Voice Controlled Wheel Chair using Bluetooth for differently abled

                                          This project is a voice operated wheel chair for the differently abled that is intended to ease the lives of the people who are physically challenged. This project, basically, is a wheel chair that can be controlled wirelessly using android devices, through Bluetooth. The software of this project is designed to run on commonly used android platforms. The application that controls the wheel chair with the voice was developed on MIT App inventor platform for android. This application utilizes the inbuilt microphone and software of android devices such as phone to listen to the speaker. Then the speech is processed in Google’s speech to text engine to interpret the voice and translate it to a text string that can be transmitted to the wheel chair using Bluetooth. This control of the wheel chair using an android phone makes it easier for implementation and cost reduction.
          

•  Software--Since the android device controls the wheel chair, it was required to design an android application that can work on all the existing smart phones and other devices. This Section explains the application development for the project.

•  Android Application--The application used to control the wheel chair is based on the android environment. This application was developed using an open source application development program called ‘MIT app inventor’.MIT app Inventor is an innovative beginner's introduction to programming and app creation that transforms the complex language of text-based coding into visual, drag-and-drop building blocks. The simple graphical interface grants even an inexperienced novice the ability to create a basic, fully functional app within an hour or less.

•  Speech to Text Conversion--The voice recognition engine that converts the speech to text is based on Google’s voice recognition software. It utilizes the ‘Google Now’ platform to convert the speech to text by listening to the speaker using the phone’s inbuilt microphones and processes the sound using the Google’s voice recognition software in real time. This combined with the android app, convert the speech into text string that is transmitted serially through Bluetooth communication.

•     HARDWARE--Since this project is intended for the economically backward people, theImplementation of this project demands that the hardware used in the project Is not only inexpensive but also widely available. This part of the project deals with the hardware implementation of the project. 

•  Motor Driver(L293D)--This project utilizes the L293D motor driver to control the motors of the wheel chair. This is a typical Motor driver or Motor Driver IC that allows DC motor to be driven in both directions. It is a 16-pin IC that can control a set of two DC motors simultaneously in any direction. It means that two DC motors can be controlled with just a single unit.It works on the concept of H-bridge. H-bridge is a circuit that allows the voltage to be flown in either direction. Change in voltage changes the direction, clockwise or anticlockwise. In a single chip, there are two H-bridge circuits inside that rotate two dc motors independently. Due its size, it is very much used in robotic application for controlling DC motors. Given below is the pin diagram of a L293D motor controller.

There are 4 input pins, pin 2, 7 on the left and pin 15, 10 on the right as shown on the pin diagram. Left input pins will regulate the rotation of motor connected across left side and right input for motor on the right hand side. The motors are rotated because of the inputs provided across the input pins as LOGIC 0 or LOGIC 1.

Pin 2	Pin 7	Condition
1	0	Clockwise Direction
0	1	Anti clockwise
0	0	Idle (High imepedance)
1	1	Idle

Table. 2.1 L293D Logic Table.

Suppose a motor is connected on left side output pins (pin 3, 6). For rotating the motor in clockwise direction, the input pins have to be provided with Logic 1 and Logic 0.  

•   Arduino  

Specifications:

The Atmel 8-bit AVR RISC-based microcontroller combines 32 KB ISP flash memory with read-while-write capabilities, 1 KB EEPROM, 2 KB SRAM, 23 general purpose I/O lines, 32 general purpose working registers, three flexible timer/counters with compare modes, internal and external interrupts, serial programmable USART, a byte-oriented 2-wire serial interface, SPI serial port, 6-channel 10-bit A/D converter (8-channels in TQFP and QFN/MLF packages), programmable watchdog timer with internal oscillator, and five software selectable power saving modes. The device operates between 1.8-5.5 volts. The device achieves throughputs approaching 1 MIPS per MHz.

•  Bluetooth Module

HC-05 module is an easy to use Bluetooth SPP (Serial Port Protocol) module, designed for transparent wireless serial connection setup. Serial port Bluetooth module is fully qualified Bluetooth V2.0+EDR (Enhanced Data Rate) 3Mbps Modulation with complete 2.4GHz radio transceiver and baseband. It uses CSR Bluecore 04-External single chip Bluetooth system with CMOS technology and with AFH(Adaptive Frequency Hopping Feature). It has the footprint as small as 12.7mmx27mm.

Hardware: Features

·         Typical -80dBm sensitivity

·         Up to +4dBm RF transmit power

·         Low Power 1.8V Operation ,1.8 to 3.6V I/O

·         PIO control

·         UART interface with programmable baud rate

·         With integrated antenna

·         With edge connector

•  Interfacing BT module with Arduino

            The Figure 2.3 shows interface between Arduino Uno and Bluetooth module HC05 and

            The corresponding connections.

•   Block Diagram

          The block diagram of the project is as shown below.

The block diagram consists of arduino Uno, Bluetooth module,motor drivr,motors,lead acid battery,ultrasonic sensors and a smart phone consisting of Bluetooth.

The voice command from the phone is transmitted by Bluetooth to the Bluetooth module(HC-05) which is connected to the arduino.the motor drivers are used to drive the motors of the wheel.The ultrasonic sensor(HC-SR04) measures the distance between the wheelchair and any obstacle in front and prevents accidents.

