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pic: Duodec-Drive (Octocanum)
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Re: pic: Duodec-Drive (Octocanum)
Garrett,
Any reason you can't put a 1/4" thick gusset plate over the corner 2x1's and just use a face mount pancake piston? Of even just nose mount the current piston. Everything would get a lot lower profile and you'd reduce your part count. (It would even be a great main frame gusset for that corner) -Aren |
Re: pic: Duodec-Drive (Octocanum)
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Re: pic: Duodec-Drive (Octocanum)
One of the cool things about this kind of drive, if it has the right configuration, is you get suspension for your Mecannum wheels for free. This insures all four wheels are in contact with the ground at all times. This makes a difference when strafing. I'd suggest flipping your design around so it pivots on the solid wheel. You'll find the Mecannum wheels will work better if you do.
We used this kind of drive this year and in Bunnybots so got to measure this first-hand. |
Re: pic: Duodec-Drive (Octocanum)
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I love the idea, I literally smacked myself on the forehead after reading your post... It made me feel foolish for not thinking of it first :o |
Re: pic: Duodec-Drive (Octocanum)
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Re: pic: Duodec-Drive (Octocanum)
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Mecanum without suspension is OK if the field is fairly flat and the chassis is slightly flexible (e.g. aluminum C-channel or square tubing). If you have a good bit of driver practice, the drivers can even get used to significantly uneven loading. Woody, our practice 'bot for 2014 Aerial Assist had only 13# on one corner wheel and about 50# on the opposite corner. We practiced with it on a patch of parking lot behind the stadium's concession stand; it was less than impeccably level. After a few hours driving, the operators had internalized the compensations. It did take a couple of practice matches indoors with "Buzz", the competition 'bot, to unlearn those compensations. (Yes, Woody actually had a 2-by-4 wooden chassis and kicker and 2-by-2 pickup arms - video of driver practice here. We decided that the practice 'bot would be different than the prototype(s) and much more like the competition 'bot in 2015.) |
Re: pic: Duodec-Drive (Octocanum)
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(Spring pulled the module back up, reducing air consumption as well) -Aren |
Re: pic: Duodec-Drive (Octocanum)
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3928's design from 2013 is so $@#$@#$@#$@# simple, that it honestly baffles me why anyone would do any variant of butterfly or octonum that isn't a copy of it. With Andymark's new 4" mecanums, and 4" wide tube, an octonum variant is easy w/ his design. It's so darn simple. |
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Does anyone have a picture or link to this approach? |
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EDIT: chassis posted here. Holes near ends on top face are where pancake cylinder mounts. |
Re: pic: Duodec-Drive (Octocanum)
![]() Uploaded it since it apparently didn't exist on CD. The piston shown is a 1-1/16" bore pancake piston from Automation direct, 1" stroke. It pushes directly down on a 3/8" steel standoff between the two sideplates of the module, and is not connected in any other way. The module was spring return default to traction mode by a spring (not shown) attached to the small tab you can see behind the omni. Pop the spring off and pull a single bolt and you could pull the module out. Any questions about it just let me know. -Aren |
Re: pic: Duodec-Drive (Octocanum)
The CAD for the module has been available for download on http://www.teamneutrino.org/seasons/...bot/butterfly/. You can see how the module works pretty well from it.
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I had only ever viewed butterfly & octocanum drives as a curiosity, but now I'll have to reconsider! |
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Re: pic: Duodec-Drive (Octocanum)
I would recommend pivoting on the traction wheel unless you have some serious side support. (See Aren's image where the module is snug between the channel.) We had a lot of problems on the 2010 148 drive with this. Your traction wheels will stay put, but the modules will flex sideways under sideloads. We used chains and had issues with them coming off. May not be such a big deal with belts, though.
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Re: pic: Duodec-Drive (Octocanum)
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The main reason I chose to pivot on the omni wheel was to keep the CIM hard mounted, rather than swinging with the module (single stage of gearing to the omni wheel). -Aren |
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