4.8 KiB
Airspeed Sensors
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!
Hardware Options
Recommended digital airspeed sensors include:
- Based on Pitot tube
- Based on Venturi effect
- TFSLOT Venturi effect airspeed sensor.
Configuration
Enable Airspeed Sensors
Airspeed sensor drivers are not started automatically. Enable each type using its corresponding parameter:
- Sensirion SDP3X: SENS_EN_SDP3X
- TE MS4525: SENS_EN_MS4525DO
- TE MS5525: SENS_EN_MS5525DS
- Eagle Tree airspeed sensor: SENS_EN_ETSASPD
You should also check 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, 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 started3: 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 is used to configure the checks).
The selected sensor is then used to supply data to the estimator (EKF2) 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).
The specific configuration for sensors that do not have a separate page is listed below:
- Sensirion SDP3X: CAL_AIR_CMODEL (provides overview of required settings), CAL_AIR_TUBED_MM, CAL_AIR_TUBELEN.
Calibration
Airspeed sensors should be calibrated by following the instructions: Basic Configuration > Airspeed.