Ok, so a little bit of background. I really want to get into MIT and just finished Junior year of hs. One of the ways I'm hoping to stand out a little bit is by building a robotics project. I've never done anything like this before, but I've made it decently far I think. My concept is a robot to hold down the strings of a guitar so I can play one handed. I went through a few rough ideas on how to accomplish this, but the one I found most practical ended up being the first idea I came up with slightly modified. I need some help if you're willing. But first, here's the outline so far:
The Physical Components
It will be a 5 fingered "hand" that has access to the first five frets (if you're unfamiliar with guitars, this is the top part of the guitar and the most used part) and is attached to the side of the guitar. Each finger will be in charge of a fret level and will consist of two motors; One will be attached to a structure on the side of the guitar. This structure will also hold a Raspberry Pi as the brain of this project. The other motor will be halfway through the finger. Each different string that needs pressed will be told to the computer as a combination of degrees of rotation of each motor.
The Code
Coding is something I have a bit of experience with.
The plan is to have a list of data points given to the computer. For example, pushing down the second string on the third fret (2/3 is the standard shorthand for this) would have the computer tell motor 5 to rotate 20 degrees and motor 6 to rotate 45 degrees or something. I would store all 36 frets (6 strings with 5 frets plus an additional possibility for each string when nothing needs held down) in a list. To play a song, I would feed the computer a list of inputs and a speed to cycle through them. A simple song like the first line of "Mary Had a Little Lamb" would be the combination of 1/0, 2/3, 2/1, 2/3, 1/0, 1/0, 1/0. Once again, each of these will be instructions to a set of motors to tell the finger where exactly to be. A more complex song would be a long stream of inputs.
The Plan
The first thing I did was to brainstorm possible ways to achieve this. The first idea was basically the same as I described above, but originally I had spherical motors on the base so that each finger could reach adjacent fret levels. This idea doesn't seem to work because I can't actually find anything that works like that IRL that I can buy. The next part of my brainstorm was talking to friends. One of them recommended servoss. These are basically a box with a tiny blade that can spin. The idea was that you would place them so each spinning blade could hold down a fret if told to engage. After some work, this was deemed by me to be impractical for two main reasons. The first is size restrictions. The strings are very close together and I could not find servos that would fit. The second is money. I would have to purchase 30 individual servos and while I am willing to spend money for this project, this is simply not feasible. As such, I circled back to fingers as they will be able to cover more than one section at a time.
The next thing I did was to design a 3d file to print out. Here is where I ran into a few issues such as attaching my project to the guitar and the issues of finer details in 3d printers among other things. I can tell you more about it later if your eyes aren't actively glazing over, but it actually was quite the process. The steps after this are to research components, buy them, adjust 3d print files to manage them, assemble everything, and finally to code the application.
I am now at the point where I have a physical proof of concept and am ready to get electronic components for my robot. Like I said before, I believe the gold standard for brains for projects like mine is a Raspberry Pi. As for the motors themselve, this is the main reason I'm making this post. I need something like a door hinge or finger joint that I can use at the beginning and halfway point of the fingers. It also needs to be no bigger than about an inch and a half wide and ideally not cost more than $25 each. I'm not sure what exactly to get and none of my friends are sure either.
What do you think I should use for this component? Do you have ideas in my plan you would change? Any advice you could offer? Do you know anywhere I could go to get resources (including more help)?
I have some photos of the project I can give so far, but I can't attach them to the post :\