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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              • I don't use stab very much, only to take off and emergencies because my radio Throttle have a large cri cri and it's difficult to mantain altitude, (but that becomes better with last firm)

        • re- I'm just checking to see if this is a tunable parameter or solely due to aerodynamics.

          At this point I believe it's aerodynamically corrected only as far as forward flight is concerned. It needs air but not be too exposed so speed causes a bubble of high or low pressure. 

          • Thanks Richard-  totally understandable and I do see this behavior with my acro quad. If you tilt, you must throttle too :D.

            I was thinking that if poshold incorporates automated altitude correction, it would sense the drop in alt during forward flight and apply more throttle as needed to compensate.  I do have ahrs_gps_gain set to 1, was thinking there might be a P gain like "POS_Z_P" that is related to determining the aggressiveness of altitude hold in forward tilted flight.  again this is only really noticeable or significant if flying into a headwind, or if in a set position hold and copter is battling a bit of headwind from any direction. copter will compensate and tend to drop in alt. if it is no longer busy compensating it will regain height. however if it keeps compensating there is chance it will work its way to the ground.

            but, i did not see it drop alt too much during set position holds - as a matter of fact, it was downright impressive :D. it only did that a couple of times. it does it very consistently with alt drop on forward tilted flight though, into the wind.

            • Here is a link that will bring you up to speed on the altitude loss with speed issue:

              • thanks - "up to speed" - no pun intended right? ;p

                I had read that some time ago- i have this exact setup with the RC timer flight platform and dome, per Leonard's findings: "Based on what I have seen so far the best approach is to sit the pixhawk on a nearly solid plate with minimal holes in it. Then cover it with a dome of some sort, leaving only a small gap around the edge. This should then minimize altitude variations caused by attitude and speed."

                during stabilize mode forward flight, or drift mode, there is no issue beyond "normal" with alt drop and simply needing to maintain throttle as needed. I am talking specifically about the automated PosHold mode, which attempts to correct both position and height. it is in this mode that the alt drop on tilted flight, into the wind, is pronounced. it is hard to compensate throttle manually since there is an imposed deadband around throttle mid stick.

                • Does it have this problem in forward flight in alt hold or only pos hold? 

                  • Richard- I want to say it does do it a bit in althold mode as well. i did not fly althold mode around as much as position hold, but i did notice some drop into the wind as well in althold-  just not as pronounced as with poshold. direction did not matter either, it would do same drop off whether forward pitch 15 degrees into wind or say roll right 15 degrees into the wind, and hold that for say 25 yards sustained. it was a gradual and consistent decline in alt. if i let go of sticks it would auto brake, then eventually pop back up to the last alt. a few times it did not pop back up though.

                    also, it was harder to apply some manual throttle to compensate in poshold mode vs althold mode.

                    on that note I was also asking if you guys typically stick with the associated 100 deadband default or slim it down to say 50.

                    keep in mind I consider this to be fairly minor- i am only bringing it up in case it is worth looking into.

  • I assume this has already been discussed but, for the life of me, I haven't been able to find a way to search this forum's database.

    I just completed an auto tune of roll and pitch. The results between roll and pitch are completely different, ie:

             Roll                     Pitch

    P      0.2312426            0.4205088

    I       0.2312426            0.4205088 

    D      0.00845350          0.01838647

    Would someone please advise whether or not this is normal, or should I be concerned?

    I'm flying a Pixhawk with 3.3 RC-12 on a Tarot FX690Pro (hex) with 3805-580 motors.

    • Thanks for the replies...

    • Developer

      Hi Tom,

      Yes, both roll and pitch should be different on a hex. Yours are very different but if your copter is flying without issue then you are fine.

This reply was deleted.


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