Feeling lost after loss of drone
- Thread starter Rasbelin
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Okay, now I'm back with the drone and here's an exclusive summary of everything and all.
First of all the P3P was recovered in two different locations.
The battery was found at the open air observation deck of the tower, which has been closed to the public for at least 10 yrs due to some Darwin award fellas tossing down small items. I've been there when it was open and it's a nice place with fresh air. The battery is intact and it's still almost fully charged. This location is at 110 metres, i.e. 361 feet.
The actual body of the drone was found at the roof of a ground level outdoor cafeteria, which is next to the base of the tower. As you can see from the pictures, it's puzzling how it's so intact after a free fall of some 100 metres (~330 feet). I haven't yet done any further investigation, except for recovering the microSD card. Some pretty nice photography, although now slightly too expensive.
There's no log file on the card. Not sure if the log was enabled or not.
The pictures are 400-900 K.
http://www.rasbelin.com/images/DJI_0004.jpg
http://www.rasbelin.com/images/DJI_0008.jpg
http://www.rasbelin.com/images/DSC00068.jpg
http://www.rasbelin.com/images/DSC00070.jpg
http://www.rasbelin.com/images/DSC00071.jpg
http://www.rasbelin.com/images/DSC00073.jpg
http://www.rasbelin.com/images/DSC00080.jpg
The drone CSI team, i.e. me, has now concluded based on the iPad flight data and the locations of the items, that the events have unfolded probably somewhat like this:
A) The drone has been flying at about 150 metres and everything has been fine. No noticable winds or any seagulls around. I've taken 8 still pictures, out of which DJI_0008 was the last one.
B) Some 10 seconds after the last shot, as I've intended to continue towards the end of the cape, where the amusement park ends, without any warning the FPV has gone black - no signal.
C) The drone has entered the RTH mode and during that, very soon after it has been initialised, the drone has started to descend at maximum speed (~15 m/s). Possibly either an engine has failed or the firmware has gone bonkers, causing the drone to crash into the observation deck some 50 metres (164 feet) lower.
D) For some reason the battery has ejected and dropped onto the floor.
E) The now powerless drone has possibly bounced from the safety cage and had a free fall down to the ground level. Taken how much G force thrust it gets during a fall that big, it's seriously suprising how intact the device is.
I'm still to compile all details for DJI and I will naturally keep this thread updated about the outcome. However it's pretty obvious that something has gone wrong and I don't see how this can have been a pilot error on my behalf, because the very likely collision has happen after I've lost control of the drone. Also pointing out that the drone has had at least a 15-20 metre (50-65 feet) distance to the tower structures while taking the shots, so it hasn't been on a direct crash course as it has passed by. This can't explain how the drone has crashed much lower than the roof of the tower, which is at about 130 metres (~427 feet), especially since the upper deck of the tower has been between these locations.
Any suggestions what I should do to the remains of the drone? At least the battery seems okay. Will take another battery later on and see if the engines can still idle and if there's any audible hickups.
First of all the P3P was recovered in two different locations.
The battery was found at the open air observation deck of the tower, which has been closed to the public for at least 10 yrs due to some Darwin award fellas tossing down small items. I've been there when it was open and it's a nice place with fresh air. The battery is intact and it's still almost fully charged. This location is at 110 metres, i.e. 361 feet.
The actual body of the drone was found at the roof of a ground level outdoor cafeteria, which is next to the base of the tower. As you can see from the pictures, it's puzzling how it's so intact after a free fall of some 100 metres (~330 feet). I haven't yet done any further investigation, except for recovering the microSD card. Some pretty nice photography, although now slightly too expensive.
