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:
3. If upgrading from 2.8.1, modify the throttle and altitude PID values:
Here is the list of major changes (a more detailed list can be found in the release notes):
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.
In stabilize mode the throttle is 100% under the control of the pilot so I'm afraid it won't help to adjust the throttle PIDs. It's a bit strange that stabilize mode works differently in 2.8.1 vs 2.9.1 because as far as I can recall we haven't really changed anything in that area.
For alt-hold can you do a flight in which you enable the RAW dataflash log messages? So enable the RAW message, do a short stabillize flight and post the logs back here so we can have a look at the vibration levels.
Hi Randy, thanks for reply.
Is it any other ways than change expo, to get a better sensitivity on the throttle?
Here's a new log for you. Had a little problem with some radio disturbance last flight, so I had to change two propellers. The new one haven't been balanced yet, but I think the raw log looks pretty good?
I recently did a long-distance, high-altitude flight test of 2.9.1, flying up the base of Yellow Mountain for nearly a kilometer, then returning via RTL. It was a very successful flight altogether, despite the big mysterious crash at the end which broke my GoPro LCD. Here's the video:
I would like determine what caused the crash. After the RTL returned the craft to the home coordinates, the quad was still over 200 meters up, and I could see that it was going to be a long while waiting for it to come down. So in order to not use up the remaining battery during the long decent, I switched to LOITER, and dropped the throttle for the fastest possible loiter decent. Then when it got to just a few tens of meters off the ground, I used the channel 7 switch to flip back to RTL. The result was that the motors instantly stopped, and the quad came crashing down. I raised throttle, and the motors started again, but too late to recover.
Is this a software bug? I have verified in the logs that the mode went directly from LOITER to RTL, so there was no stabilize mode in between where the low throttle stick would have been an indication to shut down the motors.
Some other minor issues I noticed from this flight:
1. In the log file (attached) the Baro Alt overflows and goes negative when it reaches 2^15 cm (about 327 meters).
2. In the the KMZ file generated by Mission Planner, all the high altitudes are wrong in the flight profile when graphed in Google Earth. For example, my launch elevation was about 411 meters and I climbed to a GPS altitude of 810m, but the maximum height of the graph in Google Earth is 1210m.
I hope someone can shed some light on these issues, otherwise I will dig into the code myself once I get some free time to do so. Thanks in advance for any assistance.
I posted about a similar observation over a month ago. I lost the link to that post which included my logs, but here's the video:
Crash in question @7:45
Similar to what you did, I switched from alt hold to loiter while throttle was all the way down, and the motors shut off resulting in a crash. The motors actually kicked back on after I reacted with full throttle stick, but it was too late to change the end result (you can see a jump from 8A to 0A, and back to 37A just before impact). I suspect if more people rushed their landings, we'd see more reports of this happening. At least you have a good excuse having a low battery; I was just quad racing. :P
2.9.1b fixed a similar problem with motors cutting off while inverted going from acro to alt hold. I erroneously assumed it would also address this "rapid descent auto to auto" issue... your incident is confirmation that I assumed wrong.
Is this issue confirmed or not? I can dig up my logs again if it helps.
Sorry about your crash. KevinB's right that there is a bug in there (even in 2.9.1b) in which it will cut the motors if you switch into these modes with throttle at zero. There's a warning above although now that I read it again, it doesn't include RTL in the list (i'll add that).
Loiter/AltHold/Auto bug: if you switch into these modes with throttle at zero motors will go to minimum until you raise the throttle.
#1 (dataflash overflow) is just a display issue which although annoying is at least not dangerous. It's fixed in master so 2.9.2 will display it properly.
#2 - not sure about this one. Could you post or PM me the dataflash log and kmz file?
Thank you Randy,
Attached is the log and the kmz file.
Hi David, sorry for this crash, as I said i don't recommend to do missions too far to the edge with this release due problem with inertial Z controller, all this "bug" have been fixed in the master trunk of the upcoming 2.9.2 release.
Thank you Marco, I'm sure looking forward to the 2.9.2 release.
Randy does this also affect flight behavior in those modes with throttle half way or just below half way? I had a lot of bouncing with my DJIF450Crashtest quad (2.9.1b AMP1) in loiter and alt hold and also sudden drop of a few meters on my big quad (2.9.1b APM2.5) I posted the tlog for the crash quad last weekend if you want to look at it. For some reason the APM2.5 didn't record any logs, not sure why.
Don't know if this helps, but I make my best landings by switching from Auto to Alt Hold. With the throttle at minimum the hex makes a slow controlled descent. When it is about 1-ft from the ground I switch to Stabilize and since the throttles are at minimum, it drops in the last few inches.
Speaking of landing technique, last Sunday's quad race presented a very challenging landing. I usually land in alt hold, and go to stab only to disarm, no problems. However Sunday the wind was so strong and gusty that alt hold proved to be 'too gentle'. I had 2 minor flipovers because alt hold wasn't decisive enough with the throttle.
Flipovers in alt hold @beginning and ending, @1:55 a barely successful landing/takeoff... sliding down the same hill:
You watch the part in the beginning with my friends flying fast FPV wings, hovering them one moment, 101mph the next... again very windy. Like you said, I think flipping in to stab mode right at touchdown is a smart idea especially in these type of situations where a flip is very likely. In fact I knew this after that first flipover, but my brain goes in a different planet while racing and I simply forgot. :P
In this case, it would be very cool to have the landing mode: alt hold, look at Zacc for a trigger spike, and automatically switch to stab/throttle off... reset to alt mode after throttle down/throttle up for takeoff. Nah... sounds way to complicated LOL! I accept that I just have to fly around this.
On a side note, I detuned my ratePID's ~10% before that day, in attempts to smoothen out the video. That proved to be a bad decision, and the quad flew very wobbly in high wind. Lesson learned... keep a top tune, there is no replacement for smooth thumbs. ;)