To work around the problems of camera tracking and motion sensors explained in the process page, we placed switch sensors under the floor we had built.
As mentioned previously, we used 5 switch sensors, two each of A and B and another to recognize the proximity of the user to the phone.
These switch sensors were made using two conductive papers that make a contact when pressed together.
Then, we made an electronic circuit using an Arduino board to recognize the pressure of each switch and send this information to a Processing software that calculates the number of people in the alley depending on the signals sent by the sensors.
To have realtime feedback about everything happening in the alley we created an information panel that shows which sensors the user is activating every time there is a new entry or exit.
The panel show these entries and exits, but also the time of the day (day or night), and whether all the conditions are satisfied and the installation is ready to be activated.
As you can see the panel has different icons that lights up in relationship to the conditions on the alley.
We reproduce the path of the alley, and the white line lights up when a person is walking on the switch sensors. The sun and the moon tells the period of the day. In and Out lights up when someone enters or exits from the alley. 1 person lights up when the system knows that there is just one person inside the calle.
This panel is just informative but in the work-in-progress of the prototype it was very important for us to have the the total control of what happend in the alley, in order to study the right timing to make the installation work.
The video below shows how the system works. When a sensor is pressed, on the left the corresponding light on the panel lights up.
With the fifth sensor we detected when the user was near the phone. This sensor, the same as those used for detecting the movement of users, is placed under the floor in front of the phone.
We used another sensor, to understand when the user picked up the phone, in order to either play the audioguide or start the installation, depending on the conditions.
For this we used another kind of switch sensor, with two pieces of metal that make electronic contact when touching each other.
In this case when the user picks up the phone the two pieces of metal don’t anymore make contact. This inverted behavior of the sensor was the simplest way to detect when the phone was picked up, and worked well.
Another thing we implemented on the phone was the sound for the ring and the audioguide.
The Processing software we developed could understand whether to let the phone play the audioguide, or to make it ring.
All the sound came from the audio output of the computer. We connected earphones to the computer in which we ran the Processing application, and put them inside the telephone with a long extension.
The TV is our only visual feedback for the installation. Once the users had started the installation, he is suddenly shown an old news clip concerning the death of Raul Gardini.
To do that we connected the computer to an old TV with a VGA cable, duplicating the monitor. The Processing application works in full screen and shows the video only when the conditions were satisfied and the user alonf picks up the phone, although the application shows a black screen, like when a TV is turned off.
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