A few users, myself included, appear to be having issues calibrating accels and/or arming when using APM 3.2 on a Pixhawk. I see posts here and there, but thought it may be best if those having the issue could all 'check in' to one post so that the developers can see how widespread the issue is and gather data.
My Pixhawk will arm occasionally, and will even fly successfully. Occasionally however it will not arm and I will receive the pre-arm error "Accels not healthy". A few days ago I was able to arm and fly thorugh one lipo, then after landing and swapping batteries I could not arm due to this reason. I have attached the logs from the successful flight, as well as the failed pre-arm logs, to this post.
As you can see from these images there is something amiss with IMU2. This is a snippit from the good flight, showing values for AccX on IMU1 and IMU2:
and here are the same values on the second attempt, pre-arm.
In the 3.2 release thread a few users had mentioned the issue and Randy advised to set the log_bitmask to "131070" so that it will log everything including the pre-arm checks. I encourage others having the issue to do the same and share the logs and experiences here so that we can find out what is going on here - is there a bad batch of Pixhawks in the wild that only now show the hardware errors due to something new in 3.2, or is there an issue in the APM software?
Replies
@Andrew,
Your vibration looks like around 4 m/s/s in the Z axis, but the main thing is probably the frequency, yes. You'll notice that the separation of the two Z accelerometer values increases with the amount of vibration. When the motors are idling it is fine, but it separates as you raise the throttle. That looks like aliasing to me.
Cheers, Tridge
I purchased mine in January 2014 from 3DR in an Iris and it's flawless with 3.2. Over a 100 flights with no issues.
mp
@Mark,
I don't see a previous comment from you in this thread - maybe I missed it? Do you have an issue with your sensors with a more recent test firmware that you don't have with 3.2? If so, can you post a DF log?
Cheers, Tridge
Tridge,
I apologize for the lack of information. I have not posted in this thread before but I have been following it since it started. I just started thinking recently that if it's hardware then the bugs could have started in a certain version. Like the old Pixhawks have less issues than the new ones.
When someone mentioned posting the purchase dates I posted my first thread.
I have had no sensor issues in 3.1.4, 3.1.5, nor 3.2. Besides GPS/Compass issues in the first few months of purchase that I remedied the bird has always flown flawless.
I could be way off but from reading the thread I keep thinking that some FCs made after a certain date have this issue and maybe 3.2 exposed it.
mp
Ok, so got some logs. I'm running 3.2.1 beta, had issues with drone not arming (yellow flashing, "DA-DUM" sad sound during attempting to arm). The logs say ACCEL pre-check, checking the logs it looks like my IMU1 is fine but the IMU2 isn't reporting anything.
I flew the other day, four times on three batteries, the first two or three flights was perfect and then it failed. All i did was move location and change batteries, it was pretty cold outside but well above freezing. I've seen this issue before taking it from my warm office (next to fireplace to outside, cold 50F). Anyway, don't think it's a cold thing, since i was flying fine for quite a bit (30 minutes) before i experienced the error.
I basically need to disable INS checking to get it off the ground, since it's my IMU2 i dont' think she'll fall out of the sky, but still a problem.
Attached are the logs, the one ending in "BAD" has the faulty IMU2 and disabled INS checking, the one labeled "GOOD" was my first one, perfect flight with no errors.
2015-01-27 15-24-44 _Bad.zip
2015-01-27 14-42-02_Good.zip
@Nico,
That is definitely a failed lsm303d accelerometer. Can you tell me where you bought this Pixhawk? The reason I'm asking is that the pattern I've seen so far in the logs I've analysed is that the boards with lsm303d failures are not from 3DRobotics (3DR gave me access to their serial number database so I could check if a failure was in one of their boards).
I don't see your board in the 3DR list, so I assume it is from another manufacturer. If that is not the case please let me know, as it is possible the database I have is not complete.
If it isn't a 3DR board then can you try pointing your supplier at this discussion? Given the number of non-3DR failures I've seen I suspect they have a manufacturing problem related to the lsm303d accelerometer. It would be good to let them know about this so they can fix it.
Cheers, Tridge
@Andrew,
can I send You my Pixhawk's serial number?
I also have the same issue about bad gyro health. Mine was bought in November and manufacturer is '3DR'.
Cheers, Eva.
@Eva,
It is easiest to just post a log file showing the issue. The log will also have the serial number in it.
Cheers, Tridge
Got it from thanks-buyer on ebay Jun 2014, it was a model 2.4.5 board, i'm seeing 2.4.6 boards out there now. Is it possible that fixes the issue? They have a website now
http://www.thanksbuyer.com/pixhawk-px4-autopilot-pix-2-4-5-flight-c...
So is it possible that 2.4.6 fixes the issue, looking at the changes between 2.4.5 and 2.4.6 they added a capacitor to "stabilize" the sensors. Sounds like the issue no?
- NEC original tantalum capacitor is added in back compass and main power supply, making each sensor has stable power supplying and lesser possibility of aircraft crashing
Possibly, but I can't tell from that description, sorry. You'd need to ask the vendor.
The logs show the lsm303d isn't initializing correctly. The patches I put in recently try to re-initialise it if it misbehaves, but it looks like that isn't helping.
Cheers, Tridge
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