Physical Computing - Week 4 (24-09-24)

Sensors!

This we got a break from labs and dove into more technical information around the hardware we will be using for our future projects. In the previous weeks, we have worked with a variety of sensors, mostly mechanical sensors such as the button switch (below left) and the potentiometer (below middle). I also worked a lot with force sensing resistors (below right) in my previous labs, because I found the input variables were so much more complex and posed interesting potential interactivity. 

A simple use of an FSR would be to trigger the output as soon as the FSR reading exceeds a minimum threshold, ie, if you press hard enough, a light will turn on. To make it more interested, you can program the output to only engage if the FSR readings fit within a given range, ie, you must only gently touch the FSR to turn on a light, press too lightly or too hard, and the light switches off. The most exciting for me was my lab from last week, where I mapped the sensor reading to the acceleration, so the harder you press the FSR, the faster the motor moves. 

​Based on this week's videos and readings, I am interested in exploring more motion and light sensing for our midterm project. I still haven't quite figured out how to get a decent range on the phototransistor - whenever I check the readings of the phototransistor, I get 0-14, which is not a lot to work with. The sensors covered in this weeks videos also discuss motion in the sense of distance (distance ranger) or presence (passive infrared detector), my curiosity with this is whether it is capable of detecting very small readings such as water rippling? 

Midterm ideation

Julia and I will be working together on our midterm project and we want to create an interactive sound experience that connects visual water interaction with sound distortion. Julia's initial inspiration was to utilize color readings to create difference sounds. This poses a couple of questions:

What kind of sensor can detect color readings, and is it within our current scope of knowledge? 
Yeseul suggests that we work with black ink and read the light level changes created through the ink to keep it within a manageable scope. This poses another interesting idea - we both really like the visual of "ink swirling in a body of water" and want to include this visual experience in our project. What kind of ink will have the opacity to generate a change in "light level" readings, but still have the viscosity to still disolve slowly in the water?

What kind of sound output do we want the user to experience?  
While searching through the Mozzi example library, I was especially drawn to the "light_temperature_multi_oscil" sound clip because it creates similar visual imagery that we are trying to produce with the ink swirl. The audio output consists of fluctuating ambient sounds based on multiple sensor readings, which perhaps we can utilize motion on the water surface to oscillate the fluctuating volume and control the note frequency based on light levels.
We also want to play with the benefits of 2 speakers and produce two different sound outputs. Perhaps one speaker is playing a simple beat that is also affected by the water interaction while the other is playing the oscillating ambient noise. We also discussed possibly using headphones as the audio output rather than two speakers, but that would involve us looking into writing the audio output as left and right channels. 

Below is a quick sketch from our initial brainstorm last week. This project will consist of a couple of components.

• A light source
• A vessel of water 
• Pipette to drop ink into vessel
• A platform to house sensors but also to hold the vessel in place
• Sensors: phototransistor & some sort of motion sensor? 
• Output: either speakers, or an audio jack

We are still in early stages of ideation with a bit of research to do, and will be scheduling a lot of office hours with Yeseul as well as residents for help.