Drawbridge Technique: Legal or not?

Basically, my question is, is this strategy legal? The rules say the robot must “starts free of contact with the DEFENSE and completely in the NEUTRAL ZONE”, which in this case is true. The robot loses contact with the drawbridge, and since the drawbridge extends to the neutral zone, it is completely in the neutral zone. However, is this passing “clear” enough? As the rule later states “If it is unclear whether a ROBOT has satisfied the requirements for
CROSSING or REACHING a DEFENSE, the REFEREES are instructed
to not award credit”.

Q&A was asked a similar question.

The long and the short of it is, you need to make it CLEAR to the refs who may or may not be looking anywhere near your robot that you broke contact with the drawbridge. Similar to how a lot of HPs last year put one hand up or behind their back when operating the chute door–saves a lot of “Did he or didn’t he?” on the refs’ part, which saving works in teams’ favor.

Interesting. Using an opaque manipulator would make it more obvious, but is it obvious enough?

Great observation!
Personally, I like to play it safe. The rule states that the judges can’t award points if there is a feasible argument against awarding the points. I think that the best thing to do would be to build a robot that can cross the drawbridge without using this exploit, so that you can avoid breaking the rules. And considering the number of points that it’s worth to damage a defense, I don’t think that rule-challenging is worth it.

Of course I agree, having a real manipulator would be optimal, but sometimes it is simply not feasible to tackle all the problems a game throws at you in one bot. Using this strategy to clear the drawbridge would enable a team to focus their time on other mechanisms that can do other things.

Another benefit is that this method can easily be the fastest method to breach the drawbridge. Most mechanisms that opens the drawbridge from the neutral zone would require the robot to drive back and forth at some point due to the 15" extension rule vs. Drawbridge height. Instead of opening the drawbridge the whole way with a mechanism and driving back and forth, this method only take up the time to “tap” the Drawbridge.

Here’s my thoughts on it (with my ref hat–NOT my judge hat, this isn’t their job–on):

As seen in the video, if I saw it happen, the robot would meet the definition of Crossing, assuming it were in the Neutral Zone completely when it broke contact.

However, there are 5 other robots on the field that could get in the way of seeing it or command attention for something else–say, applying a hit on somebody ELSE while they’re trying to cross a Defense. So that’s a bit of an “If”.

Your best chance to get credit is to alert the refs during practice matches that “hey, we like to use this method to Cross the Group C Defenses, can you check it?” Trust me, as a ref, we LOVE it when teams ask us whether they’re doing something per the rules during practice, because if they aren’t, they can correct it, and if they’re borderline (like some of the faster HPs last year) we get a chance to see what we need to be watching for and help the team adjust to get the result they want.

So basically, it is probably legal but risky, as far as the rules are currently written. To me it seems worth the risk, it is a very easy method of clearing it…

Thanks for the great discussion so far everyone :slight_smile:

Looks fine to me. Its clearly legal. It may be a good idea to alert the ref before hand though as others have said.

Some ideas I thought of were

A. Double tap the bridge creating a few bounces.
B. light up your robot or something that will catch the refs attention when this happens.
C. Talking to the refs

This may be much trickier to do/prove under defense though

When we tried that method we certainly wondered if it would be considered legal but fully expecting that for it to count it must be obvious to the ref or scorer that contact was broken.

I think it would be the quickest way to breach the draw bridge. Do another defense on your way to score a boulder and on the way back do a quick double breach.

This was also discussed last week here:
http://www.chiefdelphi.com/forums/showthread.php?t=141560&highlight=drawbridge

Based on the Q&A feedback, most CD posters agreed that it is indeed legal

Do you have to clear the drawbridge for a certain period of time before touching it again?

There is no set time period. However, due to the definition of Crossing (and the fact that the Crossings are scored by humans), you’ll need to clearly not be touching in order to get credit.

Fixed it for you.

Just wondering if anyone has built the team version draw bridge, what springs did you use? The ones we have (Home Depot screen door 16") aren’t strong enough to shut the bridge after it goes down.

Also, What if one robot drives through and holds a defense open for another robot(s), sort of like tag-team wrestling? How could this not be legit? Robots working together to accomplish goals seem to be in the spirit of FIRST.

We use water-filled 1-gallon orange juice jugs attached via rope to the drawbridge through a pulley. It takes slightly more force to lower it, but it has generally worked for us.

Please remember the only answer that matters is what comes from the GDC. Threads on CD cannot be used to debate any ruling on the field.

Generally true. Yet I’ve seen Eric post elsewhere that he does ref, and I’ve also seen the Q&A rule that demonstration to a ref before a match is definitely helpful in convincing the refs of something that may not be obvious. I think a specific Q&A for this year surrounding this issue would allow this scenario to play out.

Yet I think the bigger issue is whether or not the refs missed it. There are plenty of opportunities to not see something because attention-requiring action is happening elsewhere on the field. As a Week 1 referee myself, I fully expect to have to worry about this particular strategy as well. Regardless of Q&A, I would much rather a team tell me to look for something specific than to be left guessing.