Arducopter 2.8.1 is now in the mission planner and in the downloads area! Remember to do your MP configuration again after loading this code, since it erases your EEPROM and sets it to the new defaults. 

Note: Issues with APM1 user's level feature not working are now resolved.  If you installed 2.8 we highly recommend you upgrade to 2.8.1 as 430 extra bytes of RAM have been freed up which reduces the chance of memory corruption (although we haven't seen any cases of this on the APM2 at least) .

Note #2: this release has not gone out for Traditional Helicopters until they can be tested fully.  Flip and Toy mode have also not been fully tested.

Improvements over 2.7.3:

  • Improved ACRO mode (Leonard Hall)
  • Improved stability patch to reduce "climb-on-yaw" problem (Leonard, Rob Lefebvre, Randy)
  • Rate controller targets moved to body frames (yaw control now works properly when copter is inverted) (Leonard/Randy)
  • Less bouncy Stabilize yaw control (Leonard)
  • OpticalFlow sensor support for APM2.5 (Randy)
  • DMP works again by adding "#define DMP_ENABLED ENABLED" to APM_Config.h You can also log DMP vs DCM to the dataflash by adding "#define SECONDARY_DMP_ENABLED ENABLED" (Randy)
  • Watch dog added to shutdown motors if main loop feezes for 2 seconds (Randy)
  • Thrust curve added to linearize pwm->thrust. Removes deadzone found above 90% throttle in most ESC/motors (Randy)
  • More timing improvements (main loop is now tied to MPU6000s interrupt) (Randy)
  • GPS NMEA bug fix (Alexey Kozin)
  • Logging improvements (log I terms, dump all settings at head of dataflash log) (Jason)


Bug Fixes / Parameter changes:

  • fixed skipping of last waypoint (Jason)
  • resolved twitching when no GPS attached (Tridge)
  • fixed loss of altitude if alt hold is engaged before first GPS lock (Randy/Jason)
  • moved Roll-Pitch I terms from Stabilize controllers to Rate controllers
  • TILT_COMPENSATION param tuned for TradHeli (Rob)

Code Cleanup:

  • HAL changes for platform portability (Pat Hickey)
  • Removed INSTANT_PWM (Randy)

As per usual PIDs are optimised for the 3DR/jDrones quad with 850 motors and 10" props. If you're using more powerful motors/props and are seeing bad flight behaviour in stabilize, start by turning down Rate Roll P in 25% steps.

Please note that on this release we've moved the Roll and Pitch I terms from the Stabilize controller to the Rate controller. There's some evidence that says this can lead to flips on take-off if you move the roll or pitch sticks around as you take-off so we recommend you leave these sticks in the middle until you're in the air.

Please feel free to report issues you find in the discussion below and/or add them to the issues list.

Thanks and enjoy!

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    It's probably clear from the video below but absolutely no need to use plumb bobs.  It won't help because the algorithm just takes 6 orientations and tries to find the accel offsets and scaling doesn't know (or care) whether they're exactly vertical, or horizontal or whatever.  In fact, in the accel calibration process, the MP prompts you to do it in a particular order but even the order doesn't matter.  The most important thing is try not to move the copter around as you push the MP button.

I do not know the reason to use 4s LiPo instead of 3s. And the setting of accelerometer is not accurate that is described by Randy's video.

2.9 is so quick to throttle. In other words, it is so aggressive. I can not feed back of 2.9, cause I  crashed before testing detail.  Cheers:-(  


    If you're in stabilize mode you shouldn't see any difference between 2.8.1 and 2.9.  It's only once you enter alt hold or loiter mode that the new throttle will be used.

    Sorry, what's inaccurate re the accelerometer set-up video?

FYI - I've updated the Camera wiki page to show the mission planner set-up screen and how to trigger the camera's shutter with a servo.

Excellent, been waiting for this.


I did lots of things at one time. My quad is just restored. But it is already dark.  I will wait and see what is happening on 2.9-rc1, may be rc2 on next weekend.

