• Hello Dale,

    I'm also very interested in getting one recently. Please keep me updated. Did you buy it from GoodLuckBuy?



  • Hi Dale,

    I don't know anything about the Hobbyking PX4Flow unit and don't know of anyone else using it yet either.

    I would be very careful until you hear of someone else actually having success with it.

    The regular 3DR PX4Flow is barely in use at this point and is only supported by beta firmware, so any incompatabilities would not be likely to be known.

    In answer to your question PX4Flow is an optical flow system that comprises a camera and a computer (on board).

    The computer analyses the camera image of the ground to determine drift or motion in any given direction.

    Currently it is used for maintaining position over a given point on the ground and it can also be used for limited navigational capability although I do not think our firmware supports that yet.

    It works independent of GPS and can be used indoors as well.

    Carpet and concrete and even grass can work quite well, but if grass is blowing in the wind, not so much.

    It has a sonar on it so it knows what the height is, but I believe the current implementation in our flight controller does not use the sonar, but rather change in image size in order to maintain altitude.

    The Sonar on it is a major pain in the ass anyway as it is very subject to all kinds of noise and it's performance can be very erratic.

    In any case here is the APMCopter wiki page on the PX4Flow which, fortunately for all of us has been completely redone by Randy.

    Best Regards,


    • Hang on, I'm getting it working. I'm not sure what I did differently, but I got the PX4Flow working on MacBook USB with QGroundControl. From there it did an auto firmware update, and then I was able to get video. Still not seeing any optical flow data in the logs.

    • Thanks Gary,

      I went ahead and got the unit, but apparently nothing I have can talk to it over USB, neither Windows nor Mac, so updating the firmware isn't possible. The QGroundControl I downloaded doesn't look anything like the one on the ArduPilot PX4Flow page, so I don't know what that's about.


  • Hey Dale,

    The PX4-FLOW is an optical flow unit used for collision avoidance, if I'm not mistaken. Hobbyking has one that has the sonar module ( Last check it was about $106 USD + shipping. Hope this helps.

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