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
Hi!
Just an idea. Why not release a non INS - fancy version with just working code without surprises?
Here is what i gather from posts:
Sonar like in 2.6 ?
pure baroalthold like in 2.7.3 without GPS Fix Bug. (baroalthold was worse in 2.8.1)
gimbal (2.8.1? and up ?)
Stab (2.8.1 and up)
GPS (like 2.8.1 incl MTK19 support) with adjustable minimal Satcount for each function (PH/RTH/Homepos etc)
Corrected Thr/Fails / anti fly away 2.9.1 (?)
Cheers
Kraut Rob
I havent read all the comments yet, but I have a loiter bug *possibly*. Its documented in the video and I am attaching the log file as well. Basically if you flick to loiter from stabilize, you will get periodic (possibly 10 seconds or so) "motor cutout, then recovery". Changing back to stabilize seems to be fine.
Here is the Log
Craaash... I seem to be having some trouble again, in the hover a few minutes ago my quad appeared to be slowly decending in Alt Hold then continued to lose height in Stabilise, I increased throttle but it still came down, then went out of control and crashed on the garage roof! My sensation was that there was no or very little response to my throttle input. I've looked through the logs but all I can see is that the throttle responded to my input by DROPPING at first (green line) and then lagging behind, weird, battery (3S 5000mAh) was around 11.3V in the hover.
2013-02-05 18-33 19roofcrash.log
2013-02-05 18-13-06roofcrash.tlog
On Sunday I had something that has never happened before. I was flying a mission, basically just two waypoints with a parachute drop followed by a landing. I'd flown it many times before.
Short story: just after waypoint 4 the quad started to "toilet bowl" really badly and I was only just able to save it by getting back to stabilise just before it hit the ground, it actually did hit but I also had whacked in full throttle by that point so no damage. Later flights that afternoon showed no problems.
I've put a thin small tin plate under the tray that supports my APM separating it from the power wires underneath to prevent any magnetic flux coming through from the wires, the plate is not magnetic at all and appears to have had no effect on the quad (or has it?)
The problem occurs at from just before 558 on the log where I'm able to switch out of auto.
2013-02-03 07-23-09-ToiletBowl.tlog
Just some thoughts and observations on the magnetometer subject, and other things.
I was often giving the quad a couple of turns by hand before launch. This seemed to eliminate gross errors, at least for the first few seconds but now I generally do a couple of hover turns before using any nav modes. (One good turn deserves another)
Last night I secured the quad to the floor and gave it full throttle. There was a 15deg compass swing between zero and full. I suppose this is acceptable considering the copter is probably only changing its power +/- 20% from hover most of the time. I dont see a way to achieve greater separation between the APM and power bits anyway.
I should get a good log with lots of turns and power changes and use this for a permanent calibration. + to do list.
Have I got this right?
The copter calculates a bearing to the next waypoint, turns to face that direction using compass, and sets off. When it gets blown off by wind (or compass error) it seems to compensate by flying sideways instead of turning into wind like Arduplane. This is probably more noticeable on my H frame and showed up with on board video.
https://www.youtube.com/watch?v=Go_EYjBYc24
(flying right ‘wing’ down at about 40s mark)
Mine tracks great in light winds but in stronger ones it never seems to nail the drift, always snaking across the track. I guess I could improve that by tweaking something.
Also it seems to aggressively apply auto speed changes but be very lethargic at overcoming a headwind. If the auto groundspeed is set slow it may even get blown backwards,(not because the wind is greater than its maximum). Think the first may be a ‘P’ issue and the last ‘I’ (throttle rate?).
Vince
No sure what issues I am having with Alt Hold. The quad - Flamewheel 450 SK3 1040KV running 10x4.5 props.
It seems over powered not matter what I do with the PIDs. I wind them right down to try and stop the high thrust bouncing but then the quad slowly sinks to the ground. Putting 8x4.5 makes it a lot better but I should be able to tune it to the bigger props.
APM 2.5
Any ideas?
I managed to get in some more flights on 2.9.1 to dial in my quad (jdrones frame, 880Kv motors, 30A ESCs and 12 x45 props) today with mixed results. The weather was not too bad with slight winds and gusting a little later during my second flight and then calmer conditions on the third (last flight). I have recently posted my calibration results, initial PIDs and graphs showing the RAW accel values which indicate z is ok with some slight noise (tolerable on x/y)
My first flight was good in Stablize mode and then in loiter I did not have to touch the radio until the very end with some drift off the original position as the wind picked up. This was very encouraging. Even though I had no ALT hold on, I was not touching the throttle. I analyzed the logs after to see the number of satellites and check GPS data for the very end when the quad drifted. I had no less than 9 SATs, good lock and towards the end 11 SAts. I am using the MTK GPS with v 1.9 code.
