Introduction: Affordable Open Hardware Arduino-based Technology for Blind People

In this article I would like to tell you about an ultrasonic keychain the device for the blind which help detecting obstacles at a higher level at which a simple white cane cannot warn the users about. These obstacles may be high-sided cars, gate crossings, high fences etc.

The keychain can be placed around the neck or in the hand and can be used as a flash light. The algorithm of work of these devices is based on a reflection of ultrasonic waves from an obstacle. The distance to an obstacle is measured by calculating the time difference between the moment of generation of the impulse and the moment of receiving the reflected echo signal. Our developed devices have the following specifications:

Distance range of detecting obstacles 1,5 meter Approximate running time on a single charge 8 hours Vibration levels 3 (1,5 m/0,7 m/0,5 m) Type of charger mini usb

Step 1: Hardware You Need

All of the components used in assembling apart from the 3D printed body of the white cane attachment were purchased via AliExpress:

  1. Ultrasonic transducer HC-SR04.
  2. Control board Adruino Pro Mini.
  3. Battery 3.7 V 300 mAh.
  4. Voltage transducer 0.9V ~ 5V to 5V 600 mA.
  5. Charger module AC/DC 220V to 5 V 1 A.
  6. Charger LA-520W.
  7. Indicator: mobile phone vibro- motor 4x10mm DC 3V.
  8. Button PB-22E60.
  9. Body Gainta G1906 (for the keychain)
  10. Transistor: bss138 or bcr108.

Step 2: Scheme

Connect all components as shown on scheme.

Step 3: Load Firmware

Download software for Arduino and load it to them. Link to Arduino project:

Step 4: What You Will Get Inside Box

Step 5: How It Look

Step 6: End