Too much traction

[DarkFlame145]

We have run into a little snag. Turing can be really hard for our bot due to the fact we are using 4 IFI Traction wheels with a 4X4 set up. We can turn, but we got to be also moving backwards or forwards. It has been really bugging me cause I'm one of the drivers of the bot. I would love to put Omni wheels on the front, but the bot is already shipped. I was wondering is anyone else had any suggestions. The fix has to be able to be done at regionals during our tuning time. Any suggestions would be very helpful.

Here is a pic of your chassis if this will help at all:

[MiniNerd24]

Sounds like you're having the same problem we had last year. Later you'll find the traction will be totally lost (after competition though so don't worry), anyway You could either drive with a lot of jerking forward and quick switching into a turn or you could probably modify the wheels with those omni-wheels or the smooth rubber tires that come in the kit (with the shifters and those rubber wheels strafing in high gears was A-M-A-M-A-Z-I-N-G!!!)
Hope this helps.

[deshirider430]

put zip ties on either the front 2 wheels or the back 2 wheels

[JoshD]

We ran into this problem. If your going to do omni wheels, put them in the front and DON'T power them, trust me. Or, we found this out by breaking a chain, if power two wheels on the right side and one on the left side, just power the right more and it turns real nice.

[lukevanoort]

If adding omnis isn't possible, just reduce the distance between the drive wheels so the wheelbase is significantly wider than it is long. Some casters may be necessary to add to the robot for balance. Actually, if you had casters on the front and rear with drive wheels in the middle, you might (depending on drive wheel squishiness) be able to raise/lower the casters a few mm to reduce the normal force on your drive wheels. Another option might be switching to lower traction tread on a pair of wheels. McMaster-Carr has a wide variety of conveyor belt materials, I'm sure you can find a lower traction one that can be adapted to your wheels (like the PVC or Nitrile Incline conveyor belting). In my opinion, your best bet is to move the front wheel back to a couple of holes after where the idler currently is, and then move the other wheel a few more holes back to get a centered drive system with a width of 1.5*length. Casters at the ends would restore balance.

[Dan Petrovic]

I believe you can still order omni wheels and bring them in to the competition, as they are COTS.

[DarkFlame145]

Thank you everyone, like i said any ideas will be helpful

Originally Posted by lukevanoort

If adding omnis isn't possible, just reduce the distance between the drive wheels so the wheelbase is significantly wider than it is long. Some casters may be necessary to add to the robot for balance. Actually, if you had casters on the front and rear with drive wheels in the middle, you might (depending on drive wheel squishiness) be able to raise/lower the casters a few mm to reduce the normal force on your drive wheels. Another option might be switching to lower traction tread on a pair of wheels. McMaster-Carr has a wide variety of conveyor belt materials, I'm sure you can find a lower traction one that can be adapted to your wheels (like the PVC or Nitrile Incline conveyor belting). In my opinion, your best bet is to move the front wheel back to a couple of holes after where the ideler currently is, and then move the other wheel a few more holes back to get a centered drive system with a width of 1.5*length. Casters at the ends would restore balance.

We already do have ball casters on the back. I think we moved the back wheels further back so maybe if we move it forward again it will help out.

Originally Posted by InfernoX14

I believe you can still order omni wheels and bring them in to the competition, as they are COTS.

I hope so, my mentors arn't too concerned, so I'm wondering if they have a fix. I'm just trying to gather some fixes so if they dont have any we arn't trying to fix it off the top of our heads.

[Brian C]

Adding Omni Wheels will definitely help with your maneuverability. This years game is not so much about pushing and shoving as it is about being able to move around easily.

If you can put omni wheels on I would suggest you put them on the REAR not the front. The reason for this is to allow you to make turns very easily and quickly. This will allow you to literally turn on the pivot of one front wheel.

Think: Forklift units in your local home store. The front wheels are the drive wheels and the rear wheels allow it to maneuver easily around obstacles.

If omni wheels are not an option I would suggest you change out the rear wheels with the kit of parts wheels. These have less of a surface area in contact with the carpet along with a lower CoF and should allow you to makes turns easier.

Good Luck!

[ChuckDickerson]

Maybe try flipping the wedgetop/roughtop tread around such that the "back" side is facing "out" and the wedgetop/roughtop is against the metal rim on one end (front or back)?

[bigbeezy]

I would say that omni's would your best bet. ideally, you could make it a 6 wheeled robot (they dont all have to be powered) with the center wheel slightly (about an 1/8" or so) lower that the other wheels. this will allow you to turn with relative ease. however, with weight and time being an issue this prolly wouldn't help, but just an idea.

[DarkFlame145]

We have the weight to spare, but this year we really wanna get in a lot of practice matches.

[Dan Petrovic]

Originally Posted by Brian C

If omni wheels are not an option I would suggest you change out the rear wheels with the kit of parts wheels. These have less of a surface area in contact with the carpet along with a lower CoF and should allow you to makes turns easier.

Too bad surface area doesn't affect traction

Are you going to a first week regional? If so, then I'm not sure about the rules on upgrade parts. I'm pretty sure omni wheels, in your case, would be considered upgrade parts. If you're going to a regional after the first week, then you are allowed to bring upgrade parts.

It's really lame how first week regionals can't bring in upgrade parts, but every other regional can. What's the reason for that?

[DarkFlame145]

Thankfully FLR is week 2.

[Vikesrock]

Originally Posted by InfernoX14

Too bad surface area doesn't affect traction

Are you going to a first week regional? If so, then I'm not sure about the rules on upgrade parts. I'm pretty sure omni wheels, in your case, would be considered upgrade parts. If you're going to a regional after the first week, then you are allowed to bring upgrade parts.

It's really lame how first week regionals can't bring in upgrade parts, but every other regional can. What's the reason for that?

You cannot fabricate upgrade parts during the first FIX-IT window. You may still bring unlimited COTS parts to any competition regardless of intended use. Omni wheels qualify as COTS parts and would be perfectly legal to bring.

[DarkFlame145]

what does COTS stand for =P