Final Project Week 3

This week we ordered materials and began working on our prototype.

On Tuesday we cut out some foamcore hands and connected them to motors with tape. We programmed them so that they would rotate back and forth. We plan on building a lego stand and figuring out a better way to connect the hands to the motors. Amy pointed out that we can laser cut the hands instead of 3D printing them since it's cheaper and there's no functional reason why they need to be 3D printed.

We also began to work on a code to get a few LEDs to light up repeatedly in a pattern, but then we set that aside to focus on ordering all the materials we needed.

We had planned on using a force sensor that actually measures the weight on it so we could determine if a child or adult was standing on it, but we couldn't find a reasonably sized and priced sensor online. We realized that we could use a button instead. Pressing the button, no matter the weight, would cause the program to run, so we could just instruct adults not to step on it.

However, since the button is so small, we'd have to build a larger platform for the child to stand on that would simultaneously press the button. We thought about using a squishy material like yoga mat for the base of the platform and cutting a hole for the button, then putting a hard material like a sheet of plastic or wood on top. When a child stepped on the platform, the mat would compress and the hard sheet would press the button.

We also considered two sheets of hard material that are hinged on one side, with a button/buttons in between the sheets on the unhinged side. Stepping anywhere on the platform would press the button(s). We didn't like this idea as much because the platform wouldn't be perfectly level and it would move, so it could be dangerous for the kids. However, we weren't sure if the yoga mat idea would work. Luckily, we didn't have to think about it for long.

Amy found an inexpensive material ($3.95) called Velostat that comes by the square foot (big and durable enough that we wouldn't have to build much of a platform) and changes resistance depending on the pressure applied. We could connect this material to our circuit and it would act as a resistor. When there was no pressure on it, the resistance would be high, so electricity would not be able to flow through the circuit and power the music, hands, and lights. When stepped on, the resistance would decrease so that electricity would flow and the program would run.

We also needed to order a music shield ($34.95) and speakers. We went with with 8 ohm 0.5 W speakers for $1.50. Lastly, we needed to order a micro SD card to store our song(s) on.