Version 2.5 of the ArduCopter code is now available in the AP Mission Planner and in the downloads area!
The default PIDs are optimized for a 3DR/Jdrones quad with 850 motors and 10" props. If you're using more powerful motors/props, start by turning down Rate Roll P in 25% steps.
While some testers have reported very good flights with the default PIDs, some have reported that this release is a little "sharper" due to the DCM improvements and have found they needed to:
reduce stabilize P by 10% (i.e. 4.5 -> 4.2)
reduce stabilize D by 30% (i.e. 0.15 -> 0.10)
increase rate D from 0 to 0.001
Tuning loiter can be tricky. Refer to the discussions which will appear below for more community feedback on what parameters work best.
Please post your feedback in this discussion. For enhancement requests and bug report, please add them to the arducopter issues list. When possible please include logs (tlog and/or dataflash) and tell us whether you're using APM1 or APM2 and what version of the software you're using (presumably 2.5 but tell us anyway!).
Thanks for this release go to the developers (both in the core team but also those who have provided bug fixes through the issues list) and also the community members who participated in the previous release thread and provided some great detailed information in the form of issue reports and logs which allowed us to nail some bugs!
Ok, interesting stuff. The headings are still mixed up, but I think I can still make heads or tails of it.
First up, you have some HUGE misalignments between your compass heading, and your AHRS heading. Like in one place, the AHRS yaw is 79 degrees, and the mag yaw is 139. That's huge. Sitting here, I have no idea which direction it was really facing, it doesn't know which way it's reallly facing. So some of your imprecision on yaw control is going to be due to that problem.
I'm really having a hard time making sense of the logs other than that because the headings are all messed up.
But I can see that you clearly have a yaw oscillation. It's constantly going back and forth about 5 degrees. It actually looks a lot like a TradHeli graph, which isn't surprising. This is a Tri, correct?
I haven't solved that yet, but it has a lot to do with the servo movement.
OK, so yeah this is a tri. There isn't any play I can feel in the tail servo, and the props are balanced. The arms are nice and stiff too so shouldn't be influencing that oscillation.
Maybe I can try redoing the compass declination to try and get the mag heading and AHRS headings to match up? I had it facing approximately north during that logged flight, and now notice in MP that it shows North as being about 45 degrees clockwise from true north.
Here's one more log after doing another live calibration. Seems like the heading in MP pretty much matches up with the compass on my phone now, but I'm still getting the oscillation, and delayed response to yaw input.
One thing that's been quite pronounced in the last few flights is that the pitch will spike. so the tail will jerk upwards several times in a row, and from the log it looks like there are downwards spikes on pitch in, followed by the same spikes in the pitch column. I'm not touching the sticks when it happens though...
I was just looking for info about the pitch twitch:
I didn't think I saw pitch-in spikes, but I haven't completely dissected the logs. Today I captured video and tlogs with the intent of combing through it to find the event and post them for help, but I've not had time to edit the video down.
I think I've been having this problem since 2.5.4 and believe it can (rarely) be drastic enough to cause a crash.
Robert nice explanation but I have to wonder if this is more of a problem for a the traditional heli which has more yaw potential and perhaps needs different tuning with an order of magnitude higher than same the reference Aurducopter quad? I would be quite concerned at a side effect of on take off there might be a severe yaw to the previous target. Of course as a traditional heli user myself, I appreciate the nice tail response in your video. Makes me think its time to get my Trex-500e converted to use the APM :-)
Greg, there is a significant difference between tradheli and multis, for sure. But I think this is a better algorithm for all. At least, it's better than what was there, which was not good at all.
It's just a case of getting a few minor bugs out. It was a very late addition to the code, and I don't have a quad to test with unfortunately.
the way YAW is now working in 2.6 is FAR better than anything before, it just needs a tweak in terms of getting it a little more 'sensitive' so you dont have to stick all the way right/left to get some movement, I've added abour 90% negative expo and is perfect, the BOUNCE that was in previous code is now mostly gone.
Great Duran, thanks for the report. Do you feel comfortable doing a little hack on the code? I can tell you exactly which line to change to increase the sensitivity.
Sure, let me know where and what to change i will give it a try. While we are chatting code, is there anyway to lower the speed that the props spin up when starting throttle, on MK it's very low but apm it's pretty quick,m any way to lower the starting speed ??
What is going on with the board? It deleted a big reply!
no idea saw it dissapeared too, weird ??