Copter-3.4 released!

Link to Video

Copter-3.4 has been released for both multicopters and traditional helicopters and is available for download from the Mission Planner, QGroundControl, AP Planner2 and likely other ground stations as well. This is a very major release with dozens of new features that are listed in the Release Notes but also the main items are listed below.

New Features (in alphabetical order mostly):

  1. New boards/frames supported including:
  1. ADSB sensor (from uAvionix) support and FailSafe to help avoid incidents with manned aircraft
  2. Attitude control improvements including completion of move to Quaternions
  3. ACRO_Y_EXPO allows exponential yaw in ACRO mode (coming to other modes soon)
  4. AutoTune robustness improvements especially for larger vehicles (reduce chance gains go too low)
  5. Boat Mode allows easier takeoff from boats
  6. EKF improvements:
  • EKF2 includes “multiple lanes” (multiple EKFs run simultaneously using different IMUs for improved robustness)
  • Ground effect compensation especially for use on vehicles with short legs
  1. Crop Sprayer
  2. Object Avoidance with Lightware SF40c 360deg Lidar (still slightly experimental, use with caution)
  3. OneShot ESC support
  4. Optical Flow robustness improvements
  5. Polygon Fence and stop-at-fence (applies to new Polygon and existing Circular fence)
  6. Precision Landing using IRLock or companion computer
  7. SingleCopter, CoaxCopter adjust control surfaces based on throttle
  8. Terrain Following using SRTM altitudes from ground station or Lidar
  9. Throw Mode (be careful!)
  10. TriCopter compensates for tail servo angle
  11. Safety:
  • 2 second delay after arming before motors spin
  • warnings if GPS update rate is too slow

How-to-Upgrade from AC3.3:
You should simply be able to load the new firmware on top of your existing AC3.3 firmware. There should be no need to perform the radio, accelerometer or ESC calibration but you may be required to perform a compass calibration (a warning message will appear on the ground station HUD if it’s required).

There have been attitude control changes which means “rate” gains have changed a bit. If you’re moving from Copter-3.3.3 they should be automatically converted for you but in any case, with AC3.4 you will likely notice:

  • Rate Roll, Pitch and Yaw gains must be 10% lower for X, V and H style multicopters (quad, hexa, y6, octo, octa-quad,)
  • Rate Roll, Pitch and Yaw gains must be 27% higher for + (plus) multicopter frames.

If you have issues you should be able to revert back to Copter-3.3.3 using the Mission Planner’s “Pick Previous Firmware” link (Look for “AC 3.3.3”). If your ground station does not support loading older firmwares, the firmware binary can be downloaded from, please visit the Copter-3.4 support forum and ask for help)

Known Issues:

  • Pixracer PPM input was not working on AC3.4 so AC3.4.1 is being released immediately with a fix.
  • Pixracer’s 3rd compass often causes difficulty with the onboard compass calibration and a “Compass Inconsistent” message may appear when arming. It is probably best to disable the 3rd compass by setting COMPASS_USE3 to 0.
  • Pixracer may not bind reliably with DSM transmitter/receivers.
  • The LeddarOne driver has been disabled temporarily after some issues were found in testing.

We will resolve these issues shortly and include them in AC3.4.1 which we expect to release within a couple of weeks.

Please report any issues in the Copter-3.4 Forum.

A huge amount of effort has gone into this release. Thanks very much to the developers that contributed new features and bug fixes, the beta testers who put their vehicles at risk in order to help make this a smooth release and numerous sponsors including companies and individuals who helped support those contributing to the software!


Known Issues:

  • Pixracer’s status LED does not function

Thank you

Thanks for all your efforts on this major release. Good to see single/coax copter going into this one.

This is awesome!

Randy, could you please point out that Navio 2 is also supported now?

Even though, it had been supported in master for quite a few months, this is the first stable release with Navio 2 support.

Right, we’ve supported it for so long I forgot it wasn’t in AC3.3.3. Updated, thanks for the reminder!


In the past I had issues going to 3.3.3 (GPS lock) so I reverted back to 3.3.2 which for me was very stable but I really wanted to take advantage of the new 3.3.4 features (ie. Poly Geo Fence)… Test flew today and I’m happy to report all modes, param tweaks and new features are working great. As a bonus… I’m getting a much faster GPS lock. Fantastic!

Thanks so much for this great firmware upgrade.

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Just a quick question: I did a parameter compare with an older version and RATE_RLL_P/I/D, RATE_PIT_P/I/D and RATE_YAW_P/I/D do not show up for comparison. Is this intended?

Did UAVCAN support for the magnetic gripper make it in?

silverburn, Yes, that’s in AC3.4. I’ve never personally tested it but it should work.

Sorry for the slow response. All the Rate parameter have been moved to start with “ATC_”. They’re moved into the Attitude Control library and also slightly re-scaled.