Originally Posted by BBray_T1296 (Post 1394597)

You should be careful with worm gears in your drivetrain. If you slam into a wall (or other robot) at full speed, there could be a tremendous axial force applied directly to your worms.
Also you may be unable to push the robot around in your shop/etc

Originally Posted by Andrew Schreiber (Post 1394586)

Not really. Having the traction wheels on the outside makes you more stable when they are down. You are less likely to be spun (longer moment) and, have a bigger contact patch to keep your CG inside and prevent tipping. You don't need to worry about either of these with omni wheels due to them being slippy by design. (It's real hard to tip an omni bot due to them just sliding away and their habit of preserving their inertia, and spinning them is almost always easier no matter their contact patch)


Basically, there's design benefits to having your traction wheels on the outside. I can't come up with any obvious ones to having your omnis on the outside.

Originally Posted by wilsonmw04 (Post 1394619)

Come by our pits sometime. My kids would like to show you the advantages of a small traction wheelbase octocanum.

Originally Posted by Andrew Schreiber (Post 1394586)

Basically, there's design benefits to having your traction wheels on the outside. I can't come up with any obvious ones to having your omnis on the outside.

Originally Posted by wilsonmw04 (Post 1394619)

Come by our pits sometime. My kids would like to show you the advantages of a small traction wheelbase octocanum.

Originally Posted by Abhishek R (Post 1394571)

Wow. This is really cool. Do you have any video of it in action?

Originally Posted by HumblePie (Post 1394651)

Hope this works.........

http://youtu.be/arKL5XCXGfU?list=UUZ...8THLwUgtdjtgdg

Originally Posted by HumblePie (Post 1394651)

Hope this works.........

http://youtu.be/arKL5XCXGfU?list=UUZ...8THLwUgtdjtgdg


You may notice a lot of "power slide" maneuvering with the 4 omnis. What you probably won't notice is much audio, and yes it was on. The team decided to go with 4 omnis rather than 2+2 omni/traction, which would have made the driving dynamics very different. The 4 omnis did make it much easier to place the robot on the field (by pushing it sideways) since the gearboxes were hard to backdrive, at least early on. The chassis has since been converted to 2+2 for demo events, and the chassis can be maneuvered in any direction now that the gearboxes are broken in.

Originally Posted by wilsonmw04 (Post 1394690)

Looks nice. Have you tested it on carpet? One thing I noticed is that it is so quiet!

Originally Posted by Abhishek R (Post 1394624)

Both have their advantages and disadvantages. It really depends on your end goal. Putting the traction wheels in the center gives you more turning ability with more control over where the robot ends up (no drift due to omni wheels). You would probably be using the omni's to escape a t-bone or something like that.

On the flip side, putting the traction wheels on the outside means you are primarily using the omni's most of the time. I believe this is what most teams who use butterfly do, because of the reasons Andrew Schreiber said - you have a longer wheelbase for stability when you're pushing or being pushed, and are less likely to be spun around.

Originally Posted by Electronica1 (Post 1394803)

When your traction wheel and omni wheel are this close together, wouldn't it make more sense to put packaging of the system over the traction wheel base?