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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        • Part of the tilt over problem is that the FC has more authority over the motors than the pilot input. When the multi try's to reposition after landing the pilot can be countering the move with full stick inputs but the multi still tips over.

          A kill switch is an ok idea, but requires another pilot input just like flipping to stabilized mode. The goal should be to fix this problem through a way that protects novice pilots from having their multi tip over.

          I like having stabilization functioning even after I touch down. During windy landing or when landing on uneven terrain I want to see that the multi is stable on the ground before I bring the throttle to minimum.

          Could the GPS radius for position hold be loosened up when throttle is at minimum?

          Another approach might be limit the maximum tilt angle to 10* when throttle is at minimum so that the multi would not be able to lean far enough to tip over in the first place.
          • It should also be noted that a number of flight controllers actually "turn off" the integral portion of the PID during take off to prevent flipping in situations where the operator increases the throttle slowly.

          •   This "flip on landing due to a small lateral move" problem really looks a lot like an unbounded integral wind-up issue.  Preventing the error from accumulating to an unreasonable degree should do much to control this.

              Limiting a max tilt angle is also something that should be prioritized over position corrections in a landing type of flight mode mode.  I suspect that without first better limiting integral wind-up,  limiting max tilt angle won't actually be effective.

              It would seem that the ideal behavior would be as follows:  In a situation where a copter meets resistance while moving laterally, it should tilt in a controlled manner to a maximum angle and then hold that angle indefinitely.

              This may fall under the category of "easier said than done", but it seems like a reasonable goal.   Very likely the changes needed to effect this behavior would result in undesired effects in some flight modes, as such it might make sense for the changes to only be effective in landing types of flight modes modes.

  • I have been flying with rc10 since it came out and everything was fine till today.

    I was on my second battery of the night and after 5-6 minutes for some reason my Y6b suddenly rolled/yawed in place and then would straighten out again. This was in stab mode with simple mode on. This happened several time and then the copter seamed to loose power and started slowly decending. I was still able to apply roll and pitch but it ended up coming all the way down and flipping over when it hit the ground.

    After the crash I noticed that the GPS mast was a little bit loose and could easily twist 5-10 degrees. Not sure if this was caused by the crash or went loose during the flight.

    attached is the log from that flight.

    Any thoughts/insights would be greatly appreciated.

    • hmn log file didn't seam to attach so here it is via google drive

      • Developer


        Thanks for testing.

        Looks like motor #4 (bottom back) is failing.  It shows the classic signs which is sudden separation of the desired-pitch vs actual-pitch (it suddenly pitches back which is consistent with a rear motor failure) and the output sent to the back motor goes to full (i.e. it's trying to get more power out of the motor but it's not).

  • What is the best way to bias the EKF towards the IMU a bit more (or in other words, less wieghting on GPS) in rc10?  I realise that the IMU is already prioritised but can I adjust this even more?

    Is increasing EKF_POSNE_NOISE the best way to experiment with this or  EKF_VELD_NOISE?  (or should I increase both equally?)

    Currently my test machine flys well with 3.3.rc10 but I am trying to limit the movement in Poshold a bit more.  Attitude tracks very well with both AHRS and EKF, vibes are low and I have no real problems but a bit of wandering in GPS position hold modes when the GPS location changes suddenly.

    • Developer


      I think decreasing ACC_PNOISE may be best.  Increasing both EKF_POSNE_NOISE, EKF_VELD_NOISE together seems reasonable to me.

  • I have had now three times roll over / crash problem with the copter. Every time I go to test it, on the first attempt it will crash. I did complete reset for it, but didn't change the behavior. What could cause this? Any ideas? Obviously not really good "feature"..

    What happens on fist flight:

    arm, begin to add throttle. While still on the ground copter tries to lean left. I compensate with roll right and lift off succesfully. Craft flies nicely few second and then goes berserk. This time managed to ease the crash but was pretty much not possible to avoid. I picked up the copter on it's feet.

    second attempt:

    didn't boot after first one, straight arm. Lift off, still had to control it a bit on the lift off phase, but this time succesful flight and autotune. No problems at all.

    Log for latest flight:

    forgot: happened on different rc versions. rc10 in use this flight.

    • Developer


      It looks like a failure of the front left motor (#5 because you're using a hexacopter in the plus configuration) to start properly.  It displays the classic signs of a motor failure, the actual roll/pitch separates from the desired suddenly and it rolls left in the direction of motors #3 and #5.  In addition the output sent to motor #5 goes to maximum while it's opposite (#6, back right) goes to minimum.

      It might not be a straight up motor failure but perhaps the motor needs to be calibrated or it's settings are different from the rest.

This reply was deleted.


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