The second flight was very disappointing. I had good control in stab mode but was unable to hold any position using Loiter mode. In several instances the quad moved off position consistent with the wind direction and in two specific instances moved very quick off position after engaging Loiter. I had to reengage stab mode to gain control. I again checked GPS data and maintained solid lock and around 11 SATs So I do not suspect any GPS issue. It would seem Loiter mode is ok in very calm conditions but unable to maintain hold in slight winds / slight gusty conditions.
I changed my PIDs as follows from my last flights, for today's testing, but have yet to change the Loiter parameters from the defaults in 2.9.1. So maybe someone with a similar config and good loiter hold in slight to moderate winds could suggest some PID changes / advice?
On Randy's and other advice I increased the Rate P Roll and Pitch from 0.090 t0 0.12 fro today's filights. I also bumped up the " I" from 0.06 to 0.08 (Note I try to maintain original P to I ratio). I did originally reduce the Stab P roll and Pitch down from 4.5 to 3.0 and for these flights today it was on P 3.5 and IMAX from 8 to 5. Note I made these adjustments due to running 880Kv motors with 12x45. Some people have advised me to put these back on 4.5 I thought I would do this in increments. Again open to advice here.
As I say my Loiter values are default i.e Rate Loiter P 5.0, I 0.04, D 0.4 and IMAX 30.0 and Loiter Speed P0.2 I 0 etc
I am puzzled why the default Loiter values which are optimized for the 3DR Quad with 850Kv motors and 10" props would fail to keep my quad with larger motors and props from drifting off position. If anything I assumed eventually I would have to reduce the values to avoid over shoots?
My final flight confirmed the slight wind effects on Loiter. With calm conditions my quad held on position, but started drifting and did not recover when some slight breeze popped up mid flight. Another interesting effect I noticed. When holding well in Loiter my quad appeared to be rocking slightly along the roll and pitch axes. What would be the best value to change to reduce this rocking motion along pitch and roll axes while quad is not climbing or descending ie. on station in loiter maintaining altitude with no throttle input?
Now to end on a good note. I tried ALT HOLD for the first time in 2.9.1. WOW! Fantastic I switched from stab mode and loiter mode into ALT HOLD with no appreciable drop in height i.e really nice throttle calibration and end points. ALT Hold was solid; move up or down and its like the quad is stuck in the air. Very well done guys. It did not get a lot of time on ALT HOLD as the loiter drift problem keep me busy.
Sorry no logs but hoping the description and PIDs I am using might be enough for some general tuning on Loiter for larger motor quads.
Hi,
Today I have made my first flight my homemade octocopter, and I have some issues:
1- Stabilize works great with stock values except in P that I have 0.90 because I use 400kv motors, but the copter starts to yaw slowly.
2- Alt hold not works as I wish, the octa is more like an kangaroo, I'm using an XL-EZ0 but I don't know if is a problem of sonar or the baro.
3- Position mode works great if you don't use the sticks, only the throttle is used. (windy day), but maybe I have saw an issue using this mode, when the copter is in Position mode, the mission planner shows "unknown" and the yaw value is freeze (but the copter is yawing slowly as I said) but while I don't touch the stick the mode works fine. When I try to change the position without leave the "Position mode" the copter flies well but when I release the stick start to fall and I have to change to stabilize mode to be able to get the control and in the mission planner shows the actual yaw value instead of the freeze value.
My config is APM1 + sonar + mediatek 1.9 + compass + 3dr radio link.
I have attached the logs and the video showing the position mode working (not when its falls).
http://youtu.be/4UHkGXEArr8
Thanks.
P.D. I'm sorry for my bad English.
APM1_pablozg_octo_logs.zip
Test Failsafe at night
This is the effect of Loiter P too high or Loiter I too low (3 meters of radius), if your quad although it seems to be stable but corrects too much you must adjust that parameters, the default of 2.9 is too high for some configurations.
In windy conditions the problem is reduced, because the wind tends to "push the quad" in the same direction, for this reason the effect circle is much less known.
The implementation of the "X/Y Inertial Navigation" greatly reduce this effect, not enabled in this video.
A bad gps signal can also affect the Loiter, like here i think.
Sorry for the poor video quality of my poor smartphone (LOL).
Cheers, Marco
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