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  • Robot Electronics and Power - Answer Thread

    You'll find answers to the questions you have asked about Robot Electronics and Power in this Thread.

  • #2
    Heartbeat ok?

    Originally posted by FTC6124
    Is it OK for a robot to toggle a "heartbeat" servo, LED, or similar mechanism prior to the start of Autonomous and during the pause between Autonomous and Teleop for the sole purpose of providing a visual indication that the robot is operating as expected and waiting for the start signal from the FCS, or is such a mechanism in violation of RS08 and thus prohibited?
    A: No, this is not legal.

    Comment


    • #3
      Modified Servos

      Originally posted by FTC7440
      <R08> h.(i) Any combination of the following servos is allowed per servo controller: 180 Degree HiTEC HS-475HB and HS-485HB, Continuous Rotation W39177 and HiTEC HSR-1425CR, hobby servos "standard" size and smaller (i.e. standard, mini, micro) with rated stall current of 800mA or less.

      <R08> h.(ii) Quarter-scale HiTEC HS-755HB and HiTEC 785HB servos may be used.

      <R08> w. Motors, sensors, controllers, and any other electrical components may not be altered from their original state in ANY way unless specifically allowed by the Robot rules.


      TETRIX/Pitsco sourced servos automatically comply with the above by <R02>. Servos purchased from other vendors, ServoCity being one such vendor, have options which can be selected during purchase which may be considered factory modifications by the GDC. ServoCity default stocked product is 90deg rotation and modifications are made in their manufacturing facility for other options.

      Q1) Does HS-485HB with 180deg option from ServoCity comply with <R08> w.
      https://www.servocity.com/html/hs-485hb_servo.html

      Q2) Does HS-422 with continuous rotation option from ServoCity comply with both <R08> h.(1) and <R08> w. (note stall current is 520mA)
      https://www.servocity.com/html/hs-422_super_sport_.html

      Q3) Does HS-485HB with continuous rotation option from ServoCity comply with both <R08> h.(1) and <R08> w.
      https://www.servocity.com/html/hs-485hb_servo.html

      Q4) Does HS-755HB with 180deg or continuous rotation option from ServoCity comply with <R08> w.
      https://www.servocity.com/html/hs-755hb_1_4_scale.html

      Thanks!


      A: Any modification of a servo from its original manufacturer supplied state makes the servo illegal for the purposes of building an FTC Robot (<R08>.w), this includes any modification performed by the team or any other third-party, including retailers/resellers.

      Comment


      • #4
        Crimp Wire Ferrules

        Originally posted by FTC3781
        Two (hopefully) quick questions to get the season started :-) .


        Q. We're interested in using stand-offs other than the ones sold by Pitsco/Tetrix. Can we consider a threaded stand off to be really long nut and therefore legal under <R05.k>?

        Q. We'd like to use crimp wire ferrules to protect and manage wire connections. We believe these are legal under <R08.q>. Can you confirm?


        John Pflueger
        Lead Mentor - Westlake FTC - 3781, 5628, 6504, 6710
        A1: Yes, stand-offs are considered fasteners and are legal per rule <R05.k>
        A2: Yes, crimp wire ferrules are legal per rule <R08.q>
        Last edited by Administrator; 09-27-2013, 12:01 PM.

        Comment


        • #5
          Tin-Lead Solder

          Originally posted by FTC6424
          <RG03>c.: “The following types of mechanisms and components are not allowed: [...] Those that contain hazardous materials(e.g. mercury switches, or lead substrates).”

          Does this mean that all solder used must be lead-free? Or is soldering an exception to this rule? (None of the circuitry we have was soldered with lead-free solder.)
          A: FIRST does not prohibit the use of tin-lead solder but we highly recommend that teams use a lead-free solder where possible.

          Comment


          • #6
            Slip Rings

            Originally posted by FTC6424
            [<R08>r. states that "Non-NXT power, motor control, servo, and encoder wires and their connectors may be extended, custom made,
            or COTS subject to the following [...]."

            Given that slip-rings are commonly classified as connectors, would they be legal for use on a robot? In other words, would COTS or custom-made slip-rings be legal? (This would be assuming they were properly insulated, and of the correct AWG.)

            A: Commercially available Slip Rings are a COTS and are not allowed. Custom made slip rings are not allowed per rule <R08.v>

            Comment


            • #7
              Custom Video Camera?

              Originally posted by FTC6424
              <R08>y. states: “Video recording devices (GoPro or similar) are allowed providing they are used only for non-functional post match entertainment. Cameras must not have built-in wireless capability.”
              Q: Would a custom-made video recording device be allowed, as long as it did not have wireless capability? For example, would a camera sensor hooked up to a microprocessor, which in turn recorded video onto an SD card be legal? Would it be legal to have a separate power supply for this assembly?
              If not, would the fact that this does not affect match outcome allow the assembly under the rules for decorations?


              A: A custom video camera falls outside the intent of allowing simple video cameras to be placed within robots. The camera should be a commercially available camera with a simple means to verify the absence of wireless communication. It should be powered only by the manufacturer provided battery.

              Comment


              • #8
                Power Switch in Decorative LEDs?

