Uneven Y6 Yaw

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Uneven Y6 Yaw

Postby chris24g » Thu Aug 09, 2012 3:45 am

the yaw rates are very asymmetric

CCW yaw approx 12 sec/revolution
CW yaw approx 5 sec/revolution. in addition, it will continue to overshoot up to 120 deg after centering rudder

overall the yaw is very slow. good for smooth flying, but i would like faster rates

I wonder if this is the case with coaxial setups, or just a Y6 issue

this is just about the last major issue from making the AQ a solid performer
chris24g
 
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Re: Uneven Y6 Yaw

Postby Kisssys » Thu Aug 09, 2012 1:49 pm

The default PID's are way too slow for me also.

You might try these PID's, they will not fix the rate imbalance though.

// YAW rate PID
#define DEFAULT_CTRL_YAW_RTE_P 300.0f
#define DEFAULT_CTRL_YAW_RTE_I 0.15f
#define DEFAULT_CTRL_YAW_RTE_D 50.0f
#define DEFAULT_CTRL_YAW_RTE_F 0.25f
#define DEFAULT_CTRL_YAW_RTE_PM 150.0f
#define DEFAULT_CTRL_YAW_RTE_IM 150.0f
#define DEFAULT_CTRL_YAW_RTE_DM 150.0f
#define DEFAULT_CTRL_YAW_RTE_OM 300.0f

If you can compile the source code you can change the code in control.c about line 105. This should solve the rate of turn difference but may cause you to get it to overshoot badly after centering or go back the opposite direction while turning. I've not had that problem after I got the yaw rates up a little higher.

from this
if (fabsf(compassDifference(navData.holdHeading + yaw, AQ_YAW) < 90.0f)) {
controlData.yaw = compassNormalize(controlData.yaw + yaw);
navData.holdHeading = compassNormalize(navData.holdHeading + yaw);
}
to this
// if (fabsf(compassDifference(navData.holdHeading + yaw, AQ_YAW) < 90.0f)) {
controlData.yaw = compassNormalize(controlData.yaw + yaw);
navData.holdHeading = compassNormalize(navData.holdHeading + yaw);
// }

This shows up to those who are more active with yaw.
Steve
Kisssys
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Re: Uneven Y6 Yaw

Postby chris24g » Thu Aug 09, 2012 6:11 pm

thanks kisssys!

i increased the motor PIDs as you suggested and the Y6 is now very flyable :^)
it just has a tiny kick up after completing a yaw, but at least the AQ is a big step closer in getting dialed in
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Re: Uneven Y6 Yaw

Postby afernan » Thu Aug 09, 2012 7:30 pm

I had exactly the same problem like you in my quad: ccw was much slower than cw, and both very slow. I solved by increasing x3 the yaw-P value ( up to 1.5)
Angel
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Re: Uneven Y6 Yaw

Postby GoFaster » Thu Aug 09, 2012 8:04 pm

Angel -

Did you mean Yaw Rate I to 1.5?

Yaw does have a soft feeling. And seems that the overshoot is proportional to how long and far the rudder is deflected. So it seems that either default P is too low and/or I is too high. I just got Alt hold working pretty well while being eaten by insects. Yaw is next.
Are those YAW_RATE_*M values microseconds like for Tilt Rate and Tilt Angle?

EDIT: I saw in your other post that you increased Yaw_Angle_P from default of .05 to 0.15
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