mirror of
https://github.com/PX4/PX4-Autopilot.git
synced 2026-09-25 20:28:26 +08:00
69 lines
4.8 KiB
Markdown
69 lines
4.8 KiB
Markdown
# Land Mode (Fixed-Wing)
|
|
|
|
<img src="../../assets/site/position_fixed.svg" title="Position estimate required (e.g. GPS)" width="30px" />
|
|
|
|
The _Land_ flight mode causes the vehicle to descend at the position where the mode was engaged, following a circular path until touchdown.
|
|
After landing, vehicles will disarm after a short timeout (by default).
|
|
|
|
:::warning
|
|
Fixed-wing _land mode_ should only be used in an **emergency**!
|
|
The vehicle will descend around the current location irrespective of the suitability of the underlying terrain, and touch down while following a circular flight path.
|
|
|
|
Where possible, instead use [Return mode](../flight_modes_fw/return.md) with a predefined [Fixed-wing mission landing](../flight_modes_fw/mission.md#mission-landing).
|
|
:::
|
|
|
|
::: info
|
|
|
|
- Mode is automatic - no user intervention is _required_ to control the vehicle.
|
|
- Mode requires at least a valid local position estimate (does not require a global position).
|
|
- Flying vehicles can't switch to this mode without valid local position.
|
|
- Flying vehicles will failsafe if they lose the position estimate.
|
|
- Mode prevents arming (vehicle cannot be armed while this mode is selected).
|
|
- RC control switches can be used to change flight modes on any vehicle.
|
|
- RC stick movement is ignored.
|
|
- The mode can be triggered using the [MAV_CMD_NAV_LAND](https://mavlink.io/en/messages/common.html#MAV_CMD_NAV_LAND) MAVLink command, or by explicitly switching to Land mode.
|
|
|
|
<!-- https://github.com/PX4/PX4-Autopilot/blob/main/src/modules/commander/ModeUtil/mode_requirements.cpp -->
|
|
|
|
:::
|
|
|
|
## Technical Summary
|
|
|
|
Land mode causes the vehicle follow a descending circular path (corkscrew) until touchdown.
|
|
|
|
When the mode is engaged, the vehicle starts to loiter around the current vehicle position with loiter radius [NAV_LOITER_RAD](#NAV_LOITER_RAD) and begins to descend with a constant descent speed.
|
|
The descent speed is calculated using [FW_LND_ANG](#FW_LND_ANG) and the set landing airspeed [FW_LND_AIRSPD](#FW_LND_AIRSPD).
|
|
The vehicle will flare if configured to do so (see [Flaring](../flight_modes_fw/mission.md#flaring-roll-out)), and otherwise proceed circling with the constant descent rate until landing is detected.
|
|
|
|
[Manual nudging](../flight_modes_fw/mission.md#automatic-abort) and [automatic land abort](../flight_modes_fw/mission.md#nudging) are not available in land mode.
|
|
|
|
<!-- AUTO-GENERATED: mode_requirements_fixed_wing_auto_land -->
|
|
|
|
### Mode Requirements
|
|
|
|
The following requirements must be met to arm in this mode, or to switch to this mode when it is armed.
|
|
|
|
- [`mode_req_angular_velocity`](../flight_modes/mode_requirements.md#mode_req_angular_velocity) — Angular velocity
|
|
- [`mode_req_attitude`](../flight_modes/mode_requirements.md#mode_req_attitude) — Attitude/pose
|
|
- [`mode_req_local_alt`](../flight_modes/mode_requirements.md#mode_req_local_alt) — Local altitude relative to EKF2 origin ('0') position
|
|
- [`mode_req_local_position_relaxed`](../flight_modes/mode_requirements.md#mode_req_local_position_relaxed) — Position relative to EKF2 origin ('0') point but accepts poor accuracy
|
|
- [`mode_req_prevent_arming`](../flight_modes/mode_requirements.md#mode_req_prevent_arming) — Mode prevents arming
|
|
|
|
<!-- END AUTO-GENERATED: mode_requirements_fixed_wing_auto_land -->
|
|
|
|
### Parameters
|
|
|
|
Land mode behaviour can be configured using the parameters below.
|
|
|
|
| Parameter | Description |
|
|
| ----------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------ |
|
|
| <a id="NAV_LOITER_RAD"></a>[NAV_LOITER_RAD](../advanced_config/parameter_reference.md#NAV_LOITER_RAD) | The loiter radius that the controller tracks for the whole landing sequence. |
|
|
| <a id="FW_LND_ANG"></a>[FW_LND_ANG](../advanced_config/parameter_reference.md#FW_LND_ANG) | The flight path angle setpoint. |
|
|
| <a id="FW_LND_AIRSPD"></a>[FW_LND_AIRSPD](../advanced_config/parameter_reference.md#FW_LND_AIRSPD) | The airspeed setpoint. |
|
|
| <a id="FW_AIRSPD_FLP_SC"></a>[FW_AIRSPD_FLP_SC](../advanced_config/parameter_reference.md#FW_AIRSPD_FLP_SC) | Factor applied to the minimum airspeed when flaps are fully deployed. Necessary if FW_LND_AIRSPD is below FW_AIRSPD_MIN. |
|
|
|
|
## See Also
|
|
|
|
- [Land Mode (MC)](../flight_modes_mc/land.md)
|
|
- [Land Mode (VTOL)](../flight_modes_vtol/land.md)
|