Arc motion In an articulated drive train

[cadandcookies]

As a summer project, my team has decided to build an octocanum drive as a test platform, showbot, and design exercise. We've been playing around with numerous methods for actuating the drive modules, including designs similar to 525 Swartdogs' (http://525swartdogs.org/pages/CAD/2012CAD.html), 488's octocanum drive (http://www.chiefdelphi.com/media/photos/36198), and, recently, 3928's butterfly drive (http://www.teamneutrino.org/seasons/ultimate-ascent/robot/butterfly/). I've also taken a look at 148's 2011 drive train.

However, try as I might, I can't quite figure out 3928's actuation method from looking at their design. I remember talking to one of their members at the North Star Regional and I believe they said that they used a piston with no sort of connection to the module, but that doesn't sound right to me, and I honestly can't see a piston in any of their posted photographs.

Does anyone have pictures of the design or some sort of insight into their method of actuation?

[Aren_Hill]

It had a 1.0625" bore piston with the piston rod pressing directly on the 3/8ths standoff above the traction wheel.
(the entire module was packaged in a 3x3x.125wall aluminum tube, so the piston was face mounted to the top)

The module range of motion was well defined elsewhere (spring tab through the top of said 3x3 tube) so there was no room for the piston rod to go anywhere/slide off the standoff it was pressing against.

And the arc motion was so short that was not a problem either.

One advantage to this is being able to remove the module with just the pivot bolt and the small spring we had that returned the module to the up position.

Let me know if you have any other questions.

[cadandcookies]

Thank you for the information! I was a big fan of the simplicity of your design. Was the spring what attaches to the holes just above the omni wheels on the sideplate, or was that something else?

[Aren_Hill]

yup, cute little ~8lb spring hooked right into that little peg.

[cmrnpizzo14]

PM pfreivald about 1551's octocanum. They ran it the past few years with good success and reliability.