Caterpillar Robot

by Kepler, published

Caterpillar Robot by Kepler Apr 8, 2011

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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!

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~~~ ╔͎═͓═͙╗
~~~ ╚̨̈́═̈́﴾ ̥̂˖̫˖̥  ̂ ) Dude, really cool ! Tx

Very cool design, and the new photo is awesome! :-D

I will wait for more videos and updates! :-P

that's really cool. My engineering class is working with inventor right now and we are working on our final projects. could you post the dimensions?

neat job.. good job!

Yeah, sorry for the delay! Exact measurements were not a big concern in this project, so I did not really bother documenting the dimensions of each piece and the assembled robot. The final dimensions are roughly 180x60x50 mm. Like avalero said, you can always download the .scad file and modify the design to fit your needs. However, if you are going to use the same servos, it cannot be made much smaller or larger (The design I uploaded is close to the smallest possible configuration to fit all the parts, and if you make it much bigger the robot becomes impractical) Whatever you do, make sure to let us know!

Okay. Thanks guys!

I'll let you know how it turned out!


if you download the last file (with extension scad) you get the source code for modeling the pieces (there you can find de dimensions). It is written with OpenSCAD, an open and easy to use 3D design program. That could suit your students, as you can modify it, evolve it, and... contribute with imp
rovements!! In fact, this robot is part of a robotic course at our Uni.

Otherwise, let's wait for kepler to give the dimensions. Today is his birthday, so he must be busy :-P

I want to see it in live!!! What about a race when our caterpillator is finished? =P

You're on! We'll race for sure.

Greetings, programs! Oh, what an occasion we have here before us. Because your rumours are true. We do indeed have in our midst a User! A user. So, what to do? What does this user deserve? Might I suggest, perhaps, the challenge of the grid? :)

hey, it's great... he has designed a Tron motorbike!!!!

Also, a long M5 bolt fits as an axle well.

The highest inclination you show on the video depends con the servos power or on the wheel adherence?

The limitation is an adherence problem. The servo has enough torque to pull the whole weight of the caterpillar. I will try to solve the problem by adding a "solid" track on later revisions.

i am remixing it to add solid tracks right now, ill post it when it's done if you want

Yes please! I'd love to see it when it is finished!

it is almost done, i should upload something this weekend

For a solid belt, I would recommend using printed timing pulleys for the wheels. Then you could use a double sided belt (teeth on both sides) for extra grip.

I almost finished the solid version, i will just use ninjaflex rubber pads on each track "mail" (i mean track part), this is the only thing left to print, ill do this this weekend, i also have to glue them

If you made toothed wheels you could run tank style tracks on it. I've seen some 3D printable ones on Thingiverse recently...

Great videos!!!

In fact, http://www.thingiverse.com/thing:7209http://www.thingiverse.com/thi... are perfect for that. Let's see how this evolve. When are you posting a video Kepler???

Links for a caterpillar track

I have now uploaded the video!

Wow. This has awesome potential. What if you added a joint in the middle? A small amount of articulation would enable you to traverse objects better, but maybe the flex in the o-rings would be enough. If I have a similarly sized servo, I'm definitely printing one! Maybe I'll print one even if I don't. :P

Cool - use a pair to make an RC tank.

Awesome! But needs moar video!

There you go! Video on demand. :-D