Hey @Miles, per your request to see the arm, this is for you. Feel free to comment and critique.
First, any good engineering problem starts with some requirements. Here are some top-level ones for my Misty arm:
-The arm should be quickly interchanageable with no tools. Think snap off, snap on.
-The arm should be able to reach close to the ground, or far enough in front to Misty to interact with other objects. Think buttons and switches, and maybe these will have to be specially designed for Misty.
-If the arm interacts with an external object, the event should not damage the object, the arm, or Misty. No robots or humans should be harmed by using the arm. It is OK for the arm to fall off in this case.
-The arm should not move on its own, and remain in the position it was originally snapped into placed.
-There is no lifting weight requirement (for now), just props
-There is no look requirement (for now)
-There is no “Misty should still fit in case for travel requirement” (for now)
The video shows a first iteration. This design uses an embedded magnet in a “shoulder nub.” The shoulder nub is installed onto Misty. The “upper arm” also has a magnet, and holds a concave cup to the shoulder nub. Two early iterations of “shoulder nub” are shown sitting next to Misty, one turned over so you can see inside.
The magnets in the arm and shoulder are from a local hobby store.
Next steps are to investigate friction and magnetic forces to see how much lifting ability is possible. And of course design some quick connect arms.
I will try to include links to the models in the near future. If you want the STL files sooner, let me know the best way to get them to you.