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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     Sounds like compass problems.  Have you done the compassmot yet?  If you did what was the percentage of interference you saw?  below 30% is best but there's a grey zone between 30% ~ 60% where it sometimes works ok.

     A tlog would be great to allow us to see the intereference more directly.


      They should be ok.  The X and Y are a bit borderline (-3 ~ 3 is acceptable range) but Z is decent (-15 ~ -5 is the acceptable range).  Basically I think your alt hold and loiter should be ok.

Does anyone know what causes the spikes in the sonar ? What is the source of the pulsing "sudden" noise that causes the spike.

Im guessing is it an overflow of some sort ?

Funny thing is sonar seems to work without the crazy drop and restore if im really close to the ground say 1ish M. The more i lift the more dramatic the spikes.


    Yes, so maybe ther Loiter PID P of 0.2 is too low.  Actually some of the other testers have also reported that when it's that low it can't hold it's position accurately which is what you're seeing.

    You can increase the Loiter speed as high as you want but most copters can't go faster than about 13m/s (1300).

Hi Randy,

I'll do a new calibration outside on location, I did mine inside like the provided link to the video. I'll see what happens then and repost my experience. (and a log if needed).



     The problem is that the minimum throttle on your receiver is 976 and the FS_THR_VALUE is 975.  So you will find if you leave your throttle at the bottom it can accidentally trigger the throttle failsafe.

      When you turn off your transmitter what does your channel 3 value go to?  Maybe you need to lower the FS_THR_VALUE parameter value.

     I've improved the failsafe wiki page a couple of days ago.  It's here.  This line in particular is the issue you are having:

The throttle (channel 3) pwm value should be approximately as in first illustration below.  It’s value may be higher or lower but it should definitely be at least 10 higher than the value held in the FS Pwm field

Thx for your time Randy. Will try alt hold and loiter later today. Suppose I should balance my propellers first though. Before the flight loged above the copter flipped upside down due to mixed up esc wires. Two or three propellers have visible "dents".  

Randy, i did test my MinimOSD with APM 1.4 (firmware 2.9.1b) and it did not work.

Are you sure that for the APM 1.4 it is SR3 and not SR0 ?

Anyway even without those rates set, the MinimOSD board is asking for telemetry rates at power on. So i suppose that the board on this copter has an old firmware not compatible with Mavlink 1.0.

I wonder which firmware version they used for this flight? :-D

Nice work RickP on spotting the cause.

Now the confusion comes from the behaviour of the ch7 switch when it's used to enable/disable things like the fence, simple mode, etc.  The problem is the switch only updates the function's state when it's moved.  So for example, if you have a feature like Fence enabled through the mission planner but then your ch7 switch in the off position when you start the APM...well..logically you'd think it must be off 'cuz the switch is off but actually it's on until you move the switch.

I know that's unintuitive to say the least but it's always been that way and for some of the ch7 features (like flip and rtl) it could be a safety problem if it were triggered when the copter first started.

Anyway, I fixed it just yesterday in master so worst case it'll go out with AC3.1.  Sorry for the troubles!

This seems to show that you have a bad acoustic signal / noise ratio.

The cause of this can be propeller wash or wind hitting the sensor, or motors / propellers ultrasonic noises.

The first two problems can be solved using a light foam windshield and or changing the sensor location. Wind blowing across a microphone tends to make a horrible noise, will often overdrive the signal until it clips.

The last two problems can be solved changing the sensor location, hopefully ultrasonic noises are very directive.

Adding a horn can help to filter out lateral ultrasonic noise.



     Ah, I think you're right.  On the APM2 it's SR3_ but on the APM1 it's SR0_.

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