Discussions

Alt-hold problem

Posted by Michele on April 13, 2013 at 11:00am

Today I have my first flight with arducopter 2.5+ and 2.91!

The hardware are this (combo pack):

http://www.unmannedtechshop.co.uk/arducopter/arducopter-frames-and-kits/arducopter-3dr-kit.html

I use the 3s 5500mA

I configure PID in default mode!

The fly work very well in stabilize mode, but I have a strange thing happened:

I try to fly in Atl-hold mode

(in the hardware I have the sonar and I test in ardupilotMega planner) work!

http://www.unmannedtechshop.co.uk/maxbotix-hrlv-maxsonar-ez4-mb1043.html

when I fly in Alt-holt mode, the drone fly well but when I move the knob forward (pitch) a more determined it seems that the drone loses altitude and then tries to recover more violently with strong fluctuations of all directions. The video:

(but when fly in Alt-hold mode and I move knob (pitch and roll) in mode slow and delicate the drone fly very well)

Is normal?

I must tune the PID rate Ald hold?

https://www.youtube.com/watch?v=7f9jz1QWrHQ

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Replies

  • Barry Nash April 30, 2013 at 9:06pm

    here is my x,y,z. Can you tell me if it is ok?

     

    3692703417?profile=original

    Here is my X,Y,Z graph. Does it look ok?

  • Michele April 16, 2013 at 8:24am

    This my accz

    3692685439?profile=original

  • Eirik Andersen April 16, 2013 at 2:55am

    I have the same issues with my quad :(
    My zAccel is good. 

  • T3
    Richard Boyhan April 15, 2013 at 6:18pm
    Did you check your vibration. It's vital that you reduce the vibration on your copter to get either a good altitude hold or loiter.
  • T3
    Richard Boyhan April 15, 2013 at 2:41pm
    Do you get good altitude hold? Altitude hold is the bases of a lot of flight modes.
  • Reuben Bray April 15, 2013 at 2:20pm
    I'm having the same issue is it just a vibration issue that causes the loiter mode to yo yo up and down
  • T3
    Richard Boyhan April 13, 2013 at 5:41pm
    Sonar is not needed for altitude hold with firmware 2.9.1 or higher. You need to make sure your zAccel is between -5 and -15. Turn off sonar and check your zAccel. To check zAccel you need to enable RAW in your logs and then fly a short flight in stabilize mode and hover for a short time. Then browse to your log, scroll way down till you see a row with a heading of RAW, then graph your zAccel. If your values are outside the -5 and -15, then you need to either balance your props or place foam in the corners of your APM to reduce vibration. Moongel apparently works very well in the corners of your APM. Good luck and fly safe.
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