I've asked the question several times in various forums. Nobody has yet answered the question.
The most complete answer was from Randy, but did not define how INAVerr is calculated and why 255 is bad, only that it may be a problem in my logs.
It has to do with GPS and Pixhawk data communication. I have a CSGShop Neo-M8N GPS w/compass and contacted them concerning INAVerr. They say it is a Pixhawk issue; no help there.
Here are the relevant threads:
This was the first thread I started due to odd behavior (which may not be connected to this) of my copter and subsequent log analysis. I didn't know what the errors meant using Auto Analysis and Flight Log Analyzer.
http://diydrones.com/forum/topics/csgshop-neo-m8n-is-giving-pm-errors
Randy's last response:
DG,
I should be more clear. The PM message's long-loops error is a red-herring. The inav errors are likely a real problem. I don't know why in your logs it keeps having problems. Rob apparently looked at your logs and the GPS seems to be updating at the correct rate.
The latest thread drew a few others in with the same issue.
http://diydrones.com/forum/topics/inaverr-is-it-the-gps-or-fc-or-neither
Got it. The long loop errors are not a problem, but the INAVerr is likely to be a problem, but what does that mean?
So the quest continues. There are others reporting the same "problem" (if it really is), but thus far it has been a dead end determining what it all means and if there is a risk of a mechanical malfunction caused by these INAVerr data. I really don't want nor can afford to wreck my copter. QED
If anyone has some insight concerning this, by all means please speak up.
Replies
I got an PM.INAVErr of 9 through a flight in which the inertial navigation system (the gyro and accelerometer-based) all of a sudden, several times, reported that the quad instantaneously moved many meters in a split second. This has me thinking that it means Inertial NAVigation Error. Unfortunately I wasn't logging the accelerometer or gyro data at the time. The mounting platform for the APM 2.5 might have been rotated by a degree or so when it flipped over before (a mechanical error in a motor) and I didn't recalibrate it after repairing it. So now I'll check the calibration values stored, recalibrate it, and check how much it changed. Plus log the IMU values next flight.
Also, it was unable to fly on a mission when this happened, drifted off in the wrong direction, and tumbled 20 m on one occasion. The DPosX and DPosY for some odd reason changed several time for no reason connected to the mission. It was supposed to be stationary. The wind was rather high, in lighter wind it had behaved. So the problem seems to be caused by inertial data not coinciding with GPS data, and a possible error in the inertial navigation system that becomes an issue when it wobbles a lot while trying to correct for wind gusts.
I'm sorry man, if Randy et al. Can't help you, it's really doubtful anyone else can.