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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    • Developer

      Hi stubugs,

      Loiter doesn't break like pos hold. Loiter is designed to drift to a stop like stabilize does. The intent of loiter is it should resemble stabilize on a calm day no matter how windy it is.

      So when you let the sticks go it slowly drifts to a stop. If you want it to stop quicker you need to reverse the sticks in the same way you would in stabilize.

      Hope this makes it clear.

      • +1 on that - There is absolutely no reason (AFIK) to use Loiter mode any more with the new Position Hold mode available. You Devs did a **fan-freaking-tastic** job on this new mode, so thank you.

        • I think the same when this lovely mode appears but I read from devs that Loiter is usefull for videos, you can fly a constant low velocity, that's true (or what I understand in my bad english)

          • Developer

            Hi Cala and others,

            Personally I think Loiter gives a lot more control compared to Pos Hold and I personally don't use Pos Hold for that reason. I use Stab, Alt Hold, then Loiter and find Pos Hold just an ugly switching mode between Alt Hold and Loiter.

            I intend to do some work on Loiter for the next release that will make it even smoother and more responsive to stick input. I also intend to do some work on Pos Hold so that it does a better job of adjusting for wind when you are flying it around. I suspect after those changes both modes will be hard to fault. In the end Loiter will always provide the pilot with greater control, at slow speeds, than pos hold because it doesn't break when the sticks are near centre. 

            • Major problem with loiter right now is this - when GPS gets switched or gets wrong coordinates - craft darts to a side and in loiter reaction to input controls is sometimes not sufficient to counteract in time, so it you fly close to a building, like for a roof inspection - you can crash.

              PosHold reacts way faster. But core problem is still how craft reacts to GPS coordinates glitches, it really has to be fixed somehow.

              • I had this problem in loiter also when I had a 3dr 6h gps and a Neo7 it would dart say 2 to 3 ms but I cured this by changing to two 3dr gps s and this seams to have solved the problem even when loitering next to my house hope this helps
              • The problem is that the GPS signal coming from one of the Satellites is bounced off the roof causing it to be delayed getting to the GPS.  This causing the position to move towards the house and the copter compensates by flying away rapidly.

                This can be seen by flying in Stabilize mode or Alt Hold near a building and watch a trace of the GPS from the logs.

                As far as the GPS is concerned it is getting a valid signal just not a good one.  About the only thing that could be done is if the position moves very rapidly in one direction suddenly to ignore it as a bad position but how do you now how long to wait before accepting it again and what do you do in the mean time.

                I have seen where the GPS position will jump as much as 100 meters in one direction.  This happens as the copter is moving up or down near the roof line which causes the signal to suddenly bounce and disappear.

                GPS was never designed to work in or around structures.

                • I don't know if this helps, but I switched to using "pedestrian" gps mode and positioning is a lot better.  unfortunately, reflected signals are always going to be problematic without an intelligent method of filtering them out vs direct signals.

            • Thank's Leonard to clarificate, I fly a lot in FPV and I prefer this modes because no risk to drift to sides like Althold, in other way, at the begining, Poshold save my copter from a Fly Away, I made a mistake configuring Failsafe (TX and Dragon to configure) and copter stays in place waiting that I move and recover signal (FIUUU!!!!).

            • thanks for the insight- very interesting. in 3.3 rc12 i have to say that poshold flew much better than loiter. i had the same amount of altitude drop on directional travel into the wind in all three modes (loiter, althold, poshold), with poshold maybe a bit more pronounced on alt drop over say a 15 meter distance of horizontal flight into headwind. 

              maybe it is just a case of needing to raise the "altitude" P gain in tuning parameters. it is set at default 2.00

              braking, flight control was (to me) more precise and responsive in poshold than loiter.  braking in loiter is not so hot, but i understand the goal of it is to drift to a stop, so more pilot judgment is needed in flight.  poshold just 'puts on the brakes', and the amount of brakes can be tuned.

              poshold was rock solid in a fixed position on the windy days I tested it. no complaints there. i can imagine any tweaking you do to these modes is going to make them both that much better.

              Wasn't the initial intention for poshold mode to replace loiter?

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