University Application Questions

Hi Folks,


I am working in a university lab, for a PhD student, and we are currently using APM for charactering an non-standard airframe. The airframe we are working on experiences quite a considerable amount of Dutch Roll when exiting a bank.


Here are my queestions:

1. Is it possible to simply add a few lines of code that would allow yaw dampening in APM? I know that APM uses rudder to coordinate turns, but I need it to apply opposite rudder, to direction that the yaw gyro experiences. I know Micropilot and Picolopilot have it, but our micropilot doesn't fit in our airframe.


2. How hard would it be to increase the memory for datalogging? it seems that each time we make it out to the field to test, we lose a lot of data due to the log memory being full.


Thank you very much,


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  • Hi Willem,


    as Juan wrote, you could use telemetry to store you data. If you are not using telemetry, it might be able to use OpenLog directly at the telemetry port (?). It seems that OpenLog is able to use SD-cards of up to 16 GB (old firmware allows only 2 GB). That should give you the "weeks" Chris was talking about ;) I have not tried it, but I got an OpenLog and will centainly try it out in in the next weeks.






  • Hi, are you trying a kind of FBW only control? if not, bigger vertical surfaces are the easier route.If not inertia related ,normally is a lateral surface CG problem .

    Being in a Lab surely you are trying something new but bear in mind that even fighters(unflyable out of Fly By Wire) need rather big verticals .

    The best for unlimited data is to download by telemetry continously.

  • Developer

    Chris, the log wil only allow "weeks" of recording if the APM is turned off - LOL. 


    The length of time is obviously dependant on what set of messages you are recording.  Different messages are different length, and are logged at different intervals.  I typically log CTUN, NTUN, GPS, MODE, and CMD, and the log space is somewhere around 45 minutes for that message set.

  • Thanks a lot, Chris!

    I will let you know how it turns out

  • 3D Robotics

    1) That would be pretty easy. A quick way to do it would be in the Set_Servos routine of the Attitude tab.

    2) Are you erasing your log memory before going to the field? It's a 16MB chip, which should allow for weeks of continuous recording. Once you download your logs, you should clear the memory: CLI: logs/erase

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