Move PX4 Guide source into /docs (#24490)

* Add vitepress tree * Update existing workflows so they dont trigger on changes in the docs path * Add nojekyll, package.json, LICENCE etc * Add crowdin docs upload/download scripts * Add docs flaw checker workflows * Used docs prefix for docs workflows * Crowdin obvious fixes * ci: docs move to self hosted runner runs on a beefy server for faster builds Signed-off-by: Ramon Roche <mrpollo@gmail.com> * ci: don't run build action for docs or ci changes Signed-off-by: Ramon Roche <mrpollo@gmail.com> * ci: update runners Signed-off-by: Ramon Roche <mrpollo@gmail.com> * Add docs/en * Add docs assets and scripts * Fix up editlinks to point to PX4 sources * Download just the translations that are supported * Add translation sources for zh, uk, ko * Update latest tranlsation and uorb graphs * update vitepress to latest --------- Signed-off-by: Ramon Roche <mrpollo@gmail.com> Co-authored-by: Ramon Roche <mrpollo@gmail.com>
2026-06-01 19:07:45 +08:00 · 2025-03-13 16:08:27 +11:00
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+# 地形跟随/保持
+
+PX4 supports [Terrain Following](#terrain_following) and [Terrain Hold](#terrain_hold) in [Position](../flight_modes_mc/position.md) and [Altitude modes](../flight_modes_mc/altitude.md), on _multicopters_ and _VTOL vehicles in MC mode_ that have a [distance sensor](../sensor/rangefinders.md).
+
+:::info
+PX4 does not "natively" support terrain following in missions.
+_QGroundControl_ can be used to define missions that _approximately_ follow terrain (this just sets waypoint altitudes based on height above terrain, where terrain height at waypoints is obtained from a map database).
+:::
+
+<a id="terrain_following"></a>
+
+## Terrain Following
+
+_Terrain following_ enables a vehicle to automatically maintain a relatively constant height above ground level when traveling at low altitudes.
+This is useful for avoiding obstacles and for maintaining constant height when flying over varied terrain (e.g. for aerial photography).
+
+:::tip
+This feature can be enabled in [Position](../flight_modes_mc/position.md) and [Altitude modes](../flight_modes_mc/altitude.md), on _multicopters_ and _VTOL vehicles in MC mode_ that have a [distance sensor](../sensor/rangefinders.md).
+:::
+
+When _terrain following_ is enabled, PX4 uses the output of the EKF estimator to provide the altitude estimate, and the estimated terrain altitude (calculated from distance sensor measurements using another estimator) to provide the altitude setpoint.
+As the distance to ground changes, the altitude setpoint adjusts to keep the height above ground constant.
+
+At higher altitudes (when the estimator reports that the distance sensor data is invalid) the vehicle switches to _altitude following_, and will typically fly at a near-constant height above mean sea level (AMSL) using an absolute height sensor for altitude data.
+
+:::info
+More precisely, the vehicle will use the available selected sources of altitude data as defined in [Using PX4's Navigation Filter (EKF2) > Height](../advanced_config/tuning_the_ecl_ekf.md#height).
+:::
+
+Terrain following is enabled by setting [MPC_ALT_MODE](../advanced_config/parameter_reference.md#MPC_ALT_MODE) to `1`.
+
+<a id="terrain_hold"></a>
+
+## Terrain Hold
+
+_Terrain hold_ uses a distance sensor to help a vehicle to better maintain a constant height above ground in altitude control modes, when horizontally stationary at low altitude.
+This allows a vehicle to avoid altitude changes due to barometer drift or excessive barometer interference from rotor wash.
+
+:::info
+This feature can be enabled in [Position](../flight_modes_mc/position.md) and [Altitude modes](../flight_modes_mc/altitude.md), on _multicopters_ and _VTOL vehicles in MC mode_ that have a [distance sensor](../sensor/rangefinders.md).
+:::
+
+When moving horizontally (`speed >` [MPC_HOLD_MAX_XY](../advanced_config/parameter_reference.md#MPC_HOLD_MAX_XY)), or above the altitude where the distance sensor is providing valid data, the vehicle will switch into _altitude following_.
+
+Terrain holding is enabled by setting [MPC_ALT_MODE](../advanced_config/parameter_reference.md#MPC_ALT_MODE) to `2`.
+
+:::info
+_Terrain hold_ is implemented similarly to [terrain following](#terrain_following).
+It uses the output of the EKF estimator to provide the altitude estimate, and the estimated terrain altitude (calculated from distance sensor measurements using a separate, single state terrain estimator) to provide the altitude setpoint.
+If the distance to ground changes due to external forces, the altitude setpoint adjusts to keep the height above ground constant.
+:::