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  1. Stevie_UK

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    Took the P4 up by a lake tonight, though not wanting to risk going anywhere near that water (at least not yet!). So I'm showing my Son how it flies around, up and down, etc, flew up high, a little ahead of me, then decided fly it back over our heads. It looked (can be deceiving with clouds moving etc) as if it wasn't moving in our direction, so decided use the return to home. Current position or take off point - Well we'd walked across the field somewhat, so current position sounded good.

    This is where it seemed to be getting even further away, feeling as if out of control, and drifting a little too close to the water for my liking. Thinking it was the wind (very slight breeze <5mph - UAV forecast reckoned even better than that!), and now jogging towards it, seeing it near water I took her up some so VPS didn't get thrown off by the aqua! Once it was away from the water I brought her in lower hoping less wind, less drift. Still continued getting further away and decided it was safer to bring it down ASAP, was also heading worryingly close to some trees - due to the fact it seemed to want to go South for it's holidays I didn't wanna take it UP above the trees.

    Usually I land VERY smooth, this one was in longer grass and tipped over on landing, I'm guessing due to the long grass. DJI log shows it landed at 4.4M though, or at least that's where the app stops playing. I'd estimate I came down from maybe 8-12". All appears completely okay asides from a bit of chopped grass. DJI app says I had throttle at 44% at landing point. (I've just reviewed my other logs and one from other day with perfect landing says was at -0.2M so I'm guessing it is relative to takeoff point?)

    Firstly, was the water affecting compass readings, GPS, it didn't want to return home. Old mining area, so maybe something else I don't know about could be under the ground. It wasn't above water as I know that can mess things up VPSwise.

    Secondly, I'm now wary of the return to current location function (first time I tried that one), but reviewing the flight log it set it as a couple of miles South of me (off the map view in app).

    Thirdly, why does the log stop at 4.4M, I'm assuming that the 4.4M is the height the VPS is picking up, or is this worked out based on height at take off point relatively?

    During this time it honestly seemed like at times that it had a mind of it's own (and yeah that's the point I decided to bring her down). I've recently done IMU calibration, and flown well since, always make sure I do compass calibration, every other flight has went well but this has made me a little wary.

    It seems the return to current location must use phones GPS and all I can assume was that that was off - I didn't notice on the screen as the 'new' landing point was off the screen. Something to be careful of, in fact probably something I will *never* rely on!

    I'll probably not go back to that same location, in case it is something interfering there. I'll also not be flying within even a half mile of water, as drifting towards that water was rather worrying, at one point while 'drifting' it did cross a small tributary, but seeing it do that I raised altitude so it didn't get even more confused!

    I (wrongly?) assumed that return to current location would have brought her down to my return to home altitude (set at 30M), I can see sense in the fact that it didn't, but since wind was the only thing I could think of that was pulling her away so I wanted go lower.

    Thought I'd post this as to maybe get an idea of what was happening, and also maybe help someone else - That return to current location is nasty - from my experience!

    I'll have to look into uploading the logs into a decent viewer, Will the DJI Go app show when I hit return to home in detail, like return to home, return to current?

    Watching the Go log of it it was 100m away then suddenly it popped up saying it was 2126m away! (and popup saying max MC range reached.) My fear is that the drone now wanted to return to the *wrong* location, probably even more so since it thought it was beyond my set max range! It seemed at this point to only respond to up/down commands? I'm pretty darn sure I cancelled the previous return to current location request, but think the range thing kicked in and took away some control? felt that way!

    Sorry to write a novel here, but trying to think/explain how things went. What *I* think happened was this:

    I told it come home to current location.
    It picked wrong location GPS (from phone?).
    This (wrong) RC GPS was then sent to the bird.
    Bird then thinks 'Oh heck I'm past the limit set in my max range - RUN HOME' - to the wrong location!

    Lesson learned, but made me extra wary. Anyone else got a different view on what happened here?

    One other thing I should mention is ESC errors, I saw one when first got P4, went away after restart but decided to calibrate IMU to be on the safe side. I did see one tonight too, but that was after the landing in long grass, again restart got it cleared - ESC errors are caused by what and could this be telling me that indeed something was throwing sensors into confusion?

