This caterpillar track is the first step towards designing and building a printable mobile robot. My finished robot will have four of these modules, but many other designs are possible. A single caterpillar can function on its own as a simple robot that can move forwards and backwards; two modules can be joined together to form a tank-like machine, etc.

This thing is designed to work with a Futaba 3003 servo (modified for continuous rotation) and uses O-rings to make up the transmission and the caterpillar itself.

Transmission O-ring: 3mm thickness, 60mm diameter Caterpillar O-rings: 3mm thickness, 124mm diameter

This O-ring system was chosen because it was easier to prototype, but it has evident drawbacks. In future revisions I will change it to a "solid" rubber track.

Note that the pictures of the printed robot at the bottom of the page are missing the reinforcement parts. I will upload new pictures as soon as I modify it!

Video of the robot in action!! http://www.youtube.com/watch?v=efXHjjU-yYg (Simple test) http://www.youtube.com/watch?v=mVgXtljqaAQ (Highest inclination: 36º)

Update! (17/4/2011) Uploaded an HD artistic rendition of the UniTrack created by my brother Hasier Goitia. Expect more images and videos after the Easter Break!

Just print and assemble! Use 3M nuts and bolts to hold everything together (it should be fairly obvious where each part is supposed to go)

Lego axles can be used for the front and back wheels.

I have included the openscad file, but be warned! I tried to make the whole thing parametric, but since this was my first project it turned out to be a mess. I just uploaded it in case somebody wants to render the whole file (F5) and be able to take a better look at how it is supposed to be assembled. If you are brave enough you can search for "Main Parameters" and play around with those, but all the parts will probably not fit together any more!