Copter-3.3 beta testing

Warning #1: an issue has been found with Tower's Pause button which can cause the vehicle to fly to an old position if the vehicle has not sent a position update to Tower in some time.

Warning #2: Copter-3.3.2 fixes a bug found in Copter-3.3.1's desired climb rate initialisation which could lead to a sudden momentary drop when switching from Stabilize or Acro to AltHold, Loiter or PosHold.

Warning #3: Copter-3.3.2 fixes an issue found in Copter-3.3.1 which could lead to hard landings in RTL or AUTO if the WPNAV_SPEED_DN was set too high (i.e. >400 or 4m/s) and/or the WPNAV_ACCEL_Z was set too low (i.e. <100 or 1m/s/s).

Warning #4: a bug was found in Copter-3.3 which could cause a sudden crash if you abort a Take-off initiated from a ground station.  Video description is here.  The bug is fixed in Copter-3.3.1 so we recommend upgrading.

Note #1: AC3.3-rc8 corrected a long standing bug in the HDOP reporting.  HDOP values will appear about 40% lower than previously but this does not actually mean the GPS position is better than before.
Note #2: if upgrading from AC3.2.1 the vehicle's accelerometer calibration needs to be done again.
Note #3: set SERIAL2_PROTOCOL to "3" and reboot the board to enable FrSky telemetry like in previous versions.
Note #4: the wiki will be updated over the next few weeks to explain how to use the new features

Copter-3.3.1 is available through the mission planner.  The full list of changes vs AC3.2.1 can be see in the ReleaseNotes and below are the most recent changes since AC3.3.

Sadly this version (and all future versions) will not run on the APM2.x boards due to CPU speed, flash and RAM restrictions.

Changes from 3.3:

1) Bug fix to prevent potential crash if Follow-Me is used after an aborted takeoff

2) compiler upgraded to 4.9.3 (runs slightly faster than 4.7.2 which was used previously)

Changes from 3.3-rc11:

1) EKF recovers from pre-arm "Compass variance" failure if compasses are consistent

Changes from 3.3-rc10:

1) PreArm "Need 3D Fix" message replaced with detailed reason from EKF

Changes from 3.3-rc9
1) EKF improvements:
    a) simpler optical flow takeoff check
2) Bug Fixes/Minor enhancements:
    a) fix INS3_USE parameter eeprom location
    b) fix SToRM32 serial protocol driver to work with recent versions
    c) increase motor pwm->thrust conversion (aka MOT_THST_EXPO) to 0.65 (was 0.50)
    d) Firmware version sent to GCS in AUTOPILOT_VERSION message
3) Safety:
    a) pre-arm check of compass variance if arming in Loiter, PosHold, Guided
    b) always check GPS before arming in Loiter (previously could be disabled if ARMING_CHECK=0)
    c) sanity check locations received from GCS for follow-me, do-set-home, do-set-ROI
    d) fix optical flow failsafe (was not always triggering LAND when optical flow failed)
    e) failsafe RTL vs LAND decision based on hardcoded 5m from home check (previously used WPNAV_RADIUS parameter)

Thanks for your testing!

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      • Interesting, is there a parameter to speed up the ramp up ?  I have the impression, that 3.3-rc9/10 Althold moves (corrects) more than it did with 3.21 @ my setup. Maybe this is related ?

  • What is a dev's strict definition of a flyaway? I see the term bandied about often, but suspect is not properly applied in many instances.


    • Developer

      Hi DG,

      There are a couple of things that need to come together for an official fly away:

      1. the pilot loses effective control of the copter,
      2. the copter is able to sustain stable flight,
      3. the moves away from it's original location,
      4. the cause of this behaviour is not caused by pilot disorientation, accidental mode changes or similar.

      There are a couple of main problems that have caused flyaways in the past:

      1. Bugs in the code causing the copter to go to full throttle,
      2. bugs that cause the copter to stop accepting pilot commands in stabilize,
      3. GPS glitches that result in the copter thinking it is stationary when it is really moving,
      4. IMU bugs that result in the copter thinking it is stationary when it is really moving,
      5. large vibration levels causing clipping that result in the copter thinking it is stationary when it is moving.
      6. heading errors, compass or IMU problems, that make the autopilot try to correct errors in the north south direction using commands in the east west direction,
      7. errors in the copter setup that has caused any of the above.

