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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I had the problem on the quad and not on the hexAfter applying your patch, no problem with the 2 on  mode alt_hold and rtl


New specification for RETURN TO LANDING.  Very accurate function.  Unless there is a significant wind, your aircraft will return to the point it is over (well, maybe slightly "below" where it took off from.  :-)

Marco -- I think I finally downloaded the logs properly. I isolated the log that I think has today's flight in it given the Google Earth kmz file I was looking at. Let me know if this log works better to see what happened.


I've updated the version coming out of the mission planner to be 2.5.3 and added a new zip to the downloads area.


Patch fixes the following issues over 2.5 release:

   1. reenabled automatic calculation of throttle_trim while in stabilize mode

   2. enables auto trim command on Channel 7

   3. throttle_trim default increased to 450

   4. bug fix to clear loiter and nav controller's I term when switching out of these modes.

   5. added checking that PID controller's IMAX values are always positive

   6. bug fix to barometer library affecting APM1 users with temp crossing 33 deg celsius


It's this last one that's new over 2.5.2.


     I've looked at your logs and it's definitely the throttle trim issue.  Attached is a graph showing your altitude (green), the throttle output to the engines (red) and your manual throttle (blue - mostly hidden under the red line).

     You switch into loiter at 1761 and you can see the output to your motors immediately drops from 500 (which is apparently what you need) to 350 (the old default throttle_trim value).

     The latest code (now in the mission planner) properly captures the manual throttle and uses it as the base for the altitude hold.

     Very sorry to hear about (and watch) your crash.


Good morning. Thank you continue for the bug fix and tuning. I have very stable flight on 2.5.2 that I ever had on ArduCopter. I will try other features other than stable mode.

Are you talking about 2.5.3 ? Try later.


I have been silently following the project for a while,  just wanted to thank you all for the hard and beautiful work.

Randy -- thanks for looking into this (and thanks Marco). I so wish I would have had another day so that MissionPlanner would have updated my board to 2.5.3. Not sure you know, but my company makes multi-rotor kits like our popular Pro Tricopter Delrin Kit. Anyway, thanks for fixing the underlying issue.

Randy --- one last question... how was that issue missed in the testing that was done? What is different about me upgrading from a healthy Loiter version in 2.4 to then having this issue in 2.5? Would not everyone have had the same issue, including the testers? Or is it because my quad has some property that the tester's quad did not have? (this prototype cost me considerable time and money, so just want to get that clarified for my own sanity)


    Good morning!  Great to hear it's working out well.

     2.5.3 is really just the same as 2.5.2 but there's an additional bug that cropped up (and has been fixed) in the past 24h.  It's #6 on the list above and it only affected APM1 users who crossed the 33deg celsius barrier while flying.  It cropped up for two people including Marco and a guy in Australia (where i guess it's a bit warmer than tokyo).


     Again, sorry about your crash.

     The issue wasn't caught in testing because the config to enable the automatic updating of the throttle trim was missing from the config file that the mission planner uses (it was there in the config file used by people uploading using arduino).  Because all our beta testers upload using arduino they never saw it.

      So we need to tighten up on the sharing of the config between arduino and the mission planner.  95% of the config is already shared but this one sadly wasn't :-(.

Just wanted to say thanks for all your hard work on this. Haven't flown for some time but I loaded 2.5.3 onto my quad and took it out today. I had some of the most stable flying I've had in a long time. Made my day, no, week. Loiter's still a little rough on my frame, but I guess I still need to dial the settings. Going through the logs now. Thanks again!

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