Z84 elevons shivering (SOLVED)


I m wondering why the elevons are shaking so much in FBWA or STABILIZE mode ?

Please could you help me ?

if it does it in manual mode also then its probably interference from a UHF radio system.

yes as @geofrancis said + check/re-do calibration, make sure wires are not close to each other( any high frequency wires/electrical wires). If not resolved, connect both servo directly to TX receiver to check the servo’s.

Hi, in manual mode, there is no shivering

Thanks Sunny, I ve tested with my TBS crossfire unpluged in FBWA mode and the behavior is the same. Strange both servos could have a problem. Do yo think a PID setup or a picth or roll PID rate could be the reason ?
Here are my params : https://drive.google.com/file/d/1beagYD06QIAQ09FWjLAYLI3FFvBHwck3/view?usp=sharing

Thanks a lot

Sorry I didn’t catch. You mean you connected servo directly to receiver? (No ardupilot between transmitter and tbs receiver). And, behaviour is same.

Nop, nothing to do with any settings in ardupilot. No settings will cause shivering behaviour.

Few things causes this issue:

  1. Linkage connection between servo and horn . There should not have any play/gap
  2. 915/433 mhz does cause flapping issue on analog servos. My two hi tech analog servo does non stop flapping behaviour). Try 2.4ghz for testing.
  3. Last is servo. Some low quality digital/analog does this behaviour upon tiny signal movement from tx.
  4. Bad calibration.
    My suggestion. Start from scratch. Eg. Transmitter calibration, ardupilot tx calibration. And, before that I would try different servo by connecting directly to receiver ( tbs or 2.4ghz)

Thanks Sunny, I will try your adices

My apologies didn’t know it you have uploaded the video + has done the manual mode check. I was replying to the post via email.

That massive flapping issue is definitely due to calibration. In fbwa mode autopilot non stop trying to bring plane stable.

Re-load the ardupilot ( first load arducopter and then arduplane , this way it will do fresh install). Re-calibrate flight controller + transmitter in arduplane.

I am very confident it will resolve the issue.

Thanks again. I didn’t know I have to load arducopter dans after arduplane. So I will re calibrate my fligth controller and after radio calibration. May I re load the params file I ve saved before ? Sorry for my english, I m french :blush:

Sunny, You ve fixed my issue ! Thanks :heart_eyes:
After these calibrations, elevons are less shaking until GPS fix.
Just another point, elevons are very sharp, please how to soften the movement ?

Great. However, if it’s still flapping in FBWA mode even a tiny movement, you will crash, it should not have any movement. If you wing sitting stable on the ground, ardupilot will travel the servo as per required and stays in that position.
What I have feeling is , the problem is in the flight controller or the servo out pins. Try different pinout on the board eg. If you using s3 try s4s5( servo out pins on the board).

For smooth throw, you need expo and throw on your transmitter. It’s a wing, I would say 50% throw with 30% expo will do.

By the way, what board are you using ? Is it Matek .

Hi Sunny,

Ok for that I will change the pins.
The board is a Matek F405 wing