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My First unplanned flyback and near pile in

Discussion in 'Phantom 2 Vision + Discussion' started by Dartmoor Dave, Dec 8, 2014.

  1. Dartmoor Dave

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    I've had my p2v+ for a few months now, so I'm still a relative noobie and continue to make stupid mistakes, I'm first to admit. I had tried a few planned flyback RTH to see how things went but this weekend I had my first accidental one and as I found out later, when I downloaded the video, I came very, very close to piling my Q/C into a hillside when flyback to home auto triggered. I was flying up a long hill on the moor trying to keep the copter at a fixed height above the hillside during the flight, that sets the scene well enough.

    Since I also record the fpv vision app screen at the same time as recording the camera output to the sdcard on QC, after the event I was able to merge the two videos together and slo mo it through to see how the action developed through first losing the fpv vision, it froze when the signal was lost, then the R/C to phantom link went, I was flying completely blind at that point of course. Actually with the sun so low in the sky the smartphone vision screen was not that easy to see in any case, so it was easy to miss key indicators on the screen.
    Before offering you a view of the developing near pile in, I am well aware of what I should have done as soon as I lost fpv, as I had also lost visual contact with it against the moorland background on Dartmoor, UK where I was flying, in the low morning sun. I should have immediately stopped flying the Q/C in any direction but vertically up, pdq, but I didn't and almost paid the price.
    As I mentioned I produced a slow motion video of the incident so that I could study in detail what was happening and more importantly, why it happened. I've uploaded it to youtube as it might be of interest to other phantom users. It is at 1/4 normal speed for ease of following the events and signals as they triggered on the smartphone. I estimate I was < 1 metre above the ground when RTH automatically triggered and the Dartmoor tussock tops are that high so I know just how lucky I was not to pile her in.

    See
    http://youtu.be/NUn0Ct375-4

    I've a couple of questions from this experience that I hope someone might be able to answer.

    Firstly, does anyone know the time lag when flying the phantom between where the quadcopter is and what is appearing on the vision screen? Any lag could be very important if you are flying in proximity to an object, in my case the ground, almost five hundred metres away from the home point. There doesn't seem to be any difference, once I synchronise the two at the start of the video so the lag, if any doesn't seem to change over 500 metres of flying.

    Secondly, the signal message I received "Phantom Connection Broken" was not one I've seen mentioned in the dji user guide. Has anyone produced a list of smartphone vision app screen messages that can be displayed from the DJI vision app? If so could you share it with us.

    If any of you wonder what I use to obtain the smartphone fpv screen video then please have a look at the thread I started on the "first person view" section of the forum where you can read about it at some length.

    Look forward to hearing from anyone who can help

    Dave
     
  2. rbhamilton

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    That was a close one!
     
  3. Dartmoor Dave

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    Yep, it certainly was, just at the RTH point my P2V+ really was in the ****, albeit of the Dartmoor Pony variety. I've just grabbed the section of the video, at 1/8th normal speed, approaching the point when the signal dropped out and RTH kicked in.
    If you can play wmv file the take a look at this from dropbox

    https://www.dropbox.com/s/myl84y0cv33ce ... p.wmv?dl=0

    Boy was I lucky - no wonder the signal dropped out, there was the top of the hill between it and where I was with the RC by the look of it......

    Dave
     
  4. MapMaker53

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    Jeeez. That looks like it may have actually touched down for a moment.
     
  5. PsychopathRC

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    That's why you should never lose sight of your Phantom, lol.

    What's it like flying 500 meters away?

    The furthest I've flown mine is 800 feet. So around 250 meters. Was crapping myself :D
     
  6. Dartmoor Dave

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    Psycho,
    Makes for an entertaining and stressful few seconds, or longer. Too easy to lose sight of it, depending on the background, believe me, even at shorter distances. One moment I could see the P2V+ going steadily up the hill, I glanced down at my smartphone screen to check that the camera was aligned with the stone row I was videoing, looked up again and no sign of the phantom. I'd lost it against the moorland background. The flight path looked OK on the smartphone screen, at least it did until the fpv screen froze and I was flying blind. Then I had the same symptoms as you say you displayed at 250 metres :)

    TBH after the fpv dropping out I thought I was flying it back towards me but in reality I was 180 degrees out ( no idea of that as the smartphone screen remained frozen). I know what I should have done, gained height fast, moved into IOC home lock mode and flown it back or simply triggered failsafe. Easy now but when displaying certain classic symptoms it isn't just the smartphone vision app screen that froze, hand/eye/brain co-ordination took a bit of a hit too!!

    Dave
     
  7. J_K

    J_K

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    Wow. That was close!!
    Whereabouts do you fly?
    I'm only at Cullompton and was thinking about a Dartmoor or Exmoor trip this weekend.
     
  8. Dartmoor Dave

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    Hi J_K

    All my P2V+ videoing so far has been done on Southern Dartmoor so far although I'll be off to North Dartmoor too if the conditions are right. I'm a keen walker so I backpack the P2V+ and go off to some pretty remote areas to fly at times. Having said that the escapade on Saturday was fairly near Princetown less than a mile from the road linking Princetown to Plymouth in the Black Tor / Hart Tor area. Worth checking the weather to make sure it's suitable, I've had to abort a couple of flights recently because of rain or fog. Not that bad living in Plymouth, just 10 miles away but quite a pain if you've travelled 30 miles to get there!

