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Robot Inspection and Build Rules - Mechanical - Answer Thread

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  • Robot Inspection and Build Rules - Mechanical - Answer Thread

    Is there any margin for error on the robot sizing box dimensions. For instance, if the box being used at a competition for official inspection is found to be slightly smaller than 18", is it still to be used as an official sizing box? What if the size difference is what keeps a team's robot from passing inspection? How are teams to handle this?



    • Ratchet

      Originally posted by FTC8471
      Our team was wondering if we could use ratches ( the actual tool) as part of the building material. They would be used to move a robot extension into place and then lock it there.

      Thank you
      A: Yes, a ratchet is a legal COTS part.


      • Launching of Grappling Hook

        Originally posted by FTC1501PRC
        Hello ftc,

        I'm asking about the two rules RG10 and RG11 in the game manual and whether the following scenario is allowed.

        The rules in question are these:
        <RG10> Energy used by FIRST Tech Challenge Robots, (i.e., stored at the start of a Match), shall come only from the following sources:
        • Electrical energy derived from approved batteries.
        • A change in the position of the Robot center of gravity.
        • Storage achieved by deformation of Robot parts. Teams must be very careful when incorporating spring-like mechanisms or other items to store energy on their Robot by means of part or material deformation.
        <RG11> Game elements launched by Robots should not have a velocity greater than that required to reach a maximum of 1.5 meters (5 feet) above the lowest point of the Robot, nor travel a horizontal distance greater than 3 meters (10 feet) from the point that the game element ends contact with the Robot. Parts of the Robot itself may not be launched.

        The scenario in question is:
        An object such as a grappling hook, being launched within the set velocity limits, using a spring mechanism to store energy. The grappling hook is also very safe and connected to the robot, thereby not violating <G13> Robots Deliberately Detaching Parts. The last sentence of RG11 "Parts of the Robot itself may not be launched." needs clarification because how it is worded right now, it is to prevent the violation of G13. Therefore, we think that a grappling hook attached to the robot with a thick rope does not violate G13 and RG11.

        Thank you.
        A: Launching a grappling hook, even if connected by a rope or cable, is not allowed.


        • Roller Chain with Tread

          Originally posted by FTC4443
          Is this an Approved COTS part? We know all chains are legal, the pads are riveted on so are they considered part of the chain?, and we know that aggressive tracks/wheels must pass the test.

          Thanks in advance!
          A: The roller chain with tread is a legal COTS provided it passes the tile damage test.


          • Cam Cleat

            Originally posted by FTC10138
            We're looking at using an COTS cam cleat on our ropes used to hang as a safety item (in case of the dreaded emergency stop with loss of communication). These could be 3D printed as well, but I'd prefer a commercial product in this case due to the safety aspect. These are used to bind ropes in one direction, most frequently used in boating.

            Typical example:
            A: Yes, this is a legal COTS.


            • Sizing Box

              Originally posted by FTC5414
              Is there any margin for error on the robot sizing box dimensions. For instance, if the box being used at a competition for official inspection is found to be slightly smaller than 18", is it still to be used as an official sizing box? What if the size difference is what keeps a team's robot from passing inspection? How are teams to handle this?

              A: The intent of the robot construction rules is for the robot to be no larger than an 18” cube. The sizing box is a tool for enforcing the size rule. If a team believes the sizing box is incorrect then they should talk with the lead inspector and respectfully challenge the sizing box as being small. The lead inspector can make the appropriate judgement call to pass or not pass the robot based on their assessment of the quality of the sizing box. Teams should be aware of the dangers of designing to the very limits of robot size.


              • Dumbbells

                Originally posted by FTC9919
                After reading the rules in the game manual and the guidance on forums, we believe that dumbbells would be legal. At our first qualifier, it was suggested by officials that while their interpretation allowed them, to be safe we should ask in the official forum. Our team is planning to use weights similar to Neoprene Body Sculpting Hand Weights by Crown Sporting Goods that are readily available on Amazon and local sports stores. Please can we get clarification on this?
                Sincerely, FTC9919.
                A: Yes, dumbbells are legal COTS parts.


