Plaction Roughtop Tread on carpet

Technical Technical Discussion
#1

For our robot this year, we are planning on using the Plaction 8" roughtop tread wheels. The tread design will provide good traction on the carpet.

The concerns we have are:
Utilizing tank drive, when turning, will the tread get caught in the carpet?
Will turning put too much stress on the CIM motors?

Thanks so much for your advice!::safety::

#2

Describe the drive layout you are planning to use. The more info the better.:slight_smile:

#3

More specifically, how many wheels you have on the ground, how many of them are powered, are any of them “dropped”, and “wide” configuration vs. “narrow” configuration are good items to include when asking a question like this.

#4

We are using a tank drive system with 4 wheels on the ground. One CIM motor powering each side. Narrow configuration.

I apologize for being so broad, and I appreciate the guidance!::safety::

#5

The layout you described will likely have major problems when turning.

There is a good white paper on this topic: http://www.chiefdelphi.com/media/papers/1443

Things that you can do to improve your turning ability:

  • Put the wheels closer together (front to back)
  • Add middle wheel(s) and lower them slightly to shorten your effective wheelbase
  • Replace one pair of wheels with lower friction wheels
#6

Our team is planning on using plaction wheels up front and omnis in the rear to provide a good turning circle and good traction. We are using good old fashioned tank drive.

#7

We’ve used a similar design (IFI High Traction instead of Plaction) for years with excellent results. In our early days we used 4-wheel skid steering as you initially described, and went through batteries in just under 2 minutes. :ahh:

#8

Hi 3132 here

We have 2 plaction wheels in the center for drive and 2 plastic wheels on each end (front and back). We are also using 4 CIMs to give us the torque we need for those plactions to turn

#9

a cheaper solution is to buy 8" RC wheels, cut the tread off, slice them up, and zip-tie them to a KOP wheel, we did something similar for our shooter last year

#10

We are currently using a 3/32 drop on the 4 center wheels of an 8 wheel west coast drive and turning is fine.

#11

How far apart are your two center wheels?

#12

Expect high currents in the CIMs and possible low battery voltage at the end of the match. Please try the robot on carpet before you make a final decision. If you don’t have a practice field take the robot into the library, theater or any place with a lot of carpet and practice turning.

#13

All 4 wheels on each side are 9.60 inches apart from each other, using 8" wheels, with the 2 centers dropped.

#14

I can say that the 2 omnis/2traction 4WD tank steering is actually really nice. We ran it in 08 and it handled perfectly and was super simple.
Although, we had about 75% of our weight on the traction wheels, where more likely teams this year will be fairly evenly spread out.

#15

Were you using dual omnis wheels with offset rollers, or just single omnis?

#16

Are the same 4 wheels the traction wheels in all driving situations? :slight_smile:

#17

I’m a fan of the 2 traction / 2 omni offset myself. You know,

T — O
| |
| |
O — T

2 traction 2 omni makes it fairly easy to have your robot spun by an opponent, which is why I personally prefer a high traction drop center (no omni) drive in most “normal” FRC applications. Powered omnis do work more than fine, though. This year isn’t very normal.