Good evening everyone,

I represent a group of 12 students of Mines ParisTech who work on a mechatronic project: build a Ball-Droid, similar to the robot BB8 of Star Wars VII.

The robot will be composed of a sphere of 60cm of diameter and 3mm of thickness, in which a rolling base will be inserted. We will use 3 omni wheels to allow the robot to go in every direction.

You can see below the 3D model realized on Catia:

We have decided to choose a nearly whole sphere (and not to semi-spheres), with a 30cm-hole, because we’ve thought that it will be more solid and resistant. Then, we’ll have to build the robot directly inside the sphere because the opening won’t be large enough to let the rolling base go through it.

However we have to face two major problems:

-       Choice of the appropriate material for the sphere: we hesitate between PMMA and PVC. Do you have any suggestion?

-       Design and fabrication of a device to close the opening: we thought of a bayonet mount closing, with a printing in 3D of this device. However, we have doubts about the resistance and stiffness: will a device printed in 3D solid enough to support a 15kg-rolling robot when it’s in contact with the floor?  Besides, the opening has a diameter of 30cm and we don’t have the use of a so large printer. If we can’t use a larger printer, we might print in 3 pieces and glue them together with industrial glue. We might also think of another technique to manufacture it: do you have any idea of a technique and a material to manufacture this complex device? (you can see below the 3D model).

So if you have any suggestion about one of these two problems, don’t hesitate to comment this post.

Thank you for your help!