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CSGShop NEO-M8N is giving PM errors??

Posted by DG on January 31, 2015 at 5:26pm

Today I did a test flight before doing a mission. After switching to poshold, it began behaving erratically, twitching and drifting. I was able to land, but puzzled because there were no errors from the GCS.

Running auto analysis, it gave these results?

Size (kb) 8554.380859375
No of lines 114684
Duration 6 days, 22:11:00
Vehicletype ArduCopter
Firmware Version V3.2
Firmware Hash c8e0f3e1
Hardware Type
Free Mem 0
Skipped Lines 1

Test: Autotune = UNKNOWN - No ATUN log data
Test: Balance/Twist = GOOD -
Test: Brownout = GOOD -
Test: Compass = GOOD - mag_field interference within limits (8.12%)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = GOOD -
Test: GPS = FAIL - Min satellites: 0, Max HDop: 99.99
Test: IMU Mismatch = GOOD - (Mismatch: 0.62, WARN: 0.75, FAIL: 1.50)
Test: Parameters = GOOD -
Test: PM = FAIL - 17 slow loop lines found, max 7.20% on line 108374
Test: Pitch/Roll = GOOD -
Test: Thrust = GOOD -
Test: VCC = GOOD -

The logs show no GPS problems (Nsat and hdop) so I don't get it. Is this a communication problem with the GPS unit? Possible wiring issues?

6hNJO8J.png

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Tags: csgshop, gps, m8n, neo
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Replies

  • tshado March 16, 2015 at 8:39am

    Sorry, deleted my reply http://diydrones.com/forum/topics/csgshop-neo-m8n-is-giving-pm-erro...   by error

    Several threads here on DIYDrones and RCGroups have been opened to discuss about the explanation and what represent these INAVERR errors in performance monitoring in logs

    This problem was reported end of  January

    Still no answers from 3DR/Dev guys, to tell us something about this INAVERR in logs

    A ticket was opened in Github about that

    I know that they are probably busy, but could be great if somebody could tell if this INAVERR error if indicating a problem or is not

    I found a post from Randy who in last November was thinking INAVERR at 255 was not a "very good thing"

    http://diydrones.com/xn/detail/705844:Comment:1482305

    Reply by Randy on November 25, 2013 at 6:52am

    Marcus,

         Thanks for the info.  Your copter missed one GPS message and went 0.07seconds without a fresh GPS update (you can see the 400ms jump in the GPS time between lines 2593 and 2606).  You were in Loiter mode but it was so short lived it didn't upset the navigation at all.  If it was -rc6 you would have seen a very slight twitch.  If that INAVErr was 255 meaning it had maxed out the recording of errors I'd be more concerned.  For now, this is consistent with what I'm also seeing which is that we're getting occasional missed messages which we still need to get to the bottom of but in low numbers it's not dangerous.

  • tshado March 16, 2015 at 7:59am

    @Randy,

    I didn't understood that https://github.com/diydrones/ardupilot/issues/1972 was opened to to modify INAVERR counter from 8 bits top 16 bits

    I will suggest to Jdennings who opened the ticket to open another one( or modify this one title) as this error is showing with 3DR LEA 6H GPS  we can get very high numbers of errors for these GPS Updates

    As this INAVERR is meaning that  inertial nav has not received a GPS update within 0.3 seconds , I agree with you that the GPS could be running sometime very slowly (at 3.33 hz or less frequency)

    But as Lea 6H GPS is being set at 5hz upadate , I doubt GPS will update several hundred of times at 3hz and in between recovering to normal updates

    Seems more to me that code is missing from time to time GPS updates

    Of course not really easy to see  degradation on EKF results and flights performance (remenber some twitching was reported by some users ), but If GPS messages are missed several hundred of times with 3DR GPS, this is bad

    I think this problem should be investigated to nail why GPS updates are missed by code

    • tshado > tshado March 16, 2015 at 8:31am

      Forgot to add that in the logs there were not GPS message  like "bad GPS health"  or others errors pointing to a GPS errors

  • Developer
    Randy March 15, 2015 at 6:00pm

    @tshado,

    The Inav errors mean that inertial nav has not received a GPS update within 0.3 seconds.  So that probably means that the GPS is running too slowly (i.e 3hz or less) or messages are being missed.  I've never used one of these GPSs so I'm really not sure what exact technical issue is that's causing the missed messages.

