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.

I've put a patched version of 2.9.1 (called 2.9.1b) into the downloads area which hopefully resolves the more serious issues we've found with 2.9.1:
1) reduce INS_MPU6K_FILTER to 20hz
2) reduce InertialNav Z-axis time constant to 5 (was 7)
3) increased max InertialNav accel correction to 3 m/s (was 1m/s)
4) bug fix for alt_hold being passed as int16_t to get_throttle_althold_with_slew
5) bug fix for throttle after acro flip (was being kept at min throttle if pilot switched out of ACRO mode while inverted)
6) reduce yaw_rate P default to 0.20 (was 0.25)

I was wondering if some people could give it a try before we push it to the mission planner? The biggest questions are around #2 and #3.

#2 - reducing the time constant shifts the balance of power towards the barometer (i.e. weakens the accelerometer). This makes it safer for people more vibration but barometer misbehaviour appears. In particular try a fast forward flight and then flatten out. See this video around 1:55 where I'm testing a TC of 5 and you can see the drop after flattening out.

Of course, people can always increase their TC back to 6 or 7 if their copters are flying well.

#3 - this is probably the most important fix to reduce the risk of vertical fly-aways in Alt-Hold/Loiter/Auto. This problem could appear if people have a lot of accel noise and it had a bias of over 1m/s (i.e when the motors were running there was aliasing which caused the acceleration to appear to be constantly over 1m/s up or down). That limit is now 3m/s. The downside is that if you have a hard landing an alt correction may build up and take a while (30 seconds?) to recover...so you could have a bad altitude for longer after a hard landing.

Anyway, if a couple of people could give it a fly and report back then I'll push it into the MissionPlanner. thanks!

Replies

novrizal herdananto March 31, 2013 at 7:24pm

hi, i had a weird experience with baro this morning.
i'm comparing logs from a low light flight (at dusk) and a strong morning sun with a lot of shadows from trees this morning..

the dusk flight, got a very smooth barometer curve

compared to this morning flight got a vibration like barometer value..

is this means that strong light is affecting my barometer reading ?
FYI, i'm using apm 2.5 with case, and i didn't remove the foam inside the case.. also attached is my flight logs..

smooth_baro.log

weird_baro.log
zmooth March 31, 2013 at 12:50pm

I'm having trouble with the battery monitor, it shows -0.1A for current (yes, negative). This is with the 3dr power module.

Is there something wrong with my PM or anyone else having similar issues ?
Xerravon March 31, 2013 at 11:27am

Hi,

I am having a problem with one of my copters, I made a video to show the problem. I have tried everything including rebuilding it from the ground up.

It was flying, landing, everything great, best copter I had. It is on a x525 frame only I made some 3mm carbon fiber extended motor mounts.

I decided to change the top and botom center plates with stiffer ones I made out of 3mm carbon fiber, so the frame is very stiff now. Only problem is now it is not flying too good.

If ypo watch in the video, when alt hold mode and I flick the roll pitch sticks it "jumps" in the air then kind of drops back to hover alt. also I land 3 times in the video, first time it kind of shows the bounce landing, it is really not too bad in this but I think it shows enough (sometimes it will literally fly back up 4 or 5 feet) the last 2 landings land good. also notice how long it takes for the motors to shut off on the bad landing compared to the 2 good landings.

In the begining, I am just kind of flicking the stick in alt hold, that is what makes it jump like it does

thanks for any help with this, I just dont know what else to try

John
Xerravon March 31, 2013 at 12:24am

Hi,

I have a question about ing the apm25 with both the 3dr 5v power supply current/voltage sensor, and with power from a SBEC from the esc's.

What has me worried about a brownout is I have one of the long range RF900 modems on one of my quads, I am wondering if the 3dr power supply can handle the current it needs?

My question is, is it ok to use both the 3dr power board and to use power from 1 or more SBEC with the vcc jumper installed on the apm?

or can the 3dr power module handle the current needs of the RF900 modem for telemetry?

thanks,

John
marc.kulhavy March 30, 2013 at 1:32pm

One question, how does the current/future code handle user input during position hold? When flying in pos hold with version 2.9.1, it seems like the copter is fighting against my inputs. It takes some efford to "free" him. My expectation was that if I override the hold mode with my inputs, pos hold gets disabled until I let the sticks go and pos hold engages again and holds the new position.
The actual pos hold does not seem to do this, so is there a possibility to get this feature into the next version?
Regards
Marc
Jan Matuška March 30, 2013 at 4:55am

Hi Randy

, when you will have little time, can you react my questions from the past ? Thank you very much. Jan
Ivan Kostic March 30, 2013 at 3:11am

Hello!

I have changed my frame, to TBS Discovery, so it became a bit less stable, with default values. Should I try 2.91b, also with recommendations for changing tha values?

2013-03-30 10-39 1.log

https://storage.ning.com/topology/rest/1.0/file/get/3692669250?profile=original
Developer

Randy March 29, 2013 at 5:58pm

     I've put a patched version of 2.9.1 (called 2.9.1b) into the downloads area which hopefully resolves the more serious issues we've found with 2.9.1:
1) reduce INS_MPU6K_FILTER to 20hz
2) reduce InertialNav Z-axis time constant to 5 (was 7)
3) increased max InertialNav accel correction to 3 m/s (was 1m/s)
4) bug fix for alt_hold being passed as int16_t to get_throttle_althold_with_slew
5) bug fix for throttle after acro flip (was being kept at min throttle if pilot switched out of ACRO mode while inverted)
6) reduce yaw_rate P default to 0.20 (was 0.25)

     I was wondering if some people could give it a try before we push it to the mission planner? The biggest questions are around #2 and #3.

     #2 - reducing the time constant shifts the balance of power towards the barometer (i.e. weakens the accelerometer). This makes it safer for people more vibration but barometer misbehaviour appears. In particular try a fast forward flight and then flatten out. See this video around 1:55 where I'm testing a TC of 5 and you can see the drop after flattening out.

           Of course, people can always increase their TC back to 6 or 7 if their copters are flying well.

     #3 - this is probably the most important fix to reduce the risk of vertical fly-aways in Alt-Hold/Loiter/Auto. This problem could appear if people have a lot of accel noise and it had a bias of over 1m/s (i.e when the motors were running there was aliasing which caused the acceleration to appear to be constantly over 1m/s up or down). That limit is now 3m/s. The downside is that if you have a hard landing an alt correction may build up and take a while (30 seconds?) to recover...so you could have a bad altitude for longer after a hard landing.

     Anyway, if a couple of people could give it a fly and report back then I'll push it into the MissionPlanner. thanks!
Mike Mac March 29, 2013 at 12:40pm

Any news on a firmware update?
Will it be V2.10 or V3.0 or what?

.
gilberto March 28, 2013 at 10:08am

i have a problem with my sonar in the code 2.9.1 . the values are negatives and not correspond to the distance.

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ArduCopter 2.9 / 2.9.1 released

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