How to Configure Airspeed Sensor — Mission Planner Ground Station

I. Principle

The Pitot tube is used to measure the drone's airspeed (airspeed) during flight and is one of the critical sensors for fixed-wing UAVs. The Pitot tube determines the relative flight speed by measuring the difference between dynamic pressure and static pressure in front of the aircraft.

The ArduPilot flight controller uses data collected from the Pitot tube to precisely control the drone's flight, such as improving stability in automatic flight modes, optimizing cruise efficiency, and enhancing safety and flight endurance.

II. Equipment Preparation

1. Flight Controller: Any flight controller from the CoreWing F405 WING V2 / SpeedyBee F405 WING APP series is applicable to this tutorial.

2. Pitot Tube Sensor: Such as MS4525DO.

3. Ground Control Station (GCS): Mission Planner.

III. Specific Operations

3.1 Pitot Tube Installation and Wiring

3.1.1 Pitot Tube Installation

-- Images sourced from the UAV Instructor Official Account

3.1.2 Airspeed Sensor and Flight Controller Wiring

3.2 Parameter Configuration

1. Connect the flight controller to the ground station using a data cable, navigate to the Configuration/Debug page, open the All Parameters table, and search for and modify the following parameters:

Parameter Setting	Description
ARSPD_TYPE = 1	For MS4525, change to 1; for other airspeed sensors, modify according to the protocol.
ARSPD_BUS = 0	Use the flight controller's internal bus.
ARSPD_AUTOCAL = 1	Automatically calibrate airspeed during flight after takeoff.
ARSPD_USE = 0	Disable the airspeed sensor; enable it only after calibration is complete.
ARSPD_SKIP_CAL = 0	Perform indoor static calibration of the airspeed sensor upon power-up, calibrating its airspeed value in a windless state.

Important

After saving parameters, disconnect all power to the flight controller and power it on again to restart.

2. On the Flight Data page, you can view the real-time airspeed value.

3. Cover the dynamic pressure port and static pressure port of the Pitot tube with your hand to check if the airspeed sensor connection and operation are normal.

Important

If the airspeed rises linearly, it indicates that the Pitot tube connection is normal. If large fluctuations occur, check the following:

1. Hand covering holes: Ensure all holes are completely covered with no air leaks.

2. Connection: Check the airspeed sensor for loose connections or leaks between components.

3.3 Indoor Static Calibration (Ground Calibration)

1. Wrap the Pitot tube slightly with a bottle to reduce interference.

2. Power on the flight controller again.

3. Check if the airspeed fluctuates between 0~2 to complete the indoor calibration.

4. Find and set ARSPD_SKIP_CAL = 1 in the parameter table to disable indoor calibration.

Important

After saving parameters, disconnect all power to the flight controller and power it on again to restart.

3.4 Airborne Dynamic Calibration (Flight Calibration)

3.4.1 Flight Calibration

1. Take off the aircraft and switch to RTL mode once it reaches a safe flight altitude.

2. Fly the aircraft in circles for approximately 5 minutes; the longer the duration, the more accurate the calibration value.

3. Land once the time is up.

4. After landing, export the flight log to check if the calibration was successful.

3.4.2 Calibration Result Verification

1. Enter the Flight Data interface, press the small arrow, and locate the Data Flash Log interface.

2. Click to download the flash log via Mavlink.

3. Select the data for this flight and click Download these logs. Close this window after the download is complete.

4. Click Review Logs to find the log that was just downloaded.

5. In the data column on the right side of Mission Planner, click “+” to expand the list:

• First, find and expand “0” → then find and expand “ARSP” → expand “0” again, and check the “Airspeed” (red line);
• Then continue to expand “GPS” → expand “0” below it, and check “Spd” (green line).

Once completed, the interface will display both airspeed (Airspeed) and GPS ground speed (Spd) simultaneously for data comparison and analysis.

Important

Observing the curves in the image reveals a significant difference between the two data sets:

1. The checked “Airspeed” (red line) value changes slightly and stably, representing the true airspeed measured by the airspeed sensor.

2. The checked “Spd” (green line) value changes significantly because the aircraft experiences tailwinds and headwinds while circling in the air, causing large fluctuations in GPS ground speed.

3. During data analysis, focus on the ARSP 0 Mean and GPS 0 Mean values at the top of the interface. The smaller the difference between these two means, the higher the calibration accuracy of the airspeed sensor.

4. Generally, a difference within 3m/s is considered normal. If the difference significantly exceeds 3m/s, it is recommended to recalibrate the airspeed to ensure flight safety and stability.

6. Airspeed calibration is complete. Please enter the All Parameters table to modify the following parameters:

Parameter Modification	Description
Change ARSPD_AUTOCAL = 1 to 0	Disable automatic calibration during flight
Change ARSPD_USE = 0 to 1	Enable airspeed

7. Go to Configuration/Debug - Basic Parameters to adjust the desired cruise airspeed (note the unit is m/s).

3.4.3 Error Case Demonstration

1. The waveform of the data appears abnormal; airspeed is consistently lower than ground speed, affected by interference, and the Mean difference is large.

2. The airspeed sensor frequently reports errors, usually due to poor installation.

3. If the airspeed sensor value jumps after arming but was normal before arming, it may be caused by using an SD card with a slow read speed.

IV. Q&A

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