    It's hard to say how badly this will effect inertial nav's position and velocity estimates but it will have a negative effect I think.

  • tshado March 12, 2015 at 7:15am

    Hello,

    Doug Walmsley  asked me to post also my comments from

    http://diydrones.com/forum/topics/gps-issues-do-i-need-a-gps-ground...

    here

    Hello DG,

    Your post is summurazing very well the situation :

    today, after almost 1 month and a half you discovered this INAVERR problem (only reported in arducopter logs),

    it is not possible to say is these INAVERR errors are pointing to a real functionnal problem that could cause crash or fly away during flights

    With M8N GPS

    Sometime INAVERR goes up to  a max value of 255 (probably a 32 bits counter)

    Sometimes goes up around 20

    With 3DR GPS

    This INAVERR has also been reported by several users:

    http://www.rcgroups.com/forums/showpost.php?p=31022247&postcoun...

    Quote:
    Originally Posted by jdennings View Post
    Absolutely.

    I've started looking back at my logs, just looked at 20 of them for now, with flights > 15 minutes. Here's what I've found so far. Most have INAVerr > 0, with InavErr varying from 1 to 40, straight horizontal line suggesting the error happens before flying or right at the beginning. 19 logs out of 20.

    *BUT* ...

    I've got one scary one. Inaverr starts at 0, then goes to 40 about 30 seconds in the flight. Stays there for 5 minutes or so, then ramps up again to 100 right during the flight.

    This was a while back and I don't remember the flight, except I know I had no issue. Go figure. This is quite disturbing.



    I'd fall in that category. Great pos hold yet some errors.
    Going to look into this more carefully from now on, + got lots more logs to look at.

    I looked at many logs from the Y6B that had several >0 INAVErr but no indication of flight problems in missions.

    Ha! My INAVErr is 255 start to finish with the current setup using the M8N, so I'd be in the category of "I'd be concerned". Of what I don't know, but those that say they've been using them without issues either aren't pegging at 255 or are playing Russian Roulette.

    I looked at earlier logs with the 3DR GPS and it averages around 30 or so. Some have 0.

    CSGShop advertised the M8N as the greatest thing since sliced bread and probably sold a large number of units. As they say Caveat Emptor.

    What I'd like to see now is if and how people are making them work without high INAVErr. If not, then I'll just go back to the 3DR unit and live with not flying on some days.

    3701956300?profile=original

    ----------------------------------------------------------------------------------------------------------------------------

    I would suggest to open a problem in Github for arducopter code ( if not already done):

    * INAVERR are reported with 3DR GPS

    * Randy says it is a problem

    * Last sentence below  seems to point to an arducopter code problem

    * As this INAVERR is discussed on several thread on DIYDrones and RCGroups, it will allow to gather all informations in one place and allow everyone  to better foollow this INAVERR problem investigation

    http://diydrones.com/forum/topics/csgshop-neo-m8n-is-giving-pm-erro...

    Reply by Randy on February 11, 2015 at 9:44pm

    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
  • Developer
    Randy February 10, 2015 at 8:55pm

    I'd like to re-iterate that I think the PM message is a red herring.  I've added a fix that ignores the long loop time caused by the calibration done while arming and this will go out with AC3.3.

    • DG > Randy February 11, 2015 at 7:00pm

      Thank you for posting this Randy. I will assume then the errors are carried over from when caused by the calibration done while arming and show up by they hundreds in flight modes after arming.

      • Developer
        Randy > DG February 11, 2015 at 8:44pm

        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.

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