Version 2.5 of the ArduCopter code is now available in the AP Mission Planner and in the downloads area!



  1. The first ArduCopter code release optimized for the APM 2.  Leans and drift should be much reduced or even eliminated for most users.  This was accomplished through a number of core improvements to the DCM implementation by Tridge like this one and this one.
  2. Loiter and waypoint following should be improved due to a D term bug fix, some tuning and the improved DCM performance mentioned above.
  3. On start-up, the yaw heading is updated with first successful mag read (so you should no longer see the slow rotation from north to your actual heading).
  4. Increased output rate to ESCs to 490hz.  This update rate is also user selectable using the new RC_SPEED parameter.
  5. hexa copter stability patch bug fix (should resolve slight flattening when pitching forward and accelerating very rapidly).
  6. improved baro filtering
  7. fix to dataflash logging of Mag heading
  8. addition of H1 swash plate type and bug fix for proactive yaw compensation for collective pitch changes for TradHelis.



The default PIDs are optimized for a 3DR/Jdrones quad with 850 motors and 10" props. If you're using more powerful motors/props, start by turning down Rate Roll P in 25% steps.

While some testers have reported very good flights with the default PIDs, some have reported that this release is a little "sharper" due to the DCM improvements and have found they needed to:

     reduce stabilize P by 10% (i.e. 4.5 -> 4.2)

     reduce stabilize D by 30% (i.e. 0.15 -> 0.10)

     increase rate D from 0 to 0.001

Tuning loiter can be tricky.  Refer to the discussions which will appear below for more community feedback on what parameters work best.


Please post your feedback in this discussion.  For enhancement requests  and bug report, please add them to the arducopter issues list.  When possible please include logs (tlog and/or dataflash) and tell us whether you're using APM1 or APM2 and what version of the software you're using (presumably 2.5 but tell us anyway!).


Thanks for this release go to the developers (both in the core team but also those who have provided bug fixes through the issues list) and also the community members who participated in the previous release thread and provided some great detailed information in the form of issue reports and logs which allowed us to nail some bugs!


Views: 131006

Reply to This

Replies to This Discussion

Hi Marco, YES! I have strange yaw behaviour on my APM1. Very slight wandering from left to right in hover and sometime exaggerated in FFF. I'd not mentioned it yet as I've just completed a full rebuild on a 3DR and was eliminating any hardware cocks-ups before i reported. 

It doesn't happen every flight, but it does happen. I've also noticed a very slight 'wander' on roll and pitch, a bit like the old 2.2b6 rate_D twitch, but with out any rate_D. Again I suspected a build error. I'll clear all my logs and see if i can recreate some of this for your perusal.

Hi Marco. I have been flying since the early days and just upgraded my APM1 1280 board to a APM2 and put 2.5 on it. Simple mode used to work great for me, always maintaining forward as the initial direction. With the APM2 I find that it works fine sometimes, but other times it seems to forget the start direction entirely, and suddenly control forward is quad forward. Any suggestions on how to fix this would be appreciated. I attached some recent logs.


Just saw v2.5.1 beta is up.  What's changed since v2.5, and is it recommended to use this version over v2.5? Thanks

Thanks devs! just took my 3DR quad out with 2.5 on. A lot steadier and smoother in a hover. I used to have a drift to the left which needed 3/4 trim to keep it kinda still, this is now gone. It just sits where I leave it (with a small amount of drift eventually)

Throwing it around is also a lot more fun. It is a lot sharper on changing direction. Makes the old version feel like it was in water. Changing altitude is also a lot better if you stab the throttle. Seems a lot quicker at doing that.

Thanks again. Roll on weekend!


Are you using the APM1 or APM2? 

Can you tell me if this does help with the APM 1

APM1 2560. Would like a 2 but 12 week wait :( 

Just need to watch out for the alt-hold and throttle trim stuff. It might be a good idea if they made the defaults higher or the "learning" quicker? After 12 minutes of flying mine still dropped out the sky (sky is knee height) because the motors shut down.

So yes, it does help with APM1 :D



Hi there. Great job Dev Team, you guys are legends, and every new update is like a Christmas present that keeps on coming!

Does anyone have recommended PID's for the Droidworx Hex AD-6, with jDrones 850Kv motors under 10" props?

thank you!



2.5 is amazing firmware when it comes to easy flying.  The quads attitude is holding very well compared to 2.4.

Is the altitude hold fixed in the 2.5.1 firmware? When do you expect to have it available in the Mission Planner.? 

ArduCopter V2.5.1ß "yaw issue" (compass):

Reading your comments and reports on the dev list now that I think yaw is very involved in the dcm, so it is centered just two parameters that are within the dcm library, specifically in the file "AP_AHRS_DCM.h", in the line #20 and #27.
The complicated thing is find the correct parameters for your quad.
It's just a PI controller, the compass corrects the yaw as calculated by gyros in the dcm.
So if you feel the yaw is getting corrected too aggressively you just decrease these two parameters.
If you turn them to zero, then there is no correction done at all (thanks Justin for this):

_kp_yaw = 0.4;
_ki_yaw = _gyro_drift_limit * 8;

Unfortunately I am busy two days for an important job and I do not have time to play with these two values, but I hope some of you, of course expert, try to hit the correct parameters for your quads and let your impressions and value here.
Do not increase too much these two parameters and I repeat, this thing is only recommended for advanced users.
I await your report, thanks!


I will try this on the weekend, thanks.

Can I ask how Stabilise Yaw is involved in heading hold? Shouldn't it always hold the same heading (assuming it shows correctly in planner) even if gyro does not compensate correctly/enough? So why does it yaw without input _and_ show the correct new heading in planner _and_ hold the new angle?

Or in other words - gyro compensates for angle change, so it will help hold a heading, but it is not as precise. If we have a compass active it should return even if gyro is not perfect. Or not?


just returned from field and very glad with stabilize mode. Loiter not so good, starting circles with diameter cca 12 meters.

Wind was 1-2 m/s.

RTL good, very satisfied, AH seems to be good too, not that accurate because of sonar lack, just baro.

But AUTO doesn't work at all. When switched to AUTO, tricopter began descend, not too hurry, to me appeared like it want to land but I don't have AUTO_LAND even set in my flight modes.

Here is my setup:

Tricopter classic (not Y6), arms 40cm, TOW cca 1100g

APM 1.4 (2560), IMU Shield/Oilpan Rev-H

ACM 2.5.1beta


without sonar,

Default PIDs.

If someone interested I can upload logs.


© 2016   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service