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?
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Artem, I got my first pre-arming error on the new Pixhawk clone yesterday. One I haven't seen before - "Bad Velocity". You seen or heard of this one? Not many hits for it when I search. I re-powered the copter and it didn't return, then flew fine. Then when I got home I powered it back up to check pids and got the same prearm message with it inside the house.
that's I thik one of the new ekf errors, are you running 3.3 RCx y any chance? If yes, better to place to ask this question will be the ac3.3 beta thread..
p.s. are you using an m8n GPS?
Running 3.2.1
Yes I'm using a m8n.
by design m8n are much more sensitive than 6m/6h thus they are much more susceptible to noise from the onboard electronics. combined with a lack of proper saw and lna filtering on the cheaper models produces some really bad results even though they show 17+sats and hdop/pdop lower than 1.3. I usually find 3DR leah6h the best gps/compass for multies, even with 10-11 sats and hdop 1.8-2.0 my copters tend to perform better than with most m8n GPSs I've tried.
This mini-pixhawk looks amazing. Given that Banggood are replacing my controller free of charge, do you by any chance know if this product upgrade: "added the second PMEG2005CT and 350ma ResettableFuse)" is referring to improving the power supply to IMU2 - really hoping you might know, so I have more confidence in this replacement. Any idea?
at $65 worth a shot I guess...
Most likely hardware. Somewhere in this thread there was a technical description of the causes of this problem.
And if I remember right there are no genuine 3DR Pixhawks showing this behavior (LSM303D reporting false values)
But I don't think you can get a guarantee that the replacement won´t show the same error.
I went for my first real field flight tonight (running Pixhawk clone with arducopter 3.2.1), and flew flawlessly for a good 10 mins, and as the LiPo was getting low (down to 10.7v) I landed and was about to change to a new battery when I realised I'd left my bats at home. So I reconnected the same LiPo but was continually getting Bad Accel Health warnings on the HUD in Mission Planner (connected over radio telem). I tried several gyro calibrations but they kept failing, and no matter what I did, I could not get past the error. Bizzarrely when I got home I powered back up and the pre-arm messages didn't display at all and I could arm again! I just remembered this post so will enable the extended logging so will hopefully capture something over the weekend if the weather gives me a chance to get out and fly (assuming I can!)
I guess, you are really not using a pixhaw, but rather a *****hawk :) If you read several posts up, there is working solution to your problem: remove all lipo and short your main power input for 4-5 seconds, than reconnect lipo and fly!
I've just started to get this issue with IMU2 not initializing properly after being unplugged, then plugged back in within a few minutes. If I leave it 5+ minutes it'll probably initialize ok, but then if I unplug the battery and plug it back in it definitely won't. I'm running a t960 with a lot of capacitance (banks of 6 caps at each esc x 6 arms), so I think this is contributing. It's a hobbyking pixhawk. As suggested if I short the main power input terminals for a few seconds, it will initialize IMU2 correctly every time on next powerup.
Is this only something to worry about with the initialization of IMU2, or if it's doing this, is there a higher risk that IMU2 could fail in flight? If it did, would the EKF let it keep flying?
I'm running AC 3.2.1, but would expect to see this on 3.3 too.
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