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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     Yes, we need to make a little fix to make the sonar alt appear in the tlogs.  It's done on the arduplane side but not copter yet.

     The compass interference doesn't look too bad but compassmot will probably help in any case.  You can see a little blip in the mag field at the beginning but that's probably as you plugged something in so not a worry (I've seen it in someone else's logs as well once).

Vibes are borderline ok on the X/Y axis so loiter should be ok hopefully.

Hi guys. Firstly awesome job on current version. I have several multi's from large to small. My question is on tuning throttle accel. What behaviour signifies value high/low?
My large hexi is slightly bouncy in alt hold. Alt hold is already around 0.2. It hovers around 33% throttle and in stabilize if i rock it back and forward it climbs a bit. Stop the rocking and it then drops again. All help / comments appreciated!
Keep up the brilliant work dev team!
+1 for the fence on a switch too...

Isn't the 'climbing in alt-hold' thing (when you rock it around and it climbs) usually related to vibrations?

The thing where you rock it back and forth and it climbs a lot should be mostly resolved by the scaling stability patch that went into 3.0.  What'll likely help reduce it is to reduce the THR_MID parameter.  It might not get rid of it completely but it should be make it better.  What was happening previously is that when you rocked it back and forth you were basically always asking it to roll or pitch in some direction.  The old stability patch would bump up the throttle (if necessary) to give you that roll or pitch.  In a regular flight you just ask for roll or pitch moves temporarily so you don't notice an momentary climb but rock it back and forth constantly and up it would go.

Bad vibrations tend to cause a climb in alt no matter what you do to the roll or pitch controls except for the cases where the vibes are just on the X and/or Y axis.  In these cases you may find that the copter rises or falls as you lean over.

I tried to get some advice on another section of the forum about frame options to scale up my copter but no replies. I am tempted to just build a bigger version of my quad but depending on how well hexa’s can survive a motor/ESC failure that may be a better option. If they don’t usually survive a failure then the extra motors are just increasing the chance of a total failure.

I would prefer not to go all the way up to octo.

I guess the software doesn’t actually ‘decide’ it has a motor failure but just tries to compensate?

So any advice on hexa behavior with an engine out is welcome.



Your best bet is actually a Y6 instead of a hexa.

Theoretically a hexa can fly with a motor out but there are issues in making that happen.

The Y6 will fly with a motor out as you can see here

Hi Vince, i had rhe same objective as you and decided for an X8: you keep the same size quad but you get more lift power and motor redundancy.

Thanks for replies but I have a gut feeling against 'contra' prop arrangements. On some aircraft and helicopters it was a good solution when space was limited but the second prop is trying to climb up through descending, turbulent air. Theory says this will be less efficient and may have resonance but I know many say its ok. Do you use different pitch pros on the lower motor?

Craig. I guess with the Y setup both rear motors are on a servo tilt? That worries me too as its has no redundancy.

X8? im not ruling it out yet.

I would still like to know if a hexa, on an average day, will survive an engine out or not.

I had an X8 and it flew really well with one motor out. You could hardly notice any difference at all.

Hexes do tend to fly more stable than quads in my experience. Logically they should fly with one motor out. Think of it this way. With one motor out its like a rectangular quad but with another arm to the side. The flight stabilized would control the motors to compensate for this the same as it did for my X8.

Im thinking that a hexa with a motor out may only loose a bit of lift but a fair chunk of yaw control. I wonder if the logic can share out the control while reducing power to all props in the ‘non failed’ group.

I suspect there has not been much work in this area.


What I am thinking is that, during a motor failure with a hexa setup, if a controller shuts off the opposite side motor automatically and increases the power on the remaining 4 to compensate the lift deficiency, the system should be able to fly just as good. It will be a rectangular quad as John mentioned above. But this shouldn't be an issue. The quad would never have to be a perfect square. There are many quad setups in the market where the motors are not perfectly symmetrical. 

This is not true.  On a regular hexa, if you lose one motor, the resulting 5 motors give you a roll/pitch-yaw coupling.  It can still fly, but it's not going to be great.  Y-6 and all Octos don't have this problem.


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