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Robot Inspection and Build Rules - Electrical - Answer Thread

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  • #61
    NXT Cable Extension

    Originally posted by FTC7342
    Can we extend the black wire that connects the legacy module to tetrix motor controllers?


    A: NXT cables beyond the .9m length are not recommended by either Modern Robotics or LEGO. The I2C signaling done over the wires is not reliable at longer lengths.

    Comment


    • #62
      IR Remote for LEDs on Robot

      Originally posted by FTC8477
      Can we mount these lights and the remote to the robot and turn the lights on with it's remote control prior to the match starting? Meaning we will not touch the light's remote during the match and it will stay mounted on the robot.

      http://www.eachbuyer.com/croled-5m-5...EGYaAt8U8P8HAQ

      Thanks,

      Linda


      A: No. The LED's alone would be legal, but the controller module is not allowed per <RE06>.d. Additionally, <T4> prohibits all forms of wireless communication with the robot other than Wi-Fi Direct

      Comment


      • #63
        Pixy Camera Module?

        Originally posted by FTC7593
        -it communicates via I2C
        -it can be powered via USB
        see http://www.cmucam.org/projects/cmucam5/wiki for description
        (I will have to check whether it can be powered within the power limits permitted).
        While it does have an on-board microprocessor, so does the NavX; neither can be programmed while it is in the robot.
        Thanks!
        Martin Haeberli
        Mentor, FTC 7593, TigerBots


        A: No. Sensors may only be powered by the Core Device Interface or the Core Legacy Module (per <RE05> and <RE06>)

        Comment


        • #64
          Mirror

          Originally posted by FTC6832
          Rule RE06.a is about light emitted from the robot. It says mirrors cannot be used to direct that light. We want to confirm that directing incoming light IS allowed. As an example - a periscope for the cameras on the phone would be allowed.
          A: Yes, it is legal to use a mirror to redirect incoming light.

          Comment


          • #65
            Pixy Camera Module?

            Originally posted by FTC7593
            Thanks for the earlier reply related to the Pixy.
            Assuming:
            a) it is the sole device on a DIM;
            b) it draws less than the 150ma DIM maximum current;
            c) it is in this context only an I2C device
            Would the Pixy be a permitted sensor?
            See also http://www.cmucam.org/projects/cmucam5
            Thanks,
            Martin Haeberli
            Mentor, FTC 7593, TigerBots
            A: Assuming all the above can be done without violating any other rules, yes, the Pixy would be a legal sensor

            Comment


            • #66
              Originally posted by FTC4029
              Hi,

              Is it legal to power multiple servos off two common power wires (like when using a servo Y-cable), but using two separate signal cables to control each servo individually? There seems to be no rules explicitly disallowing this, assuming we use the proper gauge of wire, keep in mind the current capabilities of the controller and wiring, and power/control the setup from the servo controller only.

              Thanks!
              FTC 4029


              A: Yes. <RE05>.g allows for custom made servo control wiring.Care should be taken to ensure good wiring practices (wire gauge and proper insulation)

              Comment


              • #67
                Using a switch to short motor control wires?

                Originally posted by FTC5628
                Our team has intermittent problems with "back-drive" on our motors used for hanging on the cliff. In the future we'll use worm gears, but for now we have to deal with the back-drive issue. One method that one of the team found during his research was "motor braking" where the terminals of a motor, when shorted together, would cause a motor to stop back-driving (mostly). This led to two designs and questions:

                1 - Once the robot was hanging, the driver would press the controller button that would cause a servo to short the two motor wires together. The servo has a cleverly designed servo horn that will make/break electrical connections. After refinement of the design and with an eye toward potentially saving our fuses, the servo would first break the connection to the motor controller then short the motor wires together. Our read of the rules, particularly <RE02> and <RE05> still left us wondering if this is legal?

                2 - If the answer to #1 is "yes it is legal" - would using a DPDT switch (activated by the servo) also be legal? I would feel much better using a switch than the previous approach.


                A: No. For safety reasons, motors may only be controlled by motor controllers.

                Comment


                • #68
                  Voltmeter On Robot

                  Originally posted by FTC7330
                  We have a follow-up question to the question asked by FTC3620 and replied to in post #2 in "Robot Inspection and Build Rules - Electrical - Answer Thread".

