Anomoly during RTL tests of new hexcopter

Thanks to help in another thread, I’ve now got to the point where I have confidence in Stability and Loiter modes with my Pixhawk 2.4.8 Ardupilot 4.0.7 hexcopter, but when checking out RTL today I encountered an anomoly:

With my first 5-minute flight I loitered for a while at about 15m height, about 40m away from launch, then hit the RTL switch and the hex turned round to face the launch point, and proceeded as expected (increase height, return, loiter, descend to launch point, disarm) on three separate occasions. With another battery I repeated the test successfully once, but on the second occasion it seemed to lose track of what it was doing; When I hit the RTL switch it veered off to the right (i.e. downwind) a bit before turning round and increasing altitude. Then it flew towards the launch point, but at a lower altitude than previously and, in my estimation, losing height quite a bit until it reached the launch point, at which it then ascended to roughly the specified RTL height and then started its descent. But during descent it drifted again, this time into the wind, didn’t slow down as much as previously, and didn’t disarm when it landed about 1m away from the launch point.

There was quite a stiff breeze with gusts during these tests, but in stability and loiter modes it coped well with the wind. But could gusts of wind have upset the barometer on the Pixhawk board like it can do on my Omnibus iNav boards if I don’t cover them in foam? Or is there some programmable Ardupilot parameter which might make it less likely to behave this way?

In the four good tests I was impressed with the RTL accuracy, which was within less than 0.5m of the target. The final test landed about 1.5m away.

Not sure if it’s control issues or GPS problems, but only a .bin log will tell.
I don’t image there’s any issue with the RTL code.

You’re right of course, I’ll get the .bin file as soon as I can – probably this afternoon.

I’ve got the .bin file, size 1984KB, but whenever I try to upload it I get an error message, “Sorry, that file is too big (maximum size is 4500kb). Why not upload your large file to a cloud sharing service, then paste the link?

I don’t have a cloud sharing service – what do you guys use? Or is there a ‘trick’ to getting the forum to accept the file?

Edit: I’ve used Dropbox, it’s the only one I’ve heard of. Here’s the link

The GPS origin was set initially but at ~40s when you tried to switch to PosHold it was refused from Bad Position. The the origin was established again so this is the new home position. I’m not sure why it lost position, Sats and Hdop were good. In any case Home for RTL was not where you expected it to be.

Ok, thanks so much for that quick reply. That would explain why it was off target, but it doesn’t explain the very bumpy ride back to the launch site after RTL is initiated at 100s. So, you say sats etc. were good, so is my experience something you’d be concerned about – should I be doing some further checks somehow?

BTW, I can see what parameter is graphed, but how do you get all those notifications to show on the plot, please?

No, it doesn’t. You have a bit of a limited Log Bitmask. I was looking for RCIN and you aren’t logging that. Or some others. Default would be better than what you have.

There are checkboxes below the graphic area. It’s APM PLanner 2 if you didn’t know.

I’ve got a lot to learn! I haven’t done anything to the Log Bitmask, so I should surely be on default. I’ve just now looked it up in this site, so what’s the disadvantage of going for one of the “All+xxx” options rather than Default, other than more storage space used?

Ah, no, I didn’t know about APM Planner :slightly_smiling_face: I’ll have to check that out, thanks.

The default bitmask 176216. You didn’t make the grave mistake of loading another parameter file did you :slight_smile:

This covers most everything:

I didn’t knowingly load any parameter file. This is the only craft I’ve got which uses Ardupilot, and all I’ve done so far is go through all the setups and calibrations in Mission Planner, as well as tweak a few of the parameters such as RTL height (I reduced it a bit from the default setting) for my tests.

When I checked out Log Bitmask on the ardupilot page yesterday it said that 830 is the default bitmask, 894 is default+RCIN, etc., etc. But I’ll set it up as per your illustration before my next flight. Thank you.

OK, I’ve set up the Log Bitmask as per your example, so hopefully there’ll be more useful information in the log next time I need help :grinning: Thanks for your help.

As for the possibility of loading an incorrect parameter file, my procedure thus far has been to boot up Mission Planner, connect the copter by USB cable, and click on the MP “Connect” button. If I’ve changed any parameters I then click on the “Write Params” button and then “Save to file” before clicking on the “Disconnect” button. That’s the correct procedure, isn’t it? So far I haven’t retrieved or written any parameters from the saved files.

Write Params will save the changes to the flight controller.

Save to File will save a copy of the parameters to a file on your computer. This is optional but handy if you think you might be going back and forth later on.

Disconnect … Well, I think you have that one figured out. :slight_smile:

Successful testing today, but …

I flew three 8-minute batteries in the hex today, and executed several RTLs without experiencing the odd behaviour I had in the final flight last time. This was in winds gusting to 30mph, and landing was within one foot of the target each time. Because of the wind, position hold wasn’t very accurate, especially with respect to height, but the RTL horizontal leg appeared to be very steady.

Only problem now is I can’t review the logs because I get an error message, “Log Browse will not function correctly without FMT messages in your log. These appear to be missing from your log.” How do I fix that, please? Log Browse was working last time, and nothing has been knowingly changed except for changing the bitmask to match that suggested earlier in this thread. I’m using Mission Planner.

Post the log files, and they need to be .bin files.

Sorry, I forgot the first rule, didn’t I :grinning:

Here’s one of the log .bin files that gives me the error. All files recorded yesterday – the first flights since I changed the log bitmask – give me the same error message and can’t be read by Mission Planner.

Oops, the forum says my file is too big to upload (it’s much smaller than the maximum size they state), so I’ll upload it to Dropbox here.

You will need to post the parameter file as one cannot be extracted from the .bin log due to the same error.

OK, here’s the parameter file that was being used yesterday.

Edit: Sorry, that might be before the problem. Here’s a parameter file I’ve just saved today after increasing the RTL altitude to 3000cm. All other parameters are unchanged from yesterday.

You have LOG_DISARMED enabled so perhaps the Sd card is full…

Thanks for looking so quickly. I’d set LOG_DISARMED that way initially to check arming problems, but don’t need it now so I’ll change it after I’ve sorted this issue. I’ve just checked the SD card, and it’s 339MB used out of 16GB. Using MP I can still review logs made on it on or before 26th April, but none after that.

I’ve replaced the SD card with a new formatted 16GB one, but now I can’t get the copter to arm, so I’ve re-enabled LOG_DISARMED in case it will throw any light on the problem.

I put the original SD card back in and I get the green flashing LED when I press the safety button, and I can arm it and spin up the motors, but the LED is flashing yellow (or is it white?) and red. The log from that brief test is still unreadable, with the same error message.

Edit: I’ve just found a couple of other threads about the same issue, and reformatting the SD card seems to have cured it for them. But inserting a new formatted SD card didn’t do the job for me, and when I look at it in File Manager I see that there’s no files or folders on it, which the other threads say that Ardupilot should create automatically when there’s a new SD card.

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I’m still unable to read dataflash logs

In MP I’ve deleted all the logs, and I’ve then made a 30-second ‘flight’ in my workshop.
LOG_DISARMED is set to 1, but MP reports now that there’s no logs to download.
I’ve taken the SD card out of the craft and checked it on my laptop, and it appears to have the correct file structure and one small log file from this afternoon’s test. As reported the other day, I did try a blank formatted SD card, but no file structure was created when I installed and ran it that time.

Are there any settings I may have missed that might cause this problem? As I mentioned earlier, I don’t think I’ve changed anything apart from the log bitmask since the time when logging was woring properly.