I'm all in of course. Anything I can do to help just let me know. I'm in the Houston area, not sure where you are at but if you are around here and need a second pair of hands, albeit unskilled, I will pitch in wherever and whenever possible.

As for design mechanics I don't know how complicated you are planning on going but I think one thing that is often overlooked is palm position in relation to forward momentum. That is something that interests me. There are many other things as well but plenty of time to discuss them later.

Thanks for being willing to do this. I think whether people immediately realize it or not this is a big deal for advancing slinging as a sport.

Morphy wrote on Apr 12^th, 2018 at 10:27am:


Thanks Morphy!

As far as how complicated... I would say it should be as simple as possible and only as complicated as necessary.  I doubt we will get everything right on the first try, but you can't learn what's not there until you have something to test out, so my preferred method of development is to build something, learn from it, then iterate.  The side-benefit is that there may end up being multiple versions of Roboslinger that serve different purposes and there would be more hardware to pass around.

As far as community engagement, I think that educators would be a really good target.  Whether it's history, anthropology, physics, biomechanics, aerodynamics, or mechanical engineering, there is something here for a lot of educators to use, and I could see possibly loaning the roboslinger out to academic researchers who want to use it to write academic publications as well.  The advantage of this approach is that, by reaching out to a few educators, those people can then reach hundreds or thousands of students who might take an interest in slinging generally as a result.

As far as location, I am in the San Antonio area a few hours away from you.  I also have some family in the Houston area.

An exciting project that I follow with interest!
But if it has a rubber powered, is it then slingshot-robo?
On the other hand, these are just concepts.

Before we get too far down the road on specific designs, here are a few "ideals" I think we could aim for:

1. low cost - I could go either way on this one. It might be possible to find a rich uncle who is willing to spend thousands of dollars, but until then, I suspect that the project will be somewhat price sensitive.  Low Cost would also make it easier for other people to replicate the design.

2. Portable - I would like it to be small enough that it can be transported in the trunk of a car (maybe partially disassembled), and not so huge or heavy that it costs hundreds of dollars to ship it across the world.

3. Easy to use - Not everyone is a scientist or engineer, and it shouldn't take a PhD to use a rock chucker anyway.  Whatever electronics and sensors go on it should be either intuitive or invisible to the user.

4. Modular - We should be able to swap out parts easily with minimal tools.  It should be easy to attach any sling that is made for a person on there so we can test the same slings we throw with.  The arm should be swap-able so we can play around with stiff arms versus bendy things with simulated elbows and wrists, or whatever.  We should be able to put weights or rubber bands on the pulling end, or some other propulsion mechanism if desired.

5. high performance - this one might violate #1, but I think we can find a balance between the two.  Whenever we can afford it, we should use good quality components and keep friction on moving parts to a minimum... but there are also plenty of craftsmen here who can do quality fabrication work.  It doesn't necessarily have to be expensive to perform well if people are willing to put time into making components.  Particularly expensive components should become specific fundraising goals.

6. Community ownership - I don't want this to just belong to one person unless only one person does all the work and spends all the money.  Anyone who wants to use it or improve it and is willing to follow the community-defined rules should be allowed to do so.   Contributions of time and ideas are just as valuable as money too. Rules should be transparent and defined ahead of time so the roboslinger's use isn't ruled by the whims of one person's arbitrary decisions.  There should not be rules for rule's sake, but as problems arise, rules should follow to solve those problems as simply as possible with minimal burden on the community.  And anyone put in a position of trust as a decision maker should also have clear rules of accountability.

7. It should actually be useful for answering specific questions about slinging and for demonstrating different principles of slinging.

8. We should have fun!

That's the short list of design goals off the top of my head.  More goals are also welcome 

Morphy, wow! That’s incredibly generous!  I might want to bid on that chopper myself!

stick me down for design and 3d printing.
Not a robotics engineer - but fairly advanced 3d printer owner and builder.

One way to make cheap and consistent parts is to simply print them when and where they are needed.
.stl files are pretty small and easy to email. much easier and cheaper than posting actual parts.

Sounds like a fun project

As far as sensors and the like goes.
What platform you thinking of using ?
r-pi 3's are cheap and pretty comprehensive.
But plenty of other mini-system boards around now.

The size is going to be the trickeist part. Have to determine maximum length sling and arm length.
The rest of it's going to be fairly compact. But arm length is crucial.

Can I suggest aluminium 2020 extrusion for the arm. Lightweight, cheap, readily available and much more rigid than a tube.
Also a ridiculous amount of screws. bolts brackets etc readily available - and cheap. 

Oh yeah I'll sticky this thread.

What about adapting a trap thrower?

https://www.youtube.com/watch?v=7BbUrWn7DZk

It might be easier (and cheaper) to adapt an existing machine than to design and build a a rig from scratch.