Copter-3.3 beta testing

Warning #1: an issue has been found with Tower's Pause button which can cause the vehicle to fly to an old position if the vehicle has not sent a position update to Tower in some time.

Warning #2: Copter-3.3.2 fixes a bug found in Copter-3.3.1's desired climb rate initialisation which could lead to a sudden momentary drop when switching from Stabilize or Acro to AltHold, Loiter or PosHold.

Warning #3: Copter-3.3.2 fixes an issue found in Copter-3.3.1 which could lead to hard landings in RTL or AUTO if the WPNAV_SPEED_DN was set too high (i.e. >400 or 4m/s) and/or the WPNAV_ACCEL_Z was set too low (i.e. <100 or 1m/s/s).

Warning #4: a bug was found in Copter-3.3 which could cause a sudden crash if you abort a Take-off initiated from a ground station.  Video description is here.  The bug is fixed in Copter-3.3.1 so we recommend upgrading.

Note #1: AC3.3-rc8 corrected a long standing bug in the HDOP reporting.  HDOP values will appear about 40% lower than previously but this does not actually mean the GPS position is better than before.
Note #2: if upgrading from AC3.2.1 the vehicle's accelerometer calibration needs to be done again.
Note #3: set SERIAL2_PROTOCOL to "3" and reboot the board to enable FrSky telemetry like in previous versions.
Note #4: the wiki will be updated over the next few weeks to explain how to use the new features

Copter-3.3.1 is available through the mission planner.  The full list of changes vs AC3.2.1 can be see in the ReleaseNotes and below are the most recent changes since AC3.3.

Sadly this version (and all future versions) will not run on the APM2.x boards due to CPU speed, flash and RAM restrictions.

Changes from 3.3:

1) Bug fix to prevent potential crash if Follow-Me is used after an aborted takeoff

2) compiler upgraded to 4.9.3 (runs slightly faster than 4.7.2 which was used previously)

Changes from 3.3-rc11:

1) EKF recovers from pre-arm "Compass variance" failure if compasses are consistent

Changes from 3.3-rc10:

1) PreArm "Need 3D Fix" message replaced with detailed reason from EKF

Changes from 3.3-rc9
1) EKF improvements:
    a) simpler optical flow takeoff check
2) Bug Fixes/Minor enhancements:
    a) fix INS3_USE parameter eeprom location
    b) fix SToRM32 serial protocol driver to work with recent versions
    c) increase motor pwm->thrust conversion (aka MOT_THST_EXPO) to 0.65 (was 0.50)
    d) Firmware version sent to GCS in AUTOPILOT_VERSION message
3) Safety:
    a) pre-arm check of compass variance if arming in Loiter, PosHold, Guided
    b) always check GPS before arming in Loiter (previously could be disabled if ARMING_CHECK=0)
    c) sanity check locations received from GCS for follow-me, do-set-home, do-set-ROI
    d) fix optical flow failsafe (was not always triggering LAND when optical flow failed)
    e) failsafe RTL vs LAND decision based on hardcoded 5m from home check (previously used WPNAV_RADIUS parameter)

Thanks for your testing!

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


            • I was facing the same problem as you, Glenn. My workaround was to export the log's GPS info into a GPX file using MP, then use ExifTool to to add the GPS tags to the JPEGs from the GPX file. I then used Agribotix to make the mosaic, which worked perfectly. Let me know if you need details.


          • Are you using Pix4d?  If you are, their software will geotag for you, but with a little glitch.  The initial geolocation will all be in portrait mode instead of landscape if that's what you're shooting.  It will still process and they're looking into a fix right now but it'll get the job done.

  • hello all. Today i tried 3.3rc8. i did 3-4 flights. after looking at the logs i realize that i cannot engage position hold. while connected with telemetry mission planner confirms pos hold is engaged but the quad is not in position hold. when i look at the logs i see this error err: flight_mode-16 evey time i tried to engage pos hold. i have tried on different switches but always the same problem. mission planner confirms the new mode but the quad does not change. log attached. 

