Pitch/Roll swapped, can't find the reason

ArduPlane
1

Hello Friends,

i tried to find a solution for 2 days now. I have a fixed wing with speedybee f405 Wing and I followed the guide for elevon planes.
My problem is that roll/ pitch controls are swapped when I power the plane up with the battery. When I connect it via usb to mission planner and I move pitch/roll it seems like it works right because in RC calibration TAB and servo output TAB pitch/roll are moving correctly.

Do you have any tips for me?

2

I don’t think that the power source has much influence to the behavior of roll and pitch, but who knows.
First tip, show details about your setup including log / parameter files

3

@Train_fpv Welcome to the forum

It is best to follow these instructions systematically:
https://ardupilot.org/plane/docs/guide-elevon-plane.html

If you simply connect USB and battery for testing purposes, the servo output display will probably look the same (The display does not know how the servos are installed or what kind of mechanics you have)

Correct deflection directions of the elevons both in FBWA when tilting the aircraft and correct stick movements on the transmitter are crucial.

Rolf

4

Hello Rolf,

thank you for your advice. That is what I was trying to say. Although my channels and servo outputs are set correctly (in my opinion), the deflection directions are not correct.
E.g. I move roll: both elerons are moving parallel up or down. When I move pitch one eleron is turning up, the other on is turning down.
The opposite should be correct imo.

Kind regards

5

You probably need to switch one servo output to reverse. (Only change the servo outputs first, if it doesn’t work at all, you can also swap the left and right elevon function)

6

is your compass usb powered or only when on battery/

7

I reversed Servo 1 and now it’s working in FBWA but my rc_input for pitch is incorrect, roll is correct. The guide says, that “Reversals are critical to the process. Commanding pitch up and roll right must result in higher PWM values for RCn_in channels.”
Is it save to reverse my rc_input for pitch? It’s working fine if i reverse it.

Thanks for the help so far.

8

its also powered via usb

9

I would do a direction change in the transmitter.

10

I will do that. Could you please shortly explain why? I’m willing to learn.
But apart from that, isn’t it suspicious that roll is working fine but pitch not? I didn’t change anything on the transmitter-site in the first place.

Have a nice evening.

11

It’s pretty normal for you to need reversals on a plane. All depends on how the servos are installed so there’s no one-size fits all configuration.

The order I use:

  1. Test the plane in FBWA. The corrections should move properly. Use servo reversals to get the FC and the servos working in the right directions.
  2. Test the controls in Manual from the RC. Use RC reversals (either in firmware or in the RC, either will work) to get the controls to move in the right direction from pilot input.

If you go in that order you’ll be fine. If you try to do the RC first you can end up chasing your tail as you get it configured.

12

Alright, thank you for that summary.
After all, I ended up doing just what u said and it worked for me. That’s great.
But I am wondering if the reverse of rc_in affects any other things that I don’t have in mind.
Or in other words: Why does the guide explicitly warn you to not reverse the rc_in?

13

I’m not sure. There might be context related to the comment, or it’s a left over from an older version. If you don’t mind, post the link to the spot that caused you the confusion and maybe there’s a wiki edit in order.