Final Project Week 3

We made a lot of progress on the project this week! We cut the delrin with the laser cutter, built the delrin box, and tweaked the Arduino program. 

Putting the box together

First, we cut out our Solidworks file on the laser cutter. As described in the last post, our delrin box has notches and tabs for the panels to fit together. The LED lights will go on the outside of the front panel of the box, while the wires, Arduino board and battery pack will go inside the box. The back of the box has a panel that has two hinges, which are piano-wired, so that the battery pack can be taken in and out. The back panel had to be split into two halves so that it would not be too tall to drill.

Tabs and notches

Hinge -- piano wired

Hinge -- piano wired

Inside of box

Back panel

Tabs and notches were extremely tight and therefore had to be hammered in. We sanded down some of the ones that did not fit. Also, we reinforced some places with hot glue.

Drilling and Sautering 

Next, we had solder the lights so that the wires were long enough to go from the front panel to the Arduino board in the box. As a result, we also had to drill holes into the front panel of the board so that we could slide the wires of the LED lights, the potentiometer, and the sound sensor through the front panel and into the box.

Testing the program

We also went to the classrooms to test the range of volumes detected by the sound sensor. We found that because human voices fluctuate a lot, the readings bounced around quite a bit, therefore causing the lights to jump from one color to another. To fix this, we created gaps in the sound sensor ranges in the program. For example, for the high setting, we have the following ranges for the green, yellow and red. 

We also increased the delay for which the sound sensor reads the volume. These actions helped the lights not bounce around as much. This was important, as the flickering lights would be very distracting for the children.

We consulted with the teacher, as well, to make sure that the values we were using were acceptable and realistic volumes that one would find in a classroom of young children. 

Reflection

Unfortunately, even with the gaps in the ranges in the program, the lights still do bounce around sometimes. Charlie suggested that we create a loop to take the average of the sound readings for a certain time interval, and use the average for the reading that the lights respond to. We may look into implementing that next week. 

Also, we realized that some of the LEDs were burning out because we had not connected any resistors to the lights. So, we calculated, using V = IR, that we need 100 kilo-ohm resistors for the lights. We connected the resistors to the ground wire of the lights, so we shouldn't be getting any more burned out lights.

We're almost done! Just need to glue down the lights, potentiometer and sound sensor to the front panel and put the colored film over the lights. We will also try to continue to improve the program.