Wobbly - The 3D Printed, Walking Automaton
Wobbly is a 3D-printed, gravity-powered, walking automaton. He basically walks down slopes.
The files for printing him are in the attached files here at LMR, and are also on Thingiverse here: http://www.thingiverse.com/thing:170932
27 Oct 2013 Update:
After some feedback, I've added some extra parts for Wobbly. He no longer needs Blu-Tack or the coin.
I've added "Arm End Stopper" parts which are tight fitting rings that go onto the shoulder axel to hold all the pieces on. (This replaces the blobs of Blu-Tack that were there.)
I've also added a removable "Rocket Pack" accessory that hooks onto his back. For me, this is heavy enough so that I can ditch the coin. However, if you need some extra weight, the Rocket Pack contains a slot for placing a coin. So, you can add more weight if needed.
Also, I've added new Rounded Arms. These are actually the ones in my photos/videos. I had previous uploaded a slightly older version by mistake.
Here's how Wobbly looks now:
Note, I've provided 2 versions of the Rocket Pack part.
One is for printing with the "right way up" with the hanging hooks at the top. Because the hooks are high up and require over-hang... I wasn't sure if they would be easy to print for everyone. (The Up seemed to handle it fine, generating support, etc. But I wasn't sure if it would work for everyone.)
The other version avoids this over-hang by printing the rocket pack upside down (i.e. hanging hooks at the bottom). For this version, I've changed the coin holder so that it's not a full container. It is instead two slanted walls (forming a V-shape) that should hold the coin in using gravity. I thought having a bottom on the coin container might create overhang too. So, you can try this version if you like! The only thing with this version is that it might not work with very small coins (as they might fall through). [Note that this version needs support to print!]
I think that's all the updates I'm going to do to Wobbly for now (until I get more requests/feedback).
(Time to jump back onto some other projects!)
25 Oct 2013:
I decided to do this project for a few reasons. I've been messing around with some "swinging" style bipeds (Duckling and the still in progress Gutsy). I started looking at related designs including Robosapien and saw Jamie Samans's "Robosapien Companion" a page about mechanical walking automata that used a similar movement.
That had me wondering about these kinds of automata and made me want to make one.
Then, this week, I attended my first meeting at the Australian Antiquarian Horological Society (I thought Horology skills might be useful for robot making), and the presentation this month was on automata - which was perfect for me, and again reminded of these automata.
So, I did more research and found this walking wooden automata on YouTube (http://www.youtube.com/watch?v=UJLH5GYyVhY) which also included a link to a build instructions.
With the instructions as a starting point, I decided to try creating a fully 3D-printable version of the walking automata.
The result is Wobbly. I modelled him using 123D Design, and he was printed on my Up Plus.
Wobbly is made up of 8 3D-printed parts. (The left and right parts are identical. He's symmetrical.) He can be assembled and disassembled easily. The parts just slide together.
The arms were designed to use friction to hold him together. However, I found he got loose pretty quick... So, I used Blu-Tak to hold him together. (Using glue is a more permanent alternative, and finding some tiny O-rings would be a nice neat, flexible option.)
Getting Wobbly to walk well turned out to be an exercise in mechanical debugging! I tried him at various gradients, tried pushing him in various ways, studied his stance/positions closely, etc... In the end, I realised that he needed more weight on the back to keep him standing upright while on the slope.
To do that, I blu-tacked a big coin onto his back! That did the trick! :)
If I revise the model, I will add a coin holder on his back, kind of like those Penny Racer toy cars from when I was young. I was also thinking about changing the shape of the body to create more weight on the back. (E.g. Giving him a tail? Or turning the entire body into a T-Rex shape instead of a humanoid shape.)
The result is what you see in the video! He can walk down slopes, powered only by gravity! :D
He is still somewhat temperamental though. The slope needs to be the right gradient, and you need to give him the right nudge (not too much, and not too little). If the conditions are good, and the gods are smiling, then he walks down the slope beautifully. (If not, I find that thumping the ground a few times sends enough vibrations to get him moving again.)
So, Wobbly is not really a robot... but he is an ancestor of the robots that I'm working on.
Also, I thought he might be something that members of the LMR 3D Printer Club might want to play with.
The STL files are on Thingiverse already. But here at LMR, I'm also putting the source 123D Design files in case anyone wants to play with them (and improve/customise the design).