There's no log file on the card. Not sure if the log was enabled or not.The pictures are 400-900 K.
http://www.rasbelin.com/images/DJI_0004.jpg
http://www.rasbelin.com/images/DJI_0008.jpg
http://www.rasbelin.com/images/DSC00068.jpg
http://www.rasbelin.com/images/DSC00070.jpg
http://www.rasbelin.com/images/DSC00071.jpg
http://www.rasbelin.com/images/DSC00073.jpg
http://www.rasbelin.com/images/DSC00080.jpg
The drone CSI team, i.e. me, has now concluded based on the iPad flight data and the locations of the items, that the events have unfolded probably somewhat like this:
A) The drone has been flying at about 150 metres and everything has been fine. No noticable winds or any seagulls around. I've taken 8 still pictures, out of which DJI_0008 was the last one.
B) Some 10 seconds after the last shot, as I've intended to continue towards the end of the cape, where the amusement park ends, without any warning the FPV has gone black - no signal.
C) The drone has entered the RTH mode and during that, very soon after it has been initialised, the drone has started to descend at maximum speed (~15 m/s). Possibly either an engine has failed or the firmware has gone bonkers, causing the drone to crash into the observation deck some 50 metres (164 feet) lower.
D) For some reason the battery has ejected and dropped onto the floor.
E) The now powerless drone has possibly bounced from the safety cage and had a free fall down to the ground level. Taken how much G force thrust it gets during a fall that big, it's seriously suprising how intact the device is.
I'm still to compile all details for DJI and I will naturally keep this thread updated about the outcome. However it's pretty obvious that something has gone wrong and I don't see how this can have been a pilot error on my behalf, because the very likely collision has happen after I've lost control of the drone. Also pointing out that the drone has had at least a 15-20 metre (50-65 feet) distance to the tower structures while taking the shots, so it hasn't been on a direct crash course as it has passed by. This can't explain how the drone has crashed much lower than the roof of the tower, which is at about 130 metres (~427 feet), especially since the upper deck of the tower has been between these locations.
Any suggestions what I should do to the remains of the drone? At least the battery seems okay. Will take another battery later on and see if the engines can still idle and if there's any audible hickups.
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Wow...surprising that the gimbal wasn't totally detached after a free fall from that height. Looks like the ribbon cable is stripped as it appears the clip is still in the base of the gimbal. Does the gimbal/camera appear otherwise intact (aside from the broken mounting plate)?
Were you flying very near to the tower when you lost signal? I'm wondering if the "dish" of the tower (with the observation deck) was positioned between you/the remote and the quadcopter. If so, this sounds very similar to what happened with my crash. Metallic structure between me and my quad...signal blocked by the structure, loss of connection (black/frozen video feed), quad stops itself, waits three seconds, turns to face home, achieves RTH altitude, and then flies itself right into the structure. That impact could certainly eject the battery (as it did in my case), and the forward momentum of the quad could send it careening off the side of the structure to the ground below.
I have video of my crash showing this actually happening. I bet if you can recover yours, you might see the same thing. If that's the case, chalk it up t user error and not a malfunction. Good luck!
Were you flying very near to the tower when you lost signal? I'm wondering if the "dish" of the tower (with the observation deck) was positioned between you/the remote and the quadcopter. If so, this sounds very similar to what happened with my crash. Metallic structure between me and my quad...signal blocked by the structure, loss of connection (black/frozen video feed), quad stops itself, waits three seconds, turns to face home, achieves RTH altitude, and then flies itself right into the structure. That impact could certainly eject the battery (as it did in my case), and the forward momentum of the quad could send it careening off the side of the structure to the ground below.
I have video of my crash showing this actually happening. I bet if you can recover yours, you might see the same thing. If that's the case, chalk it up t user error and not a malfunction. Good luck!
When I lost the contact, I had already passed the radio structures and I was heading away. However I've now realised there's an FM transmitter (public broadcasting), which I was previously unaware of. It's possible that the beam has possibly obstructed the signal. I did fly up there for 4K video the day before and had no issues what so ever, which is why I now flew much closer for a few shots with the tower at the front and the scenery at the back. I've been cautious about my flights and always tried to take into consideration any possible risks, but it's true that I missed the transmitter now.
The loss of FPV might be explained by that, but it doesn't explain what unfolded after that.
