ArduCopter 3.0.1 has been released and is now available in the Mission Planner,, GitHub and the new Downloads Area.

Warning #1: Compass calibration and reducing interference is far more important than with 2.9.1b

Warning #2: GPS glitches can cause sudden and aggressive position changes while in loiter mode.  You may wish to reduce the Loiter PID P to 0.5 (from 1.0) to reduce aggressiveness (see image below of where this gain can be found in mission planner).

Warning #3: optical flow is not supported but will be back in the next release (AC-3.0.2 or AC-3.1.0).

Warning #4: loiter turns does not maintain altitude.  This bug will be fixed in AC-3.0.2.

Warning #5: This release has only been lightly tested on Traditional Helicopters.

Improvements over 2.9.1b include:

  • Inertial Navigation for Loiter and Auto meaning much more accurate control (Randy,Leonard,JonathanC)
  • 3D navigation controller follows straight lines in all dimensions between waypoints (Leonard,Randy)

         WPNAV_SPEED, WPNAV_SPEED_UP, WPNAV_SPEED_DN, WPNAV_ACCEL allows configuring speeds and acceleration during missions

  • "compassmot" to compensate for interference on compass from the pdb, motors, ESCs and battery.  (Randy,JonathanC) (Set-up video here)
  • Safety improvements:
    • simple Tin Can shaped Geo Fence
    • pre-arm checks to ensure all calibration has been performed before arming (can be disabled by setting ARMING_CHECK to zero).  (video description here)
    • GPS failsafe - switches to LAND if GPS is lost for 5 seconds
    • stability patch improvements to stop rapid climbs in very overpowered or overtuned copters
  • Circle mode improvements including "panorama" when CIRCLE_RADIUS set to zero (Randy,Leonard)
  • SONAR_GAIN parameter added to allow better tuning of sonar surface tracking
  • CH8 auxiliary switch (same features as CH7)
  • works on PX4 (some minor features still not available) (Tridge,PatH)

How to upgrade:

1. Make sure you are using Mission Planner 1.2.59 or newer (get it here)

2. Click on the MissionPlanner's Hardware, Install Firmware screen.  The version numbers should appear as "ArduCopter-3.0.1", then click the appropriate frame icon and it should upgrade as per usual.

3. Reduce the Loiter and Alt Hold PIDs if you have modified them from the defaults.  The modified PID values for the 3DR frame can be seen in the image below.

Note: Nav parameters have been combined with Loiter so do not be concerned if you can't find them.

4. Although not directly related to this release, if you purchased an APM prior to March of 2013, update your PPM encoder to the latest firmware (instructions here).

5. Try out the new version in stabilize mode first, then alt-hold, then loiter and finally RTL and Auto.

Numerous How-To videos are available:

Special Thanks to MarcoDaveC and the large number of testers on the pre-release thread who put their copters at risk during the extended testing period.  Some of their videos can be found hereherehereherehere and here.  Thanks also to MichaelO for the MP changes required for this release.

All feedback welcome.  Please put your questions, comments (good and bad!) below.

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This might be a great nonsense, but what if at firmware upload, a password was asked to handshake serial comms ? The password would be defined in the planner and the APM would be waiting for a password send from the planner to establish a successfull connection ? Just a thought.

Hi randy, it will be nice if user can reduce the copter speed when approaching home during RTL. I want it slow stop.

Hi Randy, here is the dropbox link with raw footage about AC3.1 ROI and CIRCLE function

Regarding my previous post about RTL, here is the internal log.

Thank you for your help, Mihai.


Not theoretical, and not hard.  I believe that hacking MAVlink was demonstrated a year ago.

Rui, you can't transmit the password unencrypted, or somebody can easily catch it, and then use it.  Encryption is the only way.

Encryption is basically using a password, but it can only be understood if you already know the password.  So somebody listening in can't catch it (easily).  

I was going to suggest encrypted comm, but I believe the process of decripting / encrypting all messages would be somehow slow depending on cipher length. However, there's nothing like trying it :)

I can't seem to load 3.1 rc7 to my X8.

First I updated to MP 1.2-88.

Did the upload as I usually do for my Iris. Connect cable, change port number and baud top right but don't connect.

Go to load firmware. It loads 3.01. I click "Beta Firmware". and 3.1 rc7 appears.

I click the X8. Syas "checking board version", and hangs for a good 5 minutes. After a while it will start to load Hex but hangs and then times out. My internet conection is good.

I tried loading the hex file from, and then "load custom firmware". After a pause, it begins to load Hex, and then hangs about half way through.

What gives?

I backed up to MO 1.2.86, but the same thing!

I have loaded 3.1 rc7 on my X8 using MP1.88 with no problem on 2 diff. APM 2.5 and APM 2.5.2 board (RCtimer clone). I have also loaded with MP1.87 and 86, no problem. I am using Windows 7.

Arducopter 3.1 CIRCLE around me



BLUE is MOT#3 and it looks lower than the rest before they all are shut off. I'm learning - what did I miss?


Having a bit of an issue trying to set up a 450 quad for a friend.

I have loaded RC7 and done all the setups and calibrations.

It can see many satellites (7-10) and clearly knows  where it it when connected to MP but the HUD says 'no GPS fix'

OK so now I try to fly in STAB by disabling the GPS failsafe but the HUD still says 'failsafe' when I try to arm. Im assuming its the GPS failsafe still preventing arming as its the only thing in red and there are no other warnings

CLI test for gps and compass is fine.

Any ideas?

Randy - If you pulse the motors - PWM over PWM (?) you could have the vehicle wobble fast enough during YAW stabilization and Flight control to have a controlled RTL or manual flight.

The flight controller would have to be smart enough and have an algorithm for each motor pattern config.. This would eat a lot of space. But, for your example if you varied the speed of the CW with the CCW lowering the two verses the three you could maintain an altitude. Pulsing the motors to maintain stability. Then as normal Yaw vary the motors to turn the vehicle. Be creative but, doing this fast enough you would be able to maintain a flight albeit wobbly.  Thoughts to you.

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