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I can trigger an uncontrolled descent
1469 26 2017-8-2
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Charles Adams
Second Officer
Flight distance : 294528 ft
United States
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I have no idea if my experience has anything to do with the concerns and complaints of other people, but I thought I would share it.  I must say that "uncontrolled" doesn't mean "crash".  It just means that I did not use the sticks to perform the maneuver.


I am able to cause my spark to descend to the ground without me having caused the maneuver using the sticks.  I am able to consistently cause the spark to do this.  The first time it happened shocked me.  With some persistance, I was able to figure out how to duplicate the maneuver.


I was experimenting with the obstacle avoidance, using my house as the obstacle.  When I flew backwards (away from the house) I was JUST flying backwards on the sticks.  I was not changing elevation.  Never the less, the drone flew backwards and also rapidly descended, until it hit the ground.  It bounced right back up, and it was not hard enough to cause damage.  When I flew forward, towards the house, it did the opposite...  it ascended upwards without using the sticks.  Needless to say, the first occurrence shocked me, as I was not making any adjustments to elevation.


I turned the spark 90 degrees so that I was no longer facing an obstacle, and I flew the drone back and forth.  It stayed level (no unwanted ascent or descent).  I turned it back towards the house, and sure enough flying towards the house also caused the drone to elevate, and backing away from the house caused the drone to descend.  Numerous times I had to throttle "up" to prevent contact with the ground, but I allowed it to touch down a few more times to see if it would make ground contact, and it did.


Hypothetically, if I were up against a natural "wall" on a lake, and backed away, and if the drone behaved as it did above, it would have ditched in the water.  Since I was not at a significant altitude (above ground), I don't know how far it would have descended.  It's uncontrolled ascents were only about five feet.
2017-8-2
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eylneb
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Malaysia
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hmmm sounds like an issue... raise a support case?
2017-8-2
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Charles Adams
Second Officer
Flight distance : 294528 ft
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eylneb Posted at 2017-8-2 18:24
hmmm sounds like an issue... raise a support case?

I'm going to do more testing tomorrow, make sure I can repeat it in a separate flight session, maybe using a different obstacle (fence or tree instead of house).
2017-8-2
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eylneb
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Charles Adams Posted at 2017-8-2 18:46
I'm going to do more testing tomorrow, make sure I can repeat it in a separate flight session, maybe using a different obstacle (fence or tree instead of house).

great... also if possible try to send the flight records & video evidence..
2017-8-2
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ImHereToCrash
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Charles Adams Posted at 2017-8-2 18:46
I'm going to do more testing tomorrow, make sure I can repeat it in a separate flight session, maybe using a different obstacle (fence or tree instead of house).

check your IMUs.. maybe to a IMU calibration  on a perfectly level surface.   i have not observed this myself.. i haven't tested it intentionally but i did the backup thing when i was testing distance my sensors could read me from and it did not drop or rise ..
2017-8-2
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forbsie
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I have experienced this behaviour once when flying inside just after getting Spark (on an earlier version of DJI Go 4). It was a quite gentle ascent/descent so did not cause any issue. The IMU had been calibrated. It has not happened since.
2017-8-2
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DJI Diana
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Flight distance : 2408 ft

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Could you please sync the flight records, then provide me with your DJI account email and the date this occurred? Besides, please refer to the link below to export the data for analysis, thank you in advance!
2017-8-2
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Charles Adams
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ImHereToCrash Posted at 2017-8-2 20:00
check your IMUs.. maybe to a IMU calibration  on a perfectly level surface.   i have not observed this myself.. i haven't tested it intentionally but i did the backup thing when i was testing distance my sensors could read me from and it did not drop or rise ..

Don't think it's the IMUs, otherwise I would see the behavior repeat when not facing an obstacle.  But I'll look regardless.
2017-8-3
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Charles Adams
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forbsie Posted at 2017-8-2 21:45
I have experienced this behaviour once when flying inside just after getting Spark (on an earlier version of DJI Go 4). It was a quite gentle ascent/descent so did not cause any issue. The IMU had been calibrated. It has not happened since.

