Tricopter Yaw unstable, wobbles, does not keep still – KK2 Settings

by Oscar

After upgrading my tricopter flight controller to KK2.1 from KK2.0, the original settings does not work anymore. Although I can make roll and pitch perfectly stable now, I was having tricopter yaw unstable problem. The yaw simply does not stay at the centre, and the tail servo just moves left and right. I first looked at the hardware first, which wasn’t the issue. But if you have the same issue and haven’t done those things yet, give them a try.

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  • Balance prop and motor
  • Make sure yaw mechanism is not sloppy, and movement is smooth.
  • Use Digital Servo rather than Analog Servo (if you are using the tricopter for FPV and taking videos, it’s always best to use digital servos, which is more precise and faster)

The answer to my problem was actually settings on the KK2.1.

I first make sure the channel used for the servo is set correctly.

Mixer Editor- Channel 4 - change Servo from Low to High

Be aware this is only for digital servo, setting it High will damage analog servos. Also remember to adjust Offset to make sure tail is at its centre position when hovering

I then lower PI for yaw, it does solve the wobble issue for me, but with low yaw PI gains, the yaw response become slow. However, I tried to increase servo filtering.

Misc Setting - Servo Filtering - change 50% (default) to 70%

This allows me bring yaw PI gains back up without having the wobble issue.

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Stanley Portion 26th August 2018 - 10:44 pm

I built a hecacopter x congratulation around KK 2.1.5 but it wobbles a lot and if I give more throttle it over turns PL.suggest remedy to correct the same.
Stanley Portion

FotoAmg 9th April 2018 - 3:52 pm

Hi! Could you help me? I did not find any exert in this issue:
I cannot make Triflight .7 beta3 work with Quannum Trifecta and cc3d and cheap MG90S analog metal gear servo :(
In the 0.6 RC1 I see this change: “tri_dynamic_yaw_minthrottle parameter is now removed. The yaw output is always 100% at min throttle, while tri_dynamic_yaw_maxthrottle controls the output reduction at max tail motor throttle. The yaw output is now a linear curve throughout the throttle range. The defaults for tri_dynamic_yaw_maxthrottle and tri_yaw_boost were tuned in the test bench and should work fine on all tricopters.”
Is this making issue for my build?
People with similar issue but with LibrePilot solved by reducing mixer gains from 100 to 35, but as I see “yaw output is always 100% at min throttle” and I cannot lower gain.

by arming servo twiches fast between all limits :( can be seen at configurator too so FC sends this strange min max value commands at zero throttle or low throttle.

When giving 60-80%+ throttle twitching starts to reduce greatly and almost flyable:

Someone I found with similar issue:

Gem 25th February 2017 - 7:46 pm

I have also had problems like this. I made a quadcopter and used the K.K. Mini board. Everything but the yaw is stable. I can take the quad straight up and set it down in the same spot. But, when it gets off the ground, it starts spinning very fast. I have tried to take the yaw setting down all the way to 5, but this doesn’t make a difference. I can have the trim on my transmitter in one spot, and the quad will rotate one way. If I move the trim one notch over, it will rotate the other way. It doesn’t matter how much I set the yaw down to (If I am correct, that setting should limit the yaw value, this reducing the effect of a small change in input. Maybe I’m wrong.), the quad will not stabilise. Any suggestions?