Developer

ArduCopter 2.9 / 2.9.1 released

ACRO bug (fixed in 2.9.1b): while doing flips in ACRO mode, if you switch to Stabilize while inverted your throttle will go to minimum.  To regain throttle control you need to switch back to ACRO then back to Stabilize again (i.e. switch to stabilize twice).  You never lose control of roll/pitch/yaw.

Loiter/AltHold/Auto/RTL bug: if you switch into these modes with throttle at zero motors will go to minimum until you raise the throttle.

Auto mode altitude bug (fixed in 2.9.1b): setting a waypoint altitude greater than 320m over home altitude may wrap around and instead be interpreted as a low altitude.

ArduCopter 2.9 is now in the mission planner and the downloads area!

The major improvement is we use inertial navigation to improve altitude hold.  This increased reliance on the accelerometers means you must do some additional set-up before flying:

1. Perform the new accelerometer calibration in the mission planner (video).  The auto-trim metho has also changed (video).

2. Add vibration dampening foam between your frame and the APM.  Some suggested materials: DuBro, gel, hk foam.

 3. If upgrading from 2.8.1, modify the throttle and altitude PID values:

  • Increase your Throttle Rate P, reduce I to zero, increase D
  • Increase Altitude Hold P, reduce I to zero
  • Tune Throttle Accel P and I terms but try to keep P about 1/2 the size of I

 

Here is the list of major changes (a more detailed list can be found in the release notes):  

  • Alt hold using inertial navigation (Leonard, Randy, Jonathan)
    • AUTO_VELZ_MIN, AUTO_VELZ_MAX parameters control the max climb/descent rate for the autopilot (cm/s)
    • PILOT_VELZ_MAX controls max climb/descent rate for the pilot (in cm/s)
  • Landing improvements (Leonard/Randy).  Copter will descend to 10m or until an object is sensed with the sonar.  Then slows to 50cm/s descent (speed can be adjusted with LAND_SPEED parameter). (video).
  • Surface tracking with sonar (Randy/Leonard).  Copter will attempt to maintain current distance from objects in front of sonar regardless of altitude.  Only used in alt-hold and loiter, not used for missions.  Sonar can be enabled/disabled with CH7 switch. (video)
  • Failsafe improvements (Randy/Craig/John Arne Birkeland) including bug fixes, additional check for PPM encoder failure and implementation of battery failsafe.  Set-up instructions are here.
  • Mediatek gps driver accuracy improvements and use of SBAS [Craig].  Instructions on upgrading your mediatek to firmware 1.9 are here.
  • Traditional Heli improvements (Rob) including (a) bringing heli code back into the fold, (b) enabled rate controller (previously only used angle controllers). (c) fix to rotor speed controllers - now operates by switching off channel 8.  (d) allow wider collective pitch range in acro and alt hold modes vs stabilize mode  (e) bug fix to allow collective pitch to use the entire range of servos
  • Acro trainer (Leonard). Copter will return to be generally upright if you release the sticks in acro mode.
    • ACRO_TRAINER : set to 1 to enable the auto-bring-upright feature
    • ACRO_BAL_ROLL, ACRO_BAL_PITCH : controls rate at which roll returns to level
  • Camera control improvements (Randy/Sandro Benigno):  (a) AP_Relay enabled for APM2  (b) Trigger camera with CH7 or DO_DIGICAM_CONTROL command  (c) Allow pilot override of yaw during missions and fixed CONDITIONAL_YAW command.
  • PPM sum support for transmitters with as few as 5 channels (Randy/Tridge/John Arne Birkeland).
  • Performance and memory useage improvements (Tridge).

 

As per usual PIDs are optimised for the 3DR/jDrones quad with 850 motors and 10" props. If you're using more powerful motors/props and are seeing bad flight behaviour in stabilize, start by turning down Rate Roll P in 25% steps.

Special thanks to our testing team lead Marco and the dedicated bunch on the 2.8.1 release thread who put their copters at risk while testing the pre-release version.  Some of their videos are here: 1 2 3 4 5 6 7 8

Please feel free to report issues you find in the discussion below and/or add them to the issues list.

 

Tags: ACM, APM1, APM2, ArduCopter, Heli, Quad

Views: 214988

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Replies to This Discussion

Permalink Reply by Xerravon on May 12, 2013 at 9:54pm

Hi,

I have a question about adjusting the declination using ch6.

I set it up with the min -max the same as in the MP options column  "-3.142 to 3.142" but the range I am seeing when I test, turn the knob then refresh is ".349 to -1.833"  from the middle of the knob to the end going CCW on the knob stays at .349 from the middle to the end going CW goes from .349 to -1.833.  not what I expected...

are the numbers "-3.142 to 3.142" for the range correct in the options column or am I doing something wrong?

thanks for any info on this

John

Permalink Reply by Choppy on May 12, 2013 at 10:12pm

Hi John, Did you do a radio calibration? I fall that trick all the time :)


DeveloperPermalink Reply by Randy on May 13, 2013 at 6:44am

John,

     So to be clear for anyone else reading this thread, Xerrravon's question is a 3.0-rc1 (or rc2) question.  The range is hardcoded to be plus or minus 20degrees.  So set the tuning range min to 0 and max to 1.0.  I'll fix it so it has a bigger range...maybe 30degrees.

