Could use log analysis help.

I did two flights today. One manual flight in stabilize mode, going into a loiter, back to stabilize, to RTL,and then landing in stabilize. Everything behaving as expected.


Then a second flight, with some waypoints set. Starting in stabilize, switching to auto. The copter moves towards the first waypoint. It gets high enough for me to get nervous (I had the waypoint at 200m - way too high, in retrospect), so I switch to RTL. It keeps climbing and goes in another direction. I go back and forth between stabilize, trying to get orientation on the copter, and dropping the throttle to get it down, and RTL, to hope it comes back, which it doesn't. I set it down behind a tree, with light damage: lost a prop, and one motor torn off the mount.

This is with 2.7.3 software. Any insights into the RTL behaviour would be very helpful. The copter orientation seems to jump around abruptly when I look at the log file in APM Log Visualizer 1.3.

(Edit: this an APM2.5, with the internal mag. My APM2 with external mag is in another system.)

Thank you,

Knut

2012-10-14 19-29 1.log

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  • Hmm, this reminds me of something that happened last time I flew my copter. It had been working just fine for a few flights, auto, rtl, alt hold, just loiter was a bit problematic. So I went out flying  in stabilize, and after a while hit RTL, and the copter flew back just perfectly, went straight to RTL_ALTITUDE which was set to 10 meters, and when back home decended to 2 meters which was set as loiter altitude. Excited by this I was about to show this behaviour again to a friend at the field, and set out in stabilize, flew some hundred meters away and engaged RTL. It was now so far away that it was difficult to see if it came home or what, but I was confident so just waited, but after some time I found out it was just wandering away in the wrong direction. Had to switch to stabilize, but got disoriented and in the end it ended up in the ground a little bit to hard, resulting in a broken motor mount, and has been grounded since. Unfortunately I have no logs of it.

  • Hi Knut,

    I looked at your log file, and I think I have a couple of clues.

    Whenever you went to RTL, it looks like the copter started returning in every case, but the last time it did something interesting.

    One explanation would be that you put some manual roll and pitch while you were in the RTL mode.  If not, something went askew in the software, but I would imagine that you had a bit of adrenalin going, and may have moved the stick.  I know this happens to me when I have adrenalin!

    But I think your biggest mistake was while you were in RTL the last time, you had your throttle stick at zero.  When you went out of RTL mode, the copter simply stopped, and started falling.  At this point, you were almost to the edge of the forest I see on maps.google.com.  After this, you restarted your throttle, and then I think you simply got confused with orientation (and adrenalin), and went over the trees instead of back to you, but I can't say that with certainty because there is no log of your RC inputs.

    Concerning your increased altitude when you switched to RTL, I looked at your NavTHrottle, and it looked like if you had left it a bit longer, it would have been ok.  It was starting to come down.

    IMHO, I think your copter is working OK, maybe needs some tuning, but you should also check the parameters:

    ALT_HOLD_RTL

    AUTO_LAND

    APPROACH_ALT

    Read about them here:

    http://code.google.com/p/arducopter/wiki/AC2_RTLMode

    Also, you might consider using the 'simple' mode in both RTL and Stabilize, and your orientation will always remain the same.

    Hope this helps.


    Dan Gray

    P.S.  I tell everybody 'LOG YOUR MOTORS', it's much easier to diagnose if you do, however, in this particular case it wouldn't have helped, but I suggest it for future impacts!

  • is there a list defining all the acronyms used in the logss? where a good place to get srarted as far as which data sets to review?

  • the logs are pretty hard to read. are any simpler analyzers available?

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