    2015-07-27 18-58-08.bin

    • Randy,

      Thankyou for taking a look at the problem. I am very new to apm so i am still learning. I was under the impression that when mission planner had a 3d lock and that my hdop was below 2.0 i was good to go. Is there a way to verify in realtime that my ekf is good ?
      • Developer


        If you have Tower connected it should tell you but also when arming, try arming in Loiter,  It won't let you arm unless it has a good lock and position estimate.

    • Developer


      Thanks for the report.

      Ok, so what happened here is takeoff happened before the EKF was confident in it's position (i.e. before home was set).  The EKF actually never became confident enough of it's position so the home was never set and the autonomous modes were never enabled.

      Generally we don't recommend taking off without a GPS lock if you hope to use GPS flight modes.  Bad things happen like the RTL location (aka home) is set wherever the vehicle happens to be when the EKF does finally decide it's position is ok.

      Anyway, it should be possible for the EKF to become happy while it's flying but it's not something we've tested too much on the dev team so we can look into that further.

  • Hi.

    I tried to use RC8 on the same copter that crash with RC7. After a few minutes of flight received a message in MP - Error compass variance, after that copter tilted approximately for 30 degrees and started to fly in opposite direction. Fortunately I landed it without crash.

    In logs vibrations are normal as I can see.

    2015-07-27 18-37-04.bin

    • As I can see I have acceptable level of vibration for IMU and not acceptable for IMU2. I think is it a root of problem. Is AC3.3 more use IMU2 data that AC3.2?

      • Developer


        Yes, you're right.  Thanks for the self diagnosis.  We can see that the vibration levels are quite often in the 50m/s/s range (i.e. 5G) with peaks up to 80ms/s/s (8G).  That's perhaps 4x those of my IRIS.  There's also clipping happening and it starts at the moment the EKF Check goes off.

        This data is quite helpful in that it gives us an upper bound where we know problems start happening.


        • I don't understand how it happens, that two accels placed on the same board have such different vibrations.

          And I have one more question. The same copter flies on AC3.2.1 perfectly, as I understand EKF instead of correcting a non-conformity of sensors, it strengthens them and makes flight impossible.
This reply was deleted.


DIY Robocars via Twitter
DIY Robocars via Twitter
DIY Robocars via Twitter
DIY Robocars via Twitter
RT @f1tenth: Say hi to our newest #F1TENTH creation for @ieee_ras_icra next week in Philly. It’s going to be huge! 😎 🔥 @AutowareFdn @PennEn…
DIY Robocars via Twitter
May 11
DIY Robocars via Twitter
May 8
DIY Robocars via Twitter
RT @SmallpixelCar: Noticed my car zigzagged in last run. It turned out to be the grass stuck in the wheel and made the odometry less accura…
May 8
DIY Robocars via Twitter
RT @SmallpixelCar: Test my car. RTK GPS worked great. Thanks @emlid for their support.
May 8
DIY Drones via Twitter
RT @chr1sa: @kane That's @diydrones circa 2009. Still have a box of those Canon cameras that we used to strap into planes, just like this.…
May 3
DIY Robocars via Twitter
RT @chr1sa: Our next @diyrobocars race is going to be outside at a real RC racetrack in Fremont on May 28. Fully autonomous racing, head-to…
Apr 30
DIY Robocars via Twitter
RT @f1tenth: Our Spring 2022 F1TENTH course @PennEngineers is coming to an end with a head-to-head race as a big finale. So proud of our st…
Apr 26
DIY Robocars via Twitter
RT @DanielChiaJH: I wrote a thing! Throughout the development of my @diyrobocars car I've been using @foxglovedev Studio to visualize and d…
Apr 23
DIY Robocars via Twitter
RT @SmallpixelCar: My new car for high speed. Low body, everything ( @NVIDIAEmbedded Jetson Xavier NX, @emlid RTK GPS, IMC) under the deck…
Apr 23
DIY Robocars via Twitter
Apr 21
DIY Robocars via Twitter
RT @f1tenth: F1TENTH Race training setup @PennEngineers for our upcoming ICRA2022 @ieee_ras_icra competition. @OpenRoboticsOrg @IndyAChalle…
Apr 21
DIY Robocars via Twitter
RT @fatcatFABLAB: Proud to be hosting a restarted DIY Robocars NYC Meetup April 26. Come by if you want to talk about and race self-driving…
Apr 17