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.
Replies
Well, let me add to the list.
First, alt hold is rock stable, after calibration of the acceleration it's almost perfectly level in flight with no or little drift. EXCELLENT. I have noticed that if I'm climbing even slightly when I engage alt hold it seems the motors are shutting down momentarily. When descending and engaging alt hold, an immediate throttle response to hold the altitude there. I've concluded the momentary shut down of motors isn't a fault, it's just an aggressive response to the ascent when alt hold is switched in.
I've been struggling with a couple behaviors that I'm having a hard time understanding.
The first is in ACRO mode. In 2.8.1 when roll or or pitch input is given, the copter will roll and when input is removed it will maintain the attitude it was in. I had it tuned to where it was a very stable behavior. The best way I can describe it is like an aileron input on a plane without dihedral. It would roll until the stick was returned to center, then maintain the attitude until an opposite input was given. In 2.9 I find that it behaves more as if it is in stable mode. Input causes roll, but when the stick is returned to center, so does the copter. I've not been successful in tuning the behavior away. In version 2.8.1 the RATE I gain was the parameter that I tuned. In 2.9, I have varied this from about 3/4 the value of RATE P up to about 3 times RATE P. Rate P is at 0.155, I varied from 0.120 to 0.45 using channel 6 tuning and there was a change, but not a significant change. Manually programming it and not using channel 6 tuning has the same behavior.
The other is related to Loiter mode. When I switch into loiter at speed...it will overshoot for a bit, then go into a large correction...expected. It will then overshoot by a large amount, and have a large correction...it will oscillate around that point for 5 or 6 cycles before settling down to where the corrections are smaller and it will eventually settle down and find it's spot. I've adjusted Rate loiter P gain both up and down, Rate Loiter I gain both up and down. I've not been able to improve things from the default settings.
Any Ideas?
Today I had a strange issue with my new scratchbuilt tricopter. I wanted to check the ACC Z vibration data and wanted to do some hover just to log data. As it is cold outside, I did it indoor, and I think that safed my copter from flying away.
After a short time of really nice and stable hover, it suddenly jumped up to the ceiling, felt down, jumped up again and felt down again. I was lucky that the rear prop went of the prosaver so that I could grap it there and remove the battery. I had noc control with the RC. The motors kept on spinning, no matter what I did on the RC.
After that I checked everything, but could not find anything wrong with the copter.
Then I did a full eeprom erase and reainstall of the FW. I did the whole setup process and tried again. This time with the copter tied to a heavy toolbox, so that it could only go up about 1m.
So I did a nice hover for about 5 minutes and nothing bad happened. I also tried to acitvate alt hold, but then it wants to go up and only the thread held it down.
At the moment, I do not trust the 2.9 any more. When this happens outdoors the copter would go up to the clouds, I think.
I attached the logfile. Maybe someone can see something in it.
2013-01-23 08-58 8.zip
Hi,
for me 2.9 is not working out at all.
1)There is a weird issue with the new leveling process. Whatever i do, the copter thinks that it is tilted after the process.
2)Starting the copter, one of the 4 motors sputters in low rpm, quad tilts, motors sound strained.
3)Manual leveling (15sec disarm) is gone, so i can't correct the issue. Flight and ch7 would result in death, see 1)
without changing anything, i went back to 2.8.1. - all issues gone. APM recalibrates gyros on every boot, which is a nuisance, can one switch that off?
4)After downgrading, Mission Planner still displays 2.9+ as calibration process, now with no information, buttons do not work at all. How do i get the 2.8.1 level buttons back?
greetz
MT
Just a quick observation regarding alt hold and fast flight. I have Stab_P at 4.5, and when I wang around the backyard it easily reaches 45*. Now when I am at the park in alt hold, and I give it full forward steam, it starts off at 45* until it gets to speed, then as it speeds up the pitch gradually drops off (with elevator still pegged). COOL! Why is that cool? If APM didn't reduce pitch, at a certain point drag would take too much power to sustain altitude at 45*, and the quad would start loosing altitude with the motors running @ 100%. So APM seems to sense this happening, and controls the pitch accordingly to reach the max speed my quad can go without losing altitude control. On my quad, this "terminal" speed turns out to be 40mph, which is sustained with about 20-25* pitch. As I slow down, more pitch becomes available again. This behavior makes it really easy to speed around. Before 2.9 I had trouble controlling beyond ~30mph because I kept using too much pitch. I had no idea my quad could hold solid control at 40mph... APM taught me something about how to fly a quad fast LOL! Extremely cool stuff devs!!!
Randy,
I know you have a Flamewheel 450 (or a clone) which I presume you are flying with 2.9.
If so, could you let me know what relevant PIDs you are using for it.
I lowered the Loiter rate PID - P to 2.4 as you suggested elsewhere and while it greatly improved Loiter it still "twitches" in pitch and roll quite a lot (over 10 degrees) and completely unnecessarily in completely calm air.
Previously with the stock 5.000 PID - P the twitching roll and pitch was much worse to the point of becoming unstable and temporarily blasting off in one direction or the other then working its way back.
I was hesitant to further reduce this PID.
In any case if you do have this working smoothly on your Flamewheel (clone) I would very much like to know what PIDs you have changed from default and their values.
I glued 10 mm foam rubber under the upper CP.
My question is: Is that enough, or do I need more?
Filter is 42 Hz
Greetings Peter
2013-01-23 17-21 1.zip
On evening, I setup HD wing camera on my arducopter loiter on the air about 100 meter is very stable and no wobbly.
Nice work
Could you please compile the list of changes that you have in mind for the 2.9.1 release. Eagerly await the inertial nav for loiter. With this, I am guessing we will surpass DJI.
BTW, could you please explain the COMPASS_USE parameter? I get automatic yaw movement when this is enabled. By default it was... had to switch it off for correct behaviour. What is the impact of turning it off?
FAILSAFE QUESTION:
If failsafe is engaged by turning off tx for testing purposes.
What happens when the Tx is switched on again?
It seems like it stays in RTL mode. Ideally one would want to take manual control over the copter again and land yourself.
Thanks
I just finished building a Octa and are Happy with 2.9 release. It looks great in Barometric Altitude Hold, Loiter and stabilize. All default settings except for lowering p-stabilize (roll and pitch) to 3.7
The only thing I don't understand is that when I connect my Sonar, the motors are jumping a lot, no more Altitude Hold. My throttle stick is just below midstick (same as when I did altitude hold with baro). I did test my Sonar in the Mission Planner under tests and I do get good readings, so it is working fine.
I don't see any spesific PID to tune for sonar specific? Baro and Sonar use the same PID?
Do I have to use ch7 to lock in my hover position (safe that parameter)? If I understand correctly this throttle hover position is automatically safed when you lock into altitude hold.
Please help with the latest Altitude Hold procedure and how does Sonar differ from Baro in tuning?
Greetings,
Hein
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