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# FixedWingLongitudinalSetpoint (UORB message)

Fixed Wing Longitudinal Setpoint message.

Used by the fw_lateral_longitudinal_control module
If pitch_direct and throttle_direct are not both finite, then the controller relies on altitude/height_rate and equivalent_airspeed to control vertical motion.
If both altitude and height_rate are NAN, the controller maintains the current altitude.

**TOPICS:** fixed_wing_longitudinal_setpoint

## Fields

| Назва                                    | Тип       | Unit [Frame] | Range/Enum                                                                     | Опис                                                                                                    |
| ---------------------------------------- | --------- | ---------------------------------------------------------------- | ------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------- |
| timestamp                                | `uint64`  | us                                                               |                                                                                | Time since system start                                                                                 |
| altitude                                 | `float32` | m                                                                |                                                                                | Altitude setpoint AMSL, not controlled directly if NAN or if height_rate is finite |
| height_rate         | `float32` | m/s [ENU]    |                                                                                | Scalar height rate setpoint. NAN if not controlled directly                             |
| equivalent_airspeed | `float32` | m/s                                                              | [0 : inf]  | Scalar equivalent airspeed setpoint. NAN if system default should be used               |
| pitch_direct        | `float32` | rad [FRD]    | [-pi : pi] | NAN if not controlled, overrides total energy controller                                                |
| throttle_direct     | `float32` | norm                                                             | [0 : 1]    | NAN if not controlled, overrides total energy controller                                                |

## Constants

| Назва                                                              | Тип      | Значення | Опис |
| ------------------------------------------------------------------ | -------- | -------- | ---- |
| <a id="#MESSAGE_VERSION"></a> MESSAGE_VERSION | `uint32` | 0        |      |

## Source Message

[Source file (GitHub)](https://github.com/PX4/PX4-Autopilot/blob/main/msg/versioned/FixedWingLongitudinalSetpoint.msg)

:::details
Click here to see original file

```c
# Fixed Wing Longitudinal Setpoint message
#
# Used by the fw_lateral_longitudinal_control module
# If pitch_direct and throttle_direct are not both finite, then the controller relies on altitude/height_rate and equivalent_airspeed to control vertical motion.
# If both altitude and height_rate are NAN, the controller maintains the current altitude.

uint32 MESSAGE_VERSION = 0

uint64 timestamp # [us] Time since system start

float32 altitude # [m] Altitude setpoint AMSL, not controlled directly if NAN or if height_rate is finite
float32 height_rate # [m/s] [@frame ENU] Scalar height rate setpoint. NAN if not controlled directly
float32 equivalent_airspeed # [m/s] [@range 0, inf] Scalar equivalent airspeed setpoint. NAN if system default should be used
float32 pitch_direct # [rad] [@range -pi, pi] [@frame FRD] NAN if not controlled, overrides total energy controller
float32 throttle_direct # [norm] [@range 0,1] NAN if not controlled, overrides total energy controller
```

:::