Week Three Iteration - Eric Butler


Iteration 3


Reflections


During this week's iteration, we started to conduct different tests using the code base seen below. These kinds of tests included applying different pressures to the sensor to ensure better consistency, trying different sensors, and different fingers, and comparing wearing the sensor on your finger vs your wrist.

We also had discussions which will be talked about below on many different factors such as:
    > How can we improve the sensor?
    > Getting the micro bit to interact with our breaths (Phase in and Phase out)
    > Negative observations were noticed when carrying out the testing
    
In the code below we start but setting our variables, most notably setting the max and min pulse to read on P2 of the microbit. We also have a piece of code that will reset the calibration when the A button is pressed, this is to ensure that when a different person puts on the sensor it can calibrate to them rather than using data from the previous person, delaying the results.


We also set a breath pacer variable with a calibration of 800 with a pause of 4000 ms and 550 with a pause of 6000 ms which is to give us our 4 in 6 out technique. This pacer was set to ensure that the sensor was catching a pulse correctly where the LEDs would indicate in a bar graph pattern when the pulse of the user is getting tracked correctly.

When the sensor is reading correctly we can see a box plot-like wave to show our HRV that shows the timing of our Phase In (The time the user is beginning to inhale) and Phase Out (The time the user is beginning to exhale).

The most accurate representation of how the graph should be 



https://youtube.com/shorts/Ohx-VtkL5x4?si=hxl4bSc2_e6pAVQe

Video Showing Faulty Sensor with graph flat lining

Faults / Observations


One of the major faults/observations we need to take away from this and resolve is the reliability of the sensor. During this test, it seemed like we spent too much time and attention on trying to get the sensor to read accurately than actually trying to see if 1) Our code was correct and 2) being able to "pay attention" to our breathing to ensure we were breathing correctly. A solution may be to try better sensors 

A solution we talked about to counter this issue is to possibly have a "peg clip-like" sensor that will clip onto your finger to hold it in a set position consistently. As well as this we could use the patches that will stick to your wrist as the sensor may be able to see more into your wrist. Lastly, we talked about the possibility of using multiple sensors similar to an Apple watch to further improve the accuracy although a device for this hasn't been discussed yet



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