Discussions

I wanted to share my experience with the loiter mode on the APM2.0 mediatek GPS onboard and APM2.5 with external uBlox GPS.

Generally the default settings included in 2.7x or 2.81 work well, altitude hold is accurate, hover is stable and stable mode is well stable. However I found the controls a little more friendly by altering the Rate_roll_p 1.55 and Rate_roll_d 0.0080.  The only disappoitment was the loiter mode which wouldn't hold position without constantly twitching or continuous making corrections in short shape jerking motion.  Using channel 6 I spent several days tuning different rates e.g rate loite p, with no improvement.  When I did manage to filter out the twitch the position hold was no longer acceptable, it would drift 10s of meters in random directions, completely useless.

As I've got money to burn, I decided to try the APM2.5 with the external GPS unit, I used exactly the same settings as above, and guess what, no twitch, the quad held position within a few meters even in a strong breeze.  

I'm happy I found a solution and at the same time unhappy that I didn't see this issue flagged in the forum before my original purchase which might have guided me towards the ublox GPS setup.  

Well now I'm looking for a solution for the APM2 with meidatek GPS?  Does anyone know if there's a software fix planned for the Mediatek GPS loiter bug or perhaps I could get a refund.

Quadcopter setup:

DT750 balanced

APC 1045 props balanced

Aluminium arms fibre glass chassis 1.5Kg without battery

3Sor4S 3300-5000 mah battery

APM board isolated by rubber dampeners  

Flight time 7-10mins depending on battery, type of flight and camera

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