Report on using COMPASS_LEARN=3 (In-Flight Learning)

ArduCopter Copter 4.1
1

I was able to use COMPASS_LEARN=3 for “In-Flight Learning” - here’s my report:

  1. The process started almost immediately after taking off in Alt-Hold - and the Here-3 LED lights flashed blue and red during the process.

  2. The MavLink messages reported by Yaapu telemetry were helpful and informative - reporting calibration progress 3 or 4 times as the learning process continued. Finally - after about 3 or 4 minutes - a MavLink message reported it had completed.

  3. The process set one parameter out of range: COMPASS_OFS_Z. The MavExplorer MagFit utility has always been reporting that this parameter should be about 500 on this copter - and the range only goes up to 400. Mission Planner issues a severe caution about exceeding this parameter - but will allow it. I’ve never set it beyond the published range. I’m curious to see if it makes any different tomorrow on a test mission flight or loiters.

  4. The only parameters that appeared to have been updated were the COMPASS_OFSxxxx parameters. There were no changes to COMPASS_DIAxxx, COMPASS_ODIxxx or COMPASS_MOTxxx.

I don’t know if these parameters were unchanged because their values (from MagFit) were already OK - or if the “In-Flight Learn” process does not include them. Until I can find out, I’ll still need to run MagFit to ensure all the compass calibration parameters are set properly.

Thank you.

2

It’s common for these to not change and if they do it’s typically not significant.

This is not directly related to the Compass calibration routine but a separate operation.

3

Ok - but it would be important to know if they are included in the in-flight learning process. Do you know if they are?

I’ve run the MOT calibration on Mission Planner - but MagFit includes it too - and much easier.