this is my first post here. I'm a software engineer by trade, but I have a 3d printer so that makes me a mechanical engineer, right?
Clearly not. However I do have some rudimentary skills and have built some basic things. This project is my most ambitious to date. I have a design in mind that I think is relatively simple, and I wanted some feedback on it.
First, the concept: an array of 8 laser pointers mounted into a device on the ceiling, which will point to the locations we need to place balls for various games (because he doesn't want to mark up his very nice felt on his very nice table). We play snooker, cowboy pool, and other games that have frequent ball-placement in spots that we have to eyeball, and it would be a lot easier (and cooler) if we had a laser pointer to mark the exact spot for each ball.
Well I've been getting into 3d printing and hobby electronics like Arduino etc, so I think this is a doable project, and I have a design already in mind for this device. Like I said, it's very simple (but also, very complex, depending on how you look at it).
The design (I'm not great with drawing so I will describe the design carefully, but I can illustrate anything people have trouble visualising):
8 laser "modules" that pop into a central device. Each module has 2 bearings, one on the side (perpendicular to the table), and one on the bottom (parallel with the table). The bearings each have a gear attached to them. The bottom gear/bearing turns the whole laser module in a circular motion. The side gear/bearing has an axle which goes through (or attaches to) the center of the laser pointer, and can move the laser pointer linearly.
So each laser platform can be turned on an axis perpendicular to the table to do a "circular sweep" by turning the bottom gear, and the laser can be moved in a "linear sweep" using the side-gear (with an axis parallel to the table). Essentially it's just 8 little robots inside of a housing structure. The housing structure is responsible for engaging the circular sweep of each module, so it has 8 gears in it, to one for each laser module.
The modules have the linear sweep "built-in" or in other words, controlled separately. So the central unit is responsible for turning the laser modules, but they do the linear sweep independently of the main unit.
Here's my first question - the only way I can think of to make this work is to have independent servos on the linear sweep of each laser, that way the module can be moved with the circular sweep without having to worry what direction the linear sweep drive motor is oriented. In other words, I'm planning to have 16 RC servos. 2 for each laser module. Each module has one servo for the circular sweep drive, and one servo for the linear sweep drive.
Yes, it's a lot of parts that can fail, but RC servos are really cheap, the idea is that all the parts I use will be cheap parts, and we can just snap in new ones if they break. But maybe there is a simpler design that's within my design skills that I haven't thought of, because I'm not a mechanical engineer. I'm very open to suggestions.
The next part of my question is a very naive and kinda technical one. My idea for saving the positions of the lasers for particular games is this:
On the other end of each drive axle, I was thinking I will place a potentiometer. The orientation of the potentiometer for a particular game can be saved by the device to storage, SD or something, I'll need to write the code for it, obviously, but the basic idea is to orient the lasers manually once, save the position using software, and then when we want to play Snooker we just hit the Snooker button and the lasers orient themselves in place.
My question here is, given the level of accuracy I will need to have in order to save/load a position of the lasers, and re-orient them in software when we change the game, can saving and reloading the locations using a potentiometer measurement be accurate enough? Will I need expensive pots? Or should I consider a different approach from the start? I don't think a pure mathematical solution would work, the amount of skill it would take to mount the device on the ceiling "perfectly" to support a 100% math-driven approach is out of my reach, and besides, stuff moves over time, even pool tables, floors and ceilings. So I think saving and loading of positions using sensors is the way to go.
Any and all ideas are welcome. Thanks for your time!