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4.7:Copter_trim #6622

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3 changes: 3 additions & 0 deletions common/source/docs/common-auxiliary-functions.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -296,6 +296,8 @@ Supported Features
+----------------------+----------------------------+----------+---------+---------+
| 181 | VTOL QuickTune | | X | |
+----------------------+----------------------------+----------+---------+---------+
| 182 | AHRS AutoTrim | X | | |
+----------------------+----------------------------+----------+---------+---------+


Intended as continuous PWM range control inputs:
Expand Down Expand Up @@ -594,6 +596,7 @@ Other functions are:
ICEngine start / stop Controls ICE engine starter output :ref:`ICE engines<common-ice>`
Autotune_test_gains After autotune,allows selecting tune(high) or pretune gains
VTOL QuickTune Autotunes QuadPlane VTOL PIDs, see :ref:`quicktune`
AHRS AutoTrim Auto Trim for Copter, see :ref:`autotrim`
ROLL Input ROLL input channel. (replaces RCMAP)
PITCH Input PITCH input channel. (replaces RCMAP)
THROTTLE Input THROTTLE input channel. (replaces RCMAP)
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66 changes: 29 additions & 37 deletions copter/source/docs/autotrim.rst
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Expand Up @@ -10,69 +10,61 @@ Wind of course has a strong effect on your copter and will push it around. Howev

For most users this procedure is not necessary because the :ref:`accelerometer calibration <common-accelerometer-calibration>` does a good job of setting the trim values.

Save Trim
~~~~~~~~~
AHRS AutoTrim
~~~~~~~~~~~~~

Save trim is the simpler method and involves essentially transferring your radio transmitter's trims to the autopilot (`video demo here <https://www.youtube.com/watch?v=ayA0uYOqKX4>`__).
With AHRS AutoTrim the roll and pitch corrections are captured as you fly in a stable hover. Setup a :ref:`common-auxiliary-functions` switch to "In Flight AHRS trim adjust" ("182"). We will use CH7 in the following:

1. Check that your CH7 switch goes above 1800 on the MissionPlanner's Hardware > Mandatory Hardware > Radio Calibration screen

.. image:: ../images/MP_SaveTrim_Ch7PWMCheck.png
:target: ../_images/MP_SaveTrim_Ch7PWMCheck.png

2. Set the CH7 Option to Save Trim on the Software > Copter Pids screen and press the "Write Params" button
2. Set the CH7 Option to "AHRS AutoTrim" on the Software > Copter Pids screen and press the "Write Params" button

.. image:: ../images/MP_SaveTrim_Ch7.png
:target: ../_images/MP_SaveTrim_Ch7.png
3. Find a wind free environment with sufficient space to fly your copter without crashing into something

3. With your CH7 switch in the off position, fly your copter in Stabilize mode and use your transmitters's roll and pitch trim to get it flying level
4. Put the vehicle in STABILIZE or ALT_HOLD mode.

4. Land and put your throttle to zero
5. Arm the vehicle and lift into a hover. The vehicle must be flying in order to enable autotrim. Flip the switch that you setup(CH7) to its High position (>1800us). "Autotrim running" message will be sent to the GCS.

5. Release the roll and pitch sticks and switch the CH7 switch high for at least 1 second. The words "Trim saved" should appear in the MP's Flight Data screen's Messages tab
6. Fly your copter for about 25 seconds in a stable hover in position, keeping it from drifting with the pitch and roll sticks. As the trim is adjusted, less and less corrections with the sticks will be required.

6. Reset your transmitters roll and pitch trims back to the center and fly again and it should fly level now. If it does not repeat steps 3, 4 & 5
7. Once satisfied, flip the switch low, saving the trims, and land. "Trim save" message will be sent to the GCS.

