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Add Acro note
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@hamishwillee
hamishwillee committed Jul 31, 2024
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9 changes: 8 additions & 1 deletion en/config_mc/pid_tuning_guide_multicopter.md
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Expand Up @@ -93,7 +93,14 @@ The related parameters for the tuning of the PID rate controllers are:

The rate controller can be tuned in [Acro mode](../flight_modes_mc/acro.md) or [Manual/Stabilized mode](../flight_modes_mc/manual_stabilized.md):

- _Acro mode_ is the best way because it allows for isolated rate control testing, but it is significantly harder to pilot. If you choose this mode, make sure to [disable all stick expo and have reasonable maximum rates for all axes](../flight_modes_mc/acro.md#stick-input-mapping). From PX4 1.15 on the defaults are set for this purpose to a maximum rate of 100°/s linear mapping for all axes.
- _Acro mode_ is preferred because it allows for isolated rate control testing.
However it is significantly harder to pilot.

::: warning
If you choose this mode, you must [disable all stick expo and have reasonable maximum rates for all axes](../flight_modes_mc/acro.md#stick-input-mapping).
For PX4 v1.15 and later the defaults are set for this purpose to a maximum rate of 100°/s linear mapping for all axes.
:::

- _Manual/Stabilized mode_ is simpler to fly, but it is also much more difficult to distinguish if attitude or rate controller causes a certain behavior.

If the vehicle does not fly at all:
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34 changes: 24 additions & 10 deletions en/flight_modes_mc/acro.md
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Expand Up @@ -27,7 +27,21 @@ Manual control input is required (such as RC control, joystick):

## Stick Input Mapping

The default roll, pitch, and yaw input stick mapping for Acro mode is shown below. The curve enables a high turn rate at maximum stick input for performing acrobatic maneuvers, and a zone of lower sensitivity close to the stick center for small corrections.
The default values for expo and rate [parameters](#parameters) are _beginner friendly_, reducing the chance that users will flip the vehicle when first trying this mode, or when using Acro mode for manual rate tuning.

Unfortunately they are poor for Acro flying though!
The following values are more reasonable for experienced users:

- [MC_ACRO_R_MAX](#MC_ACRO_R_MAX): `720` (2 turns per second)
- [MC_ACRO_P_MAX](#MC_ACRO_P_MAX): `720` (2 turns per second)
- [MC_ACRO_Y_MAX](#MC_ACRO_Y_MAX): `540` (2 turns per second)
- [MC_ACRO_EXPO](#MC_ACRO_R_MAX): `0.69`
- [MC_ACRO_EXPO_Y](#MC_ACRO_EXPO_Y): `0.69`
- [MC_ACRO_SUPEXPO](#MC_ACRO_SUPEXPO): `0.69`
- [MC_ACRO_SUPEXPOY](#MC_ACRO_SUPEXPOY): `0.7`

The roll, pitch, and yaw input stick mapping for Acro mode using the values above are shown below.
The curve enables a high turn rate at maximum stick input for performing acrobatic maneuvers, and a zone of lower sensitivity close to the stick center for small corrections.

![Acro mode - default input curve](../../assets/flight_modes/acro_mc_input_curve_expo_superexpo_default.png)

Expand All @@ -47,12 +61,12 @@ You can experiment with the relationships [here](https://www.desmos.com/calculat

