GPS problems on a Thunder Tiger Raptor E550 with Pixhawk

Posted by Wolfgang on October 24, 2016 at 5:46am

Hi all,

I started a new project with a Raptor E550 using a Pixhawk.

I mounted the Pixhawk in front of the frame. Normal orientation.

The GPS was mounted in the tail boom 700mm away from the Pixhawk.

In my first tests the heli was very unstable and was shaking in roll-axis.

I reduced several parameters to get it better.

After a few flights it works but is very nervous.

See attached parameter-file.

ALT-Hold works fine after setting it's parameters.

In Loiter-Mode the heli starts toiletbowling.

Compass calibration is done and works.

I didn't manage to stop it.

Can anyone tell me what to do ?

Is it possible to use AUTOTUNE for my heli so as for other copters ?

Thanks for your help.

Wolfgang

Raptor-tune-4.param

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Replies

  • Miguel Marta December 21, 2016 at 11:39am

    Hi Wolgang,

    Had the opportunity to test it again, now flying 3.4.3,

    Reduced both accel x and y from the default 111000 to 55000 and success!

    It flies great! still some tuning to be made, specially on the tail, but i'm happy.

    Thank you for your input!

    https://www.youtube.com/watch?v=B3zgnuhEDwE

    Merry Christmas

    Miguel Marta

  • Wolfgang December 20, 2016 at 11:57am

    Hi Miguel,

    yes documentation is really poor. I searched all the web. I only found very old hints on the web.

    I thought about 46 hours to fininsh our heli project.

    We needed 80 hours to do it.

    Good Luck

    Have a nice Christmas time

    Regards

    Wolfgang

  • Miguel Marta December 20, 2016 at 8:54am

    Hi Wolfgang,

    Thanks for the help, wish I had received the notification of your reply 1 hour earlier! 

    This Morning the oscillations were so strong, that one of the swash links came off and the helicopter went up and left really fast, I hit throttle hold right away and only the blades and the landing gear broke, I have more blades but i'll have to source a new landing gear... 

    I already had reduced accel_z_p to 0.2 because of the alt_hold oscillations but never occurred to me to also reduce on Roll

    I'll try reducing the Accel parameter on roll next time. 

    Comparing to multicopters, it's really hard to find information, 

    I'll keep you informed of our successes 

    Wish you luck

    Miguel Marta

  • Wolfgang December 20, 2016 at 5:28am

    Hi Miguel,

    we had the same problems when we started this project.
    During the project we changed firmware from 3.3.3 to 3.4.1
    This helped a lot.
    It was nearly impossible to tune our heli in 3.3.3.

    You need to reduce the ACCEL parameter for the roll axis.
    We mounted pixhawk in front and the GPS-module on the tailboom.
    Sometimes we had problems with the 2 compasses with inconsistant compass
    warning.
    We also use 90° swash plate setup.
    I made a video from our last testflight.
    https://www.youtube.com/watch?v=925fFLmwHDE

    Good luck

    Best Regards
    Wolfgang

  • Miguel Marta December 18, 2016 at 3:22pm

    Hi!

    What a coincidence! I'm also starting a new project, installing a Pixhawk in a Raptor E550, and i'm also having violent shakes on the roll axis! Because I didn't want to take chances first flights were with a training kit, those with carbon rods and balls, it flew perfect, i was only when i removed the training kit that shakes appeared.

    Please check this vid filmed today of the problem
    https://www.youtube.com/watch?v=dumXtQ2ZRrM


    Are you running a 90º or 120º Swash plate? i'm running the 90º.

    The e550 has the motor behing the main shaft, so i mounted both Pixhawk and GPS on the front because i didn't want to risk having gps wires passing near the motor and ESC

    Have you solved the issue?

    Regards

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