                Originally posted by FTC6424
                <R08>e.: “Exactly one (1) power switch that turns the robot on or off per Battery Pack. The power switch MUST be installed between the battery and all electronics that it powers. [...]”
                Q: Since purely decorative LEDs may be powered by a separate 9V battery, does that battery need to have a power switch? Or would it not count as a battery pack at all?


                A: yes, a single power switch for turning on/off the LEDs (manually before/after matches) may be used. This switch should be visually distinct from the TETRIX power switch to ensure that field personnel are able to readily identify the main power switch for the robot.

                Comment


                • #9
                  Non-TETRIX Power Switch?

                  Originally posted by FTC7440
                  Hi,
                  <RG08> e. Exactly one (1) power switch that turns the robot on or off per Battery Pack. The power switch MUST be installed between the battery and all electronics that it powers. Matrix Battery Pack Power Switches must be placed side by side on the robot.

                  Q: Are alternative appropriately rated switches permitted or are we constrained to TETRIX and MATRIX supplied parts?
                  Thanks!


                  A: All robot power switches MUST be manufacturer provided (i.e. TETRIX switches for TETRIX robots & MATRIX switches for MATRIX robots). No other switches may be used. Field personnel MUST be able to quickly visually identify the robot power switch to be able to turn off robots on the field if it becomes necessary.

                  Comment


                  • #10
                    Custom Power Distribution?

                    Originally posted by FTC7440
                    Hi,
                    <R08> q. Anderson PowerPole, and similar crimp or quick connect style connectors for joining electrical wires are allowed. Power distribution splitters may also be used (and are strongly recommended) to make wiring easier. All connectors/distribution splitters should be appropriately insulated.

                    May a team construct their own power distribution system by using connectors soldered to a circuit board? As noted in <R08> q. appropriate insulation should be used.
                    Thanks!


                    A: There is nothing in the rules that prohibits this. Care/caution needs to be used when constructing the distribution system. Particular attention should be paid to wire gauges. See <R08>.o for wire gauges per connection type.

                    Comment


                    • #11
                      Custom Cable for NXT Sensors?

                      Originally posted by FTC7440
                      Hi,
                      Can an NXT sensor connected to a Prototype Board use a custom cable?
                      We understand NXT sensors connected to an NXT or sensor multiplexor must use only LEGO certified cables.
                      Thanks!


                      A: No. The cable should be a standard NXT cable. Custom NXT cabling is not allowed per <R08>.o

                      Comment


                      • #12
                        HiTechnic Controllers connected to Sensor Prototype Board?

                        Originally posted by FTC7440
                        Hi,
                        <R08> n. i. All power used in the circuits connected to the Prototype Board must be derived from the power connections provided within the board. No batteries or external power sources are allowed.

                        Does a HiTechnic motor or servo controller count as a "circuit" or "controller"? I.e. can we send I2C signals from a Prototype Board to a motor "controller" which is in turn powered by the main robot battery.
                        Thanks!


                        A: No. Connecting a HiTechnic motor or servo controller to a sensor prototype board is beyond the intention of allowing the development of custom sensors. Control of motors or servos other than via motor/servo controllers connected via daisy-chain to an NXT is NOT allowed.

                        Comment


                        • #13
                          Violation of Sensor Prototype Board Current Limits

                          Originally posted by FTC7440
                          Hi,
                          The HiTechnic Prototype Boards have specified maximum current outputs for the various supply rails available for external circuits. If higher than the specified maximum current is drawn does this violate any FTC game rules?
                          Thanks!


                          A: Violating the maximum current draw for the prototype boards risks damaging the NXT and/or causing unexpected behavior, including the possibility of loss of control of the robot. Intentionally designing a circuit that violates the limits would fall under one or more of <S1> and <G18>.

                          Comment


                          • #14
                            Interconnection of Sensor Prototype Boards

                            Originally posted by FTC7440
                            Q: If a robot uses more than 1 HiTechnic Prototype Board each with attached circuits only powered by the respective Prototype Board is it permitted to communicate between these attached circuits using the following mediums
                            a.) direct electrical connection
                            b.) optical
                            c.) magnetically coupled
                            Thanks!


                            A: There is nothing in the rules that prohibits interconnection of multiple Sensor Prototype Boards, as long as no other rules are violated.

                            Comment


                            • #15
                              Capacitors to Store Energy?

                              Originally posted by FTC7440
                              <RG10> Energy used by FIRST Tech Challenge Robots, (i.e., stored at the start of a MATCH), shall come only from the following sources:
                              a. Electrical energy derived from the onboard TETRIX or MATRIX battery pack, HiTechnic 9-volt Battery Box for the sensor multiplexer, MATRIX Battery Box for powering the Samantha unit (MATRIX robots only), the battery for the visible LEDs, and the NXT battery.

                              Circuits and sensors connected to the HiTechnic Prototyping Board may contain capacitors on supply rails which will become charged when the NXT controller is powered on before match start. Does this stored energy comply with the <RG10> restrictions.
                              Thanks!


                              A: No. Use of capacitors to store charge for generation of higher than normal currents and/or voltages would be a violation of <S1>.

                              Comment

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