VTOL Quad - replace VT_TRANS_THR

[hamishwillee]

Hi @RomanBapst (&/or @sanderux )

Link checker shows that VT_TRANS_THR disappeared at some point. Possibly replaced by VT_F_TRANS_THR

I've marked up the bits that are affected in the tuning guide. Can you please advise how this should "properly" change.
There is a degree of urgency because we'll be cutting the PX4 v1.11 release soon, and it would be nice if the docs were accurate-ish at this point!

[xdwgood]

By the way, can we delete this in tailsitter?

This function also seems to have no effect（_thrust_transition always 0.0）：
https://github.com/PX4/Firmware/blob/master/src/modules/vtol_att_control/tailsitter.cpp#L270

[RomanBapst]

@hamishwillee

Possibly replaced by VT_F_TRANS_THR

Yes, you are absolutely right. We now have VT_F_TRANS_THR and VT_B_TRANS_THR for front-and backtransition respectively.

[hamishwillee]

Thanks @RomanBapst - can you make the changes directly in this PR by editing the page? I'd prefer that :-)

Otherwise I can do it and you review, but that's me guessing how this works, while since you "know" should be a few minutes change.

[RomanBapst]

@hamishwillee Hang on, I wasn't done yet I need to add some more info. I will collect it here and can also do the changes :-)

[RomanBapst]

Backtransition throttle VT_B_TRANS_THR:

• only used for standard vtol (you can set negative values and then you can have reverse thrust if your ESC supports that)
• tailsitters and tiltrotors use the throttle from the mc position controller

Front transition throttle VT_F_TRANS_THR:

• only used for standard VTOL, pusher throttle will be ramped to that value

[RomanBapst]

@hamishwillee Aight, please have a look

[hamishwillee]

Looks great. Thanks very much! Merging

[hamishwillee]

PS Re #702 (comment)

That is pretty interesting but not relevant to THIS doc which only applies to standard vtol (quad). You have comments about this in the param itself, so the info is captured.
There might be more work to be done in https://docs.px4.io/master/en/config_vtol/vtol_back_transition_tuning.html - a quick scan would be appreciated to confirm yay/nay :-)