Natalie and Logan's Lamp

4) Sensing Description 

After we pivoted our concept to a motion detecting lamp that forces you to get up, move, and change locations, we figured out what we needed in order to make that happen. It was necessary for sensing of motion to be our primary sensor, which would then talk to the arduino, then actuate in the lamp. For our sensors, we used four PIR sensors (or passive infrared sensors), separated by a physical barrier so they can only “see” a quarter portion of the room. Here’s a picture of the PIR sensors. 

5) Logic Description 

For our lamp, we want to use passive infrared sensors to detect where a person is in a room and then use that information to power the light bulb closest to them. We also wanted to start a timer that after one hour triggers a new behavior which signals to the person that they need to move.

Pseudo-code

Check each sensor

If(sensor is active) {

         Light that zone

         Start timer

         Turn off other zones

} else {

         turn zone off

}

if(timer expired) {

         flash lights until person moves to other zone

}

6) Actuation Description 

Since our project involves motion-detecting, we felt that what would most adequately actuate motion detecting would be a light. For our light, we decided we wanted to create a lamp that sectioned off four sections of the room, so we knew it would be some sort of lamp with four bulbs that was able to light a good portion of a room. We wanted the lamp to have one light that turns on when you are in front of it or in that quadrant, and if you are in that quadrant for an hour, then all lights go on an off in a circular motion until you have moved into a new quadrant. 

7) Prototyping Update 

After ordering four passive infrared sensors, we wrote code specifically to test how the PIR sensors work. Essentially, if the sensor saw motion we wanted it to turn on a small LED and write to the console. The test was successful, however we learned that each sensor would report motion for a short period of time (up to 8 seconds) after motion ceased. This was a problem if we intended to make it so that only one light was active at any time.

We also bought and tested a 4-channel relay to allow the Arduino to interface with the light bulbs. We modified the Blink code found within the Arduino examples to learn how quickly each light could be activated and to test what trigger the relay expected from the Arduino. This was also our first successful attempt at powering our lights via a wall outlet.

8) Physical Housing Description 

The physical housing is made of 1/4 inch white acrylic, cut on the laser cutter and glued with acrylic glue. We knew we wanted to make the physical home a hanging lamp, so that it could sense separate areas from the ceiling rather than from close to the ceiling, and wanted to make it relatively light in order to keep the weight of the overall item down. The physical home allows all of the logic (the arduino, the relays, the battery, all of the associated wires and the PIR sensors) to fit inside of the center box, and the lightbulbs to situate within each arm with their associated wires into the center box. Below is an image of what was lasercutted, as well as an image of the piece.

9) Prototyping Update 2 

At this point, the code to detect which of the four zones a person was in was finalized. In order to address the issue of the delayed PIR response, special code was introduced so that only when the sensor transitioned from OFF to ON would a pulse be sent to the Arduino as opposed to whenever the sensor detected motion. This meant that you could quickly move from zone to zone and have the lights change accurately. However, moving back and forth between two zones will cause the system to fail to recognize a change. This issue is unsolvable as it is inherent to the PIR sensors and how they report motion. This was also the first time we fully assembled our circuitry and lights. Fortunately, everything worked as expected.