Auto Trim
~~~~~~~~~

With auto trim the roll and pitch trim are captured as you fly in a stable hover.

1. Find a wind free environment with sufficient space to fly your copter without crashing into something

2. Put the vehicle in Stabilize mode
8. Take off again in stabilize mode and check if your copter is flying level now. If not repeat steps 4 - 7 again.
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or AltHold mode

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done


3. Hold throttle down and rudder right for 15seconds or until you see the small red, blue and yellow leds flash in a cyclic pattern
.. note::

4. Fly your copter for about 25 seconds in a stable hover
You can manually set the trim by modifying the :ref:`AHRS_TRIM_X <AHRS_TRIM_X>` and :ref:`AHRS_TRIM_Y <AHRS_TRIM_Y>`. Roll trim is :ref:`AHRS_TRIM_X <AHRS_TRIM_X>`, Pitch trim is :ref:`AHRS_TRIM_Y <AHRS_TRIM_Y>`. Both values are in radians with left roll and forward pitch being negative numbers.

5. Land and put your throttle to zero and wait for a few seconds (the trims parameters are being saved)
.. note::

6. Take off again in stabilize mode and check if your copter is flying level now. If not repeat steps 2, 3 and 4
It is nearly impossible to get rid of all drift so that your copter remains completely motionless without any input.

.. note::
Save Trim
~~~~~~~~~
.. note:: the above AHRS AutoTrim method is preferred since it does not involve moving transmitter trims after RC calibration.

You can also test these procedures above are operational on the ground with your battery disconnected. Connect your autopilot to the mission planner and observing the Flight Data screen as you simulate completing the steps above.
Save trim involves essentially transferring your radio transmitter's trims to correct the autopilot's accelerometer trim. Normally, once :ref:`common-accelerometer-calibration` is done, you never want to change the transmitter's trims, but in this case it is done **temporarily**. The "Save Trim" function ("5") is assigned to any free RC channel, usually a switch based one, using an :ref:`common-auxiliary-functions`. For the example below, Channel 7 will be used.

.. image:: ../images/MP_SaveTrim_FlightDataScreen.jpg
:target: ../_images/MP_SaveTrim_FlightDataScreen.jpg
1. Check that your CH7 switch goes above 1800 on the MissionPlanner's Hardware > Mandatory Hardware > Radio Calibration screen

.. note::
.. image:: ../images/MP_SaveTrim_Ch7PWMCheck.png
:target: ../_images/MP_SaveTrim_Ch7PWMCheck.png

You can manually set the trim by modifying the :ref:`AHRS_TRIM_X <AHRS_TRIM_X>` and :ref:`AHRS_TRIM_Y <AHRS_TRIM_Y>`. Roll trim is :ref:`AHRS_TRIM_X <AHRS_TRIM_X>`, Pitch trim is :ref:`AHRS_TRIM_Y <AHRS_TRIM_Y>`. Both values are in radians with left roll and forward pitch being negative numbers.
2. Set the CH7 Option to Save Trim on the Software > Copter Pids screen and press the "Write Params" button

.. note::
.. image:: ../images/MP_SaveTrim_Ch7.png
:target: ../_images/MP_SaveTrim_Ch7.png

It is nearly impossible to get rid of all drift so that your copter remains completely motionless without any input.
3. With your CH7 switch in the off (Low) position, fly your copter in Stabilize mode and use your transmitters's roll and pitch trim to get it flying level

Video demonstrations of Save Trim and Auto Trim
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
4. Land and put your throttle to zero

.. youtube:: 5z0zuwicZh8
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By the way, I think these two videos are still available...

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@Hwurzburg Hwurzburg Mar 4, 2025 •
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but thet are incorrect now...need to be remade with new autotrim sections... preferably as the first section...or even without save trim, as we discussed, it might be time to depricate it

:width: 100%
5. Release the roll and pitch sticks and switch the CH7 switch high for at least 1 second. The words "Trim saved" should appear in the MP's Flight Data screen's Messages tab

.. youtube:: e3OF9ih50PU
:width: 100%
6. Reset your transmitters roll and pitch trims back to the center and fly again and it should fly level now. If it does not repeat steps 3, 4 & 5

Desktop method
~~~~~~~~~~~~~~
Expand All @@ -88,7 +80,7 @@ lower "Calibrate Level" button.
Please note though that making the HUD level while the vehicle is on the
ground does not necessarily mean it won't drift horizontally while
flying because of other small frame issues including the flight
controller not being perfectly level on the frame and slightly tilted
controller not being perfectly level on the frame, CG placement, an/ord slightly tilted
motors.

.. |MP_SaveTrim_Ch7| image:: ../images/MP_SaveTrim_Ch7.png
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