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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  • 3702014420?profile=original

    3702014488?profile=original

    3702014519?profile=original

    ALIGN 500DFC Pixhawk AC3.3 rc5 test at the seaside,I try to change INS_ACCEL_FILTER and INS_GYRO_FILTER parameters for the 15Hz, indeed better.But I do not try to use the automatic landing mode.

    2015-05-27 18-09-35.bin

    • good result,zhangsir

  • On Friday, I played around with the yaw controller a little bit, I added a Yaw Acceleration Feedforward, which is different from the Yaw Rate Feedforward you're already familiar with.  The idea being it gives the servo a little more movement whenever the Yaw controller is asking the yaw to accelerate.  It seems to be working very well for me.  This is more useful for sports flying than UAV-type flying.  I'm using a yaw rate of 450 deg/sec, and 1440 deg/s/s acceleration rate, and I'm not getting a bounce on stopping anymore.

    I haven't decided if this will go into 3.3 yet, or wait for 3.4.  It's a really late addition, but it's also pretty simple.  If you set the parameter to zero, it will have no effect.  What do you guys think?

    • I'm keen to try this addition out. Sounds really cool. Also keen to see how it goes with pitch and roll axes.
    • Hi Rob,

      another nice feature for those who like to play with parameters. On the other hand there are FBL-systems like Graupner GR-18 that have a default PID setting which is good for at least 450 to 700 class and the tuning freaks can use the expert menu.

  • 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.

    •  AC3.3 rc5  is also a bug:Circle mode does not change height,Even if the throttle stick minimum and maximum are invalid;Multi-motor (Hexa) firmware is true……

  • I just realized that when you upgrade to 3.3, they replace the INS_MPU6K_FILTER with the two parameters INS_ACCEL/GYRO_FILTER!  These default to 20Hz which makes measured vibrations quite a bit larger (since I was set to 10Hz originally).

    I recommend making sure your IMU filters are set appropriately because they won't transfer.

    This has caused me all sorts of problems that I'm lucky to have survived. 

    • Hi Ray, yes, this is true.  I'm actually flying on 20Hz with my Goblin 380 and it's OK, but it's a very smooth heli being all belt drive, no gears, and only 2 shafts.

      So it is possible.  IIRC, I've had other helis flying on 20Hz as well.  Maybe my Trex500.  A lot of it depends on your vibration damping too.

  • Rob, thanks for the coding and the warning on rc5.

    After tracking down every vibe on my heli (there are a lot of sources), a complete redesign of my mount, and changing my filter rate from 20 to 15 hz, I had a very success flight today.

    Stabilize, Loiter, and Auto worked in all phases of flight. Land detector worked every time.  I've retuned by increasing my pitch and roll FF terms.  FF makes it very snappy.  The slightest Pitch D took out all the bobbles and now it maneuvers with precision.  I plan to put in a little more time with yaw tuning and then start tweaking some of the lesser used params.

    I'm finally enjoying 3.3 (not that upgrading gained me anything).

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