Hello, I am building a thrust vector belly sitter but am running into trouble with the motor outputs.
The vehicle has two, wing mounted motors, tilted by servos.
The autopilot is a Pixracer R15, running Arduplane 4.4.4 (flashed a few days ago with latest stable).
Following the instructions here I have set the following:
Q_TAILSIT_ENABLE → 1
Q_TAILSIT_MOTMX → 0
Q_FRAME_CLASS → 10
Q_FRAME_TYPE → 1
Also, following the instructions here I have setup the outputs as follows (channel - servo function - description):
1 - 77 - Elevon Left
2 - 75 - Motor tilt left
3 - 73 - Motor throttle left
4 - 74 - Motor throttle right
5 - 76 - Motor tilt right
6 - 78 - Elevon right
When I boot, I get the following strange messages in Mission Planner:
PreArm: SERVO2_FUNCTION=75 on disabled channel PreArm: SERVO1_FUNCTION=77 on disabled channel
The channels in the messages correspond to my left elevon and motor tilt.
When arming, I can:
spin both motors via RC.
Get correct responses from right elevon via RC.
Get correct responses from right elevon in STABILIZE
Get the right tilt servo to move when switching between MANUAL and QSTABILIZE
However, I am getting nothing on the left elevon and tilt servo.
Also, before I set the correct Q_x params, I had proper functionality on the left elevon (servo channel 1). As soon as I set the Q_x params and rebooted, my elevon was inoperable and these messages started.
Does anyone know what might be causing these strange messages?
Possibly answering my own question, I think I got it. I saved and then did a reset of the params and started again from scratch.
Second time round, I did not get the same errors and now elevons and tilt servos respond properly. Comparing the two sets of params, I think the reason for the error was that in the old set (the one giving the error message) I had:
Q_TILT_ENABLE → 1
Q_TAILSIT_ENABLE → 0
whereas, in the new set (no error message):
Q_TILT_ENABLE → 0
Q_TAILSIT_ENABLE → 1
The key to make a QuadPlane a tailsitter is to either set Q_FRAME_CLASS =10 or Q_TAILSIT_MOTMX non-zero. That tells the QuadPlane code to use the tailsitter VTOL backend.
To make a QuadPlane a tailsitter is to set Q_TAILSIT_ENABLE to “1” or “2” to tell the QuadPlane code to use the tailsitter VTOL backend.
Now, since I am on Arduplane 4.4.4, I set Q_TAILSIT_ENABLE → 1 but I also had Q_TILT_ENABLE → 1 from having followed the guide in section “Setting up a Tilt-Rotor”. If both these are enabled, Arduplane complains that one of them should be set to 0 as has been reported in this thread. So, in the old version I set Q_TAILSIT_ENABLE → 0 but had left other settings configured.
It seems that Arduplane 4.2 introduced this change in configuration but parts of the documentation have not caught up with it.
docs are correct, BUT,you do have to know what TYPE of vehicle you have Tailsitter or Tilt rotor…they are not the same thing, hence two different pages in the wiki
I guess the nomenclature is somewhat confusing. I would have thought the thrust vectoring of TVBS counts as a tilt rotor. Tail sitters come in vectored and non-vectored flavours and tilting rotors is a method of getting vectored thrust.
the wiki is very clear on not confusing a vectored yaw tailsitter as a tiltrotor…right at the top of the tiltrotor page is this note: This is distinct from tailsitters where the autopilot and main fuselage change orientation when moving between hover and forward flight. Do not use the information below for a Tailsitter, some parameters are shared, but use the instructions in the Tailsitter Planes.