    Dave
     
  9. J_K

    J_K

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    Yeah. Not a big walker. Like to fly from next to the car :D
    And you're right. It would suck to drive all the way down there and be fogged/rained off.
     
  10. Dartmoor Dave

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    In my first post in this thread I asked for help with a couple of related questions. One was about lag time between fpv on the screen and what the P2v+ was actually doing. I've found nothing on that yet so any info will be welcome.

    My second question related to messages appearing on the smartphone when signals dropped. I've had ones relating to gimbal lock and battery although neither of those recently as I now have a remove before flying flag on the gimbal plastic lock.

    I found some useful stuff on another thread titled "Phantom Connection Broken" and I'll summarise that info here as it might useful to some of us

    RF SIGNALS and DJI VISION APP SCREEN MESSAGES

    There are two RF signals sent between the remote control and the Phantom
    WIFI RF SIGNAL
    There is a 2.4 Ghz wifi video/telemetry connection for FPV on DJI vision app. The antenna for this is within the wifi booster module and the face of the wifi booster should be pointing at the Phantom for best reception
    If the wifi connection is lost then after a couple of seconds the message displayed is
    “PHANTOM CONNECTION BROKEN”
    the fpv screen freezes and all information on the screen remains as it was until the link is re-established by the phantom returning within wifi range
    CONTROL RF SIGNAL
    There is a 5.8 Ghz control signal connection to actually fly the phantom. This antenna for this is the short stub dipole that is just behind the wifi booster module. This should be sideways onto the phantom for best orientation.
    If this signal is lost the message you should see on the vision app screen is
    “CONTROL SIGNAL LOST”
    When this occurs and you remain in GPS mode with sufficient satellites auto return home (failsafe) is activated and a few seconds later you’ll see the COMING HOME message as the P2V+ heads back home ( you hope) at around 7.5 m/sec

    However if you have already lost the wifi connection then you WILL NOT see the “Control Signal Lost” Message and the “Coming Home” message won’t be displayed until a few seconds after your wifi link has been re-established.

    Writing that has clarified some points in my own mind, I think my understanding is correct and hope it has helped some others too.

    There may be other messages and if so I'm sure someone will respond.

    Dave
     
  11. justin00

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    *edit* found a list of all the errors.. will post up tonight.
    No descriptions though which is annoying...
     
  12. Meta4

    Meta4 Moderator
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    RTH is blind and it's up to the pilot to consider what is a safe altitude to clear all obstacles.
     
  13. Dartmoor Dave

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    No issue on the RTH Meta4, it was all downhill and the height of 42 metres above home point was what it stayed at for the whole of the RTH. As I was blind flying before the failsafe cut in, as wifi link had dropped and screen had frozen then I should have kicked in some extra height as soon as I realised that the link had dropped. Within 2 seconds of the lost wifi connection message RTH kicked in as the control signal was lost too.

    A question lingers though, If the RC control signal is lost and RTH auto triggers, assuming you get control signal back, can you poke in extra height whilst the phantom is returning in autofailsafe mode? I think not. My reading is that you have to leave failsafe mode to kick in extra height otherwise if it is 20 metres or more above home point that is where it will remain. If it is under 20 metres it will rise to 20 metres.

    Pleased to see that Justin00 has found a list of all the error messages, look forward to seeing them, we can work out what they mean between us.

    Midnight here in the UK, and so to bed

    Dave
     
  14. Meta4

    Meta4 Moderator
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    If you get control signal back you just have to flick the S1 switch down and up to get full control back and do whatever you like - continue flying or return home in control. No need to leave it in RTH.
     
  15. Mako79

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    +1
    I always try to regain control ASAP and fly her back. I flick on Home Lock and pull the right stick back. It may be slower, but you getting stunning video flying backwards and looking sideways. you also get less prop interference.

    If your phantom is stock, try an FPV booster so that the FPV is greater than the Transmitter controls. This way, you can always ensure you can see the errors and have less chance of FPV drop out.

    Also, did you fly this over a hill. In other words, did you lose sight of the phantom over the hill?
     
  16. eyecon82

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    Yep, I always regain control. I trust my piloting skills better than some automated thing
     
  17. Dartmoor Dave

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    Thx for the feedback on this.

    Just to clear up a few points.

    I had installed fpv booster on my phone and I was intending to do two runs up the hill to compare dropout distance with and without the booster running, I know now that without it running I got 406 m before wifi fpv signal dropped out. Losing sight of it and the situation that developed put me off repeating the flight with the booster on. Better to do it located at a local high point rather than from the bottom of a long hill in retrospect.

    I did not fly the phantom beyond the top of the hill. Within 5 seconds of losing fpv the control signal had also dropped out and RTH auto activated, I was at about 42 m above home point (that was the height RTH was at when the fpv recovered on the way back) . Home point was at a height of 338 m. My online mapping software shows that the hilltop flattens off and the hillside was around 380 m max on the line that I was flying. That indicates that I didn't fly over the hill but just beyond the point where it flattens. the effect is the same - I lost line of sight and the control signal dropped and it explains how I was so close to piling in.

    I do fly in NAZA-M mode and once I had regained visual on the phantom I flicked out of failsafe mode and flew her back to me as I also prefer to be in control when I can see the phantom.

    I was actually surprised to find that auto flyback was at 7.5 m/sec, I'd assumed it was rather slower than that based on information I'd read.

    If anyone is interested I can show the map, the line and the profile.

    Dave