of Braille pin. Main advantage of this air gap is to reduce the current and for less heat generation.
B . Fabrication of Braille cell module and Braille display:
According to types of armature there are two types of armature, and according to their lengths three type of Braille pin are there. The variety of flapper and Braille pins are used to specialized design and fitting in Braille cell module. Here Braille cell mechanism has six Braille pins and six flappers. The figure 3 shows a Braille cell module.
Fig .3 Fabrication of Braille cell module
The full function of Braille cell shows in the figure 2. Six flappers are in the circuit board with tactile surface. And the tactile surface has six holes for holding six Braille pins. The uses of finger tip on the surface, we can identify which pin is to be raised and which letter are mentioned.
VII. SPECIFICATION FOR BRAILLE DOTS
Refreshable Braille specifications are listed in below specification table. The values are listed below are best fit value for current standard Braille system.
The top of the Braille dots are domed. The each domed has unspecified radius of curvature.
When dot is raised, the particular dot should be supported by force of> 25 grams.
BRAILLE DOT SPECIFICATION
Braille dot base diameter
Height of 8 dot Braille cell lines
Distance between centers of corresponding dots in the same cell
Distance between centers of corresponding dots in horizontally adjacent cells
Height of 6 dot Braille cell lines
When the Braille reader touch the surface, the Braille pin should provide a minimum of 20 grams lifted force, while depressed <0.1 mm from its top height.
Dot height should be uniformly for adjacent dots: Â±0.05 mm. Minimum displacement of the un-raised dot in below reading surface value: 0.025 mm.
Measuring of Braille line spacing and height using the centres of a top dot of the cell and also consider vertically adjacent cell.
Braille concept also used in tactile display, if it has additional dots to fill in the gaps of between Braille cells and Braille graphs between cells within cells of each line.
VIII. SPEECH SYNTHESIS
Speech synthesis is the process of developing a human speech in an artificial manner. This system is called speech synthesizer. It can be implemented in hardware or software. Here, text to speech (TTS) system used to convert the normal text message into speech. The relevant speech for each text already created and stored in the data base. Each system has different size of data base unit; the speech unit that stored in phones or diphones, but it may lack clarity of output.
Diphone synthesis is recording a transition between the phones. Number of diphones depends on the language content. These diphones are used to store the words and improve the quality of the output of speech. Synthesizer is an alternatively used to identify the model vocal tract and also creative the completely synthetic of other human voice output.
The quality of this system increased when the similarity of human voice into the database and ability to understood the voice. This system mostly used by the visually impaired people to reading the message and computer documents. The figure 4 shows the block diagram of speech synthesis.
Fig.4 Speech synthesis
A text-to-speech system is composed of two parts:
AÂ front-endÂ 2) AÂ back-end
First, it converts the text message (numbers, abbreviations) into equivalent of written out words. This process is called pre processing. The front end assigns phonetic transcriptions and that converts into the corresponding speech, also match to the system database; the process of converting phonetic transcriptions into words is called grapheme-to-phoneme conversion. Finally in the front end phonetic transcriptions converts output as symbolic representation. The back end is the output end; this is used symbolic linguistic representation into sound. in this system the corresponding output speech is delivered in the speaker.
IX. SPEECH RECOGNITION (SR)
Here speech recognition is the translation of pronounced words into text message. It is also called automatic speech recognition or speech to text (STT).
This is a computer technology that is used to recognize and understand the input speech, by using digitizing and matching with the database. Now a day's all the available devices are speaker dependent, it can recognize one or two person only. Also recognize discrete speech then normal speech. This technology is mainly used for helping people in working around their disabilities. In this project STT using message application is mainly for helping visually impaired people; it convert the input speech signal into corresponding text message. Before using this technology, we supposed to improve the quality of the system by training with specific person voice in the database; it is called "speaker dependent" system and it gives more accurate transcription.
Fig .5 speech recognition block diagram
The system will not be trained means that is called as speaker independent systems. Natural intonation for the synthesised speech will be generated by prosody generator. A flexible pitch contour is selected to suit the type of the sentence from the database. Figure 5 is shows the block diagram of speech recognition.
For a given input text message, intonation for the sentence is determined based on nature of the sentence and then it generating the corresponding pitch contour; the speech units extracted from system database. Pitch and time scale changes are collect out in according to the pitch contour. Finally, trained speech units are performed to produce speech of the output.
Still now Braille technology is used by the blinds only for the reading purpose. But here, using this Braille system both reading and replying the messages possible by visually impaired people. In this project using Braille technology the blind people can access the message application in mobiles as a normal people. Using this system uneducated people also may use the message application in mobiles.