Wookong Soft as S**T Syndrome

[multi-prop-chop]

I have a skyjib 8 with wookong m. Basically my problem is this:

80% of the time it flies like its on rails - fills me with confidence when I fly it.

20% of the time it feels like the gains have been halved, it feels soft and unstable, I loose yaw authority, It doesnt hold well in gps mode and generally is just horrible to fly and worst of all, I start to get the wobble of death.

This happens despite checking all the parameters in the wookong, being scrupulous with mechanical and electronic checks, triple checking c of g and recalibrating gps. This will all happen with the same payload and regardless of location and wind conditions. I am in contact with someone who builds multi rotors for a living and 4 of his clients are reporting the same strange behaviour.

I just wondered if anyone else is seeing these issues?


Cheers peeps.


MPC

 

[EastCoastJib]

Yes....

 

[kloner]

Sometimes this can be a motor bearing issue.... might not be gone yet, but might be leaving and showing it's face in certain temps when the metal inside gets to certain tolerances. Your flying the 5.22 firmware?

 

[multi-prop-chop]

Hi kroner, good idea. I will check the bearings, but I think I have been plagued by this since getting the wookong.

Mpc

 

[gtranquilla]

Does it fly well in little or no wind then you get a lot of wobble if there is wind?

I have a skyjib 8 with wookong m. Basically my problem is this:

80% of the time it flies like its on rails - fills me with confidence when I fly it.

20% of the time it feels like the gains have been halved, it feels soft and unstable, I loose yaw authority, It doesnt hold well in gps mode and generally is just horrible to fly and worst of all, I start to get the wobble of death.

This happens despite checking all the parameters in the wookong, being scrupulous with mechanical and electronic checks, triple checking c of g and recalibrating gps. This will all happen with the same payload and regardless of location and wind conditions. I am in contact with someone who builds multi rotors for a living and 4 of his clients are reporting the same strange behaviour.

I just wondered if anyone else is seeing these issues?


Cheers peeps.


MPC

 

[multi-prop-chop]

Hi that could be part of the issue yes.

Paul

 

[gtranquilla]

I had similar problems with the larger Multirotor 800 mm airframe. It seemed impossible to dial out the wobble with Basic and Attitude tuning....... But then I replaced the smaller motors with larger/more powerful and the problems disappeared......
Original motors were the Turnigy Multistar 4822 - 690kv. The replacement motors were the Turnigy Multistar 4830 420 kv...... using Carbon fiber 15 inch 4.7 pitch props.

My reasoning was that the DJI WooKong controller algorithms were designed to accomodate a range or MR arm lengths relative to a limited range of motor speeds/torques..... if the motor speed/torque changes can't stay ahead of the motor arm angular momentum then the control algorithms can't do their intended job to immediately stabilize the airframe horizontally.

However I also read somewhere the the P - proportional gain can be adjusted to resolve higher speed wobbles while the I - Intergral gain can be adjusted to resolve the lower speed wobbling......

Hi that could be part of the issue yes.

Paul

 

[multi-prop-chop]

Hmmm I run axi 2120's - pretty big powerful motors!

Mpc

 

[multi-prop-chop]

Thank you for your input btw.

Mpc

 

[gtranquilla]

Then it is either a bearing issue as Kloner suggests (and he is right 99% or 100% of the time) or the following tuning adjustments might help for flying in wind where wobble becomes the issue.......
http://www.rcgroups.com/forums/showthread.php?t=1375728

General guidelines:
For stable flying with less wobble / jitter ( AP / FPV):
Lower P if you have fast wobbles
Lower I if you have slow wobbles
Higher D to smooth changes

Hmmm I run axi 2120's - pretty big powerful motors!

Mpc

 

[multi-prop-chop]

Thank you