Problems with PID'S ?? help Rookie
« on: March 01, 2020, 11:46:50 pm »
Hello everyone, I'm experimenting with cc3d to put on my helicopters.
I have assembled and configured it in a 500 size helicopter, but I have a lot of vibrations on the plate.
I have tried in assisted mode, attitude and rate, but in all the same thing happens to me.
I have to say that the mechanical adjustment is well done, and the configuration of the cc3d too, I get -12 + 12º.

The tail is perfect on axislock.

I hope you can guide me in my fine adjustment.
Greetings ;)

karla

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Re: Problems with PID'S ?? help Rookie
« Reply #1 on: March 02, 2020, 01:24:34 am »
Hello :)
Do you think you have vibrations (could be from an infinite number of mechanical imperfections on the frame) or oscillations (often some PIDs set too high)?
There is very different approach to troubleshoot it
- have a look here for start?
https://forum.librepilot.org/index.php?topic=1689.msg12284#msg12284

Re: Problems with PID'S ?? help Rookie
« Reply #2 on: March 02, 2020, 08:34:08 pm »
They are not vibrations, the helicopter accelerates without vibrating more than normal.
when it takes off there are rapid oscillations in the collective, I know what the PIDs are, but I don't know how to deal with it.
If I put the PIDs too low or at 0, I imagine that the cc3d does not correct, but I can correct the cycle with the sticks.
If you want I can put my UAV file and check it out, to see that it looks out of the ordinary.
Greetings and thanks for the quick response.

karla

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Re: Problems with PID'S ?? help Rookie
« Reply #3 on: March 03, 2020, 01:37:35 am »
That is good news, vibrations is a curse.
Sure, post your uav file here and I can have a look at it.
So, the tail holds okay using axislock in rate mode, that's good.
Some questions:
. you have a flybar or not?
. what version of Librepilot are you using?

Meanwhile some general steps when tuning PIDs found here https://forum.librepilot.org/index.php?topic=1588.msg11596#msg11596

Basically first you need to have arrived at a desired rotor head speed at hover, with a combination of throttle and collective curves. If head speed changes, then your PIDs need to change as well so keep it constant for now. Then take one thing at a time, first tail, then roll and pitch. Since yaw is okay already move on to roll and zero out the D term and the I term. leave rest as is. Since its oscillating now, I would cut the roll P term in half and try hover. You might need to do the same with pitch.
Its very good to know at what point oscillations start. With that reference I cut it some 30-40%. Then move on increasing the I term to oscillation and cut it down from there. Lastly D term that can be used to increase P and D terms even higher or just leave it at default. By now you should have a flying Heli.

Re: Problems with PID'S ?? help Rookie
« Reply #4 on: March 05, 2020, 03:37:34 pm »
Well, I'll take a look at the weekend.
Thanks again

Re: Problems with PID'S ?? help Rookie
« Reply #5 on: March 05, 2020, 09:00:25 pm »
That is good news, vibrations is a curse.
Sure, post your uav file here and I can have a look at it.
So, the tail holds okay using axislock in rate mode, that's good.
Some questions:
. you have a flybar or not?
. what version of Librepilot are you using?

Meanwhile some general steps when tuning PIDs found here https://forum.librepilot.org/index.php?topic=1588.msg11596#msg11596

Basically first you need to have arrived at a desired rotor head speed at hover, with a combination of throttle and collective curves. If head speed changes, then your PIDs need to change as well so keep it constant for now. Then take one thing at a time, first tail, then roll and pitch. Since yaw is okay already move on to roll and zero out the D term and the I term. leave rest as is. Since its oscillating now, I would cut the roll P term in half and try hover. You might need to do the same with pitch.
Its very good to know at what point oscillations start. With that reference I cut it some 30-40%. Then move on increasing the I term to oscillation and cut it down from there. Lastly D term that can be used to increase P and D terms even higher or just leave it at default. By now you should have a flying Heli.

Hello again, I don't have Flybar, it's Flybarless.
The version of librepilot is 16.09.

Here is my UAV file.
I hope you can guide me.
Greetings
« Last Edit: March 05, 2020, 09:06:22 pm by vmerino »

karla

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Re: Problems with PID'S ?? help Rookie
« Reply #6 on: March 06, 2020, 10:34:47 am »
Thank you.
I see no major issues with your settings.
However, I noticed you are changing the overall response settings rather than the PIDs (inner loop).

Focus in these settings



Re-read my advise on how to go about it.
Don't hesitate to ask if it's unclear!

« Last Edit: March 07, 2020, 01:34:02 am by karla »

Re: Problems with PID'S ?? help Rookie
« Reply #7 on: March 06, 2020, 08:01:29 pm »
Hi, I'm glad you don't see the uav file wrong.
I have to say, save the configuration with swash platye 140º and then save it again as 120º, I have not done it because I do not understand it well (I am from Spain and my English is basic)

Then I also read that the Piruette Compensation can cause the plate to oscillate as it tries to correct the angle continuously (I don't know if I understood correctly).

Does the general response configuration refer to this?


Re: Problems with PID'S ?? help Rookie
« Reply #8 on: March 06, 2020, 11:42:13 pm »
I suggest that beginners (not doing stunts, do not know exactly what Pirouette Compensation does) have Pirouette Compensation turned off.

Example: It helps for some stunts, but hurts if your heli is not perfectly balanced.

It should not make oscillation better or worse.  Enabling Piro Comp on an unbalanced heli and doing pirouettes (spinning on yaw) will wobble, but it stops when you release yaw back to neutral.  Any quick yaw motions will have the effect of adding some roll or pitch.
https://forum.librepilot.org/index.php?topic=4651.msg31493;topicseen#msg31493

If you click the Advanced tab at the top of Stabilization it will show the view that karla posted.  You are both looking at the same settings.  Your view is more basic.  Karla's view shows more settings.
« Last Edit: March 07, 2020, 07:43:23 pm by TheOtherCliff »

karla

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Re: Problems with PID'S ?? help Rookie
« Reply #9 on: March 07, 2020, 01:32:25 am »
Quote
I have to say, save the configuration with swash platye 140º and then save it again as 120º, I have not done it because I do not understand it well
Don't worry about that, it is saved as swash plate CCPM 3 servo 120 in your file, and that should be correct for a standard Trex 500.
I think that advise was because there was a bug in the SW that did not properly save the settings, however, I think that was fixed already in ver 16.09 but not sure.