I agree that the descent is kind of gentle (faster than a controlled landing, not enough to do damage when it makes contact with the ground).  Just a little bit alarming when it hits ground without any instructions to do so from me
2017-8-3
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Charles Adams
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DJI Diana Posted at 2017-8-2 22:19
Could you please sync the flight records, then provide me with your DJI account email and the date this occurred? Besides, please refer to the link below to export the data for analysis, thank you in advance!DJI Quick Tips - Spark - Exporting the Flight Data

I will do so, but I'm going to test some more first.  Given my profession, I don't like "bugs" logged unless there is a clear reproducible test case.  So for DJI, I'm going to make sure that I can reproduce this before I send any data.

Besides, my post wasn't intended as any kind of "complaint".  I thought that I might have stumbled across some clue to other peoples more alarming results (dropping out of sky, losing control, etc).
2017-8-3
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forbsie
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Charles Adams Posted at 2017-8-3 05:32
I agree that the descent is kind of gentle (faster than a controlled landing, not enough to do damage when it makes contact with the ground).  Just a little bit alarming when it hits ground without any instructions to do so from me

Yep agree 100%, it was alarming .. made me nervous to fly outdoors for a few days
2017-8-3
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Charles Adams
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I just came in from flying, trying to reproduce my unintentional descents.  I failed to reproduce it.  During the flight I had a strange occurrence where the app was showing a red "aircraft disconnected", but I still had video and full control of the craft.  This is really twitchy.
2017-8-3
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DJI Diana
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Charles Adams Posted at 2017-8-3 17:08
I just came in from flying, trying to reproduce my unintentional descents.  I failed to reproduce it.  During the flight I had a strange occurrence where the app was showing a red "aircraft disconnected", but I still had video and full control of the craft.  This is really twitchy.

Just to verify, did you use the RC to control the drone or just the APP? What mobile device are you using? Was the video view stuck after you got the "Aircraft Disconnected" message?
2017-8-4
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Charles Adams
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DJI Diana Posted at 2017-8-4 00:12
Just to verify, did you use the RC to control the drone or just the APP? What mobile device are you using? Was the video view stuck after you got the "Aircraft Disconnected" message?

My flight was with the Galaxy S7 Edge, running the latest DJI GO 4 app, connected to the remote via OTG cable, flying the Spark.  Spark, controller, and battery all have the latest updates.

The video was not frozen, it continued to show camera view perfectly.  No lag, no artifacts, and very responsive to aircraft movements.  Also, the aircraft was perfectly responsive to stick controls.  It was a beautiful flight.  The only anomaly was the application reporting that the aircraft was disconnected.

The flight started with a connected aircraft, and green for GPS lock.  I noticed during flight that I had the disconnected message.  I have no idea how long the message was there, as the craft was responding perfectly.

I thought I'd mention it in the forums, and I suspect DJI may want flight logs.
2017-8-4
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Charles Adams
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DJI Diana Posted at 2017-8-2 22:19
Could you please sync the flight records, then provide me with your DJI account email and the date this occurred? Besides, please refer to the link below to export the data for analysis, thank you in advance!DJI Quick Tips - Spark - Exporting the Flight Data

DJI Diana, I have a question.  I tried to upload my "data upload" files using the "Upload Data Files" option in the DJI Assistant 2.  I was presented a dialog that asked for various pieces of information, including "Mobile Phone".  Every format I tried to use to enter my mobile phone number was rejected.  What is the expected format in the "Mobile Phone" field?
2017-8-4
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RichJ53
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I was reading your post and went out to see if I could produce your issue. I could not get the Spark to act like you are describing at all. I have had the aircraft disconnect from my remote controller (only when on 5.8G) but it worked just as it is designed to RTH perfectly... and I took over again when it was close.

The Spark only has 1 IMU, 1 compass so they do not have a back up like the Mavic / P4P or Inspire 2. Make sure you calibrate everything before you test this again.

