Version 2.5 of the ArduCopter code is now available in the AP Mission Planner and in the downloads area!
Enhancements:
Tuning:
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!
Permalink Reply by yovio on June 13, 2012 at 9:59pm Hi Randy,
Early this week I tried 2.6 from GIT, I guess it should be Delta. In one occasion I would like to try how stable my quad when I immediately crank up the Throttle to lift up the quad very fast. The quad lift up ok, but when I tried to move the quad using Aileron and Elevator) the orientation of the quad become mess (I fly in Stabilize-Simple mode) and I immediately land the quad.
I'm not sure whether this is because of the new yaw code, and unfortunately I don't have log for that flight.
The issue only happen once, after that I always lift up the quad slowly.
Permalink Reply by Joonas on June 14, 2012 at 12:15am This is just a hunch, but I had similar issues with the yaw orientation getting messed up. My problem was that the compass offsets were wrong. Now the thing seems to be that the compass offsets get somehow corrupted between the flights, since the offsets are ok after the calibration, but seems like there are completely different values after few flights which make the yaw drift just like you and few others here have decribed.
Don't know if the yaw offset calculation really is flawed, but it might be worth keeping an eye on.
Permalink Reply by Chapelat Daniel on June 14, 2012 at 10:17am "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
Permalink Reply by Gustav Kuhn on June 13, 2012 at 10:45pm Over 100 000 views, and many replies.
I'm waiting for my new 2560 board, to join in the fray, but reading about many frustrated builders out there, I'm close to giving up.
I haven't had any funnies on the rather short flight I'm doing, but then, I haven't really done much in the line of nav or position hold lately.
Maybe the code is getting too complicated ?
Cam ship people require basic stability, and maybe nav/rth.
I would be happy with that, I don't need Simple mode or Acro.
Fancy lights and maybe camstab can also be left out, on a big 'copter with professional stab gear, it can have it's own stab electronics.
Not venting, just throwing around some thoughts.
And impatiently waiting for my 2560 board.......

Gustav: Do you mean APM 2? (Not sure why you would be waiting for an APM 1 2560 board). As for length of this thread, that's typical for a beta testers thread. Please don't confuse it with the normal experience for people flying release code in the Mission Planner. Most people have no problem with that.
Permalink Reply by Gustav Kuhn on June 14, 2012 at 12:10am Hi Chris,
Yes, APM1.
The "nice to have" budget is severely strained this year :-(
And I'm entirely happy with APM1 1280 in my fixed Wing :-)
Another sucssefull flight with 2.6Delta. 2.5.4 was already very stable, but still with those yaw glitches, however 2.6 it's great. I had never had such flight stability before. Yaw may be a little slower but no glitches at all and since I don't need any agressive yaw maneuvers, for me it's working great. However, hovering a well balanced and leveled small hexa it's just perfect. I have also been making auto flights and it behaved super. For now I'm testing a uBlox NEO 6M gps, wich seems to give me better accuracy and precision. I've managed to get loiter in a 2x2mts box today without wind. In the last days I also made some flights with some strong winds of 40 / 50km/h and I must say I was impressed with how well the hexa behaved. It made the autoflight path with little deviation and loiter fought against the wind bravely. I'm flying a Xaircraft hexa pro frame (550mm motor to motor), 10x4.7 props, 6000mah 25c 3S battery (wich gives me approx 15m flight time), sunnysky 2212 980kv motors on an APM1+oilpan and it's a very well balanced setup. I give you my param file if anyone can find it usefull.

Rui, unfortunately it was decided to pull my yaw fix from the code, but you can still access it by doing a custom compile if you want.
http://code.google.com/p/ardupilot-mega/source/detail?r=d15f57acbfb...
You need to put ALTERNATIVE_YAW_MODE ENABLED in your APM_Config.
I think that for some people the new yaw mode was good, because it's super stable and predictable. Predictability is really important for some people, depending on their flying. For others, they want responsiveness.
Regardless, I'm still working on this, trying to come up with something that is the best of both worlds. In the meantime, you can use my original yaw code by compiling with it enabled.
Permalink Reply by Marc Puig Pasarrius on June 14, 2012 at 5:12am
Permalink Reply by Marc Puig Pasarrius on June 14, 2012 at 5:21am 
Wow, I really think you guys should try investing in some MuMetal magnetic shielding. I think that possibly a thin sheet between the power section and the Flight Control section might help a lot. I've managed to get quite clean mag signal on my heli by putting a lot of distance between the mag and the power, but you don't have that option with a multi-copter unfortunately.

Permalink Reply by Dave C on June 14, 2012 at 7:05am Good call Robert.
I follow advice from Angel previously and twisted all my powerlines (in fact every single pair/triplet of wires in my build) and this has help reduce the spiky interference significantly.
However in pursuit of perfection I have also just spoken to a company in the UK (supplier of Mu metal) regarding this issue and after a fascinating conversation we decided the best way to go was to test the effectiveness of a magnetic shield. Upshot is i have some samples coming my way, firstly a 1mm sheet that I am going to install between the APM and the esc's/motor and battery wires.
I'll untwist all my cables and do some testing. If i have success I'll post the details.
Also regarding the yaw, i have to say that I like both methods now, but the original yaw calc does work much better on my tri, whereas the alternative approach you have suggested is great on the quad - less responsive slightly, but as you say more predictable.
Anyway, i just got my old logitech joystick working with the laptop, so screw any more testing for now - I'm off to fly 2.6 epsilon on the tri, top gun style :D
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