I have recreated a 3D printed robot which can adjust its height to fit into tight spaces and even crawl under (some) doors. Here is a video showing my recreation in action:

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This robot is based on an existing design (called “STAR”) from a 2013 research paper. That design comes from David Zarrouk, Andrew Pullin, Nick Kohut and Ronald Fearing at the Biomimetic Millisystems Lab, UC Berkeley.

Here is a link to the original paper on this robot:
https://people.eecs.berkeley.edu/~ronf/PAPERS/dzarrouk-sprawl-icra13.pdf

I have included a Bill of Materials (BOM) in .pdf and .xlsx form, which show the quantities and materials needed. I have also included the information needed to make the electronics from off the shelf components, as well as pictures of the final Protoboard layout. This is in the .zip file called “STAR Electronics and Assembly Notes.zip”.

Please keep in mind this is not a beginner level project. The mechanics are fairly straightforward, but the electronics are an involved project. Especially if you want the robot to be low profile enough to fit under a door.

I have also included the Arduino sketch that I used to run the robot. Good luck and enjoy!