Introduction: Proximity Sensor
White cane is the most popular device for blind and visually impaired people. It is used as a mobility tool to detect objects in the path of a user.
Even though white cane is very helpful and effective, there are some other technologies that could make moving around a little bit easier. We thought that we could improve the ability to detect obstacles using a distance sensor combined with a small vibration motor, similar to those used in mobile phones. After a small internet research we came across a cheap and easy to build system that could offer this kind of functionality.
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Step 1: Materials and Tools
- ATTINY85 Digispark
- vibration motor
- 9V battery
- bipolar switch
- two cable glands
To make the distance sensor we used Dremel Versatip and Dremel 3000 with sanding bands.
Step 2: Prototype
The system is based on a small ATTINY85 Digispark microprocessor and a HC-SR04 ultrasonic proximity sensor. To test its effectiveness we ordered all the items and made a small prototype.
The sensor turned out to be quite good in detecting obstacles, especially flat surfaces such as walls, furniture, etc. More problems occurred with detecting edges and various materials (the signal easily dissipated).
Step 3: Process
The first step in building a final sensor was to design a casing in which the sensor could be placed. We decided that the sensor will consist of several removable modules, so that it could be attached to clothes or a white cane. A microprocessor, along with a battery and a vibration motor, will be placed in a small casing that would be kept in the pocket. Both elements will be connected with adjustable cable.
The part that will be placed on a white cane or attached to a garment consist of a HCSR04 sensor, a small cable gland and magnets.
The casing has been designed using CAD software - we decided to create a simple construction, similar to the one pictured on the drawing above.
All the components were printed using a 3D printer with the use of ABS – a material with decent mechanical properties.
Each part required little work - we had to remove all supports, cracks, and surface irregularities. To do this we used Dremel versatip, a multi-tool and a fine sandpaper.
All electronic components were soldered together according to a scheme and placed in a printed casing.
Step 4: Final Words
Despite the fact that it will certainly not replace the white cane and other equipment necessary to move for blind and visually impaired people, it can give valuable clues about a position of some obstacles, especially if those obstacles are walls, furniture and other large objects.