The project consists of a pair of glasses that is equipped with a bunch of sensors and some buzzers/speakers that sound if/when they detect an obstacle within the range of their sight. The main goal of the project is to facilitate the daily routine of blind people.
|Name||Skill and interests||Role/Respontabilities|
|Luca Gadda||IT interests, assembly skills||Drive Folder|
|Giulia Lodi||3d modelling, manual skills / assembly||Logbook|
|Caterina Mantovani||3d model, graphics, assembly skills||Responsible|
|Lisa Sciannaca||English, technology||Resp. english|
Objectives (MAX and/or min):
Our first goal was to build a pair of glasses with some sensors, such as ultrasonic sensors, that can detect an obstacle and alert the blind person through a mini speaker;
Another goal was to build a completely new structure of the glasses, using Onshape and a 3D printer. By doing this, we would make the sensors fit and also achieve the goal of making the final glasses as comfortable and light to wear as possible;
The final goal will be to use and make sure the glasses can work.
An Arduino mini, a power supply, two ultrasonic sensors, a servo motor, two buzzers, some cables, 3D printing materials.
v=ƛ/T → ƛ=vT ; Lambda (ƛ) is the distance traversed by a wave during a certain amount of time (T).
Description of the design and physical phenomena involved in light of the theoretical basis
Vcc – is connected to the 5V supply voltage.
Trig – is the “Trigger” pin that must be activated to send the ultrasonic signal.
Echo – is the pin that produces a pulse that is interrupted when the reflected signal from the object is received.
GND – is connected to the reference potential, the ground.
Let’s try to understand its operation in detail:
A 5 volt pulse of at least 10 μS (microseconds) duration is applied to the Trigger pin.
A train of 8 ultrasonic pulses at 40 KHz is generated that travel away from the sensor into the surrounding air. More accurate measurements are obtained if the obstacle is in front of the sensor or in a hypothetical circular sector of 30° amplitude (15° on both sides with respect to the frontal direction).
The signal on the Echo meanwhile becomes high and starts recording the return time waiting for the reflected wave.
If the impulse is not reflected, the signal on Echo returns low after 38 ms (milliseconds) and should be interpreted as absence of obstacle. Remember the HC-SR04 is capable of measuring distances between 2 and 400 cm corresponding, for the maximum limit, to about 23 ms of signal duration on Echo.
In the first prototype we had thought of using a PIR sensor to detect people, but in the end we found out that the “PIR sensor” was just a sensor that detects motion, so it was useless because we chose to use the ultrasonic sensor for that purpose.
Another problem was the structure of the first prototype: the weight was not equal on both sides of the glasses and the structure was too fragile. We solved this problem by creating a new 3D model of the glasses with a stronger material and by placing all the electronic parts more equally.
The next possible step could be adding a camera that can alert the blind person if there are red or green lights.