      There are a number of things that are considered to be flyaways by the general community that we don't consider flyaways for the purposes of support and code development. These are all defined by the code working perfectly and following every command it received. They are generally a result of the pilot not understanding how their system works or mistakes setting up things like their radio. Some examples are:

      1. RC failsafe not set resulting in the copter losing RC link in Alt_Hold or Stabilize. The copter then maintains or increases altitude and floats away with the wind. I lost my first copter this way because I was using failsafe to set RTL rather than use the low throttle RC failsafe.
      2. Pilot becomes disoriented and literally flies the copter away from themselves. This is often expressed as "I had a fly away, the copter took off in the wrong direction and crashed into XXXXX"
      3. An auto mission or RTL is engaged accidentally.
      4. RC failsafe is activated but the pilot doesn't realise.
      5. Loiter or RTL is activated when there isn't a GPS lock and the pilot doesn't realise and the copter floats away on the wind.

      Our most serious fly aways prevent the pilot switching back into Stabilize and recovering the copter. This is why the developers stress that everybody should learn to fly in Stabilize as it is the simplest and most reliable mode available to the pilot.

      Fly aways are very rare in our full releases and are mainly caused directly by mechanical or setup issues on the copter. However, only a couple years ago they were reasonably common so at any hint of a fly away the devs tend to jump on it like angry bees to find that bug we may have missed. This normally results on us discovering a pilot error or mechanical problem very quickly.

      The final point I will make most of our effort in this area is to make it as easy for pilots to NOT make the mistakes that might cause any of the issue I described above or detect them in the code as early as possible and communicate them to the user.

      That is my quick go at answering the question... 

      • Thanks Leonard.

        In all honesty, in the several hundreds of flights I've done with 4 different AC powered MR's (3 Pixhawk, 1 AUAV-X2), I've had one confirmed flyaway/crash in July, but was due to a hardware issue with the AUAV. Other than that, no crashes!  

        Well, there was the one time I changed the compass orientation to 'roll 180' on my first 3DR Y6B, took off in stab, switched to Loiter IIRC and the copter tried to circle the earth at 45 deg angle at full throttle into a swamp only damaging one motor fortunately. Of course it was the FC's fault until one of you guys spotted the real

        Oh, and the rollovers when learning how to take off as coming from a small KK2 quad to the Y6B was quite a jump. Chalk that up to noob learning how to take off.

        Other then that, I've had no crashes; zero, nada. Ok, there was a few times they tipped over on landing and tried to dethatch the yard,  but the good news is that crash detection works! And trying to do AT when it was too dark to see the copter and it floated into the woods (at low altitude); no damage, whew. 

        I'm building another copter, this time an X8 (just can't bring myself to build a flat) unless I change my mind by Monday when ordering the components. By the time it's built, we should be into AC 3.4...... can't wait. For the record, I only use the Dixie Cup quad for testing with rc's until Randy gives me that warm fuzzy feeling the code looks ok for the other machines.


      • Developer

        Thanks for the clarification Leonard.

        It's a big topic so if anyone wants to discuss it more, it would be good to create a new discussion (anyone is welcome to do it) and post a link here.

  • Hello folks,

    I am running 3.3rc10 on pixhawk-lite - Just finished the autotune (2 steps, pitch then rool +yaw), a bit windy today (5 - 7 miles wind) so it took 12 minutes for pitch and 18 minutes for rool+yaw. After that it flew very good, stablize, pos-hold, land, rtl etc worked as rather well.

    However, it seems the log got truncated somehow. Do I need to select all+disarmed in order to see the complete log.

    2015-09-04 17-06-59.bin

    2015-09-04 17-27-58.bin
  • Hi

    I've also seen some issues with the compass variance but the ONLY way to try to understand these problems with enough probability of success is to have log files and possibly a small photo of the physical layout of both the flight controller and external compass.

    So, keep the logs coming :) I'm sure Paul will hate me but it is the only way to trace this :)


  • A couple weeks ago I mentioned my copter drifts a lot when between (rather than above) trees, but with ~15 satellites and a low HDOP. M8N GPS.  Someone asked for a log, and I finally made one. 
    I'm not sure it's an issue, as the copter is definitely stable above the trees.   

    But if you want data, here are some logs.

    I also had an attempted fly-away, on rc10 in loiter.  It was the first time it's ever happened to me.  Historically, my copters have all been very stable once up in the clear sky.  
    I'll post a link to my attempted fly-away discussion, in case anyone working on 3.3 wants to see those logs.
    Attempted fly-away

    I've attached an image of the amount of drift over a couple of minutes, while the copter is actually stationary, and a log.

    • Do you have one or two GPS units? Just wondering.  IIRC Randy recently recommended not using two until a fix in 3.4. Someone please correct if that is not the case.

      • No, only one.. 

        I've got two copters, one has an H.K. m8n, and the other has an RTFQuads m8n.  They both show the same drift. 
        I've ordered an expensive csgshop one, to see if it really makes a difference, like some others here have said.  Probably be a week or two until it's delivered.  

This reply was deleted.


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