Chief Delphi - Ball deflectors.....don't

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Re: Ball deflectors.....don't

To me, from the matches I watched, it seems like the problem really is teams don't try to ballance soon enough, and that they don't use bridge pushers build for "the rigor of the game." This seems less like a failure of FIRST, but rather a failure of teams to design durrable and functional mechanisims. Not that I think our team's will be any beter, though.

Re: Ball deflectors.....don't

I saw a bridge balance not count because balls were under the bridge and were supporting it...

Re: Ball deflectors.....don't

Quote:

Originally Posted by JackS (Post 1138397)

I saw a bridge balance not count because balls were under the bridge and were supporting it...

Really? Did the teams put the balls there, or even somewhat allow them to go there? If not it should have counted.

Re: Ball deflectors.....don't

Quote:

Originally Posted by Billfred (Post 1137975)

Well, that's a new development... (Okay, so there were two coaches in 2001...but it's practically new.)

Can any of the other Week 1 events confirm this change?

Alamo did not have this change as far as I am aware and I was an inspector on the field for a lot of the competition.

Re: Ball deflectors.....don't

We were not allowed a fifth member at Kettering. Instead we tried to use crowd members to tilt a sign we had (we have four signs - 3, 3, 2, 2.) if a ball was stuck under a bridge (which confused our driver the very first match.)

However when we moved on the second day, even us in the crowd couldn't see the bridge from the other side.

Re: Ball deflectors.....don't

Whether it's part of the design challenge or not, it's frustrating.

It's possible for the balls to get pinched between the polycarb 'deflector', and the field boarder on the alliance color bridge. Even with our ball pickup device, designed to lift the bridge and suck balls out, we couldn't clear them when they got like that. It's rare, but they're just plain stuck, and in a manner I don't think anyone expected.

Balls trapped under the bridge decided many matches. It's a bummer, and short of a change to the deflector that FIRST is likely unwilling to make, it's going to be a common one.

Re: Ball deflectors.....don't

Quote:

Originally Posted by Gary Dillard (Post 1137969)

Head ref announced new rule today: teams are allowed to have a fifth team member on the side of the field giving hand signals so they can tell if there is a ball there, or anything else they want to signal apparently. Interesting.

How did you find this out? Was there any particular regional that this was announced at?

Re: Ball deflectors.....don't

Quote:

Originally Posted by Andy A. (Post 1138642)

Whether it's part of the design challenge or not, it's frustrating...

Balls trapped under the bridge decided many matches. It's a bummer, and short of a change to the deflector that FIRST is likely unwilling to make, it's going to be a common one.

It's water under the bridge at this point [pun intended] but having
just losing in the semis in Hatboro-Horsham due to this issue,
I have to agree. If you look at the original bride video here:

http://www.youtube.com/watch?v=-AMaq...eature=related

the big difference between the video and the actual field was the polycarb sheet sagged badly. It not even close to a flat sheet as shown in the
video and was ineffective in having balls roll back out.

It would be an egregious violation of the rules and gracious professionalism,
but an effective strategy would be for inbounders to 'accidentally'
send balls under an opponents bridge...

Re: Ball deflectors.....don't

Quote:

Originally Posted by slijin (Post 1138687)

How did you find this out? Was there any particular regional that this was announced at?

The head referee at Smoky Mountains came to our team and the team next to us in the pits first thing Friday morning and asked to speak with the drive teams; he specifically told us we were allowed to have a fifth person that did not count toward our 4 on the drive team that could stand on the side of the court and give hand signals. I assume he did the same to all the teams there.

Re: Ball deflectors.....don't

Quote:

Originally Posted by Gary Dillard (Post 1138753)

Interesting. Thanks for the info; I wonder if refs at later regionals will also allow it, considering forum consensus seems to be that this wasn't allowed at Kettering or Alamo.

Re: Ball deflectors.....don't

Quote:

Originally Posted by slijin (Post 1138843)

Interesting. Thanks for the info; I wonder if refs at later regionals will also allow it, considering forum consensus seems to be that this wasn't allowed at Kettering or Alamo.

Nor at Gull Lake.

Re: Ball deflectors.....don't

That's frankly quite bizarre. It would seem that the head ref overstepped his boundaries, and changed the rules quite dramatically. I hope that they had a chat with FIRST before this rule change.

Re: Ball deflectors.....don't

Quote:

Originally Posted by Nuttyman54 (Post 1137516)

**With the exception of 118's hanger mechanism, pending legality rulings. It's worth noting that 179 can hang from the bridge without climbing on it, but someone needs to get on it first for them to be able to balance by hanging, thus they would require the assistance of another robot (and another robot requires theirs).[/size]

Quote:

Originally Posted by Justin Ridley (Post 1137900)

As we posted yesterday in the Alamo thread, the GDC made a decision regarding our bridge balancing mechanism. We wanted to provide a little more of the details that were provided to us. A picture of us using this mechanism to balance the co-op bridge with 488 was posted in the Alamo thread. This was a very exciting moment and the Robonauts are proud of achieving this on Thursday of our first regional.

The head ref at Alamo approached our team prior to opening ceremonies on Friday. He told us that a telecon was held last night amongst the GDC and they determined our robot’s mechanism fell under their definition of the word “grapple” when interacting with the bridge. It would therefore be a violation of [G10] when used, and be penalized accordingly. We were told it was not the GDC’s intention that teams utilize the features at the edge of the bridge to hang or lift off of during a balance.

During a break in matches at the beginning of the day, the head ref explained this ruling to the crowd. During this he read the following definition for Grapple: “The use of a tool to catch, hold, or rake to gain a physical/mechanical advantage”.

In our conversations with the head ref he expanded on this definition, talking about devices which react against multiple surfaces to create a moment or torque.

We understand that we took a risk in this design. Nonetheless, we are disappointed in the ruling the GDC has made. Even more, we are disappointed that the risk we took was created only because FIRST refused to answer direct Q&A questions related to it. Answering the following question could have clarified this situation very simply and early in the build season. At the time, it was our honest belief that if FIRST intended for this to be illegal, they would have stated so here.

located here.

Re: Ball deflectors.....don't

Quote:

Originally Posted by Gary Dillard (Post 1138753)

As I understand it, this is not an official FIRST rule change, but within the discretion of the local Head Ref. The ruling essentially said that teams could have someone outside the court perimeter (past the curtains) making hand signals to indicate a ball under the bridge. This person could be anyone and was NOT an official drive team member.

Essentially, the teams were being allowed to formalize an otherwise unofficial signaling system which has always been available.

Dr. Bob

Chairman's Award is not about building the robot. Every team builds a robot.

Re: Ball deflectors.....don't

Quote:

Originally Posted by Gary Dillard (Post 1138753)

At GSR we were told that we could have the Safety Captain handle the robot cart, and stand on the sidelines with the carts. We were not told that he/she could give hand signals, though I suppose you could.

The 'solution' is for drivers to recognize how a bridge behaves when a ball is trapped in a place they can't see. If it's not working, stop trying to drop the bridge and figure out a way to either tip it up to clear the ball or pursue something else.

It is possible for a robot to get on the bridge from the other side and 'crush' the ball enough in most cases for a second robot to get on the bridge on the ball side. It depends on where the ball is under the bridge and how much of a lip the robot can climb over.