                • Worm Gear

                  Originally posted by FTC10780
                  We are a new team this year and are still trying to get up to speed on the ins and outs of the rules.

                  We are thinking of using a TETRIX Max Worm Gear Box on the robot. We are not sure if this is legal or not.
                  The TETRIX Max Worm Gear Box utilizes a 4:1 gear ratio for slow and smooth rotational motion

                  A: Rule <RM01.c> allows the use of single degree of freedom COTS gear boxes, which includes a worm gear box.


                  • Adding parts to Robot and Re-inspection

                    Originally posted by FTC8045
                    We have a static part which is completely legal. Sometimes we place this on our robot and sometimes we give it to our alliance partners.

                    The part does not extend the robot beyond the 18" limit, and has no electrical or moving parts. Our robot passes inspection with it attached.

                    The question came up at our last match if we should have our partners re-inspected when we place this part on their robot. If we add a minor bolt or tetrix part, to their (or our) robot it seems obvious that no re-inspection is necessary. On the other hand, giving our partners a complete complicated assembly would seem to require a re-inspection.

                    Can you give us any guidance to help clarify what is deemed necessary for a robot to be re-inspected for our refs/inspectors at our next tournament?
                    A: If a team adds parts to the robot that changes or enhances performance (vs. just a fastener) that robot must be re-inspected prior to being allowed to play in their next match. Teams that are planning to modify their bot between matches should be aware that Robot Inspectors typically have other duties once matches begin so getting a bot re-inspected may take some time.


                    • Spray Adhesive on Tread

                      Originally posted by FTC6938
                      To give the drive train more traction, is spray adhesive allowed on the treads provided it is not being left behind on the field?

                      FTC 6938 - Team RPG
                      A: No, teams are not allowed to spray adhesive on their treads, wheels, etc. There is too much of a chance of field contamination.


                      • Coban Wrap

                        Originally posted by FTC8690
                        We would like an official ruling on being able to wrap our wheels in Coban wrap.


                        and if it is legal, would we be able to rewrap between matches, if need be?
                        A: Coban wrap is a legal COTS material and may be used to wrap the wheels. Remember that these wrapped wheels are still subject to the same field damage requirements as any other wheel and tread system.


                        • Low Friction Tape

                          Originally posted by FTC0359
                          According to <RM01-D> and numerous Q&A responses, high-traction tape on wheels is not allowed. For further clarity issues, we would like to leave no room for misunderstanding and ask if tape to reduce friction (we use Gaffer's) would be allowed on our robot's wheels to reduce traction.
                          A: Yes, wrapping wheels with a tape that will not result in field damage is allowed. The properties of gaffers tape with regard to field damage is not well known so teams using this may be required to prove to the Inspectors that the robot will not damage the tiles.


                          • Scopes

                            Originally posted by FTC10138
                            I know from <G4> that any alignment device needs to be permanently attached to the robot and in compliance with the build rules. Would one or both of the following inexpensive scopes be permitted? While they are COTS, I'm not sure if the zero, elevation and windage adjustments would violate the 1-DOF requirement (and the red-dot scope has an internal battery to power it's light source). They also include mounts. Please note these are NOT laser sights, just scopes.

                            1. Optical Scope, e.g.,
                            2. Red-Dot Scope e.g.,
                            A1: The Optical scope has three adjustments that allow motion in three directions essentially providing three degrees of freedom. There fore the scope is not a legal COTS part.

                            A2: Since the scope is a functional, not decorative, device it must be powered by the main battery. The internal battery is illegal.


                            • Sponsor Logos

                              Originally posted by FTC9915
                              We would like to acknowledge our major sponsors by displaying their logos or names on our robot. We've seen this done on some robots, but are unsure what FIRST guidelines are. Are there explicit guidelines for display of logos or sponsor names on robots? (We would expect the logos/names to be relatively small, much, much smaller than team numbers, for example.)
                              A: Sponsors are very important to maintaining and growing FTC and we encourage teams to place their sponsor logos on their robots.


                              • Rope Lock Tiedown

                                Originally posted by FTC7026
                                Is a rope lock tie down, as seen below, legal/approved for this season?

                                A: This appears to be a simple, single DOF device and as such is a legal COTS part.