    [edit]: I can't say for sure it was ESC errors I saw, I've probably done too much reading and looking for a reason as to tonights episode! Logs don't show them, and I checked other flight logs from tonight too in case they showed anything up.[/edit]

    Novel over, thanks in advance for the replies :)
     
    #1 Stevie_UK, May 5, 2016
    Last edited: May 5, 2016
  2. frands1

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    WOW
    I'm sure that if you share your log some people with better knowledge than me can help you understand what's going on... Or at least we all learn ;)
     
  3. Stevie_UK

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    Phantom Log Viewer - PhantomHelp.com

    You'll see the point where RTH jumped, and where I increase altitude as it moved toward (and then across a little) water. What I am puzzled about is how it landed at 4metres. You also see how I tried to get it away from any of that water but it seemed it just wanted to whizz off Southbound (at what seemed like faster than the 5mph in logs). Just got her down in time 5 metres further we'd have been at the trees!

    Looking at the logs, and considering it took me 40 seconds or so to get to the landing point, I'm thinking it recorded landing at 8.5ft but then got false readings as it was upside down but still switched on?

    Any views on the log? It seems I did take it out of RTH mode once I realised what was happening, but seems like *maybe* a failsafe if it believes it's out of RC range and returns to home anyway??
     
    #3 Stevie_UK, May 5, 2016
    Last edited: May 5, 2016
  4. frands1

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    This is scary!:

    upload_2016-5-5_16-11-32.png

    in 0.1 s, home point change from 337.1 to 6982.6ft, yet at "only" 2.8mph
     
  5. Stevie_UK

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    You should have been there.. Trying not to panic but *knowing* something was up, seeing it fly off towards that stretch of water, fighting whatever 'magnet' was pulling it southbound at what seemed much faster than 5mph.

    There are many windfarms to the North a mile or 2, Maybe they had something to do with it? Bouncing GPS signals or RC signals around?
     
  6. Dacon Productions

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    Why not ATTI?
    Use your map (if loaded) and point the triangle (drone) towards you, follow the line.
    Use the radar info to bring it to you.
    When windy we play games as lift it up to about 150 ft and set it on ATTI, let it drift a good distance away (about 1 mile) and fly it back by hand.
    Not too many people can handle this and are afraid, when something happens they do not know how to handle it.
     
    Jussaguy, KevMo Photog and WetDog like this.
  7. Stevie_UK

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    I've read many people saying get used to flying in ATTI mode, and indeed I should, in fact only recently I read a post that did indeed suggest that to someone when their drone was wandering away. I decided on a Phantom last year, largely at that point based on good reviews and the RTH feature as this seemed like a good failsafe. I waited, read more, and only recently decided it was time :)

    What I will be doing now is increasing the distance to RC as I do feel like the drone was pulling away from me once that warning flashed up, even after I took over flying it truly felt like something was pulling it South other than the wind (which I now see was the direction of the updated HP). I also tried the pause button on the control but I can't remember at what point during the flight - it may have even been before it decided to head away from me.

    Next flight will be in a place I know to be flat, free from wind turbines, free from water, and away from old mineworkings. I'll probably still stay in PGPS mode, But I'll likely be pulling that sticker from over the mode switch (and enabling it in the app?).

    How much control do you have in ATTI mode, as in do you have to keep the P4 in the air, or does it hover if left alone (in zero wind)?

    After another hour (or three) of hopefully safe flying I'll be giving ATTI mode a go. The failsafes are great, but do take control away from you and even before this was something I didn't want to rely on. Do you fly ATTI all the time yourself now?

    Only other thing I forgot to mention was there was an update to DJI app today - probably not related, but my job is diagnosing tech stuff, so I'm trying to mention *anything* that may be a symptom - Sorry if I go on!

    I've looked through the logs in spreadsheet form, see the gyro go a little crazy a quarter of the way through the flight, then again towards the end (near the end could be the craft flipping once it landed or it could have been me picking up and inspecting).

    Anyone else care to comment? If anyone is fluent in reading the csv logs there seems to be a lot more information in there - unfortunately my screen isn't wide enough to see it all at once, and my knowledge on the csv logs is basic at this stage.
     
  8. Stevie_UK

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    Not sure if from the logs anyone can get the 'playback' of the flight, after reading this I thought to replay them in the DJI log and see the triangle pointing towards me all the time I'm fighting it, only deviating at the point where I'm pushing to avoid going above the water, then again pointing towards me. I'm assuming the arrow is pointing 'forwards' and I'm now thinking hard as to whether I was indeed pushing forward, but it seems since I knew the orientation at that point and at the point where I moved to avoid the water that is is likely I was moving forwards (towards me). The logs will show whichever way and hopefully someone familiar with them will draw a better conclusion.

