Tail Servos are shaking

ArduPlane Plane 4.3
1

Hi,
I have a problem with my servos. I have a fixed-wing v-tail uav. When the plane is at non-manuel mode, at level and armed, ruddervators are beginning to shake. Normally, in some modes, like FBWA, servos makes noise and shakes with too small movement. But in my problem, servos are approximately moving ±5 degrees. This is really huge movement and unsafety condition for a flight.

Before weeks, I made a flight for autotune settings with the plane. After the autotune flight, I made another flight with the same plane. Servos did not shake at that time, and give good response for my command. However, now, they are shaking.

I have kept the parameters before the autotune flight and uploaded the plane. Shaking did stop. But, I don’t understand why the shaking did stop.

What is the different between two conditions? The parameters are below.

after_autotune.param (18.6 KB)
before_autotune.param (18.2 KB)

When I upload “after_autotune” file servos are shaking and “before_autotute” file servos stop shaking.

Thanks in advance for your help.

2

Here is the log file. When you look at CIN and COUT, you can see the shaking. Thanks again
https://drive.google.com/file/d/1AV0aypJnwhjbScyVtDXK6lBd9bNLRwiY/view?usp=sharing

3

I forgot to say something. When I make a search on the Internet, some people are encountered with the same problem, and they say when they unplug the GPS the shaking stopped. I try the same thing.

When I unplug the GPS the shaking stopped, but when plugged, the shaking begun. Can GPS affect the shaking? Is shaking possible if the mode is FBWA? Because as I know, GPS does not affect anything in FBWA mode.

4

Unplugging the gps to make the shaking stop is very strange. My guess is that the person who posted it had their GPS wire close to a transmitting antenna.

Normally the shaking is because of electromagnetic interference (EMI) of some kind which normally comes from any antenna that is transmitting (receiving has no effect) at all. The more power it transmits with the more it can induce a voltage in a long wire (typically the longest wires go to the tail section but any long wire will do). The longer the wire, the more susceptible the component.

If you have any wires anywhere next to an antenna, move them. If the wire is perpendicular to the antenna that makes it even worse.

Unplug anything that transmits and see if that helps.