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A project log for Telescopic Cube: Low-res programmable matter

An attempt to make a mechanical low-resolution cube that (together with others) could reorganize into arbitrary shapes.

peter-jansenpeter jansen 02/07/2023 at 06:400 Comments

I thought I might post my first attempt at creating a (very low resolution) programmable matter robot voxel, in the shape of a cube.  

The concept is as ridiculous as it is simple: have a cube that contains (a) a telescoping linear actuator that can lift the cube bot higher than other cube bots, and (b) an X/Y stage that allows moving the cube relative to the actuator, so that (when lifted up), the cube can essentially move itself over to be on top of a neighbouring cube. 

The current prototype isn't quite there, and has a number of issues that I'm not entirely sure how to get around: 

Challenges to going forward:

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The idea started off with the cube above -- a 240mm (approximately 10 inch) cube, with a linear actuator mounted on an X/Y stage.  Of course, the issue with the version above is that the actuator is too short to lift the cube higher than itself -- so it needs a different, telescoping actuator.  I cobbled a quick test together, by cascading two linear actuators together: 

And, aside from the obvious wonkiness, it appeared to work -- the cube had lifted (just barely) over its own height.  Immediately after taking this picture the cube fell over and destroyed both actuators, so it was clear that they needed to be properly enclosed in a telescoping mechanism.  I designed a quick series of telescoping square tubes, that use Kapton tape to decrease their friction.  When contracted, the mechanism is about 210mm high, while when extended it reaches about 440mm -- more than twice its length.  

Below is a view of the inside of the telescoping actuator, which is just the two actuators mounted side-by-side.  The telescoping square tube has three parts (top, middle, and bottom).  The left actuator is mounted to the bottom and middle parts, and the right actuator is mounted to the middle and top parts.  When they're engaged, the actuator extends. 

I mounted the telescoping actuator to an X/Y stage that's largely 3D printed.  To test the idea for testing in the video at the top, I populated a DC motor for only a single stage. 

After having this idea in my head for some years, and finally testing it, I think it's unlikely to work particularly well unless a bunch of things changed (like, the availability of inexpensive telescoping actuators that can extend more than three times their compressed length).  But, even if it were to work perfectly, my sense of things is that there are enough limitations that there are likely plenty of ways to accomplish the task better. 

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