FRC 2010 Team Update #5

[Alex Cormier]

http://www.usfirst.org/roboticsprogr...nt.aspx?id=450

Some interesting updates and fixes.

[Racer26]

Daww, i cant pick up an E-stopped robot to earn ELEVATED or SUSPENDED points for it? GDC, you're no fun.

[Chris is me]

Red card for "inappropriate use of the E-stop"? Wow, that will be fun to argue with refs about. There's a software problem and it can't drive, so we e-stop, but it's not obvious, so we get a red card?

[Vikesrock]

Originally Posted by Chris is me

Red card for "inappropriate use of the E-stop"? Wow, that will be fun to argue with refs about. There's a software problem and it can't drive, so we e-stop, but it's not obvious, so we get a red card?

Under the changes in the rules, the robot not being able to drive is not an appropriate use of the E-Stop as it is not a safety issue.

[Karthik]

The changes to <S03> and <G27> have eliminated some fun strategies. However, these changes do make sense considering it's called an "Emergency Stop".

[jgannon]

Originally Posted by Karthik

The changes to <S03> and <G27> have eliminated some fun strategies. However, these changes do make sense considering it's called an "Emergency Stop".

Can you elaborate? I'm having trouble envisioning any strategic benefit to e-stopping your robot that couldn't be achieved through the control system.

That aside, I'm pretty strongly opposed to the changes to <S03> and <G27>. I have e-stopped our robot in the past when there wasn't an impending safety issue. Once, the battery in our Chicklet ran low, causing it to send out random commands, and causing the robot to start chewing itself up. In retrospect, unplugging all the controls would have had the same effect, but we couldn't make that diagnosis during the match, and it was a lot quicker to just disable the robot. In another case, the robot took a major impact, a 6-gauge wire came loose, and we lost power. Hitting the e-stop deactivated the hurricane light over our driver station, giving the other alliance a signal that they didn't need to run into us any more. These are not safety issues, but I feel that we're well within our rights to protect our robot as best we can when things go awry.

I fully agree with Chuck that a non-responsive robot is a potential safety issue, even if it isn't apparent to an outsider. Remember the 8.3V glitch from 2006? If you were watching the Operator Interface, you could tell that the robot was about to flip out. I believe that my drivers and I are the people most qualified to determine if our robot is potentially unsafe, and I really resent that now I'm going to hesitate before I e-stop, even if there's an absolute safety hazard, so I can think about whether the head ref will see it the same way I do. That's not safe.

If this rule stays on the books until the competition, I'll likely instruct my drivers to yank the Ethernet cable out of the Classmate in emergency situations, safety-related or not; no rule prohibits it, and I'm expecting that FMS would react as if you e-stopped. GDC, please reconsider.

[dodar]

I like the addition of being able to control a ball with a mechanism that goes above the bumper zone

[Don Wright]

Originally Posted by jgannon

Can you elaborate? I'm having trouble envisioning any strategic benefit to e-stopping your robot that couldn't be achieved through the control system.

Your opposing alliance can reliably get an 8 point hang from the center field position of the tower.

Before the 20 second final period starts, you drive your robot to the position they need to be in and you block the tower (even touching their tower) and press e-stop.

If they can't move you, you now stopped them from getting 8 points and because you are e-stopped, you can't get any penalties...

Well...not anymore...

[jgannon]

Originally Posted by Don Wright

Your opposing alliance can reliably get an 8 point hang from the center field position of the tower.

Before the 20 second final period starts, you drive your robot to the position they need to be in and you block the tower (even touching their tower) and press e-stop.

If they can't move you, you now stopped them from getting 8 points and because you are e-stopped, you can't get any penalties...

Well...not anymore...

Aha, that's kind of cute. Thanks for explaining. Nonetheless, I still see a lot of problems here:

I'm not convinced that this needed to be fixed. It's not the cleanest tactic, but it's clever and not a game-breaker.

I'm not convinced that it couldn't have been fixed without touching <S03>. Instead, further change <G27> to void the clause when it is being used as part of an intentional defensive strategy.

I'm not convinced that it's been fixed as-is. The same effect is still very achievable without violating <G34> and <G35>, particularly since the defender is protected by <G13>.

[Marc P.]

Originally Posted by Don Wright

Your opposing alliance can reliably get an 8 point hang from the center field position of the tower.

Before the 20 second final period starts, you drive your robot to the position they need to be in and you block the tower (even touching their tower) and press e-stop.

If they can't move you, you now stopped them from getting 8 points and because you are e-stopped, you can't get any penalties...

Well...not anymore...

I was thinking about this as well. Strategically, it makes sense to block the opposing tower to prevent the 8 point hang. Is it an "appropriate" use of the e-stop? I wouldn't think so.

What I do know is, if I spent 6 weeks designing/building/debugging/perfecting a creative hanging mechanism, I'd like the opportunity to show it off without some "box on wheels" skirting the intent of <G34> and <G35>. It's pretty clear from those rules the GDC intended for robots to be able to hang without interference.

I do agree the drive team members should be able to e-stop if they feel something isn't right with the robot. However, if I were a referee, I'd find it very suspicious if a robot conveniently "broke down" in front of an opposing tower every match, and I'd cite the "obviously intentional" part of <G34> and <G35>.

Of course, if there is a clear or obvious mechanical or electrical failure, like popped chains, smoke billowing out, or a battery that came loose, there's no question of intent. I'd sincerely hope no one intentionally causes anything like that for a cheap strategic advantage.

[jgannon]

Originally Posted by Marc P.

However, if I were a referee, I'd find it very suspicious if a robot conveniently "broke down" in front of an opposing tower every match, and I'd cite the "obviously intentional" part of <G34> and <G35>.

Being in front of an opponent's tower has always been legal, and that strategy doesn't become more effective by e-stopping. As far as I can tell, all this outlaws is making contact with the tower before the FINALE and then hitting the e-stop to remain there until the end of the game without penalty. I don't think that's enough of a game-breaking play to make this broad of a change. That's a matter of opinion, though, in which case I'd argue that you can eliminate this particular strategy with better language in <G27> while leaving <S03> alone.

[Brandon Holley]

I think what the GDC is getting at is the e-stop should not be a part of any team's strategy or plan for a match. It should be there simply in the event that should things start getting out of hand, teams can shut down their robots...thats all.

-Brando

[Vikesrock]

The blocking move is far more effective if you stick part of your robot into the tunnel. It is very likely that the only way to dislodge you in that situation would be a tunnel bot from the opposing alliance coming from the other side of the tunnel.

As you are touching the tower, E-stopping would have been the only way to prevent a penalty in this scenario.

[Chris is me]

Why can't one just limit the E-stop red card to intentionally doing an action that would gain you a penalty otherwise? This also reinforces the "you can't e-stop in the opponent's zone" ruling. That way any driver doesn't have to go "hmm, will the ref see the wayward movement of my robot as "broken" or not? oh wait, the arm just failed because I hesitated to see if I'd be disqualified rather than immediately hitting the button to keep safe"

[JesseK]

Originally Posted by Karthik

The changes to <S03> and <G27> have eliminated some fun strategies. However, these changes do make sense considering it's called an "Emergency Stop".

It's posts like these that are the reasons that the GDC must be so strict with their intent