Modernday devices are using infrared beam and infra red low power output lasers to visual impairment aids. The basic principle is that when the infrared light get emitted from a led, it get scattered on obstacles. As the distance between obstacle and ir emitter decrease the ir detector detect more and more scattered beam. So the intensity of scattered beam is inversely proportional to the distance to the obstacle. But efficiency, reliability, and accuracy of such devices are not that much impressive. And such aid devices are costly as the ir detector is specifically fabricated for that purpose. So we can use ultrasonic waves for range detection, and if we couple a buzzer or vibrational motor with it , blinds will be able to detect obstacles easily. As the working of such ultrasound devices rely on ultrasound echolocation principle, which is entirely different from the ir detector, it is more reliable and the distance variation can be detected more accurately. Such devices are more user friendly, low power consumption, and require low or no maintenance at all. If you have a computer at home and arduino ide softwarte on it, you can calibrate it yourself without any knowledge in computer programming.
Working mechanism:
The hc sr 04 ultrasound module send out ultrasound waves periodically. If the detector detect rebound ultrasonic waves, it send out a high voltage pulse to arduino board. Arduino board calculate the time difference between emission of waves and detection in microseconds, and convert it into inches or centimeters. The arduino microprocessor sent out a buzzer sound whose frequency depend upon the distance to the obstacle. So as distance vary, buzzer sound frequency also vary and it give the user a distance spatial sense.

Step 1: Materials Needed:

1. Arduino nano v3 . c
2. Ultrasonic hc sr- 04 module
3. Buzzer
4. Multi led 1
5. Single color led 1
6. 1000 kΩ resistor 2
7. 100 Ω resistor 1
8. Single strand wires
9. 9 v battery
10. 9 v battery connector
11. Slide switch

Step 2: Algorithm:

1. Set uping the hc sr 04 module.
2. Defining arduino pins and variables.
3. Send out ultrasonic waves in periodic manner.
4. If the detector (echo) detect ultrasound wave, it send out a high voltage to microchip.
5. Arduino calculate the time difference between sound and echo and convert this into centimeters.
6. We are a defining a condition that if the distance is below 80 cm, it sent out a 25 microsecond intermittent buzzer sound whose frequency is (80 – distance) x 75.
7. An led is lighted if the device not detect an obstacle, and an another led is lighted if the device detect an obstacle. This is only optional.

Step 3: Circuit Diagram and Making the Connections:

This is circuit schematics. just connect the components to respective arduino legs and connect the arduino to pc or laptop via usb cable. if you buy genuine arduino board then programming wont be a trouble. it's ftdi chip will take care of the programming via arduino ide program found at arduino.cc website. if you buy cheap clones of it from ebay and amazon which cost only a few bucks, then you need to download and install ch 340 g usb driver. it is available in google. just type it and you will get it. or search it in wooduino.ca website.

Step 4: Program:

// Code for an open-source ultrasonic visual impairment aid device

const int TRIG = 8;
const int ECHO = 7;
const int BUZZ = 5;
const int LED1 = 12;
const int LED2 = 13;

void setup(){
pinMode(TRIG, OUTPUT);
pinMode(ECHO, INPUT);
pinMode(BUZZ, OUTPUT);
pinMode(LED1, OUTPUT);
pinMode(LED2, OUTPUT);

void loop(){
long duration, inches, cm;

digitalWrite(TRIG, LOW);
digitalWrite(TRIG, HIGH);
digitalWrite(TRIG, LOW);

duration = pulseIn(ECHO, HIGH);
inches = duration / 74 / 2 ;
cm = duration / 29 / 2 ;

Serial.print("in, ");
if(cm < 80){
tone(BUZZ, (80 - cm) * 75 ,25);
digitalWrite(LED1, HIGH);
digitalWrite(LED2, LOW);
tone(BUZZ, 0 ,50);
digitalWrite(LED1, LOW);
digitalWrite(LED2, HIGH);


Step 5: Just a Moment:

Just copy the program and paste it in arduino ide and upload to arduino. remember to select appropriate com port and nano board. if any doubt remains just contact me. devilprometheus@gmail.com

Step 6: Conclusion

Now the device is ready. just on the switch. the 'on' led will be on. this means the device is functioning. Then if the obstacle is within the speculated range, the other led will on and a variable sound depend upon the distance will give as output. As the distance is lesser, frequency of rhe output sound will be greater. So blind people can use it to sense their surroundings.

About This Instructable




Bio: An inconspicuous individual who try to seek knowledge in the field of advanced physics to provide a bright future.
More by Wilfred aka devilprometheus:Programming low cost arduino boards having ch340g usb chip. Project L.U.V.I.A (Low cost Ultrasonic Visual Impairment aid) 
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