Ardupilot project releases new firmware Copter-3.4

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 Notes5 but also the main items are listed below.

New Features (in alphabetical order mostly):

  1. New boards/frames fully supported including:
    • Parrot Disco and Bebop
    • Intel Aero
  2. ADSB sensor (from uAvionix)2 support and FailSafe to help avoid incidents with manned aircraft
  3. Attitude control improvements including completion of move to Quaternions
  4. ACRO_Y_EXPO allows exponential yaw in ACRO mode (coming to other modes soon)
  5. AutoTune robustness improvements especially for larger vehicles (reduce chance gains go too low)
  6. Boat Mode2 allows easier takeoff from boats
  7. EKF improvements:
    • EKF2 includes “multiple lanes” (multiple EKFs run simultaneously using different IMUs for improved robustness)
    • Ground effect compensation1 especially for use on vehicles with short legs
  8. Crop Sprayer3
  9. Object Avoidance with Lightware SF40c 360deg Lidar (still slightly experimental, use with caution)
  10. OneShot ESC support
  11. Optical Flow2 robustness improvements
  12. Polygon Fence and stop-at-fence (applies to new Polygon and existing Circular fence)
  13. Precision Landing2 using IRLock or companion computer
  14. SingleCopter, CoaxCopter adjust control surfaces based on throttle
  15. Terrain Following using SRTM altitudes from ground station or Lidar
  16. Throw Mode4 (be careful!)
  17. TriCopter compensates for tail servo angle
  18. 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’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!