Is it normal that the servos jitter if the ACM is in fly mode?

The jitter can not come from electrical noise, because there is no jitter at all as long as I am in CLI mode and e.g. setting up the board with the "heli" commmand.

In my opinion it is triggered by the noise of the gyros and accelleration sensors, so the ACM wants to correct by swashplate movements, which leads to the servo jitter.


Do you have the same effect or are all your servos "quiet" as long as the board is not moved?


Would it help to solder the filter on the oil pan?


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What mode are you in .... stabilise... alt_hold etc?


what are your PID settings for stabilise?


Good point.

The standard ones coming with the firmware on mission planer.


P 0,7

I 0,025


P 0,7

I 0,025

Imax both 7

If the standard values should be that wrong, is there anywhere a good starting point for traditional 450 size?


They look pretty good to me, your servos should be fine, how bad is the jitter?

what version code are you running? 

I have the filters soldered on my board, have done since the beginning.


Servos are heating up a lot, as they constantly jitter.

I expected them to stand still as long as the board is not moved around.

Would it help to post my IMU readings? Maybe too much noise?

ok turn the system off, what voltage are you running to the ACM and servos.

which servos are you using?


5V, Hitec HS-65HB

See attached how it looks like when I run "test" "imu".

Is there too much noise from the ACM?


i cant tell from the picture, but it seems really odd that the servos are heating up this is worrying. 

Firstly i would check the servos by connecting directly to the reciver, i'm sure they will be ok but its worth checking.

Reload the code

Then i would go back through the Heli setup. 

Even when i had large PID settings and my servos were jittery they never heated up. I don't understand why this would be happening.

Solder the filter pads too. this should help.

Randy might be able to help.


Ok, thanks. I will try.

Would be also interesting to know what other boards show when running the "IMU" command and the ACM is not been moved at all.


Just found something strange. When showing the setup in CLI. There is a line:

140: IMU_SENSOR_CAL : ??


Any idea what this means?



No i dont, i'm not a coder, one of the other guys on here should be able to tell you. 

Sorry i can't be any more help.

Damn, checked the servos. They are fine.

But I am one step further: It is an issue of the APM's signal to the servos. Probably something with the modulation. Maybe setup error from my side. I will check what I can find out.


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