Servers by jDrones

Preflight Calibration for Airspeed sensor

I’m running Arduplane 3.4.2 with APM 2.6. When I read the information about configuring the airspeed sensor, it recommends the use of the Preflight Calibration function from Mission Planner. However, at the field, I only have access to an Andriod phone or tablet where I’m running the 3DR Tower app. Earlier versions of DroidPlanner appeared to have the ability to issue the Preflight calibration command, but it is not available in the current version.

Is there a reason this couldn’t be automatically done in the firmware? For example, I’m leaving the plane sit quietly for the GPS to initialize and lock. Couldn’t the airspeed sensor be calibrated during that time without issuing the MAV_CMD_PREFLIGHT_CALIBRATION command?

Alternatively, could this be triggered through some sort of stick command (full rudder left, full elevator down). I can’t change the Tower app, but creating a custom version of the APM firmware is within my reach.

Thanks

It’s now done automatically when you arm the Pixhawk.

Is the change described somewhere you can point me at? git commit? readme?

I’d like to see how they did it.

Thanks

Sorry I can’t provide a reference. I saw it in discussions amongst developers at some point.

You find it in Mission Planner under Actions

The plane will automatically calibrate the airspeed on startup if ARSPD_SKIP_CAL is set to 0. However this means that on startup the airspeed sensor shouldn’t be exposed to the wind.

The downside to calibrating on boot is that you will usually experience some drift on the sensor as it heats up, causing the value to be slightly off by the time you takeoff. With that said, this is still better then not calibrating.

The reason you can’t continuously calibrate on the ground is that it’s not possible to tell if there is wind blowing across the sensor.

Servers by jDrones