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Runaway Robot

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  • Runaway Robot

    Hi Everybody,

    Our robot was programmed in App Inventor and drove fine till I stabilized our chassis and made it more rigid. Since then, the robot jiggles more and sometimes runs for a few seconds completely by itself. It actually has run over our field barrier once. Right before the robot runs away, the robot controller shows the "There was a problem communicating with a Modern Robotics USB device" error. and tells me that I need to restart the robot.

    Is anybody else experiencing this issue? Does anybody know an App Inventor way to make sure the robot does not run away? (App Inventor is preferable, but Android Studio is fine as well)

    Also, is this related to the "Unable to open Modern Robotics USB DC Motor Controller unable to find USB device with serial number" error (aka jiggle effect)? This error is different in that it can't be fixed with a simple restart. I found I have to go through a weird process to fix it: turn off the robot, unplug the phone, unplug the motor controller, turn on the robot, plug in the motor controller, plug in the phone, restart robot. However, I would really like a better solution.

  • #2
    We had this same problem. Our problem was one USB cables. If you have your robot on and the phones running then wiggle all your USB cables. See if one of them makes any of the lights flickers on your robot.


    • #3

      Thanks Tom,

      Yeah, we found that the USB mini-B ports on the motor controller and servo controller were the problem. Apparently these connections are not very stable and wiggling the cords caused the errors we were receiving. We 3D printed a part out a slightly flexible material that would hold these cords in place. That seemed to fix most of the errors for us.

      So it seems like the key to having an "error free" run is to make sure all of these connections are completely secured.


      • #4
        My two cents: If you have access to a 3-d printer, printing out module holders w/ USB strain relief is really the way to go, if you're experiencing USB errors.