Serious RTH firmware bug, are you seeing it?
- Thread starter smiller
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Error in my reported distance, was only 1/4 mile out, sorry. All other data is good.
On 12/7, using auto takeoff, I flew out in a straight line 1/4 mile, hit RTH on the controller and the craft turned and returned to home with 3 to 5 feet deviation. Just prior to decent the AC was at the same height I started with.
I am using an iPad Air 2 for my device.
Out of the box I did one FW update, one IMU and compass calibration, and the RTH setting is default.
On a side note related to other expressed member concerns , I have never experienced a high wind warning.
Screenshots available upon request.
I hope this helps.
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Flew out 6500 feet away. RTH stayed at 200 feet the whole way home. I'm running the current firmwares and on iOS.
OK, I think I've figured out why some are seeing the problem and many are not. If you are below the preset RTH altitude at the time that RTH is initiated (which is probably most commonly the case) the aircraft will climb to the preset altitude and return home, just as it should. In fact mine does that too. But... if you are already above the preset RTH altitude when RTH is initiated then the problem seems to occur, as if the unit is trying to climb to RTH altitude but somehow doesn't realize that it is already above due to some software bug, so it climbs continuously. I can repeat both scenarios reliably.
This is not correct behavior of course, if the unit is above RTH altitude it should hold its current altitude on the return home in that case, not increase altitude apparently without limit. But for now at least you can avoid the issue by ensuring that your RTH altitude is set above your planned flight altitude.
If anyone has a chance to test this theory (i.e. set your RTH altitude to maybe 25 or 30 meters and then fly above that altitude out at least a few thousand feet and initiate RTH, and then see what happens) I'd appreciate it. If we can confirm the above behavior I can update DJI.
This is not correct behavior of course, if the unit is above RTH altitude it should hold its current altitude on the return home in that case, not increase altitude apparently without limit. But for now at least you can avoid the issue by ensuring that your RTH altitude is set above your planned flight altitude.
If anyone has a chance to test this theory (i.e. set your RTH altitude to maybe 25 or 30 meters and then fly above that altitude out at least a few thousand feet and initiate RTH, and then see what happens) I'd appreciate it. If we can confirm the above behavior I can update DJI.
Possibly, but I fail to see how this could be any kind of hardware problem since the unit flies perfectly in all other flight modes and if there was a hardware problem of this magnitude you would certainly see some other effect. That, and the fact that everything works properly when below preset RTH seems to point pretty clearly to a software issue. I think most likley it is a combination of some causative factors or settings that we haven't figured out yet. I'm convinced that if an 'unaffected' unit duplicated the same settings environment then it would see the problem, but there are so many variables I can't guess what that combination might be.
I think the takeway is that anyone making long flights should test operation of their P4P for this issue (uncontrolled altitude gain during RTH when you are operating above the RTH preset altitude.) If you are experiencing this issue you could easily and unknowingly climb to real airplane altitudes on a long RTH return path.
I was mistaken. I double checked my logs and both flights that I tested RTH was initiated below RTH height.
So I just went outside and tested now. I had RTH set to 180 feet and I was flying at 250 feet. At about 3800 feet out I lost both transmission and image, and it auto initiated RTH. A few seconds later the TX reconnected and I watched and sure enough!!! If you are above RTH set height and you are far enough out, it just CLIMBS. And it seems to climb as fast as it can climb too. It got to almost 500 feet before I hit down on the left stick. This made the drone go down as long as I held the stick down (while still in RTH). But as soon as I let the stick go, it climbed uncommanded again! Not until I was about 1500 feet away from RTH did the uncommanded ascent stop.
Definitely something not right on the P4Pro! I'm happy to post flight logs if someone wants to tell me how.
So I just went outside and tested now. I had RTH set to 180 feet and I was flying at 250 feet. At about 3800 feet out I lost both transmission and image, and it auto initiated RTH. A few seconds later the TX reconnected and I watched and sure enough!!! If you are above RTH set height and you are far enough out, it just CLIMBS. And it seems to climb as fast as it can climb too. It got to almost 500 feet before I hit down on the left stick. This made the drone go down as long as I held the stick down (while still in RTH). But as soon as I let the stick go, it climbed uncommanded again! Not until I was about 1500 feet away from RTH did the uncommanded ascent stop.
Definitely something not right on the P4Pro! I'm happy to post flight logs if someone wants to tell me how.
Yep, it's frickin scary. And the hardest part has been convincing people it's real
But at least you can avoid problems if you are careful to not use RTH above the RTH preset, until DJI fixes it. I would hope it would get priority because it is a potentially dangerous bug.
I have sent flight logs to DJI that clearly demonstrates the problem but it wouldn't hurt if anyone experiencing this problem sends a report to: [email protected] , and if you can supply the .DAT flight logs from your flight (can be downloaded from the P4P via the DJI Assistant 2 PC application) that would be helpful. When downloading flight logs via DJI Assistant check both the 'Flight Control File' and 'Vision Module File' checkboxes next to the flight.
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Tested it again, same result. Seems pretty easy to reproduce.Yep, it's frickin scary. And the hardest part has been convincing people it's real
Yes, once you see it you will be able to produce the same result at will. I think it might well affect all P4P units, but just not widely noticed yet since most tend to operate below their RTH preset.
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Just FYI to all, this moring DJI CS got back to me and reported that their engineers had confirmed the bug. Basically what happens is that sometimes when RTH is initiated above the preset RTH altitude setting and the unit erroneously thinks it sees an obstacle (perhaps confused when it yaws around to point homewards) it rises to avoid the imagined obstacle but instead of stopping after a short distance it continues to climb continuously. The problem should be fixed in the next firmware update.
I'm almost 100% sure that someone tested it with OA off and it still climbed. Maybe RTH OA was still on
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Can't say, that's only what DJI reported to me. The English wasn't great but I'm pretty sure that's what they were trying to say.
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Didn't see this thread, but had the same thing happen just yesterday, with latest firmware (12/30/16)
http://www.phantompilots.com/threads/bizarre-run-away-altitude-on-return-home.100613/#post-103657
http://www.phantompilots.com/threads/bizarre-run-away-altitude-on-return-home.100613/#post-103657
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