# 空速传感器

Airspeed sensors are _highly recommended_ for fixed-wing and VTOL frames.
They are so important because the autopilot does not have other means to detect stall.
For fixed-wing flight it is the airspeed that guarantees lift — not ground speed!

![Digital airspeed sensor](../../assets/hardware/sensors/airspeed/digital_airspeed_sensor.jpg)

## Hardware Options

Recommended digital airspeed sensors include:

- Based on [Pitot tube](https://en.wikipedia.org/wiki/Pitot_tube)
  - I2C MEAS Spec series (e.g. [MS4525DO](https://www.te.com/usa-en/product-CAT-BLPS0002.html), [MS5525](https://www.te.com/usa-en/product-CAT-BLPS0003.html))
    - [mRo I2C Airspeed Sensor JST-GH MS4525DO](https://store.3dr.com/mro-i2c-airspeed-sensor-jst-gh-ms4525do/) (3DR store)
    - [Digital Differential Airspeed Sensor Kit - MS4525DO](https://store-drotek.com/793-digital-differential-airspeed-sensor-kit-.html) (Drotek).
    - [Holybro Digital Air Speed Sensor - MS4525DO](https://holybro.com/collections/sensors/products/digital-air-speed-sensor-ms4525do)
    - [Holybro Digital Air Speed Sensor - MS5525DSO](https://holybro.com/collections/sensors/products/digital-air-speed-sensor-ms5525dso)
  - I2C Sensirion series (e.g. SDP33)
    - [ThunderFly TFPITOT01 Lightweight Pitot Tube](https://docs.thunderfly.cz/avionics/TFPITOT01/)
    - [Drotek SDP3x Airspeed Sensor Kit](https://store-drotek.com/848-sdp3x-airspeed-sensor-kit-sdp33.html)
  - DroneCAN interface
    - [Holybro High Precision DroneCAN Airspeed Sensor - DLVR](https://holybro.com/collections/sensors/products/high-precision-dronecan-airspeed-sensor-dlvr)
    - [RaccoonLab Cyphal/CAN and DroneCAN Airspeed Sensor - MS4525DO](https://raccoonlab.co/tproduct/360882105-652259850171-cyphal-and-dronecan-airspeed-v2)
    - [Avionics Anonymous Air Data Computer with OAT probe](https://www.tindie.com/products/avionicsanonymous/uavcan-air-data-computer-airspeed-sensor/)
- Based on [Venturi effect](https://en.wikipedia.org/wiki/Venturi_effect)
  - [TFSLOT](airspeed_tfslot.md) Venturi effect airspeed sensor.

## 配置

### Enable Airspeed Sensors

Airspeed sensor drivers are not started automatically.
Enable each type using its [corresponding parameter](../advanced_config/parameters.md):

- **Sensirion SDP3X:** [SENS_EN_SDP3X](../advanced_config/parameter_reference.md#SENS_EN_SDP3X)
- **TE MS4525:** [SENS_EN_MS4525DO](../advanced_config/parameter_reference.md#SENS_EN_MS4525DO)
- **TE MS5525:** [SENS_EN_MS5525DS](../advanced_config/parameter_reference.md#SENS_EN_MS5525DS)
- **Eagle Tree airspeed sensor:** [SENS_EN_ETSASPD](../advanced_config/parameter_reference.md#SENS_EN_ETSASPD)

You should also check [ASPD_PRIMARY](../advanced_config/parameter_reference.md#ASPD_PRIMARY) is `1` (see next section - this is the default).

### Multiple Airspeed Sensors

:::warning
Experimental
Using multiple airspeed sensors is experimental.
:::

If you have multiple airspeed sensors then you can select which sensor is _preferred_ as the primary source using [ASPD_PRIMARY](../advanced_config/parameter_reference.md#ASPD_PRIMARY), where `1`, `2` and `3` reflect the order in which the airspeed sensors were started:

- `0`: Synthetic airspeed estimation (groundspeed minus windspeed)
- `1`: First airspeed sensor started (default)
- `2`: Second airspeed sensor started
- `3`: Third airspeed sensor started

The airspeed selector validates the indicated sensor _first_ and only falls back to other sensors if the indicated sensor fails airspeed checks ([ASPD_DO_CHECKS](../advanced_config/parameter_reference.md#ASPD_DO_CHECKS) is used to configure the checks).

The selected sensor is then used to [supply data to the estimator (EKF2)](../advanced_config/tuning_the_ecl_ekf.md#airspeed) and the controllers.

### Sensor-specific Configuration

Other than enabling the sensor, sensor-specific configuration is often not required.
If it is needed, it should be covered in the appropriate sensor page (for example [TFSLOT > Configuration](airspeed_tfslot.md#configuration)).

The specific configuration for sensors that do not have a separate page is listed below:

- **Sensirion SDP3X:** [CAL_AIR_CMODEL](../advanced_config/parameter_reference.md#CAL_AIR_CMODEL) (provides overview of required settings), [CAL_AIR_TUBED_MM](../advanced_config/parameter_reference.md#CAL_AIR_TUBED_MM), [CAL_AIR_TUBELEN](../advanced_config/parameter_reference.md#CAL_AIR_TUBELEN).

## Calibration

Airspeed sensors should be calibrated by following the instructions: [Basic Configuration > Airspeed](../config/airspeed.md).

## See Also

- [Using PX4's Navigation Filter (EKF2) > Airspeed](../advanced_config/tuning_the_ecl_ekf.md#airspeed)
- [Airspeed drivers](https://github.com/PX4/PX4-Autopilot/tree/main/src/drivers/differential_pressure) (source code)
- [VTOL Without an Airspeed Sensor](../config_vtol/vtol_without_airspeed_sensor.md)