## Parameters

| Parameter | Description |
| ----------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| <a id="MC_ACRO_EXPO"></a>[MC_ACRO_EXPO](../advanced_config/parameter_reference.md#MC_ACRO_EXPO) | Acro mode "exponential" factor for tuning the stick input curve shape for roll and pitch. Values: 0 Purely linear input curve 1 Purely cubic input curve. Default: 0.69. |
| <a id="MC_ACRO_EXPO_Y"></a>[MC_ACRO_EXPO_Y](../advanced_config/parameter_reference.md#MC_ACRO_EXPO_Y) | Acro mode "exponential" factor for tuning the stick input curve shape for yaw. Values: 0 Purely linear input curve 1 Purely cubic input curve. Default: 0.69. |
| <a id="MC_ACRO_SUPEXPO"></a>[MC_ACRO_SUPEXPO](../advanced_config/parameter_reference.md#MC_ACRO_SUPEXPO) | Acro mode "SuperExpo" factor for refining stick input curve shape for the roll and pitch axes (tuned using `MC_ACRO_EXPO`. Values: 0 Pure Expo function, 0.7 reasonable shape enhancement for intuitive stick feel, 0.95 very strong bent input curve only near maxima have effect. Default: 0.7. |
| <a id="MC_ACRO_SUPEXPOY"></a>[MC_ACRO_SUPEXPOY](../advanced_config/parameter_reference.md#MC_ACRO_SUPEXPOY) | Acro mode "SuperExpo" factor for refining stick input curve shape for the yaw axis (tuned using `MC_ACRO_EXPO_Y`. Values: 0 Pure Expo function, 0.7 reasonable shape enhancement for intuitive stick feel, 0.95 very strong bent input curve only near maxima have effect. Default: 0.7. |
| <a id="MC_ACRO_P_MAX"></a>[MC_ACRO_P_MAX](../advanced_config/parameter_reference.md#MC_ACRO_P_MAX) | Max acro pitch rate. Default: 2 turns per second (720.0 deg/s). |
| <a id="MC_ACRO_R_MAX"></a>[MC_ACRO_R_MAX](../advanced_config/parameter_reference.md#MC_ACRO_R_MAX) | Max acro roll rate. Default: 2 turns per second (720.0 deg/s). |
| <a id="MC_ACRO_Y_MAX"></a>[MC_ACRO_Y_MAX](../advanced_config/parameter_reference.md#MC_ACRO_Y_MAX) | Max acro yaw rate. Default: 1.5 turns per second (540.0 degrees/s). |
| Parameter | Description |
| ----------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| <a id="MC_ACRO_EXPO"></a>[MC_ACRO_EXPO](../advanced_config/parameter_reference.md#MC_ACRO_EXPO) | Acro mode "exponential" factor for tuning the stick input curve shape for roll and pitch. Values: `0` Purely linear input curve, `1` Purely cubic input curve. Default: `0`. |
| <a id="MC_ACRO_EXPO_Y"></a>[MC_ACRO_EXPO_Y](../advanced_config/parameter_reference.md#MC_ACRO_EXPO_Y) | Acro mode "exponential" factor for tuning the stick input curve shape for yaw. Values: `0` Purely linear input curve, `1` Purely cubic input curve. Default: `0`.69. |
| <a id="MC_ACRO_SUPEXPO"></a>[MC_ACRO_SUPEXPO](../advanced_config/parameter_reference.md#MC_ACRO_SUPEXPO) | Acro mode "SuperExpo" factor for refining stick input curve shape for the roll and pitch axes (tuned using `MC_ACRO_EXPO`). Values: 0 Pure Expo function, 0.7 reasonable shape enhancement for intuitive stick feel, 0.95 very strong bent input curve only near maxima have effect. Default: `0`. |
| <a id="MC_ACRO_SUPEXPOY"></a>[MC_ACRO_SUPEXPOY](../advanced_config/parameter_reference.md#MC_ACRO_SUPEXPOY) | Acro mode "SuperExpo" factor for refining stick input curve shape for the yaw axis (tuned using `MC_ACRO_EXPO_Y`). Values: `0` Pure Expo function, `0.7` reasonable shape enhancement for intuitive stick feel, `0.95` very strong bent input curve only near maxima have effect. Default: `0`. |
| <a id="MC_ACRO_P_MAX"></a>[MC_ACRO_P_MAX](../advanced_config/parameter_reference.md#MC_ACRO_P_MAX) | Max acro pitch rate. Default: `100.0` deg/s. |
| <a id="MC_ACRO_R_MAX"></a>[MC_ACRO_R_MAX](../advanced_config/parameter_reference.md#MC_ACRO_R_MAX) | Max acro roll rate. Default: `100` deg/s. |
| <a id="MC_ACRO_Y_MAX"></a>[MC_ACRO_Y_MAX](../advanced_config/parameter_reference.md#MC_ACRO_Y_MAX) | Max acro yaw rate. Default: `100` deg/s. |

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