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!


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"Hi Randy

I tested this morning 2.6 Epsilon  Avionics: APM-1.0 with Sonar & baro - Setting: DJ 450 X config - Engine: 880 kv - Propeller: 10 * 4.5 - 11.1V 3s lipo 4500 mha batteries - PID: original and modified (there were a few breeze at times, I have loved without wind)

- I had no problems yaw (seems to be the same behavior as (2.5.4)

- Stabilize dans1.5M2 is the atitude with sonar range from + - 20cm (really good!)

-then I mostly try to improve my PIDS

- No problems either with logs I hope this helps with this essay,

I am attaching my logs, tips on PIDS would be welcome,

thank you Daniel


Try combining it with some aluminum.  Aluminum can help to block rapidly changing magnetic fields.  Though it's the more slowly changing ones that actually mess up the mag.  Anyway, worth a shot.

That'd be somethin' to be seen  ;-)


I have yaw burst issue. When i fly with stab mode hexa can make 360 degree yaw without touching any sticks.


You have a lot of compass noise and it gives inconsistent values (compared to gyro yaw). Try to recalibrate the compass in the Mission Planner (It helped me to get better compass values).

I have gone through several batteries on 2.6 Epsilon (quad 10x4.7 apm2 880kv)- so far-

Altitude hold now fixed, can add or remove weight and it holds well. I did increase AH P to .9, rest all default.

Have not seen simple mode problem that was in last version

Loiter was best I have seen lately, maybe 2m drift at worst (low wind)

Yaw seems OK, did not twist on takeoff

The latest stable mode is remarkable. I have not bothered with autotrim, balancing blades, or any of that nonsense and it will hover motionlessly in no wind- even better, it has the best sound I have heard.  How they sound in low wind is a big clue to how well it is working.

I did try 12x3.8 blades and the default pids left me with a little oscillation. I tried lowering a bit and it got better, but the 10x4.7 with pids at .18/0/.04 is still the best.

The video of the 2.6 final version is on my youtube channel...
In the description the specs of my quad.

Bests, Marco

Yes I had 0.1 for Stab roll and pitch I. I'll try setting it to 0 and see if it fixes it.

That corona 919MG looks interesting, could be worth a try for the price. I just went with the bms-385max and turnigy 380max as those were what were recommended for the kit I bought.

That does make sense about the cause of the yaw oscillation.

I will try that yaw dead band patch if you want to post it. I have just moved to 2.6 Epsilon, and the yaw oscillation has pretty much disappeared, or at least been reduced by an order of magnitude (along with the pitch spikes I was also having). I am running a lower value for stab yaw p of 5 and rate yaw p of .15. I haven't tried adding rate yaw D or I, but will give them a go and see what happens.

So I have set stab rate/roll I to 0, and it's noticeably better.

One thing I keep coming across is that perhaps the auto trim values aren't fine enough. Eg I will enter auto trim mode while hovering, and will make the smallest taps on the sticks that I can to oppose any drift, and then not touch the sticks and see if it's still drifting, but it's very hard not to cause an overshoot in any direction. If the trim that is being added as part of this process was smaller for each tap on the sticks, I think it would make it easier to get to a perfect drift-free hover without overshoot.

Good call, the rapid spiking doesn't matter too much as it all happens too quick for the avionics to be influenced, servo lag particularly in the case of my tri. But in order for everything to work (including future developments) as we all want we should strive to produce smooth curves where output occurs just after input, but produces the desired result no matter what.

And we are oh so close, with some brilliant minds on the case. 

So if you forgive me i'd like to once again give a big (drunken - can you tell?) thank you to everyone carrying out the real work in this DIY project. 

Beer's, on me.

My anecdotal experiences of 2.6eps...

APM2, stuck to tupperware with sellotape foam, tupperware bolted to frame (i.e. total disregard for antivibration - at half throttle the gps unit could give you a massage if correctly placed! I'm doing this on purpose - I call it NDT, i do balance my props and motors, it's nothing but madness not to ;).) If I can get it to work well like this, then an isolated APM and perfectly balanced, high spec frame is going to reign supreme


Light, and quite bent, (jakub) tri frame 60cm m-m.

Turnigy c2830 1050kv motors, one of which grinds a bit.

Turnigy  40a, esc's (heavy but i had them lying around) stock firmware

10*4.5 props

3s 2.2's or 2.65's (must try some 4s....)

Xbees always active, stuck right next to APM

Spectrum receiver the other side to the xbees

Piss poor analogue tail servo i robbed out of an 'art-tech' heli \0/ (yes, i know...)

Hardware 'kill switch'. I'm in tight space, a run away is not an option.

Upshot is (remember this is 2.6 Epsilon)

Acro - usable, fun, what raw RC flying is all about, i think there may be a few tweaks - tuning or code, not sure as not tuned yet, too busy flying acro.

Stabilise - the most stable its been for me. I almost did a vid of me flinging the tri in the air unpowered and then just hitting the throttle to bring it level and fairly still -  it was inspiring so much confidence! Then remembered I was in the garden so settled for trimming long grass, dusting the barbeque, nudging the motobike till the tilt alarm beeps ( i must do a vid of that actually), and trying to further train my brain in nose-in and side-on orientation. Not bad for an untuned, ropey looking, bent, overpowered tri.

Alt-hold - baro-only for now.

Just spot on, the APM2 baro is great and the code seems spot on, and for me the defaults for throttle and alt rate were fine. I was flicking the switch 3 feet up, giving full pitch forward into full pitch back over and over again, over a space of 20 feet (length of my 'garden' if you've seen it) I just skimmed the grass with either the tail or the front arms for about 2 mins, never got more than 4 feet away, never got closer than 2 feet. Sonar is now only really good for terrain following/avoidance and showing off 'using the force' ;)


Bare in mind small area, built up, so not proper testing. Nasty swirly winds, tried below the fence line a few times before i went for it, and i was impressed so went for it. The tri is light and was getting, literally, thrown 20 feet downwind, in almost any direction due to swirling gusts between buildings, but it was leaning back towards home all the way with power and determination. It needs tuning/tweaking ;) but the new default params are much better, i will be tuning and keeping a close eye on any ideas anyone has on improving the code for this, I'm actually starting to understand some of it...


When the rain stops...

I have a few minor issues, most of which probably (shoddy) hardware related. I'll test and report if necessary. 

The last few beta releases have been a great step forward, looking forward to the fruition of the work going into yaw, loiter and auto.

Well done all :)

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