If im going for 8 wheels at all, and 4 of them are omni wheels, that are placed in each corner, and my question is, which 4 wheels should i use in the middle of the robot to get smooth turns?
You probably want two traction wheels, like the ones in the kit of parts, Colson wheels, or use custom tread wheels. With outer omnis you don’t need a drop center either.
Mecanum for smooth as butter turns, otherwise i would use colsons
Don’t use mecanum wheels on a tank drive. It’s a bad idea.
However, colsons are a good suggestion. Other options are AndyMark HiGrip, Vex VersaWheels, AndyMark performance wheels, and more.
Most of the time it’s still suggested to run a very slight drop center (1/16" maybe? Someone else should chime in with a number) because you can’t be sure the field will always be perfectly flat.
Will concur on mecanum equals bad. The mecanum wheels will slow you down and you’ll lose traction.
I moved this topic from control system to technical.
Literally just anything other than more omnis and mecanum.
Yep, this is correct. We ran a 1/8" drop center with corner omnis this year.
Depends, though. If you’re driving on a field with a lot of protected zones (2017 and 2018 come to mind), the reduction in turning scrub can mean more agility and lower current draw.
But I wouldn’t do that for a game like 2019 that has nowhere to hide, since that does come with the very high risk of being…escorted around the field.
3/32" served us very well in 8wd WCD with 6" VEX omnis on the corners and white KOP wheels on the inside.
Dude, if you have 8 omnis in tank, the t bones will be too brutal protected zones or not. That’s literally asking for defense.
Dude, 3310 would like a word with you. You can tell what they’re running (all-omni 4WD) from the picture, but they also show a clear shot of the underside in their season video when it’s on the rope.
While I hate to play “how many wins ya got”, it’s hard to call something invalid after that kind of season.
but but but… I guess I’ve got some matches to watch.
This very much breaks my intuition. All-omni tank seems like an excellent way to do some sick sideways drifting (useful in 2017) but also to get bowled over by defenders in T-bone action.
Then again, we ran mechanum in 2017, and did fine really till 16 pulled some awesome defense on us at Midwest.
Agreed that if you’re going 8 wheels then 4 Center Colsons, corner omnis and a slight drop center works well. For this year’s game, even 4 traction wheels in center is worth consideration, gives you higher ability to push or resist being pushed.
All-omni tank allows you to get out of t-bone situations much easier, since you don’t have the sideways traction of the wheels working against you when trying to break away.
Watch a few of 67’s matches.
Well I may not have done a great job of saying so, my opinion is that under medium defense the driveing will be bullied a lot not that it’s impossible to drive.
I’m glad you have proof to prove me wrong, but I don’t appreciate you flat out saying that I thought the wheel configuration was “invaild”. To me, it’s just not my first choice.
We used 8WD corner omni, with colsons, vex traction, and WCP pneumatic wheels in the center. Depending on how much grip, suspension, or slide you want when traversing the field you pick your characteristic based on what you want. We wanted to slide around defenders more so we went with colsons for 2019. When using the super grippy wheels, if you get tboned the right way using a tall robot the wheels work against you and you get knocked over since your wheels grab the carpet so well. Colsons prevent that a bit in that they allow more sliding for those big hits but enough traction in the forward direction to push others around or hold your ground when needed for scoring. We kept a set of pneumatic wheels for when we wanted to go up ramps but ended up not even needing them, the colsons were sufficient.
Is that 4W omni or a H drive? Hard to tell, but it looks like they might have that 5th wheel since I see some sideways action in some cases. If so then this is a hybrid!
If you’re looking for a cheaper/andymarkier solution than a colson, check out their smoothgrip wheels. We used the 60A 6" smoothgrips this year, and they’re definitely an improvement from HiGrips, if only for their superior wear pattern. We had no trouble shoving around teams on Daly, and only had to replace them once in our four competitions.
Nope no 5th wheel. Just 4 omni’s in tank powered by 6 mini cim’s. The sideways action was our driver just being ridiculously good at manipulating that robot to drift and make some crazy counter defense moves. The reason that drive train did so well was because our driver, he is seriously something amazing to watch. Sad to see him graduate in a month.