When I hear
- Easy to do
- Quick and dirty
I always think of a Cartesian robot or a three axis XYZ mechanism.
But why would you want to use this instead of a more human robot arm ?
Multiple reasons :
- Way easier to control : Cartesian is somehow more intuitive that cylindrical coordinate systems. You will not have has much math involved and the development time is going to be that quicker.
- Easier to make.
- Very effective. Cartesian robots were once the norm and they still are widely use, there is a reason for that
Using an arduino to control a Cartesian robot is probably going to be more straightforward and easy to make than a robot arm.
In case you still want to use an arm, you should start checking out Denavit-Hartenberg parameters. Here is a pretty good explanation about them. You can still apply it to a Cartesian robot if you just want to expand your knowledge and understand this. After all, it's only a convention.
Now that we have a likely platform lets dive into your problem.
You want to pick up balls and put them in a trailer. Since you don't have to do any recognition work (you know all the balls locations) it's one thing off of your shoulders. You only want the robot to go to precise locations, on after the other and do its job.
Thus the positions should be hard coded. Or you could simple give a file with different position as an argument.
Then, depending on what is the support for the balls (a shelve ? just lying on the floor on the floor ?) you could either grab them with a clip (sorry for giving you an image there : Google translate told me the word is a clip but I'm unsure that's the good word) or, push them of a table to fall into a trailer or use a suction cup... It's time to get creative ;) !
I just though about something else that you could do if the balls are on the floor. Why not a mobile base that rolls around and pick up the balls ? That's another feasible cheap possibility. And there is plenty of documentation on this :).
I saw your other question as well so I'm going to comment the answer there to give you my guess on how to do the actual movement from one point to another.