I think there's related thread, but I'm starting a new one because I think the issue I'm seeing may be different than the diagnosis in the other thread suggests. (I also expect that I'm far less experienced than most here, and hope some of you will share your knowledge and experience so I can catch up a little.)
On Saturday, my 3DR X8 (APM 2.5) ran beautifully, and I got some very nice area video.
On Sunday, I upgraded the firmware to 3.1.2, and found the machine operating a lot differently (read: poorly).
On takeoff, I switched to LOITER, and after a few seconds, the machine began to jink around in increasing amounts and wound up over the fence and in a tree.
I replaced the propellers, and did some homework.
One item I found suggested the possibility that the parameters may not have been initialized when the firmware was upgraded, so I reset the APM, did an EEPROM Erase and reloaded the 3.1.2 firmware.
On ARMing and powering up slowly, the props on one arm did not start with, nor run at the same speed as the others. With some more research, I found and followed a process to calibrate the ESCs, and this seemed to correct this issue.
After takeoff, I again switched to LOITER (which has been a godsend for a newbie operator). The copter began to yaw right, and I tried to stop the yaw. The machine began to move laterally, I gave it some altitude to ensure that it would be above any nearby obstacles. Meanwhile it began to fly a widening spiral, rapidly picking up speed. In seconds, it was moving a higher rate than it ever had, had tilted pretty far, and was losing altitude.
The resulting crash was pretty destructive, and far beyond my spares inventory.
All this occurred in 67 seconds.
Here's the interesting thing: I have both the logs AND a time-synchronized video of the flight.
I'd be most grateful for diagnoses and advice from experienced flyers...
Replies
Someone else posted this link, as a potential explanation of Loiter issues with some GPS receivers:
http://www.insidegnss.com/node/4030
I guess you need to have an affected GPS receiver, and be within the 'unhealthy' satellite's footprint for this to be an issue.
I'm in the UK, and have an APM 2.6 with uBlox LEA-6M GPS with Compass, and have no loiter issues (with 3.1.2, 3.1.3 and 3.1.4) on my hex.
+1 No loiter issue with 3.1.4, 3.2-RC1 (Using LEA-6H) in Australia (NSW)
Do you check number of sats and hdop? (Should be below 2)?
Do you check on the ground that your altitude isn't going up rapidly by itself?
Do you wait at least 10 minutes on the ground and recheck the values above?
I think im a victim of a few similar crashes with 3.1.2, 3.1.3 and just now with 3.1.4. It seems too only happen when i switch to loiter. After a short period of time the copter decides to slide to its right straight into the ground for no reason. The logs show the back right motor increasing to full power for no reason. Before the 3.1.x series things were fine.
Alt-hold seems to be great, except for the slight drift that happens with alt hold it never crashes. However switching to loiter the problem described above appears.