Arducopter 2.7.2 is now in the mission planner and in the downloads area Some positive reports on testing can be found in this discusssion by John Hanson.

Note: just as the release was going out an issue was found re support for the all Camera Gimbals on the APM1s (it doesn't work) and with 3 axis gimbals on the APM2 (2-axis works ok but not 3).  If you're one of these people, please wait for 2.7.3 which will be out shortly. 

 

UPDATE: 2.7.3 is now in the Mission Planner

 

Functional Improvements over 2.7.1:

  • Fast waypoints (Jason) - if the turn angle between two waypoint the copter is less than 60 degrees it does not slow down
  • Navigation improvements and logging including switching to filtered location for distance calculations (jason)
  • Flip improvements - more aggressive and flexible flip code based on attitude instead of timing (Jason)
  • Improved camera control - you can now control any axis (roll, tilt, pan) with any rc channel.  it probably makes most sense that you will use 6 but others are possible too.  Unfortunately these changes required we change the set-up procedure so the mission planner gimbal set-up screen needs to be modified again.  Please refer to the AC_Camera wiki page for how to manually set-up the gimbal (Amilcar)
  • Flybar acro mode for TradHeli (Robert)
  • "Fast gains" - allows strong correction of attitude using accelerometers while the quad is stationary on the ground but relies more on gyros while flying (Tridge, Jason)
  • Baro filtering improvements (Tridge)

 

Bug Fixes:

  • DMP timing fix (Randy) - the MPU6000's dmp unit was inadvertantly turned on and caused timing delays in the main loop- xbee bricking issue (Craig / Tridge)
  • Dataflash fixes (Jason)
  • Engine ticking - was a combination of roll/pitch rate D term being too high and the dmp timing fix above (Randy, Emile)
  • Faster heading correction on start-up - resolves issue with simple mode getting incorrect heading if you took off very soon after start-up (Tridge)


Code Cleanup:

  • Increased maximum number parameters (Tridge)
  • Formatting changes to code (Pat)
  • Replaced "int" with "int16_t" everywhere (Randy)


As per usual PIDs are optimised for the 3DR/Jdrones quad with 850 motors and 10" props. If you're using more powerful motors/props and are seeing bad flight behaviour in stabilize, start by turning down Rate Roll P in 25% steps.

There is still some question on whether the default Roll/Pitch Rate P (0.175) is high enough (it was 0.185 in 2.7.1) and also some people feel the Throttle Rate should be higher (currently 0.300 but some say 0.330 or even much higher would be better).

Please feel free to report issues you find in the discussion below and/or add them to the issues list.

Thanks and enjoy!

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Hi Guys,

A question from a different angle. I'm using a mega 2 board and I love flying my quad. You guys did a great job, thanks. Here is the question - If I can stream the quad's position to 10cm (Say usinga L1,L2 RTK GPS receiver), can the position corrections be done more reliably(agressively)? Currently my position hold runs within a 10 to 20m radius. Can I get position correction to keep my quad within...say 0.5 of a RTK position?

Thanks again for hours of great fun.

Antonie

My understanding is that civillian use of GPS is only accurate to 3-meters, or a 6-meter circle.

Maybe the next version of the uBlick GPS modules will include a WAAS receiver?

From Garmin:

100 meters: Accuracy of the original GPS system, which was subject to accuracy degradation under the government-imposed Selective Availability (SA) program.

WAAS Accuracy Diagram

15 meters: Typical GPS position accuracy without SA.

3-5 meters: Typical differential GPS (DGPS) position accuracy.

< 3 meters: Typical WAAS position accuracy.

There is some testing going on using http://www.rtklib.com/ for the positioning (requires an ground station) the accuracy seems to be around 0.5m. The problem with the traditional GPS is lots of noise and drifting, meaning that basically if you leave your code based receiver standing on the ground, you might get position drift of around 20-40m over time, thats why you need a ground station to keep this drifting on check.

RTK gps also uses the carrier waves phase to determine the location, so the initial position is determined from the code measurement, and the more accurate position is derived from the carrier wave phases ( carrier wace has phase length of around 19cm) so theoretically you can get even centimeter accuracy.

The position correction for the current arducopter gps modules is not possible as far as I know since to my understanding, they are purely code based.

The ublox does provide WAAS positioning in the US and other SBAS positioning in other parts of the world 

Very interesting.  But is it implemented in the Arducopter code?

Thanks for the link.  I was not aware of the accuracy of Glonass receivers.

The fix types have nothing to do with the arducopter code.  

The GPS will provide WAAS positions regardless if it is connected to the APM or not.  The APM just uses the positions provided by the GPS and is aware if they are GPS or DGPS accuracy.

Does the MP screen tell us if there's a GPS dGPS fix, or how many satellites it sees, or if we are getting WAAS augmentation?

GPS vs DGPS was not implemented in the early days, so not yet.  I want it to, but not yet.  It does show a 3D fix, the number of sats, and the HDOP though

Interesting I found this http://www.seeedstudio.com/depot/grove-serial-rf-pro-p-794.html?cPa...  It looks identical to the 3DRadio.. ? Has anyone tried it?

PIDs... why has the default PID changed so much from Version 2.6.1?  The Sab Roll/Pitch I was near 0.000  before if I recall correctly and was recommended to set to 0.001 but now in 2.7.3  the I setting is 0.050 which seems a lot of difference.  Also IMAX went from 40.0 to 8.0  Why such big changes when the other settings seemed not to bad?

Yes!

Our prayers have been satisfied. Here's the new firmware for the PPM encoder:

http://code.google.com/p/ardupilot-mega/downloads/detail?name=ArduP...

A big thank you for the development team.

That was quick!

I'm happy now and ready to start flying confident!

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