[FTC]: Can I add non-slip material to 4" Tetrix Wheels?
 

Rookie Coach alert!

We had our robot on a ramp for the first time tonight and the traction of our rear-wheel gear drive 4" Tetrix wheels is not what we are wanting. We wanted to use 4" Hi-Grip AndyMark wheels but we ran into difficulties mounting them in a satisfactory way so we went to the Tetrix wheels. Now we are having to rethink.

Reading various forums, it sounds like teams attach (glue?) strips of non-skid to their wheels. I know sheet materials are legal (and several non-skid sheet materials have been posed and approved in the rules forum) and glue/adhesives are legal... but how does increasing the diameter of the 4" wheel come into play and aren't we modifying a standard part by doing something like this?

I'm posting here before I ask in the rules forum because: (a) I'm a total FTC novice and I'm not even sure I'm asking the questions correctly, and (b) I get great answers fast here on Chief Delphi! :)

THANKS!

Re: [FTC]: Can I add non-slip material to 4" Tetrix Wheels?
 

R5
o. Wheels of any type up to 4” diameter. Wheels that have exposed features likely to cause damage to field and/or game elements are not allowed.

Emphasis mine. My opinion, in addition, is the non-slip makes the wheel larger than 4".

Re: [FTC]: Can I add non-slip material to 4" Tetrix Wheels?
 

As long as you add the padding and did not purchase it pre-attached, it should be OK (we do something similar with special Lego tires on the 4 inch wheels). For an official answer post on the official FTC forums.

Re: [FTC]: Can I add non-slip material to 4" Tetrix Wheels?
 

Jacob, I believe your team was asked to return the wheels to stock for this very reason, they were too big.

Re: [FTC]: Can I add non-slip material to 4" Tetrix Wheels?
 

I had my coach post on the official forums for a ruling.

Re: [FTC]: Can I add non-slip material to 4" Tetrix Wheels?
 

The 4" limit only applies to purchased non-Tetrix/Matrix/Lego wheels. Teams can modify or build wheels to be > 4" as desired, subject to the allowed materials, field damage, and 18" size constraints. There are several official forum post dealing with this issue and it might be a good idea to have printouts handy as the above posts make it sound like some teams have been wrongly failed at their tech inspection.

All that said, if you have a quick way to make your robot 4 wheel drive (chains or gears?) you will likely get HUGE improvements in traction and drivability.

Re: [FTC]: Can I add non-slip material to 4" Tetrix Wheels?
 

And an official answer...
http://ftcforum.usfirst.org/showthre...ull=1#post9028

Re: [FTC]: Can I add non-slip material to 4" Tetrix Wheels?
 

I think another team from our school had this happen. For whatever reason, we were not called on it.

Re: [FTC]: Can I add non-slip material to 4" Tetrix Wheels?
 

I have asked for a better explanation. The revised rules and the inspection checklist still imply 4" as a maximum. So there is at this point some confusion.

Re: [FTC]: Can I add non-slip material to 4" Tetrix Wheels?
 

Al,
We asked about this in post #71 on the official forum.

http://ftcforum.usfirst.org/showthre...ull=1#post7778

The answer was "A: Yes, you may modify a legal COTS wheel with a custom tread and make it larger than 4" diameter."

Re: [FTC]: Can I add non-slip material to 4" Tetrix Wheels?
 

We qualified for our regionals! We are in shock.

We definitely need to improve our drive system. We are too slow and we have unpredictable traction around and on the Ramp. Should we go for driving all four wheels? Do we need to go for four motors or is two motors on a chain/gear drive enough?

How do you analyze this sort of question?

Re: [FTC]: Can I add non-slip material to 4" Tetrix Wheels?
 

In my experience working with the ten Eagan Robotics FTC teams this year, either of the setups you mentioned would be just fine, especially considering your main problem is "unpredictable traction"-- the main solution for which is making sure your wheels have the same or similar traction and are getting the same or similar power from your motors.

If I were you, I would ask the question of which fits into your existing robot with the least amount of work.

That being said, under nearly any normal circumstances, a 4-motor drive will beat out a 2-motor drive in terms of pushing power. If your only goal is behaving predictably around the ramp and you have a better use for two DC motors, by all means a 2-motor chain drive should behave just fine.

Unfortunately I'm not at our workspace right now, but I'd be happy to get you pictures of our various drive setups if you'd like.

On another note, good job qualifying for (I presume) your super-regional tournament, and good luck when you get there!

EDIT: You can also check out some of the pictures in the FTC link in my signature for photos, but most of them don't focus on the drive trains.

Re: [FTC]: Can I add non-slip material to 4" Tetrix Wheels?
 

Congratulations!

Without knowing all the details of your robot, I think the best advice I can give is to experiment and find what works. We had a very successful 2 motor, 6 wheel drive bot two years ago. It was slow but our design was such that we didn't need much speed. That said, if we hadn't spent our allotment of motors elsewhere, we definitely would have added them to the drive train.

Again, congratulations on your advancement!

Re: [FTC]: Can I add non-slip material to 4" Tetrix Wheels?
 

Having a good drive base is really where every robot needs to start. TOO many times does our team see rookies with only two wheels motorized, usually direct driving them. Direct driving the wheels is really bad on the motors. Ypu really need to either gear or chain drive every wheel you have.

To give you an idea on a good drivebase, we use 6 wheels, all geared together, using the medium 80tooth gears on the motors, and the 120 tooth gears on the tires. Reason being for 6 wheels, one falls off, you can STILL drive. Not stuck. Along with all the wheels being geared, we run to motors per side of the robot, wired into the same motor port. 2 Motors left, 2 motors right. Alot of pushing power as well! Any robot that tries to play defence against us, just gets pushed out of the way. If you want to see our bot in action, look on youtube, Valley X Robotics, or here, www.valleyx2844.com <--- pictures of it on the website.

Re: [FTC]: Can I add non-slip material to 4" Tetrix Wheels?
 

We currently have two 40:80 gear driven 4" AM Hi-Grip wheels with two dual omni wheels on the other end. It works but...

Thinking through Saturdays events, it became obvious a lot of our weaknesses are traceable to inadequate traction, being too slow, and not being able to smoothly and reliably transition over the ramp edges.

I think having four driven wheels would be a big step to better.

We only own one motor controller so that is what we started with. Later I was able to borrow a motor controller for our lift motor and flag motor. For regionals I think I can borrow another motor controller.

We are definitely going to undertake a major whale dive into drive systems during the off season.