Can wheels extend past the frame?

[toastnbacon]

Our team is using casters in the back corners. Is it leagal if we turn and the casters turn past the frame perimeter?

[waialua359]

Our team is using casters in the back corners. Is it leagal if we turn and the casters turn past the frame perimeter?

edit.

[toastnbacon]

Under very unusual circumstances, but normally no. Our frame is only 26" wide, though.

[EricH]

If the casters go beyond the FRAME PERIMETER as defined in Section 8.2 of the Manual, then no, it is not legal. It is not one of the exceptions listed in <G30>.

FRAME PERIMETER – the polygon defined by the outer-most set of exterior vertices on the ROBOT (without the BUMPERS attached) that are within the BUMPER ZONE. To determine the FRAME PERIMETER, wrap a piece of string around the ROBOT at the level of the BUMPER ZONE - the string describes this polygon. Note: to permit a simplified definition of the FRAME PERIMETER and encourage a tight, robust connection between the BUMPERS and the FRAME PERIMETER, minor protrusions such as bolt heads, fastener ends, rivets, etc are excluded from the determination of the FRAME PERIMETER.

<G30> ROBOT Volume – During a MATCH, no part of the ROBOT shall extend outside the vertical projection of the FRAME PERIMETER, except as follows: [list of exceptions]

If the GDC isn't allowing bolt heads to extend past the FRAME PERIMETER, except in one very specific case, then I doubt that they'd allow a caster to do the same.

Now, if your lower frame is smaller than your upper frame, and the caster goes beyond that, but not beyond the FRAME PERIMETER, then you'd be OK.

[IndySam]

No they can't.


Please take it as friendly advice from someone who has used them before. I will never ever ever use casters on a FIRST robot again.

[Chris is me]

Use ball casters and your problem goes away completely. If you're going to use casters, use ball casters; swivel casters are such a hassle anyway.

[Rich Kressly]

Agreed on all fronts...
Your situation is definitely illegal for 2010. Swivel casters on an FRC robot can lead to a lot of headache and heartache anyway. When I was with 103 we had a propensity to use them and had some negative results. They have since gone with ball casters on a few robots with MUCH better results. McMaster sells them for sure, but you might want to consult the teams that have used them to help with your selections.

[qwertyuiop[]\]

dont even bother with casters. just use omniwheels if u can obtain them. they are even less of a hassle

[toastnbacon]

Thanks! We think we managed to fix the problem by simply moving the casters further inside the frame. Is it legal if they don't pass the frame Perimeter?

[Akash Rastogi]

Thanks! We think we managed to fix the problem by simply moving the casters further inside the frame. Is it legal if they don't pass the frame Perimeter?

As advised before, switch to ball casters instead if you can't purchase some Omni wheels.

[GaryVoshol]

Thanks! We think we managed to fix the problem by simply moving the casters further inside the frame. Is it legal if they don't pass the frame Perimeter?

It's legal. Now read from some of the other posts here whether it's advisable or not.

[toastnbacon]

Yah, We thought about omni wheals, but we figured it would be to easy to push us around. I also proposed the ball casters to the team, but everyone thought the swivel casters would be fine. Could someone put the cons on here?

[Chris is me]

Omni wheels and casters should be equally easy to be pushed by. What resistance to pushing would casters give you?

[EricH]

More to the point, Chris, is "what resistance to normal motion do swivel casters give you?" I've heard the horror stories of teams using them, only to have their robot go a little crazy when a caster didn't act like it should have.

I've also seen teams use ball casters with some success; most teams opt for omni wheels of some form instead of casters as you can get a little bit more forward "oomph" from omnis.

Short and sweet: swivel casters won't give you any less resistance to being pushed around; in fact, they might be the ones doing the pushing. Ball casters are better about not pushing you around. Omnis give you a little bit more forward/aft push (though not much).

[Edoc'sil]

The big thing is a caster bot cant go straight to save its worthless life. The one place you cannot cut corners on in you bot is in your drivetrain. Fork over the cash for omnies. IMHO if it was legal a peg leg would be better then a caster.

[EricH]

IMHO if it was legal a peg leg would be better then a caster.I don't see any rules preventing peg legs. They just can't have metal feet.;) OK, and they might cost too much...

[Daniel_LaFleur]

Yah, We thought about omni wheals, but we figured it would be to easy to push us around. I also proposed the ball casters to the team, but everyone thought the swivel casters would be fine. Could someone put the cons on here?

Swivel casters give the worst of all scenarios. They give no traction (for pushing or resisting being pushed), and will (guaranteed) be facing in the wrong direction and cause your robot to not drive straight when starting to move. They do allow for fairly easy rotation of the robot. Cannot be powered. Swivel casters without suspension tend to get "shopping cart syndrome".

Ball casters also provide no traction,but do not interfere with the robot going in a straight line. They allow for much easier turning of the robot (easier than swivel casters). Cannot be powered.

Omnis provide traction (if powered) in one direction but not in the perpendicular direction. They allow for fairly easy rotation. They are expensive compared to casters.

Hope this helps.

[toastnbacon]

Thanks, this has all been a big help. Everyone else on my team still doesn't believe any of it, but I'm hoping when we drive around, they'll come to their senses.