Discussions

APM 3.1-rc4 yaw PID tuning

Posted by MHA on October 21, 2013 at 3:36pm

Guys,

I need some help in setting up yaw PID's. My TBS Discovery with APM2.6 has a poor yaw performance. It seems not very locked and what is most annoying it is slowly oscillating which is most visible in onboard video footage.

To get to the root of the problem I did some log analysis and found that actual_yaw is indeed tracking nav_yaw but leaves some +-3 degrees slow oscillations. Please have a look at this log screen and my current PID's. Any ideas where to start or how to systematically set up the yaw PID's?

Thanks,

Michael

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Replies

- Edgar Scott > Edgar Scott April 25, 2014 at 7:53pm
  
  Rate YAW P 0.25-stab yaw 5.0
  Worked GREAT
  
  Rate YAW P 0.10-stab yaw 5.0
  
  Looks not as good but okay
  
  Rate YAW P 0.10-stab yaw 1.0
  
  1.0 in the Stabilize P made it rock like a drunk driver, landing was hard as it was swaying
  - Esteban Jaramillo > Edgar Scott April 25, 2014 at 9:04pm
    
    wow man, thank you very much, I was gonna do it myself tonight with my F450 but you saved me a lot of time, hopefully I can get my frame as stable too
Edgar Scott April 24, 2014 at 4:24pm

Michael, I am having the exact same issue, with a TBS Disco Pro.

So I'm a little confused

P: 0.2
I: 0.02 (1/10th p)
D: 0
IMAX: 8

Are we saying bump up the P to say 0.3 and leave the rest as is to see if in stops it?

Can you post your latest PIDs doe yaw P/I/D/Imax

Here is what I have
- MHA > Edgar Scott April 24, 2014 at 4:58pm
  
  This is my current PID's
  - Edgar Scott > MHA April 24, 2014 at 5:25pm
    
    Thank you very much for such a prompt reply, I hope it stops my oscillation, this has been driving me nuts.
    
    So it sounds like the more I increase the P the less oscillation, not really sure what the I does, but with increase risk of waypoint overshoot.
    
    here was mine :(
    
    Once again thank you for taking the time, I'll try it out in the morning.
    - Esteban Jaramillo > Edgar Scott April 24, 2014 at 7:07pm
      
      plz post videos after the PID change, also I think the max number for the YAW P is 0.3
      - Edgar Scott > Esteban Jaramillo April 24, 2014 at 9:24pm
        
        I still wonder, does
        
        less P = less oscillation
        
        or
        
        more P = less oscillation
      - Edgar Scott > Esteban Jaramillo April 24, 2014 at 9:21pm
        
        Oh dang yea, I hope that wont cause it to be uncontrollable, actually 0.25 is the max, I wonder if anything over 2.5 actually does anything? Guess Ill change it to 2.5 as I don't want to crash
        
        Yaw axis rate controller P gain (ArduCopter:RATE_YAW_P)
        
        Yaw axis rate controller P gain. Converts the difference between desired yaw rate and actual yaw rate into a motor speed output
        
        Range: 0.150 0.250
        
        Increment: 0.005
        
        Yaw axis rate controller I gain (ArduCopter:RATE_YAW_I)
        
        Yaw axis rate controller I gain. Corrects long-term difference in desired yaw rate vs actual yaw rate
        
        Range: 0.010 0.020
        
        Increment: 0.01
        
        Yaw axis rate controller I gain maximum (ArduCopter:RATE_YAW_IMAX)
        
        Yaw axis rate controller I gain maximum. Constrains the maximum motor output that the I gain will output
        
        Range: 0 800
        
        Increment: 10
        
        Units: Percent*10
Esteban Jaramillo April 21, 2014 at 7:10pm

Can you share your YAW PIDs please, how is it working so far?
Developer

leonardthall October 23, 2013 at 12:27am

When tuning the yaw I would suggest keeping the Rate I term 1/10 the Rate P term to keep the overshoot after a yaw command, to an acceptable level.

Start with the Rate D set to zero. Increase Rate P on the slider between something like 0.25 and 1. If this doesn't help you can increase the Stab P term but don't go over about 8 without doing an AutoTune to see what the maximum safe value is.