Permalink Reply by Xerravon on May 13, 2013 at 10:09am

Hi,

Thanks,  I dont know if what I did is correct, but I lined my copter up pointing north with a regular compass and tweaked the declination numbers till the hud and compass gauge were north (0 degrees)  not sure what it will do with motors running, but now that I understand the ch6 declination, I can always tweak it again.

thanks again

John

Permalink Reply by palo sestak on May 13, 2013 at 3:41am

Hi all,

slightly off-topic but perhaps others will be interested too:

Will be supported in some later version of ArduCopter V-Tail configuration, e.g. for quad?

I did some searching through discussions here on DIYdrones but didn't find satisfactory answer to this question.

Someone advise just change motor mapping, but i thing it is not that easy and I really didn't find actual solution (changes in source code) how to make it possible.

Permalink Reply by Xerravon on Wednesday

Hi,

I have a quad I put an apm25 on, it was working during setup. I then went out to fly and it would not arm. Finally I noticed the altitude was reading 200 feet. I did an altitude test in cli and got this

Does this mean I have a bad sensor?

thanks,

John

Permalink Reply by Tony Foate on Wednesday

TAKEOFF STABILITY WITH 2.9.1b

I have an issue with run up and takeoff stability.

My F330 is difficult to get off the ground nicely i.e. with no pitch/roll manual interaction.

Once it is in the air, it works well. Alt_Hold also works smoothly.

It hovers nicely at 419 (from the log) which aligns with around 40% throttle on my DX8.

The Mod/Stabilize line in the log suggests a hover speed of 320 approx. Why not 419?

I have left THR_MID at the default of 500.

Initially, with THR_MIN at the default of 130, the unit acted by a provoked pit bull terrier – sprang into the air and had to be brought down with a total throttle cut.

I now have THR_MIN at 35. Tests at higher settings did not help.

How should I approach analysis to achieve an orderly takeoff?


DeveloperPermalink Reply by Randy on Wednesday

Tony,

     I don't think setting thr-min to 35 is a good idea.  That number represents the size of the ESC's deadband at the bottom of the throttle.  So if the number is too low then the motors could stop momentarily while you're descending because the APM will send an low throttle request to the ESCs that they will interpret as meaning, "cut throttle".  130 (the default) is a bit conservative) but 35 is too low I think.  Usually anywhere below 80 will cause problems.

     One of the problems with 2.9.1b (and all previous versions) is that the alt hold and loiter controllers I term runs up between the moment that you engage auto and the time that you raise the throttle above zero.  This is fixed in 3.0 (release candidate #3 is just about to begin testing) but until then you may find that it's a little smoother if you do both the switch into AUTO and raise the throttle at the same time (or close to the same time).

     The Mod/Stabilize line is showing too low a cruise throttle (aka TRIM_THROTTLE - which is the autopilot's best guess at how much throttle it needs to give to hover) because of the landing just before the take-off.  when you're descending the throttle is lower than normal and this is leading the autopilot to guess too low.  Generally it doesn't matter much now that we have intertial nav because the autopilot figures it all out again pretty quickly.  I think if you manually set that TRIM_THROTTLE to a low value (like 150) just before you do the take-off you'd find that it was a touch smoother...but you know...it's all sorted in 3.0 so you might choose just to put up with it until then.

Permalink Reply by Tony Foate 14 hours ago

Hi Randy,

Thanks for the response.

I manually set TRIM_THROTTLE to 150 as suggested.

Took a lot more throttle to get the unit moving but still did not give a smooth take off.

Of course, as soon as one lands, TRIM_THROTTLE is reset automatically by the autopilot.

I am not game to increase THR_MIN above 35 without some other parameter adjustments to avoid the inevitable undignified leap into the air.

I do not use the AUTO mode. ALT_HOLD entry and exit works flawlessly once the unit is in the air.

My challenge is the takeoff. I would like to set THR_MIN back to the default of 130 but I need to balance this with some other adjustments to avoid a disaster.

What should I do?

Regards

Tony

Permalink Reply by Harley Engholm 5 hours ago

How bad is the behavior on taking off? I think all quads do some wobbling and are touchy while in ground effect. Mine wobbles and I have to be careful on liftoff and landing while close to the ground (couple of feet). If it is violent, there may be some other issue.

Permalink Reply by Gustav Kuhn 2 hours ago

What quad do you fly?

Yes, you have to lift off "briskly", to about 1 meter above ground, goes for conventional RC heli's too.

All the air underneath a rotary wing/s aircraft on take off, and near to the ground, does really weird things.

At our scale, 1M seems to do the job.

Same with landing, plan ahead, get to above your landing spot, firmly/gently reduce power, put it down.

Confined spaces really messes up, or fine tunes :-), your start/end skills !!!

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