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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  • Hi folks,

    I'm new to this community and I must say great work done my many here, thank you.

    Quick question. I just upgraded from 3.2.1 to 3.3. How do I turn off the low voltage audible alarm while my Pixhawk is powered by USB without having to set FS_BAT_VOLTAGE to zero then remembering again before flying. It didn't do it in 3.2.1. Voltage does read correctly on the HUD so I don't need to calibrate the device.



    • Never mind. Found a failing USB power supply. Once changed the Pixhawk is now operating as it should, and did,at the correct USB voltage and alarm silent.

  • 3702113322?profile=original3702112933?profile=originalAttached are graphs of accels for IMU 1 and 2 and vibration which I believe reflects IMU2 the LMS303D.  This is a 3DR Pixhawk

    The accel readings for the Z axis show considerably higher amplitude on IMU2.  It appears the difference is noise / vibration on IMU2. as average amplitudes seem close. But vibration on IMU2 appears factors above IMU1.

    The vibration show very low readings on X and Y and higher as expected readings on Z.  On higher motor output / acceleration IMU 2 appears to be clipped whereas I would suspect IMU 1 would be fine.  

    Looking at the board layout the LMS is out at the corner of the board where I would guess it is seeing some board vibration.

    Is this vibration difference  IMU2 being higher a consistent difference typically seen?  Has anyone attempted adding some vibration reduction foam to support the board corner to reduce this?

    The copter seems to be handling well even during acceleration but I am concerned around the clipping seen. This was a 15 minute flight and I am not sure if this number of clips is a serious issue.   Obviously 0 is best.  No  issues with Alt Hold very stable on altitude while flying.

    I have done a few of revisions on vibration control and reduced the aount of z vibration and clipping events significantly but may have to do more.

    • Developer


      I think we generally see the lsm303d being noisier than them mpu6k but not to the extent shown in these logs.

      The two sensors run at different frequencies (mpu6k is 1000Hz, LSM303d is 1600Hz) so I guess it could be very high frequency vibration that's being aliased down to the 400hz main loop rate (we average the received sensor values at 400hz)... or maybe you're right that it's the sensor's position on the board.  I've certainly heard a PCB can acting like a trampoline due to vibration (apparently 3DR hit this problem during the development of the Solo).

      I think the vibe levels you're seeing are borderline ok.  200 or 250 clipping events is not many really but it does indicate that the vibes are close enough that they occasionally go out of range.  My IRIS for example always has zero clipping events unless I really bang it into the ground on a hard landing (like here).

      • Randy,

        I went ahead and made a custom anti-vibration mount for the Pixhawk as well as did some reduction in the servo wire leads by removing redundant grounds etc.

        The clipping was happening during high motor output and I was concerned that in a situation where continuous high output might be required that flight performance and stability might be affected or even if a prop was imbalanced.

        Results after installation are dramatically lower.

        Comparing IMU 1 and 2 there now is very close agreement between the two on the z axis.

        There are now zero clipping events even with hard vertical accelerations.3702724306?profile=original




        • Nice vibration levels, but I'm afraid removing gnd wires from ESCs on pixhawk is a recepy for disaster due to known sync loss issues especially with low kv high voltage, high pole count motors + SK/blheli ESCs. 

          • I am not using SK or BLHeli in this copter.  I m using Castle ESC with their multirotor software.

            I have never had any sync issues with these. Have used the Castles on many multicopters and low 

            KV heli motors.  I have had a couple of cases with SK sync issue on high pole count pancake motors and am careful on firmware revisions on these. However for higher end builds with expensive payloads tend to rely on the Castles.

            • Castle are well known for quality they also tend to be rather expensive. Since July I use HW xRotor40a-Pro, with breaking enabled they are as as fast as spiders 40a flashed with blheli on low kv otors, but barelly get warm. 

          • Developer

            Ah, I didn't notice that change.  I've heard this same info from Rob Lefebvre.

This reply was deleted.


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