Roll problem with FBWA mode.

Posted by Grazziani Resende on February 28, 2017 at 5:50am 
I was flying with a glider in FBWA mode, when from the movement of the ailerons 
he did a spin. 
I do not quite understand, because it's set to do at most 40% of roll. 
Does anyone know how this could have happened? 
Hug.



You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –
Follow

Replies

  • Mossbackfarm March 1, 2017 at 7:30pm

    Sure thing...has happened to me more than I'd like :)

    Grazziani Resende said:


    Hello, it makes all sense what you wrote. I just got to see it now. Before he turned, he was very slow.

    Thank you very much!

    Mossbackfarm said:

    Without a dataflash log, I can't tell for sure, but when you hit RTL, you had some compass and EKF/POS variance issues.  Nav_roll was maxed at 40, which is proper, but when you rolled over, your speed was pretty low compared to the rest of the flight.  Could be a tip stall?

  • Grazziani Resende March 1, 2017 at 5:23pm


    Hello, it makes all sense what you wrote. I just got to see it now. Before he turned, he was very slow.

    Thank you very much!

    Mossbackfarm said:

    Without a dataflash log, I can't tell for sure, but when you hit RTL, you had some compass and EKF/POS variance issues.  Nav_roll was maxed at 40, which is proper, but when you rolled over, your speed was pretty low compared to the rest of the flight.  Could be a tip stall?

  • Mossbackfarm March 1, 2017 at 7:59am

    Without a dataflash log, I can't tell for sure, but when you hit RTL, you had some compass and EKF/POS variance issues.  Nav_roll was maxed at 40, which is proper, but when you rolled over, your speed was pretty low compared to the rest of the flight.  Could be a tip stall?

  • Nobel0 March 1, 2017 at 1:33am

    Hello again dear Grazziani, :D

    I have to say i am not expert in this, but you can investigate :D

    As far as i know, in FBWA mode if you do the left aileron ( ex. hard left) the PH will hold the pitch not the roll, so you will not need to accommodate the pitch, it will do it for you.

    So yes it will do continuous roll, not fixed at 40%, and it will change as long as you center the stick or do right aileron. I suppose that if you want to do only 40% roll to left, you have to just toggle the stick to left one time.

    I have to say that, i still not fly in FBWA, but i configured it already and waiting for good weather to maiden :D

    Look at this thread for more assistance:

    http://ardupilot.org/plane/docs/fbwa-mode.html#fbwa-mode

    Hope this will help

    FBWA Mode (FLY BY WIRE_A) — Plane documentation
  • Grazziani Resende February 28, 2017 at 5:06pm

    Yes, you understood everything right. I did the motion compensation tests successfully. My question is: When I use the radio control stick to left position in FBWA mode, should it stop at 40% or will it continue turn up until the stick return to center position?

    Nobel0 said:

    Yes, Pixhawk should stabilize the glider and dont let it goes upside down at the first instance.

    Did you test the FBWA functionality before the flight? it should try to compensate at what ever movement you do with the glider, so if you roll the glider to right, it should compensate that.

    Hope i got what you meant :D

  • Nobel0 February 28, 2017 at 1:26pm

    Yes, Pixhawk should stabilize the glider and dont let it goes upside down at the first instance.

    Did you test the FBWA functionality before the flight? << it should try to compensate at what ever movement you do with the glider, so if you roll the glider to right, it should compensate that.

    Hope i got what you meant :D

  • Grazziani Resende February 28, 2017 at 12:26pm 
    What happened is that in FBWA mode he managed to exceed 40% and was upside down. 
    Should not the pixhawk block this movement?



    Nobel0 said:

    Hello Grazziani,

    Excuse me if i got this wrong, did you mean the glider made a spin after you give ailerons? and is it a spin or roll you mean?

    As i remember, the APM or Pixhawk when it set to the FBWA, it will keep giving 40% roll until you move the sticks again i could not remember well, but hope one will get it straight for you.

    Cheers

  • Nobel0 February 28, 2017 at 12:12pm

    Hello Grazziani,

    Excuse me if i got this wrong, did you mean the glider made a spin after you give ailerons? and is it a spin or roll you mean?

    As i remember, the APM or Pixhawk when it set to the FBWA, it will keep giving 40% roll until you move the sticks again << i could not remember well, but hope one will get it straight for you.

    Cheers

This reply was deleted.