Hi everyone.

I recently assembled a new octo-copter(running 3.3.3) with a LIDAR.

In loiter mode, it can hold the height good.

But in auto mode(the Dalt is 8m), it will drop slowly, the LIDAR's result is almost 2m. 

I wonder the pixhawk does not use the LIDAR' result for height at all.

Any ideas? Thanks!




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  • Developer


    That all looks reasonable.  Copter-3.3.3 doesn't use the lidar during Auto mode so it's unlikely to be the Lidar that is the cause of the descent.  I haven't looked at the logs in depth but I see a descent at the end when it's in RTL.

    Copter-3.4 uses Lidar during mission (i.e. AUTO) but it's not official release yet... still in beta testing.

    • Hi Randy

      I've just fly my Quad-rotor with 3.4RC1.

      It will descent slowly, almost crash in AUTO mode.

      I don't think the LIDAR is used in AUTO mode.

      Any ideas? Thanks!

      here is the tlog in the attach files.

      2016-06-16 12-18-53.rar

    • Developer


      I can't do much with tlogs I'm afraid.  If you've got dataflash logs that would be much better.  Let's do the support over here.

    • Hi Randy Thank you for your reply.

    • Randy

      in Copter-3.4RC1, i can't change the PID parameters. why?

    • Developer

      We've renamed some of the parameters.  They start with ATC_ now.  Best to use the beta mission planner.  By the way, we're doing Copter-3.4 support here: http://discuss.ardupilot.org/c/arducopter/copter34

    • You said it!

      I've downloaded the MP_1.3.38, and now I can change the PID parameters.


      Awesome! You guys have done a great job! 

    • And what's the relationship between EK2 and EKF?

    • Randy,

      My octa  is now running 3.4RC1, in the parameters. should I need to change EK2_ALT_SOURCE to 1 in order to let pixhawk use LIDAR ?

      and the default value of EKF_ENABLE is 0, should I need to change it to 1?

      There isn't any parameter description at all.


    • Developer

      No need to set the alt-source.  Instructions to set-up the lidar are here (you've probably already seen them): http://ardupilot.org/copter/docs/common-rangefinder-landingpage.html

      EK2 is for the new EKF that is included with Copter-3.4.

      Rangefinders (landing page) — Copter documentation
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