All the best
Rich
2017-8-4
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Charles Adams
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I looked at the flight logs (I KNOW HOW TO DO THAT NOW) and I can't find any anomalies there.  The flight logs demonstrate a fairly ordinary flight.  I'll have to figure out how to make a recording of my display so that I can demonstrate visual evidence of the behavior if it ever happens again.  That the first time I've noticed it.
2017-8-4
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ciesnik
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When I lost my Spark, right before I had the same issue with "Aircraft disconnected", but I could still see a perfect live view and the AC responded to all input, which I have seen analyzing the cached video afterwards. I have got this strange behaviour only with the Android app. When I was flying with an iPhone before it did not occur.
2017-8-4
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hallmark007
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Charles Adams Posted at 2017-8-4 12:49
I looked at the flight logs (I KNOW HOW TO DO THAT NOW) and I can't find any anomalies there.  The flight logs demonstrate a fairly ordinary flight.  I'll have to figure out how to make a recording of my display so that I can demonstrate visual evidence of the behavior if it ever happens again.  That the first time I've noticed it.

Could it have anything to do with VPS , what was the ground underneath the spark like, did you have good light , was the ground underneath Spark level, remember VPS needs good light good textured ground underneath it to work properly, if conditions are not optimal then VPS can do strange things.
2017-8-4
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JProcter
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I've not had any issues I'd called significant, I get inconsistent behaviour disconnects around Bluetooth devices. I get great results when I leave my Apple Watch off and turn off Bluetooth on my iPhone. Could your problem be interference?
2017-8-4
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Charles Adams
Second Officer
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United States
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hallmark007 Posted at 2017-8-4 14:26
Could it have anything to do with VPS , what was the ground underneath the spark like, did you have good light , was the ground underneath Spark level, remember VPS needs good light good textured ground underneath it to work properly, if conditions are not optimal then VPS can do strange things.

My grass has some poor spots which may have impacted lighting, but the odd thing is that I turned 90 degrees and repeated the back and forth flight across my yard, with no unwanted descent.  When I turned back to the house, it repeated.

I've got those logs still (I just need to figure out which ones they are), so I'll do some analysis.
2017-8-4
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DJI Diana
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Charles Adams Posted at 2017-8-4 05:17
My flight was with the Galaxy S7 Edge, running the latest DJI GO 4 app, connected to the remote via OTG cable, flying the Spark.  Spark, controller, and battery all have the latest updates.

The video was not frozen, it continued to show camera view perfectly.  No lag, no artifacts, and very responsive to aircraft movements.  Also, the aircraft was perfectly responsive to stick controls.  It was a beautiful flight.  The only anomaly was the application reporting that the aircraft was disconnected.

Have you tried to connect your phone to RC via WiFi? If yes, how is it going, do you have the same issue? As for the OTG cable connection, we didn't test it and it isn't official. I would recommend you use the WiFi connection. As for the data, no need to use the Upload Data Files, just save them to local, then upload them to the Dropbox, then provide us a link to download it.
2017-8-6
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MaikR
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Hi,
I experience the same thing.
Spark connected with controller with WiFi (no OTG) to a iPhone 6s.
Flying towards an object until it starts beeping (obstacle avoidance). Then gently fly backwards (just right stick down), it descents slowly. Stopping and fly forward it ascends. Can repeat that. When no obstacle was detected it will not descent or ascent by itself.
2017-8-7
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Charles Adams
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MaikR Posted at 2017-8-7 02:51
Hi,
I experience the same thing.
Spark connected with controller with WiFi (no OTG) to a iPhone 6s.

I tried to reproduce it for DJI and could not.  If you have your flight logs of that flight, can you give them to DJI?
2017-8-7
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MaikR
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Charles Adams Posted at 2017-8-7 08:31
I tried to reproduce it for DJI and could not.  If you have your flight logs of that flight, can you give them to DJI?

Okay I will try to find out in what flights I have it or maybe create a new flight with the test only.
2017-8-7
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Kyokushin
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People please, when you are doing tests like this please write what f/w you used on AC, RC, and what app (android or mac)
2017-8-7
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Charles Adams
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Flight distance : 294528 ft
United States
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Kyokushin Posted at 2017-8-7 21:16
People please, when you are doing tests like this please write what f/w you used on AC, RC, and what app (pc or mac)

Latest firmware, latest app, Galaxy s7 edge connected to RC using OTG, surface pro 4.
2017-8-8
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