    I'd be interested if the logs show a drag to the South even when I tried pausing or letting go of the controls. Or was this purely down to me?

    EDIT: just checked that flight log playback with controls displayed, and indeed I'm pushing forward towards me while the drone continues to head away from me :/ Seems I even tried going the other way for a second just in case my orientation of the craft was off (it did speed up at that point which says that I did indeed have control and it was responding to commands).

    Again, no wind, just a craft with what seemed to be a mind of it's own and regardless of my input wanted to be home - to the wrong home!

    To what extent do these failsafes, in particular return to home take over from the operator, especially in this case where it falsely believed it was over the distance limit set in the app?
     
    #8 Stevie_UK, May 5, 2016
    Last edited: May 5, 2016
  9. volace

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    I see that the bird was so far from what is supposed to be home point , and at certain time it refused to respond to your pull because it says ' maximum distance reached' since you are pulling it further away from her false home . This can make sense if you already have a maximum distance setting in your DJI go .


    Sent from my iPhone using PhantomPilots mobile app
     
  10. thunderbird

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    Keep in mind if you practising in Atti mode always keep an eye on screen or LOS
    Once i had within LOS and in Atti mode but looking into Camera settings, After 1 minute i notice the bird heading towards the tree with the wind, I took control quickly and learned my lesson, I do practice hovering and landing during heavy wind in Atti mode within LOS that helps me to get used with Atti mode.

    Sometimes I bring the bird up to 300ft more windy and practice to hover
     
  11. chazz

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    If I googled your home point coordinates correctly seems you are near a wind farm...Maybe that had something to do with the compass error...Well at least the posters in this thread think it can...Wind farm signal interference

    Or I may be way off...
     
  12. Stevie_UK

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    That's maybe why the homepoint GPS ended up the wrong place, but is it right that the bird took over and wanted to continue South (towards it's false HP) regardless of any input, I see in my logs that I'm pointing towards me (North), full throttle forward but still drifting South at a steady speed.

    My take on it is that because it triggered the Distance > max set in app that it just took over, even after cancelling RTH.

    I've posted the log on the DJI forums too and hope I get some input there. I'm thinking software issue, but clearly since it takes over from the pilot it could be dangerous. Maybe a separate variable for RTH point as well as a TAKEOFF point. Either way, taking control away from the person flying aint good and I class myself as extremely lucky.

    I wish there was a way to view that log as a live flight (like in the DJI GO flight log) for you guys, maybe DJI has an app? From me personally reviewing it, only thing I can say I did was not notice at the time that it picked up a false (off the map) RTH.
     
  13. chazz

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    You may be right about not canceling the RTH because of the distance setting in the app and I know the first thing I would do is turn of the distance limit...

    The guy in this thread Dont fly around transmitters. My first crash had a similar instance with a max height and vertical speed false reading...I'm not saying you did anything near what this guy did but it is an example what could happen...
     
  14. Stevie_UK

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    Interesting video, similar as his 'max altitude reached' mine was 'max distance'. I'm considering switching off the max distance/altitude as it worries me that these things can go wrong. He however had likelihood of strong interference and I assume decided to 'chance it', be nice to see what his logs said so we could see which sensors were affected. I keep away from anything electric or radio.

    Part of me *likes* the distance limit, I like to set myself limits - and then expand them gradually, but my experience now tells me to switch it off until autopilot stuff/sensory malfunction is fixed!

    Wish I had video to show but I was more out for a leisurely fly and demo with just a few still images.
     
  15. chazz

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    I must be going nuts as I didn't see the mention of the wind farms before I posted...Sorry
     
  16. Stevie_UK

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    Not nuts, hard to work out what happened tbh, yeah I can blame GPS (probably on the phone), but to 'travel' 6000ft in less than a second (do I win a prize for that?) No reason why there isn't a failsafe for that, the algorithms wouldn't be that hard - obviously a false reading. I have to be honest, I've been scared to take her out today - ended up coming to work instead (and yeah I'm STILL here at after 8pm)!

    I've re-calibrated everything again and enabled multiple flight modes in the app so I can be ready next time - though I've put the sticker back over it for now. My next few flights will likely be low, testing auto features. I think ATT mode is gonna be used sooner than I anticipated.

