Quick Start Guide
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Before flying, please connect to the ground station to check that there is no wind and ensure that the airspeed value is within the range of 0~3m/s (if it exceeds the range, need perform airspeed offset calibration)
Hold the pitot tube with your hand and blow air into the pitot tube. If the airspeed value changes according to the airflow speed, the inspection is complete.
The airspeed ratio of different installations and individual airspeed gauges will be somewhat different. The airspeed gauge needs to be calibrated on the first flight.
//Enable automatic airspeed calibration
- ARSPD_AUTOCAL=1
Method A: Lift off in QStabilize or QLoiter multi-axis mode and switch to FBWA (self-stabilizing A mode) to control the drone to fly and hover for about 5 minutes. After the ground station message bar prompts that the calibration is completed, execute the landing. With calibration's completion, set ARSPD_AUTOCAL to 0.
Method B: If you don’t know how to fly in FBWA mode, you can fly with the airspeed sensor enabled but not using it (ARSPD_USE=1; ARSPD_TYPE=8; do not fly in windy condition when performing this operation); the aircraft will fly using ground speed (relative ground speed), and use Loiter mode to hover for about 5 minutes after takeoff. When ground station message bar indicate the calibration is completed, perform landing. After the calibration is completed, set ARSPD_AUTOCAL to 0.
The setup and configuration described in this chapter applies to the DroneCan Airspeed sensor with a controller running PX4 firmware.
Run QGroundControl, set the parameters below. Restart the vehicle to save the configurations.
Set UAVCNN_ENABLE to Sensors automatic Config
Reboot
Set UAVCAN_SUB_ASPD to Enable
Set UAVCAN_SUB_DPRES to Enable
Reboot
If you have multiple airspeed sensors, then you can select which sensor is preferred as the primary source using ASPD_PRIMARY. Value 1, 2 and 3 reflect the order of started airspeed sensor:
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 selected sensor first and only falls back to other sensors if the selected sensor fails the 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.
Select "Q" icon > Vehicle Setup > Sensors (sidebar) to open Sensor Setup.
Click the Airspeed sensor button.
Shield the sensor from the wind (i.e. cup it with your hand). Take caution not to block any of its holes.
Click OK to start the calibration.
Once asked, blow into the tip of the pitot tube to signal the end of calibration.
Blowing into the tube is also a basic way to check that the dynamic and static ports are installed correctly. If they are swapped, then the sensor will read a large negative differential pressure when you blow into the tube, and the calibration will abort with an error.
