AC3.3 TradHeli Release Discussion

WARNING to TradHeli users:

Do not attempt to fly AC3.3 until you hear otherwise from me.  I have not even bench tested it yet, let alone test flown it.  There are quite a lot of changes that have gone in that could be crash-o-matic for helicopters.

AC3.3 release for Tradheli is likely to be delayed.

This post will serve as the official release progress thread for TradHeli.

Warning: DO NOT FLY RC6!  It has a critical bug that will likely end in a crash.

Warning for RC5:

RATE_YAW_FILT_HZ param will change defaults from 5Hz to 20Hz to be more suitable for helicopters.  If you have never changed this parameter from 5 before, then it will automatically update the value to 20 without warning.  This much faster filter will probably require reduction in your P and D terms, and the yaw may oscillate badly.  Be prepared to retune these.  As a safety measure, probably cut them in half for your first take-off.

Warning #2 for RC5:

I accidentally broke the Landing Detector.  It will probably never trigger.  You should land in Stabilize mode, or be prepared to shut down the motor as soon as it touches the ground in Alt_Hold, Loiter, Auto, etc.

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    • Were you flying rc5?

      I believe I accidentally broke the landing detector for tradheli on RC5.

      • No, I was flying rc4.
        Landing detector worked on that. I'll try to land on rc5 as soon as the rain stops.
        One thing I found that I didn't see in 3.2.
        If I switch to loiter or auto after spool up, no problem.
        Today, however, I tried to arm in loiter. Upon spool up, the copper spun around 270 degrees. I believe that it's related to an issue previously mentioned in this thread.
        Maybe a bad reaction to the initial vibration.
        I always get a 15 degree movement in stabilize but this was extreme. I rarely switch to loiter before spin up but just testing.
        • Please note, the land detector on rc5 is totally broken, no point testing that.  You can fly it, but don't do auto-lands.  Or if you do, just shut it down as soon as it touches.

        • Flashlog Link

          See above for the flash log.  The yaw problem happened half way through this log.  I switched to loiter before starting the rotor.  On the ground the heli had a significant yaw nearing flight RPM.

          45.BIN
          Shared with Dropbox
  • I've added an important warning to the discussion:

    Warning for RC5:

    RATE_YAW_FILT_HZ param will change defaults from 5Hz to 20Hz to be more suitable for helicopters.  If you have never changed this parameter from 5 before, then it will automatically update the value to 20 without warning.  This much faster filter will probably require reduction in your P and D terms, and the yaw may oscillate badly.  Be prepared to retune these.  As a safety measure, probably cut them in half for your first take-off.

  • Ok, I cause of the problem that Ray found that cropped up after RC1, where the collective doesn't move when disarmed.  There's a couple ways I can fix it.  One of the easiest ways, to complete eliminate this new throttle filter (collective filter) that the multirotors guys added, eliminate it from helicopters.  I believe it defaults to Off, so we don't see the effect right now, other than when disarmed.

    The idea with this thing is that it slows the rate of change of the throttle (collective) changes even in manual modes.  Now, normally, I'd hate the idea of this, something getting between me and manual control.  However, after flying a Solo where it's turned on, I actually kind of like it.  It does help smooth out manual flying the same way RC_Feel and the ATC_ACCEL controls do.

    So I'm not sure I want to get rid of the option of using it.

    What do you guys think?

    • Ok, so I have the fix working with the filter code otherwise intact. That was easy.  I think I will keep it this way.  The filter won't affect you unless you turn it on, and now we have collective when disarmed.  This should go out with RC5.

      • That sounds good Rob, thanks.

  • AC3.3 rc3 :

    A strange attitude to take off a key confusion problem occurs:

    https://www.youtube.com/watch?v=GXKqD--HgkM

    Althold or loiter mode switch set high speed drop suddenly:

    https://www.youtube.com/watch?v=Mb8cXEccoN8

    AC3.3 rc4:

    3702005690?profile=original

    •  zhangpengsir

      I looked at your logs and see that near the point you lift off, your Y axis accerlations are near +- 20gs. This is most likely caused by main and tail rotor vibrations reacting/amplifying with the ground through your skids.  It changes based on the skids, lift and blade tracking.  

      Yaw control seems to be affected by high vibes too.  I've experienced the same type of liftoff in loiter.

      Your main rotor didn't seem to be on speed before lift off (as well as tail).  Is there a way to take off in Guided while letting it spool up a little more?

      Suggestions:

      1.  Vibration control by balance and isolation/dampening.

      2.  Let the copter settle under partial lift before switching into auto modes.  This gives the RelAlt a chance to stabilize.  

      3. I have had luck lowering my MPU sampling rate to 10 or 15 Hz.  This helps reduce measured vibrations.

      4. Find a way to get the heli to spin up completely before allowing liftoff.

      I'm not sure on the the loiter altitude change but I had climbs when switching and I think I fixed it by lowering THR_MID.

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