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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    • Nice flying field!!!! I wish!!!!! 

    • My opinion in your post

  • I have a 2nd 3DR Pixhawk which I test from time to time using the GPS on serial port 2 as the original gps port got ripped off on a flip over.  I tried a few flights on v3.2 and it worked, but didn't feel comfortable enough to fly it that way so took it off.

    I've put this crippled Pixhawk on a quad for some more testing this weekend.  I put the latest beta on from today.  I notice my status  says  no gps but if I look at the detailed status in Mission Planner, I see the # of sats and hdop data.

    Is there anything new in any of the versions that might be relative to what I'm trying to do to help make this somewhat reliable using the sat connection into the serial port?  Will tower show the # of sats and hdop?

    Sorry for the simple questions, but have been away while and have decided to put my good Pixhawk on an 20 lb x8 if I can get over some of my calibration problems.... Just thought I'd reacquaint myself with the lastest firmware and a less expensive lighter quad first. 

    Thanks in advance for any advice.  Hope it's ok to post this here. 

  • hi Randy , my apm hexa is take off with 15-25% thorttle and hover with 20% thorttle. really hard to control and land. can you help me how do i fix it ? i'm flying hexa size 900. motor 380kv sunnysky. props 15.5 tarot, esc 40a hobbywing. battery 6s 5500 genace.

    thanks you so much!

    • Developer


          The short answer is probably to add extra batteries to the vehicle to increase it's weight so that it's hover throttle is at least 30%, then reduce THR_MIN if possible (it must always be high enough to keep the motors running even when the battery is low) and accurately set the THR_MID to whatever the CTUN.ThrOut values shows.

          I think this is a better solution than trying to keep the hover throttle at only 20% because the THR_MID value is limited to 30% ~ 70% and having it not match the vehicle will lead to various problems with the transition from manual to auto flight modes, the landing detector and pilot throttle feedback when landed in modes like AltHold and Loiter.  Also with hover at only 20% the attitude and position controllers don't have much room to work with.  In some ways it's similar to trying to control a vehicle with a very low battery (i.e. hover throttle of 90%) - vehicles with low batteries also don't perform well because they hit their (upper) limits.

      • Randy

        yes i agree. i leave all by default, it's diffrent so much with my hex f550. i don't know why i take off with f550 with must over 50% throttle. but with hex s900 then only 20-30% is take off, really hard to control and landing, really easy crash. do you have any tips of your parameter thorttle accel and more ?

        i see in THR_MID is 700, so i need to drop it to 300-500 ? any ideal ?

        thanks you!

        • Add weight! You are way over powered. My T960 is the same, hovers at like 30% so I added some dummy weight to help and it does. Still no where near the proper 50% but at least now setting THR_Mid to about 40% is close and it doesn't skyrocket or fall on flight mode transitions now :)

          • oh thanks you. so i must add add weight, battery or something ? then fly test and take out ? or i put it forever ?

            • I have a photo quad with 390 kV and 15x5 props, and I'm loaded with a 10.000 mAh 6S for 34% hover. And that's with only four motors !

              For your hexa, a 16.000 mAh pack would be fine, probably even a 20.000 mAh. 

            • I went from flying with 2 2200 mah 4S to 2 5000mAh 4S and that helped a LOT. I will be buying some 5000(+) 6S soon and then adding my gimbal and stuff should bring it down to my needed 50% :)

              Another thing you could try is smaller props for now. It will not be as efficient and will cut down on flight time, but it would help bring your throttle closer to the golden 50% :)

              or just add some weight. Doesn't really matter what you use really just make sure it doesn't toss off your COG and also keep in mind more weight = less flight time so adding dummy weight will decrees the time you get to fly which is why I elected to use bigger batteries so that I offset the extra weight with more reserves :)

This reply was deleted.


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