@Holt: Not exactly like that. It lost the signal much higher up and there's the upper deck between those locations. It didn't exactly teleport 50 metres lower.
The loss of FPV might be explained by that, but it doesn't explain what unfolded after that.
@Holt: Not exactly like that. It lost the signal much higher up and there's the upper deck between those locations. It didn't exactly teleport 50 metres lower.
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Glad you found your drone! After sending me the .txt file via email I was able to generate the Google Earth file and do a bit more looking. Started to write this up but had to get some sleep. Great news (except for the damaged drone part) that it was recovered.
Here is a picture of your drone flight perspective. Ive added three Points of Interest 1) Connection Lost, 2) Reconnection, 3) Possible Strike. These points were added by looking at your log file, and entering coordinates where I saw significant changes in data.
According to the generated Comprehensive CSV, you lost Radio Contact for 6.6 seconds at 12:50:53.9. Marking this point in Google Earth as "Connection Lost" place mark the tower was pretty much in a straight line between your takeoff point and the bird (blocking signal, or radio interference?) By the time it reconnected 6.6 seconds later, at 12:51:00.5, GO HOME (OSD.FlyState) had already automatically been initiated with a status of CRUISE (OSD.GoHomeStatus). You can tell it was disconnected by loss of radio control because of OSD.flightAction of OUTOF_CONTROL_GOHOME. There are no records of data for these 6.6 seconds. Typical behavior is it would climb to your RTH orient itself and fly in a direct line home.Your GoHomeHeight was 50 Meters so it wouldn't of climbed just oriented and begun return home.
Being that the tower was in direct line between you and the bird...If you follow its once again reporting path...it looks like it traveled directly into the tower on its GoHome path and maybe hits at 51:02.1. Its as this point the Pitch Yaw and Roll (OSD.pitch, OSD.roll, OSD.yaw) seem to change direction significantly. Marking the GPS coordinates at that point (Strike Possible) on the map seems to match positionally also. The path becomes quite wobbly for a short period (perhaps trying to recover from a strike)....and then follows a controlled but circular arc to the right, away from, and then back towards the tower. Perhaps striking the tower the first time damaged the flight contols... or compass interference. It follows this curve for another 21 seconds...and terminates again very close to the tower....perhaps striking it again, ejecting the battery....bird sliding off the top, to the ground.
I don't have a great explanation for why it followed the circular path as it seems to me had it misaligned the compass, it would've followed a arc path towards the home point, not back towards the tower. Prop damage seems most likely, could be other interference. GPS does not look like it was interfered with as the GPS recorded flight path has no jumps in it (other than the 6.6 seconds where you lost connection). At possible first contact you were traveling at 6.4 m/s. At the end of the flight path (possible last collision), you were traveling at 15 m/s...or 54 kph. Certainly conceivable the battery would pop out.
Sorry about your loss. It does seem like something (either physical blocking of radio signal, or radio interference occurred), resulted in lost of signal, with it reacting and flying normally and returning to home...until the 1st strike occurred. It seems you were quite unlucky (ignoring the fact that this wasn't a completely danger free flight) as you likely could have returned unscathed had your bird been a few meters to the right, or to the left...allowing a RTH without striking the tower. It isn't likely a coincidence that you lost signal when the tower was directly in line with your bird and you.
Not to throw salt in the wound, but it is a good lesson for us all. If one is EVER flying around obstructions, always set your RTH height higher than the obstruction. This is a perfect example as if the flier had done that, although yes he may have lost signal...the bird may have climbed over the obstruction and returned safely. It seemed to be doing that perfectly...until it hit something.
If you'd like to look at all this yourself:
GoogleEarth with added PlaceMarkers (just load into Google Earth...double click on "Strike Possible" to jump to the strike perspective: http://1drv.ms/1MPRGMc
Comprehensive CSV: http://1drv.ms/1MPRxsc
Here is a picture of your drone flight perspective. Ive added three Points of Interest 1) Connection Lost, 2) Reconnection, 3) Possible Strike. These points were added by looking at your log file, and entering coordinates where I saw significant changes in data.
