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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     Is it possible that it's only arming when you have it connected to your computer using the mini USB cable?  In this case the reason is that it's failing the board voltage check.  So for some reason the ESCs or power module (not sure which you're using) are not providing a high enough voltage.

Those are very low vibration levels.  very impressive.

Your quad looks good John; looks professional. I wasn't thinking a platform at this level. 12" props will pull some amps for sure. For a quad at this size 9 minutes may not be so terrible.

I am not a pro on the power setups but you may want to checkout how a 4s setup would work for you. It may be a more efficient setup.

Battery monitors Steve recommended are very affordable at HK. If the treshold voltage is programmable, it may work for you. But 3.7v per cell under load is way too conservative even for a brandnew pack. At your current setup, this probably means no more than 5 minutes of flight.

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.

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. 


     Do you have one of the Android ground stations attached?  I suspect you do and what's happening is the mission planner is getting confused by the heartbeats in the tlog from the other ground station.  So basically I think it's a playback issue in the mission planner.  I don't think that during the flight you saw that constant armed/disarmed thing going on.

     More than the ESCs I wonder what is on the level below the APM with the "NoH1669" written on it.


     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.

Ill do some bench testing with my hex and take out one motor and see what I come up with. Watch this space

Thanks for that.

So normal hexa will crash with failed motor and octa, x8 y6 should all be ok? I would defiantly be happier doing commercial work with motor redundancy.

In a tandem motor arrangement Im guessing there is a fair efficiency loss as the disk loading had doubled but failure tolerance may be worth the trade off.  I don’t suppose ecalc will give accurate results for that.

I wouldn't say it will definitely crash. It will start spinning constantly in one direction. With a full opposite rudder, the rotation may be stopped. The platform will definitely NOT flip and fall out of the sky. Considering the platform is not too heavy and not severely under-powered.

So there is definitely a chance of recovery I would say. The result maybe a hard landing.


As I will be starting a build from scratch to have motor redundancy I think the hexa arrangement is borderline at best.

I started out quite anti tandem propeller arrangements but it seems the x8 has a lot going for it. (I would do H8.)

I cant find a lot of info on tandem props, other than old NASA pdfs. They seem to suggest that the second prop should have a steeper pitch than the first. Makes sense but then it may affect the failure case.  Also I assume its good to have a large gap between blades, space allowing.

Im sure this must have been discussed at length on some multirotor forum but so far I cant find it.


Just more motors are not a guarantee for more redundancy. If one motor disintegrates in the air you are lucky, if it bruns out and melts your esc you have a good chance for a short on the mainpower line, a fried FC/RC or at least a simple reset of the FC wich can take long.. If you want some redundancy you will have to have a lipo for every motor and opto decoupled esc to the FC (and 2 FC/RC would be fine as well).

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