    Wish I knew more about the logs, or someone with some in depth knowledge would give me some heavy feedback. Personally from looking at them in playback I'm impressed as to how I handled things, not a scratch on even a prop, avoided that water, and came down within 5 metres of some trees - if it had continued on it's Southbound journey I'm wondering if obstacle avoidance would have kicked in, I'm not sure since it seemed to be INTENT on getting to that false landing point!
     
  17. ianwood

    ianwood Taco Wrangler
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    GPS signal was solid throughout the flight. The home location was likely reset by the phone which probably doesn't have GPS or it was turned off.

    DJI needs to fix this so they don't use a low quality fix for resetting the home location. Moral to the story is don't update your home point unless you have GPS on your phone and it is turned on.
     
  18. darbyhouse

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  19. Stevie_UK

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    ianwood, sounds like it probably was, but with no failsafe, and no way of taking control back afterwards it's rather a dangerous issue. I've disabled the max range in the app now, and enabled the other flight modes, JUST in case. I've not flown since asides from a short test flight to make sure everything was working. I have again recalibrated the IMU, just in case, but since everything was showing SAFE TO FLY, with no warnings it maybe wasn't necessary.

    I'll be testing phone GPS at that point very soon, just to see how stable/unstable it might have been. Something else worth considering is that most Android phones will use GPS *and/or* Wireless AP locations to try and figure out where you are, it occurred to me that maybe google picks up the birds AP (I saw settings for an accesspoint in a .conf file) and since it looks 'default' perhaps google picked up on where a P4 was previously? I'd never flown anywhere near the false RTH point, but maybe someone else had! Not even sure if there is an AP enabled in the drone, I'll do some wireless sniffing when I get a chance and report back on that.

    There needs to be an override though - there probably is, but it's likely undocumented. A way of forcing a NEW RTH point EVEN if it thinks it's out of range. There has to be of handling a new 'situation', a 'what if this happens' - I appreciate that there will be much simulating and testing during all development, but there has to be something that can cause an interrupt request in case of a new situation so it can be dealt with.

    One thing I do notice on going back over the flight data is when it shows 'LANDING' - it seems to stop drifting, maybe I should have just let it land, maybe it would have, or would it simply have got the OUT OF MAX DISTANCE warning and rose again to 30M to head to it's false 'home'.Since it had drifted away from me I wanted to be right there to be sure the landing point was safe. Running and trying to keep an eye on screen as well as regain control was a little daunting! tbh afterwards I can't straightly remember trying to initiate an auto landing but looks like the drone did, so that is one thing I tried! (among everything I could think of!)

    Another poster past few days with similar experience suggests that ATTI mode made no difference, maybe he truly was out of radio range at the time.

    The algorithms need to be altered for the failsafes, if suddenly the bird is 6000ft away and yet has only flown 1000ft then quite obviously it's a false reading for either the bird or the controller location. In either case, hover, take more readings and if still the same simply hover and return control to the user. Needs fixed ASAP I'd say.

    Other ideas would be a good quality GPS in the controller as well as the drone - and a failsafe we can ALWAYS activate which is return to RC point.

    Maybe a separate variable for RTH and RTC would be enough, as long as we are able to take control EVEN if it thinks it's out of range.

    I've forwarded my logs to DJI, hopefully they'll be in touch via phone so I can explain exactly what the circumstances were. My drone appears fine, everything including props look brand new so I've been lucky. My *very* short test flight showed no obvious abnormalities. Obviously this is a concern to all of us though, an extra thing to add to the list of things to watch out for!

    I also urge others to go over my logs and report back, the more people looking at these logs and suggesting ideas the closer to perfection our drones (and our flying!) will become.

    Logs here
     
    ianwood likes this.
  20. ianwood

    ianwood Taco Wrangler
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    Yes. Everyone should do this. Learn to fly ATTI mode and use it in cases like this. And unless your battery is dangerously low or the drone is flying away, stop, breathe, take stock of what's going on and only then do something. And if it's flying away, switch to ATTI and correct for wind. Try re-engaging GPS briefly to see if it behaves. If not, bring it in under ATTI.

    There is no AP in the P4. It's not using WiFi. Most likely the phone is using basic WiFi triangulation to determine location. Why DJI allows this is beyond me. But, it's a good reminder. DJI introduces features quickly and haphazardly. They often have bugs. YOU are the beta tester. Try each feature carefully and with a back up plan.