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Motors and Servos - Answer Thread

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  • Motors and Servos - Answer Thread

    Answers to questions posted pertaining to Motors and Servos.

  • #2
    RE15 - Servo Modification

    Originally posted by FTC8045
    Hi, we'd like to upgrade the karbonite gears in our sail winch quarter scale servos to metal gears. There is no direct replacement and slight modifications are necessary as described here. Is this modification/replacement allowed as described? Thank you
    A: Yes, teams may replace the gears in their servos with metal gears.


    • #3
      RE09- Changing motor gearboxes

      Originally posted by FTC11639
      The rules state that legal motors include the am-3102 motor (20:1 gearbox), the am-3103 motor (60:1 gearbox), and the am-3104 motor which is a motor with no gearbox. So, removing the gearbox and changing gear ratio is similar to using an am-3104 with a custom gearbox (hence, not modifying the motor). Is this gearbox modification legal?
      A: Yes, this is legal.


      • #4
        RE15 - Removing Encoder

        Originally posted by FTC9819
        Are we allowed to remove the encoder on the Andymark NeverRest Series? (AM-2964, AM-2964a, AM-3102, AM-3103, AM-3104)

        We just need to shorten the overall length.

        Thank you!
        A: Yes, teams may remove the encoder from the NeverRest motors.


        • #5
          RE09 - EV3 Motors and Sensors

          Originally posted by FTC12102
          Are the EV3 motors and sensors legal?
          A1: Only the motors listed in rule <RE09> are allowed. No other DC motors are allowed.

          A2: EV3 sensors are allowed provided they meet the restrictions listed in Rule <RE11>.
          Last edited by Broadway Joe; 10-26-2016, 02:17 PM.


          • #6
            RE16 - Continuous Rotation Modification

            Originally posted by FTC8688
            Are we able to modify a 90 or 180 degree servo to make it continuous rotation servo? Specifically the Hi-Tec Servo Model HS-485HB which list Specifications as 360 degree Modifiable.
            A: Because the modification involves changing or modifying the gears and does not involve the electronics or wiring this modification is allowed.


            • #7
              RG02 b - Initialization Routine Warning Label

              Originally posted by FTC8424
              Hi there! We just went through an inspection before our league meet and the inspector told us that we needed to have the servo movement stickers next to EACH servo that was on our robot, not just a single one to alert folks that the servos might move. In the past we only needed one and it's not exactly convenient for us to have a place to put those near every servo. Do we really need multiple stickers, or will one do for the entire robot?
              A: Rule <RG03b> requires just one warning label located near the Main Power switch.


              • #8
                Linear Actuators

                Originally posted by FTC5401
                Are we able to use these actuators on the robot?

                Zowaysoon 12V Electric Linear Actuator 100m/4inch Stroke 1500N DC Motor Linear Motion Controller with Limit Switch

                Stroke length:100mm(4inch)
                • Voltage: 12VDC** Noise Value: >65dB
                • Load/Thrust/Force Capacity:1500N =150kg(330Ib)
                • Speed:5.7mm/s
                • Duty Cycle: 25%** Protection class:IP54

                Answer: No. The above linear actuator is not an allowed DC motor nor an allowed servo and falls under the <RE17> Additional Electronics rule


                • #9
                  Linear Servos

                  Originally posted by FTC11255
                  Are linear servos allowed? There is no notion that they are, or are not. It is just the rotational ones that are allowed. Assuming the connection to the servo controller is the same, can a linear servo be used?

                  Answer: <RE10> does not constrain the nature of the output of a servo. For a servo to be legal, it must:
                  • be marketed/sold as a servo
                  • be electrically compatible with allowed Servo Controllers (6v and within the current limit for the controller)
                  • be controlled/powered by an allowed Servo Controller

                  Team using "unusual" servos should be prepared to support the legality of their servos by bringing documentation for the servo (specifications, etc)


                  • #10
                    Motors and Servos - Answer Thread

                    Originally posted by FTC7190
                    My team and I were wondering whether it is legal per rule RG01J to remove air from a funnel using a vacuum pump. We are not compressing or storing air and there are no pistons or valves involved in the design. The vacuum pump is from Amazon: We are not using the motor that comes with the pump. We are converting it to an AndyMark NeverRest motor. Inside the pump is a piece that spins. This pieces turns at an offset and makes the rubber part on the outside pump out the air from the funnel. There is only one degree of freedom in this design. Thanks so much!
                    A: We found out that it is a diaphragm pump. Our ruling is that as long as the outport port of the pump is not blocked or sent through a hose, the pump should not build up any pressure. If those constraints are followed, then this would be considered a legal part.


                    • #11
                      12v Linear Servo

                      Originally posted by FTC6433
                      Please clarify the legality of this Servo:

                      Assuming it is controllable from the MR Servo Controller Module and meets the specified power requirements, is it legal because of Rule RE 10 as it labeled as a servo, or is it illegal because it violates the COTS 1 DOF rule RM 02?

                      Answer: This servo is not allowed. This servo is not compatible with the allowed servo controllers. It requires a 12v power connection in addition to the standard servo control signals.


                      • #12
                        RE09 - Gearbox Removal

                        Originally posted by FTC8699
                        May we remove the gearbox on Tetrix or Neverest motors and just use the motor?
                        A: Yes, the motors may be used without the gearboxes.


                        • #13
                          RE10 - Linear Servos

                          Originally posted by FTC3491
                          We were hoping to confirm that the Actuonix (formerly Firgelli) L12-R and L16-R series linear servos are still legal for use.
                          A: Linear servos are legal provided they are the 6 Volt version and have the three wire connector that plugs into the Servo Controller.


                          • #14
                            Additional Servos on Servo Controller w/ VEX EDR Motors

                            Originally posted by FTC11260
                            The rules state "Core Servo Controllers and Legacy TETRIX Servo Controllers may control up to two (2) VEX EDR 393 Motors
                            per module. A VEX Motor Controller 29 must be used in between a servo module and each VEX EDR 393
                            We would like to control 2 additional servos and are wondering if we need to use another controller to do so. I understand the 5 amp stall requirements, so I suspect the answer is no. Our servos and motors will be used one at a time, so having multiple stalled devices is unlikely. Thanks for you reply.

                            Answer: No. Two EDR Motors fully consumes the power budget for the Servo Controller.


                            • #15
                              Servo Boosters

                              Originally posted by FTC6299
                              We have been having a lot of problems with getting servos to work properly when the cables reach a certain length, so this serves to be a big problem when there are servos on the end of a lift mechanism. We found that the signal from the modern robotics servo controller was not strong enough to properly control the servos at extended lengths (starting around 3-4 feet of extension), but boosted extensions sold by servo city fix this problem. However, we were not sure whether or not these extensions were legal. Are servo signal boosters legal?

                              Answer: No. Servo Boosters would fall under the category of "Additional Electronics" and are not allowed per <RE17>