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Control System - Answers

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  • Control System - Answers

    Answers to your questions about the control system.

  • #2
    Originally posted by FTC4634

    Subject: REV Expansion Hub Connections

    Question: Since USB hubs are allowed between the phone and the control modules for the purpose of adding a webcam, can we connect the secondary Expansion Hub the the USB hub instead of chaining it to the primary Hub over the 485 bus?

    Answer: Yes. There is nothing in the rules that prohibits using a USB hub to connect to a second Rev Expansion Hub.


    • #3
      Originally posted by FTC4634

      Subject: Mixing REV Expansion Hubs and Modern Robotics Core Control Modules

      Question: Is using MR controllers in addition to 2 REV Hubs an allowed configuration? RE08 is unclear as to whether using MR controllers is only allowed when using them alongside a single REV Hub.

      Answer: Yes. <RE07> and <RE08> do not place limits on one type of module (REV vs. Modern Robotics) when the other is also used. Be aware that in order to use a Modern Robotics Core Control Module, teams must use a Modern Robotics Core Power Distribution Module as well.


      • #4
        Originally posted by FTC4634

        Subject: Replacing the Case of a REV Expansion Hub

        Would it be allowed to 3D print a custom case for the Lynx PCB inside the Expansion Hub? This seems to be allowed by RE15 as no parts on the PCB would be modified, and simply changing the case should have no effect on safety.

        Answer: No. Replacing the case on the REV Expansion Hub is not allowed. Inspectors need to be able to clearly and quickly identify the components used in a robot.


        • #5
          Originally posted by FTC5110

          Subject: Are Variants of Allowed Phones also Allowed?

          Question: Are we permitted to use locally available variants of the Moto G5 phone such as Moto G5s?
          The G5s is Qualcomm MSM8937 Snapdragon 430 like the G5.

          Answer: Only the phones explicitly listed in the Game Manual have been tested and are known to work. Until other phones are tested and explicitly approved, they are not allowed.


          • #6
            Originally posted by FTC9999

            Subject: Replacing CPDM with a COTS USB Hub

            A recent rule change allows the RC phone to connect directly to a powered COTS USB hub. Thank you! Essentially, the powered COTS hub serves the primary function of the MR Core Power Distribution Module (CPDM), namely to supply power MR modules and to allow the RC phone to communicate to the same. The CPDM seems to be a superfluous component as a result of the rule change that allows the use of a powered COTS hub.

            Moreover, the USB bus on a powered COTS hub is much faster than the USB bus of the CPDM; thus the CPDM slows down communication between the MR modules and the RC phone. The CPDM is also a communications bottleneck further slowing down communication between the RC phone and MR modules. This likely increases MR module response times and sensor latencies. Minimal response times and latencies are vital requirements of robotics.

            The CPDM appears to be an expensive component which serves only to add several unnecessary points of failure and to slow down communications between the RC phone and the MR modules. We request a rule change that disallows the use of the CPDM when the phone is connected to a powered COTS USB hub. We also request to allow a powered USB hub to be powered directly via the 12V robot main battery, as are most of the other controllers and components on the robot (including the CPDM). Many COTS USB hubs that are powered via ~12V (i.e. 9+ volts) feature ESD immunity on each port. None of the COTS USB hubs powered via 5V supply seem to have this feature.

            Answer: There is no current plan to allow the replacement of the Modern Robotics CPDM with a COTS USB hub.


            • #7
              Originally posted by FTC4174

              Subject: Using Modern Robotics CDIM with REV Expansion Hubs

              Question: My team wants to use both the REV Expansion Hubs and a Core Device Interface Module on our robot, as one of our sensors requires the DIM. We also are using a USB webcam on our robot, so our robot controller is plugged into a generic powered USB hub, which then connects to the other devices. We've tried plugging in the DIM into this USB hub (alongside the camera and REV hubs), and it does appear to function, without needing a Core Power Distribution Module (as the DIM does not have a +12V PowerPole port).

              We cannot plug the USB devices into the hub of the Power Distribution Module because it has a USB 2.0 full-speed hub (12 Mbps max speed) while our camera requires USB 2.0 high-speed (480 Mbps max speed) (confusingly, high-speed is faster than full-speed!) Is this configuration legal?

              Alternatively, we could plug the PDM into our USB hub, and then the DIM as the only device connected to the PDM. Would this alternate configuration be legal?

              Answer: <RE07>.a requires the use of a Core Power Distribution Module if any Modern Robotics Core Control Module is used within a robot.


              • #8
                Originally posted by FTC9794

                Subject: Soldering to Internal Connections in USB Hub

                Question: Is it legal to solder a wire to the 5 volt and the ground on the board of the USB Hub included in the Electronics kit? These two wires would be plugged into the auxiliary 5 volt port on the REV hub in order to make the hub powered so it can be used for Web Cameras.

                Answer: No. Per <RE15>


                • #9
                  Originally posted by FTC9999

                  Subject: New Phones

                  Question: FTC Engineering has confirmed they have tested the Plus variant of Motorola Moto G5 phone and have found no issues other than the minor issue common to Moto G5 and E4 phones.

                  Is the Plus variant of the Moto G5 phone legal for competition?

                  Answer: Work done by FTC engineering to test new/updated models of phones will reflect in future allowed phones list (i..e. next season).


                  • #10
                    Originally posted by sramachandran2017

                    Subject: Multiple USB Cameras within a Robot

                    Question: This is regarding:

                    RE14 c(iii)(i)

                    iii. A USB hub that connects to the built-in USB input port of the REV Expansion Hub. If a powered hub is used, it must draw its energy from either
                    i. A commercial USB battery pack, or
                    ii. A 5V auxiliary power port on a REV Expansion Hub.

                    We are planning to use 2 USB cameras on the robot in addition to the Phone camera for navigation.

                    There were doubts about how to wire up the power and what would be legal in the RE14 c(iii)(i) setup.

                    We are planning to use a "Y" cable to give additional power to the camera and connect to a hub.

                    Wiring diagram is attached as a picture.

                    We called Rev Robotics to see how we could connect USB Camera to get power Aux port. They did not have any answers and suggested to get clarity from the forum.

                    Thank you in advance for the guidance.

                    Answer: The USB battery may power ONLY the USB hub. The cameras would need to be connected to the hub and draw their power from the hub.


                    • #11
                      Originally posted by jduval2018
                      Q: Are Servos that can run at 6.0 volts but may run above that allowed? For instance, the Hitec HSB-9370TH Servo has a voltage range of 6.0V - 7.4V.

                      A: Yes. almost all servos are specified with a range of operating voltages


                      • #12
                        Originally posted by FTC12090

                        Subject: Game Pads

                        Q: I have been using the Logitech F310 gamepad per the game rules and have determined that these gamepads tend to have very poor linearity. Our pair of controllers joystick jumps from 40% power to 100% nearly instantly. I found an Xbox 360 wired controller (which was very tough to find, 7 local GameStops resulted in 1 controller because they are no longer made) as this is the only other allowed gamepad. The Xbox 360 gamepad had perfect linear response from 0 to 100%, but is almost impossible to find. I see them listed on Amazon, but the product comments have many people stating what they received was a knock off controller. Can the gamepad list get updated for next season to allow for a commonly available gamepad that is a better choice than the Logitech F310?

                        A: The equipment used for the driver station is assessed annually as part of the update of Part 1 of the Game Manual