# VTOL attitude controller

**URL:** <https://discuss.px4.io/t/vtol-attitude-controller/21213>\
**Category:** PX4 Autopilot\
**Created:** [February 28, 2021, 5:16pm UTC](https://discuss.px4.io/t/vtol-attitude-controller/21213 "2021-02-28T17:16:15Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Junfeng1](https://discuss.px4.io/letter_avatar_proxy/v4/letter/j/7bcc69/32.png) [@Junfeng1](https://discuss.px4.io/u/Junfeng1)\
**Post date:** [February 28, 2021, 5:16pm UTC](https://discuss.px4.io/t/vtol-attitude-controller/21213/1 "2021-02-28T17:16:15Z")

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Hi !  
I have a question about the controller diagram of VTOL UAV. As you know the PX4 user guide provide most of the controller diagram of the VTOL flight controller excluding the detailed controller diagram of the part of the VTOL attitude controller which may be composed of the swich or blending of the MC controller and FW controller. So what is the specific logic of this part? It seems the user guide dosen’t mention this in detail. If you guys know about this, please give your opinion.

Thanks a lot and best regards.

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**Author:** ![notoriou5](https://discuss.px4.io/user_avatar/discuss.px4.io/notoriou5/32/5862_2.png) [@notoriou5](https://discuss.px4.io/u/notoriou5)\
**Post date:** [March 11, 2021, 7:05am UTC](https://discuss.px4.io/t/vtol-attitude-controller/21213/2 "2021-03-11T07:05:30Z")

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The MC commands are faded out during the transition. You can read up on how this works in this function:

> <https://github.com/PX4/PX4-Autopilot/blob/8816601efb8c26b709a2c1117479af115436155b/src/modules/vtol_att_control/tiltrotor.cpp#L280>

just look for _mc_\*\_weight parameters.

And then you apply those fading weights to the output here:

> <https://github.com/PX4/PX4-Autopilot/blob/8816601efb8c26b709a2c1117479af115436155b/src/modules/vtol_att_control/tiltrotor.cpp#L431>

Hope this helps 🙂