 I will follow your instruction on your video. I did not think that accelerometer setup needs so accurate orientation and hold some time to reduce unnecessary movement.

Anyway, I am so excited about this new version.

Appreciate for hard working dev. team and yourself. 

Randy I have been watching the code development over the past 12 months and it looks like there have been some significant feature enhancements. Well done to you and the dev folks. The trouble is every time I read the various issues people have at each new release I have been reluctant to move from the 2.0.54 which is nice and stable. Also I must admit there are so many new settings now I am lost. I can at least mangae the PId tuning in 2.0.54 :-)

Anyway when I read your updated Camera wiki it prompted me to ask if APM has a mode yet which combines Altitude hold and GPS position. I want to be able to move into a mode where I can safely operate the camera gimbal to frame the shot and take photos. APM does not seem to have this feature yet. In loiter you still have to input throttle changes to maintain altitude from what I have read on testing. Also within how many metres can Loiter realistically hold on station / position in the current release with the new Ublox LEA GPS?

Hopefully with 2.8.1 I can perhaps move off 2.0.54 now its listed as final. I purchased an APM 2 several months back but shortly after the hardware was changed again so now I think I will need to puprchase the newer 2.5 to get all the new features in the new code?


     Loiter includes altitude hold and position hold so that should be what you want.

     Yes, all the parmeters is a bit daunting.  To help with that we've started a effort to document all parameters.  It's a work in progress but we should get there in the near-ish future.

     Of course I live and breath arducopter but personally I find setting up a new copter pretty easy even if they're significantly different size from the standard 3dr quad.  I generally just use the standard parameters but use CH6 to tune Rate Roll P and Rate Pitch P.  I also usually decrease Rate Yaw to 0.200.  Dave C has created a good discussion about tuning here, follow that and I expect you'll end up with a quad that's far better tuned than mine.  You know, we've been discussing the possibility of auto-tuning but it'll take a big brain to focus on that for a month or so to figure it out I think.

     We're actually testing 2.9 now and depending upon how testing goes, it'll probably be out in the mission planner in a week or so.  Compared to 2.0.54, the list of improvements is a mile long but compared to 2.8.1, 2.9's has greatly improved alt hold.  FYI - after 2.9 is out we will focus on loiter with inertial nav.

I'd wait for 2.9, it's going to be even better :)


Loiter will hold inside a 2m box easily is low winds, provided you throttle is in the middle it will hold altitude very well too. You can then use headtracker/camera switches to line up your shots, I',ve got mine working nicely now.



And no you don't need to buy new hardware, I'd just recommend either flashing your mtek gps (as just recently descibed by crashpilot), or buying a ublox.




Hope this help me avoid the copter drift 5km/h on the side as soon it takes off... this is making it impossible to even try inflight calibration of accellerometers


     There is a slight change to how the auto trim works.  There's now a "save trim" as well as "auto trim" method.

     "Auto Trim" - This method is unchanged from 2.8.1.  It's invoked by holding the throttle down and rudder right for 10 ~ 15 seconds.  You then have 25 seconds in which you should fly and try to maintain a stable hover.  The average roll and pitch values over that time period are saved as to the AHRS_TRIM_X, Y parameters and used from then as an adjustment to your attitude which should mean it flies level.

     "Save Trim" - you must set this up on the arduCopter Config screen's CH7 Opt field.  Then you fly and use your radio trims to get your copter level.  Then land and flick the CH7 switch once, remove your radio's trim and fly again.  It should fly level.  Essentially what you're doing here is transferring your radio's trims to your APM.

I've already started updating the wiki with this change and others ahead of the official 2.9 release.


There's some improvements to the failsafe behaviour as well in 2.9.  I've updated the Failsafe wiki page to reflect the changes.  it's pretty accurate for the throttle failsafe but details are still a bit sparse for the battery failsafe.  Personally I've never successfully invoked a battery failsafe because the battery capacity got low...that's probably something that needs more testing.

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