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  • Lag Issues in TeleOp for Control Hub

    Hi,

    We've had our Control Hub for several months, but just a few days ago a new problem occurred without us changing our programs at all. There now seems to be a strange lag occurring when we run the TeleOp, where it responds to input commands a few seconds late. This seems to reflect what is shown on our Driver Station, where even though we stop inputting values, it takes a second or two for it to show the correct value in the telemetry. Sometimes the robot will not even receive the no-movement input and will keep moving. While sometimes we are able to hit stop on the Driver Station, a few times it will not respond either, forcing us to turn off the robot with our power switch.

    We have tried changing gamepads, input ports, Driver Stations, TeleOp programs, and connection wires. We have even reset the Control Hub, which seems to have lessened the problem a little, but it is still an issue that impedes our practice. Finally, when we switched back to the dual-Expansion Hub setup, there seemed to be no problems at all, so we are sure it must be something with the Control Hub. Has anyone else had this problem? If so, how did you fix this?

    Thank you!

  • #2
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    On a separate phone, download a WiFi monitoring app. Check the WiFi traffic during a period of slow response on the Control Hub. Also, try to find out if your school/facility recently enabled WiFi suppression.
    .

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    • #3
      The WiFi traffic seems normal, and we are also now experiencing this with the old two-phone-two-Expansion Hub setup (although at a slightly less extreme level). We do not have any WiFi suppression enabled. We have changed around and reset every component involved in TeleOp operation, and we are completely stumped now.

      We recently went to a meet, and this problem plagued our two-Expansion-Hub setup, causing an incredible amount of lag (and a couple of penalties). Upon coming home, we took apart our robot, threw them on a dummy chassis, and saw no lag at all! This occurred with the Control Hub as well. However, upon rebuilding our robot, the problem reappeared. We even switched all of our DC motors from Tetrix to REV, so we can't see how that could be causing the problem either. It seems very unlikely that our robot hardware is the problem, though, since our telemetry values are still lagging as well.

      We think it may have something to do with our USB splitter (for our gamepads), so we are going to order another one tonight. However, when we started using this new splitter we didn't have a problem for quite a bit of time, so any other info about potential causes would be much appreciated.

      Thank you!

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      • #4
        .
        Sounds like you are doing very thorough troubleshooting.

        Your posts didn't mention DS (and RC) phone housekeeping, which can include these items:
        • Uninstall or disable all apps that are not needed for robotics.
        • Remove the SIM card.
        • Remove Google accounts and any other accounts.
        • Install all system updates (really all).
        • Forget all WiFi networks.
        • In the WiFi Direct menu, forget all remembered groups and cancel all listed connections.
        • Make sure each phone has only 1 FTC app installed, latest version.
        • Purge obsolete log files.
        • Airplane mode on, WiFi on.
        Try joining the gamepads and DS phone with a powered USB hub, just to see the effect. I have seen the external 5V resolve a marginal connection.

        Look into Match Logging, a useful feature in the DS Settings menu. Enter a Match Number at the top of the DS app home screen.

        And, although it's "never the code", you might post a link to your teleop code.

        .

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        • #5
          Update: the problem seems to be the connecting Expansion Hub, which was actually used in both setups. Since the battery is connected through this hub, we think there may be some internal power connection problem in this hub that was causing a temporary lapse in power and disconnected our program (or maybe something else, we're hardly the experts on the internal components of an Expansion Hub). Anyways, we switched out our Expansion Hub with a new one today in one last effort, and we didn't see any lag whatsoever during our six hours of practice.

          Thank you all so much for your help! We will be sure to refer back to this thread if we ever encounter another similar problem.

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