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  • Table size in tournaments

    Hello all,

    My team recently participated in a scrimmage, where they had provided two tables for the competition. I noticed that the width of both the tables were almost 93 1/2 inches compared to the 93 +/-1/8" as specified in the Table Build Guide (https://www.firstinspires.org/sites/...able-build.pdf). There were huge gaps between the East and West sides and the mat. A few of my team's missions failed. Lesson learned.

    I voiced my observations to the organizer, but since it was a scrimmage, not much as done.

    Are the table dimensions more strictly enforced in the actual qualifier Tournaments?

    First time coach here.

    Thanks
    Last edited by csmileyk; 10-18-2018, 07:01 PM.

  • #2
    In my experience, you should not assume that the tables at the tournaments will be exact in their dimensional tolerances.

    FIRST LEGO League Mentor and Referee/Head Referee since 2011.

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    • #3
      Originally posted by Tom Mosher View Post
      In my experience, you should not assume that the tables at the tournaments will be exact in their dimensional tolerances.
      My understanding is you can be sure that the "south" edge of the mat will be flushed against the wall. The "east" and "west" mat will have the same gap with the "east" and "west" walls. The "north" wall will have all the "gaps" in the other direction of the mat.

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      • #4
        Originally posted by ws1088 View Post

        My understanding is you can be sure that the "south" edge of the mat will be flushed against the wall. The "east" and "west" mat will have the same gap with the "east" and "west" walls. The "north" wall will have all the "gaps" in the other direction of the mat.
        I agree with regard to the orientation of the mat within the table.

        Teams would be wise to be prepared for the exact dimensions of the table to have more variance than is specified in the table construction document. I've refereed matches on tables where the mat was fractionally larger than the table, so there were notable ripples. And I've refereed matches with half-inch gaps between the mat and the east, west, and north walls.

        So my advice is "be prepared".
        Last edited by Tom Mosher; 10-18-2018, 07:47 PM.
        FIRST LEGO League Mentor and Referee/Head Referee since 2011.

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        • #5
          Originally posted by Tom Mosher View Post

          I agree with regard to the orientation of the mat within the table.

          Teams would be wise to be prepared for the exact dimensions of the table to have more variance than is specified in the table construction document. I've refereed matches on tables where the mat was fractionally larger than the table, so there were notable ripples. And I've refereed matches with half-inch gaps between the mat and the east/west walls.

          So my advice is "be prepared".
          Thanks for your advice. Question: would the practice tables be similar to the actual competition table in venue usually?

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          • #6
            Originally posted by ws1088 View Post

            Thanks for your advice. Question: would the practice tables be similar to the actual competition table in venue usually?
            Generally similar, yes, in that you shouldn't trust any of them.

            At least at tournaments where I'm involved in the event setup, I'll select the tables that are in the best condition for the competition area, the next-best for the Robot Design table, and the worst tables for Practice.
            FIRST LEGO League Mentor and Referee/Head Referee since 2011.

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            • #7
              I'm generally more concerned with selecting tables for competition that have a smooth flat surface, and walls that aren't splintered or warped. I have never measured the table dimensions as part of selecting the tables.
              FIRST LEGO League Mentor and Referee/Head Referee since 2011.

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              • #8
                Note that none of this table variation is a bad thing. Teams who design robots that can accommodate variation will be more successful at the robot game, because there are much bigger sources of variation than the size of the table. Competition area lighting, ripples in the mat, the fresh texture on competition mats that haven't been used for months of practice, the exact placement of the dual lock that holds the mission models to the mat, changes in the robot's mechanical performance after being transported to the event, these are all sources of variation.

                No matter what size the tables are, they'll be the same for every team at the tournament.
                FIRST LEGO League Mentor and Referee/Head Referee since 2011.

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                • #9
                  Also, do not assume the mats themselves are the exact same size. One season, when I had access to two mats, I observed that one mat was about 1/2 inch longer than the other mat.

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                  • #10
                    Originally posted by timdavid View Post
                    Also, do not assume the mats themselves are the exact same size. One season, when I had access to two mats, I observed that one mat was about 1/2 inch longer than the other mat.
                    This season, we have a couple of mats, they are not cut exactly the same and are different lengths E-W. We have been to state championships where the south wall had almost 1 inch warp. The robot squared to the wall and then drove north, at the north wall, it was almost 2 inches off due to the warp. This all falls under normal Robot Game Rules, GP4 Variability.
                    FLL coach Trash Trek on, State 5x, World 3x, ref, judge advisor.

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                    • #11
                      Table creation and storage can be pretty big burdens on partners and tournament directors. Yes, to all the statements above. Expect variances, esp tables larger than spec. Most plywood these days (in US) is sold oversized, and if you just attach walls without any measuring/trimming - yes - you get gaps east/west/north.

                      As tables age, warping is also not uncommon.

                      So if your region is hurting for tables, see what you can do. Fundraising, offer to build new, offer to store in better conditions, etc. All contribute to having a better tournament experience.

                      A West wall gap is something that at first will look detrimental to teams when they first encounter it. But there are some straightforward solutions to it if you give the team a chance to brainstorm it out. Seeing this in a scrimmage match is perfect timing. North wall gaps can be harder, but it looks this year for IO, all northerly models are based on mat position, not wall position.

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                      • #12
                        Touch sensors are a great solution to an ill-defined wall location.
                        FIRST LEGO League Mentor and Referee/Head Referee since 2011.

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                        • #13
                          The other thing to point out is that many competitions have more than one table - which also have variance from each other. So being able to tolerate the variance is pretty critical to successful runs. We sometimes intentionally practice with different table skews. I find that leveling is one of the most challenging to deal with because it leads to drift in seemingly straight routes.

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                          • #14
                            I've heard of screw heads sticking out of the wood, screwing the wall-follower robots. The mat is often not aligned to the south wall (as per regs). Warped tables screw up wall-followers. Tilted tables mess with the gyro. I've seen the mat curled up on competition tables.

                            Assume nothing, make your robot/programming as robust as you can, and hope for the best. Sometimes bad luck hits the best teams. The most important thing is for the kids to learn and have fun.

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