This week I completed my calibration curve that relates the voltage drop across a force-sensitive resistor to the mass of an object placed on it. I made the curve by placing known masses on the sensor and recording the voltage reading associated with it. I created a scatter plot in Excel of voltage vs. mass and generated a regression equation to give a general equation through which I can relate voltage to mass. I was very excited to see that my curve was almost perfectly exponential. I did not expect to get such a clean curve, so it was a pleasant surprise to see a very clear exponential curve with an R-squared of 0.992. I coded this equation into the voltage-reader program I’ve been using on the Arduino, and now I can find the mass of objects placed on the sensor +/- ~1%. These results were very exciting for me.
I also started thinking about the engineering questions associated with my project (i.e. how will I hold/transport the electrical equipment, how will I measure the hardness of the ice quickly, etc.). My professor introduced me to a website called TinkerCAD where I learned to design simple devices for 3D printing. I spent a few hours one day designing a device that will allow me to sandwich the force sensor between two aluminum cylinders and produce a force with a clamp. I’ve already printed one of the prototypes and I’m currently working on revisions. Hopefully I will have the final design printed this week.
My goal is to actually test my device and curve this weekend on ice to see how things should go once I’m in Alaska. I learned a ton of new things this week and I feel really happy with the progress I’ve made. Alaska is getting closer and closer and I can’t wait for this experience to arrive.
I don’t have any pictures of these devices at the time of writing this, but I will upload some within the next few days.
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