For our project, we were interested in the intersection between engineering and art. A lot of the past projects we had seen were fairly performative, but we wanted to try making a device that could be used for aesthetic purposes instead. Moire patterns apply physical concepts to create an incredibly unique effect, so producing them seemed like the perfect end goal for us.

What it does

We use a conveyor belt system to move two patterned transparencies over each other which creates a light interference pattern called a Moire Pattern. The movement of the transparencies should mimic harmonic motion (think of a pendulum), and the user inputs how far they want to pull back this imaginary pendulum (amplitude).

How we built it

We were given an XY plotter that we mounted one of our transparencies on top of. We only needed to move the XY plotter in one axis. The XY plotter also had a potentiometer that could be used to read the position of the head. Professor Deliwala lent us an H-Bridge, which allowed us to take in the position of the head of the plotter and output the velocity at which the head should be moving. We were able to do this by coding a simple sinusoidal function. Additionally, we used a NodeMCU that took in the amplitude that the user would specify through the Blynk app. This amplitude would then be applied in the code to ensure that the amplitude of the sinusoidal function was matched to the user input, which would then be reflected in the movement of the XY plotter. We then created a platform to put right above the XY plotter using some laser-cut materials, and placed a transparency on the platform that would stay in the same position. With the transparency on the XY plotter moving and the transparency on the platform staying still, a Moire Pattern was created.

Challenges we ran into

The XY plotter itself was quite finicky because the lead screw usually came loose and would detach itself from the motor. We had to tighten it after every few runs. Additionally, we spent quite a bit of time trying to figure out the mathematical function to model the velocity on because the motor would not speed up and slow down at the positions that we wanted it to. Finally, figuring out the circuitry for the XY plotter was quite a challenge because we were originally thinking of modeling it based on the XY plotter circuitry from ESE 215 which is...intense. However, the H-Bridge allowed us to do what we wanted with the potentiometer and was very easy to wire.

Accomplishments that we're proud of

Actually creating the pattern; we were quite unsure that the pattern would show up because the XY plotter moved quite slowly but it worked out great!

What we learned

Even though we didn't end up wiring the XY plotter the way it was modeled in ESE 215, we learned quite a bit about how the plotter worked just by attempting it. We also learned how to use an H-Bridge, which we probably wouldn't have used in any other course had we not made this project.

What's next for Moire Pattern

Right now we only have the pattern moving on one axis. However, when the pattern moves in two directions, specifically when it is rotating, it creates a Moire pattern that looks equally if not even cooler, so figuring out how to control both axes could definitely be in our next steps.

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