Code:

#include <SoftwareSerial.h>

SoftwareSerial BT(10,11); //TX,RX respectively

String readvoice;

int in1=3;

int in2=4;

int in3=5;

int in4=6;

int pwm1=8;

int pwm2=9;

int pwm=255;

int trig=12;

int echo=13;

int time,dist;

void setup()

{

  BT.begin(9600);

  Serial.begin(9600);

pinMode(in1,OUTPUT);

    pinMode(in2,OUTPUT);

      pinMode(in3,OUTPUT);

        pinMode(in4,OUTPUT);

        pinMode(pwm1,OUTPUT);

      pinMode(pwm2,OUTPUT);

         pinMode(trig,OUTPUT);

  pinMode(echo,INPUT);

}

void loop()

{

  while(BT.available()) //Check if there is an avilable byte

  {

    delay(10);//Delay added to make thing stable

    char c = BT.read(); //Conduct a serial read

    readvoice += c; //build the string

  }

  digitalWrite(trig,LOW);

  delayMicroseconds(5);

  digitalWrite(trig,HIGH);

  delayMicroseconds(10);

  digitalWrite(trig,LOW);

  time= pulseIn(echo,HIGH);

  dist= (time/58.2);

  Serial.println(dist);

  delay(1000);

  

  if(dist<90)

  {

     digitalWrite(in1,LOW);

  digitalWrite(in2,LOW);

  digitalWrite(in3,LOW);

  digitalWrite(in4,LOW);

  analogWrite(pwm1,pwm);

    analogWrite(pwm2,pwm);

  }

 if(readvoice.length() > 0){

    Serial.println(readvoice);

    

    if(readvoice == "forward")

    {

   digitalWrite(in1,LOW);

  digitalWrite(in2,LOW);

  digitalWrite(in3,HIGH);

  digitalWrite(in4,HIGH);

    analogWrite(pwm1,pwm);

    analogWrite(pwm2,pwm);

      delay(500);

    }

   

    else if(readvoice == "back")

    {

  digitalWrite(in1,HIGH);

  digitalWrite(in2,HIGH);

  digitalWrite(in3,LOW);

  digitalWrite(in4,LOW);

    analogWrite(pwm1,pwm);

    analogWrite(pwm2,pwm);

      delay(1000);

           digitalWrite(in1,LOW);

  digitalWrite(in2,LOW);

  digitalWrite(in3,LOW);

  digitalWrite(in4,LOW);

    }

    

       else if(readvoice == "left")

    {

     digitalWrite(in1,LOW);

  digitalWrite(in2,LOW);

  digitalWrite(in3,LOW);

  digitalWrite(in4,HIGH);

    analogWrite(pwm1,pwm);

    analogWrite(pwm2,pwm);

      delay(1000);

             digitalWrite(in1,LOW);

  digitalWrite(in2,LOW);

  digitalWrite(in3,LOW);

  digitalWrite(in4,LOW);

    }

      else if(readvoice == "full left")

    {

     digitalWrite(in1,LOW);

  digitalWrite(in2,LOW);

  digitalWrite(in3,LOW);

  digitalWrite(in4,HIGH);

    analogWrite(pwm1,pwm);

    analogWrite(pwm2,pwm);

      delay(1500);

             digitalWrite(in1,LOW);

  digitalWrite(in2,LOW);

  digitalWrite(in3,LOW);

  digitalWrite(in4,LOW);

    }

    

       else if(readvoice == "right")

    {

     digitalWrite(in1,LOW);

  digitalWrite(in2,LOW);

  digitalWrite(in3,HIGH);

  digitalWrite(in4,LOW);

    analogWrite(pwm1,pwm);

    analogWrite(pwm2,pwm);

      delay(500);

             digitalWrite(in1,LOW);

  digitalWrite(in2,LOW);

  digitalWrite(in3,LOW);

  digitalWrite(in4,LOW);

    }

      else if(readvoice == "full right")

    {

     digitalWrite(in1,LOW);

  digitalWrite(in2,LOW);

  digitalWrite(in3,HIGH);

  digitalWrite(in4,LOW);

    analogWrite(pwm1,pwm);

    analogWrite(pwm2,pwm);

      delay(1000);

             digitalWrite(in1,LOW);

  digitalWrite(in2,LOW);

  digitalWrite(in3,LOW);

  digitalWrite(in4,LOW);

    }

    

       else if(readvoice == "stop")

    {

       digitalWrite(in1,LOW);

  digitalWrite(in2,LOW);

  digitalWrite(in3,LOW);

  digitalWrite(in4,LOW);

      delay(100);

    }

    readvoice="";}} //reset the variable

Conclusion:                                   

Thus, by utilizing a simple android device, this project was implemented. An application for android was developed for the differently abled people to control the wheel chair using simple voice commands. A bluetooth connection was established between the android device and the wheelchair. Therefore, by doing so the cost of hardware was reduced and its scope of implementation was greatly increased. Since the application is based on android platform, future upgrades are solely dependent on firmware updates. As the utilization of smartphones is exponentially increasing in developing countries like India, this project aims to assist the differently abled by means of these Android smartphones.