                  The question was "Would a digital volt meter be allowed on the robot?".

                  Our follow-up question:

                  Would a volt meter be allowed if it can only be activated by holding down a button and the button would never be activated in a competition? Such a configuration in our thinking would serve no purpose other than being extra weight during a competition, but would allow us to check the battery between competitions without removing it. Another justification would be electronics that are not connected to electricity aren't really electronics (maybe a broad ruling such as this would be useful for other teams).

                  Thanks,
                  Team 7330


                  A: No. All parts on the robot must be legal, regardless of usage within any given match.

                  Comment


                  • #69
                    Robot Inspection and Build Rules - Electrical - Answer Thread

                    Hello,

                    We have some vex 2-wire 269 motors. We were wondering if we could use those or do we have to use the 2-wire 393 motors?

                    Comment


                    • #70
                      Other Vex 2-wire Motors

                      Originally posted by FTC5116
                      We have some old vex 2-wire 269 motors. Can we use these motors instead of the 393 motors?


                      A: No. The Vex 269 motor is not allowed.

                      Comment


                      • #71
                        Max Number of Servos when Servos not Used

                        Originally posted by FTC5501
                        With this years game we need to switch the side some mechanisms are on depending on which alliance we are on. If we have more than the max number of servos on our robot but only the max number are plugged in and active is this legal? When we don't use a certain mechanism we unplug the servo and plug the other servo in.


                        A: No. The servo limit applies to all servos on the robot, regardless of their status/use. Servos that are not currently in use still count against the limit.

                        Comment


                        • #72
                          Definition of Servo Manufacturer

                          Originally posted by FTC9791
                          Hello,

                          Ruling #33 and its followup #41 are somewhat unclear, and seem rather backwards when interpreted in the strict sense. They appear to extend the limitations of modifications on servos specified in <RE02> to the sellers, not just the manufacturers. Therefore, is the onus on the teams to ensure that their servo vendor has not made modifications (i.e. contact the seller if the listing is unclear), or is it simply that a servo which is advertised as modified post-manufacturing is illegal? In addition, what exactly is the definition of a seller versus a manufacturer? Our interpretation was that a manufacturer is any entity that took components that do not qualify as a servo, and then modified or machined those components into something that does qualify as a servo. Under <RE02>, the team cannot be the entity that is the manufacturer. However, a custom-servo manufacturer could be the entity. This seems to be a bit backwards, as a team could order a custom servo to circumvent any <RE02> rule, while being forbidden from customizing servos themselves.

                          Thank you,
                          9791


                          A: A servo manufacturer is the one that creates the servo initially. Any modifications made to a servo post-manufacturer are not allowed.

                          Comment


                          • #73
                            Custom LED Controller Allowed?

                            Originally posted by FTC8862
                            Robot electronics answer #62 comes very close to answering my question, but it asks about a COTS decorative light controller. Would a custom-built controller circuit for LED lights be considered part of the "light source," or would a custom-built controller circuit also be considered "other electronics?"

                            Sorry to press the point, and thank you for clarifying

                            Matt


                            A: A custom built controller would fall under <RE06>.d and not be allowed.

                            Comment


                            • #74
                              LED's in parallel with Motors or Servos

                              Originally posted by FTC7842
                              May we wire an LED and appropriate resistor in parallel with servos or motors? The are passive components and would be powered through the core power distribution module.


                              A: No. The described connection would not be allowed. The LED as describe is NOT powered by the Core Power Distribution Module (it is powered by a motor or servo controller)

                              Comment


                              • #75
                                Yet Another Servo Clarification

                                Originally posted by FTC9791
                                Under ruling #72 that reiterated the previous stance on servo manufacturers, is the following action legal?
                                A student affiliated with the team, acting independently from the team, takes a power window motor (or similar) which in its current state is classified as a motor, and then designs and builds controller circuitry that turns the motor into something that uses feedback and is compatible with the servo controller - a servo, according to the best definitions we can find online or in the game manual. The student then gives the newly-manufactured servo to the team.

                                If this action is not legal, what rules prevent it and why?

                                Thank you,
                                9791


                                A: No. This is an assembly of parts that are individually not allowed. The student does not qualify as a servo manufacturer. <RE04> constrains motors. <RE06>.d constrains all other electronics

                                Comment

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