Hey guys, i have recently solved all the GPS issues by replacing the MediaTek GPS unit to the uBlox. I have had a 100% success rate so far with GPS reliability.
However, when using the RTL feature, i noticed my quad just fell out of the sky. It attempted to turn to the direction of home, but just "fell". It did not do it every time. I have also had issues with the altitude hold.
Is there some tests i can do for altitude and maybe some kind of calibration?
Thanks!
Replies
Decrease the min. and max pitch angles. Set a higher ALT_HOLD_RTL parameter value. Do not use the "default altitude" feature (uncheck it) when planning missions - apparently?? it affects the ALT_HOLD_RTL parameter. Do verify the value of the parameter again after writing the mission. The unit it centimeters so eg. 20000 is a normal value...
If you cant live with the steep ups and downs in RTL, I suggest you set a waypoint over your launch location and use that instead, and use RTL only for emergencies. The steep climb is good in hilly terrain, as otherwise the plane may fly into a hill even if ALT_HOLD_RTL was set high enough.
Also, do check that the altimeter shows correct altitude at ground before start. APM will use an early GPS altitude for barometer calibration. A little _too_ early sometimes. After a little more time the GPS alt. will be better but the baro offset error will remain. I check the altimeter after init and if off by more than 20 meters, push the reset button. That will cause a better GPS fix to be used when the barometer is calibrated again and the creep as GPS improves is eliminated.
Regards, Soren