According to the generated Comprehensive CSV, you lost Radio Contact for 6.6 seconds at 12:50:53.9. Marking this point in Google Earth as "Connection Lost" place mark the tower was pretty much in a straight line between your takeoff point and the bird (blocking signal, or radio interference?) By the time it reconnected 6.6 seconds later, at 12:51:00.5, GO HOME (OSD.FlyState) had already automatically been initiated with a status of CRUISE (OSD.GoHomeStatus). You can tell it was disconnected by loss of radio control because of OSD.flightAction of OUTOF_CONTROL_GOHOME. There are no records of data for these 6.6 seconds. Typical behavior is it would climb to your RTH orient itself and fly in a direct line home.Your GoHomeHeight was 50 Meters so it wouldn't of climbed just oriented and begun return home.
Being that the tower was in direct line between you and the bird...If you follow its once again reporting path...it looks like it traveled directly into the tower on its GoHome path and maybe hits at 51:02.1. Its as this point the Pitch Yaw and Roll (OSD.pitch, OSD.roll, OSD.yaw) seem to change direction significantly. Marking the GPS coordinates at that point (Strike Possible) on the map seems to match positionally also. The path becomes quite wobbly for a short period (perhaps trying to recover from a strike)....and then follows a controlled but circular arc to the right, away from, and then back towards the tower. Perhaps striking the tower the first time damaged the flight contols... or compass interference. It follows this curve for another 21 seconds...and terminates again very close to the tower....perhaps striking it again, ejecting the battery....bird sliding off the top, to the ground.
I don't have a great explanation for why it followed the circular path as it seems to me had it misaligned the compass, it would've followed a arc path towards the home point, not back towards the tower. Prop damage seems most likely, could be other interference. GPS does not look like it was interfered with as the GPS recorded flight path has no jumps in it (other than the 6.6 seconds where you lost connection). At possible first contact you were traveling at 6.4 m/s. At the end of the flight path (possible last collision), you were traveling at 15 m/s...or 54 kph. Certainly conceivable the battery would pop out.
Sorry about your loss. It does seem like something (either physical blocking of radio signal, or radio interference occurred), resulted in lost of signal, with it reacting and flying normally and returning to home...until the 1st strike occurred. It seems you were quite unlucky (ignoring the fact that this wasn't a completely danger free flight) as you likely could have returned unscathed had your bird been a few meters to the right, or to the left...allowing a RTH without striking the tower. It isn't likely a coincidence that you lost signal when the tower was directly in line with your bird and you.
Not to throw salt in the wound, but it is a good lesson for us all. If one is EVER flying around obstructions, always set your RTH height higher than the obstruction. This is a perfect example as if the flier had done that, although yes he may have lost signal...the bird may have climbed over the obstruction and returned safely. It seemed to be doing that perfectly...until it hit something.
If you'd like to look at all this yourself:
GoogleEarth with added PlaceMarkers (just load into Google Earth...double click on "Strike Possible" to jump to the strike perspective: http://1drv.ms/1MPRGMc
Comprehensive CSV: http://1drv.ms/1MPRxsc
Very good insights! Much appreciated! 
Your 3D model looks pretty much like mine, except from a different direction. Yes, I'm now leaning towards radio interference, which has possibly dropped the visuals. However it's seriously mind boggling how the drone has managed to end up hitting the lower outdoor deck. Based on the physical damage, I can see how it has smashed into something, but dunno about two hits.
The major difference now was that the drone was momentarily behind the radio structures. I admit to that being an error on my behalf as my flight planning had missed some details regarding the tower. As for RTH, I assumed it would maintain the current altitude, if it's higher than the setting? Or does it really ascend to it? If so, then I certainly have to change the setting.
As for those who will probably find me being a loony, I just point out that this was the second flight in the same location and I had taken into account where a possible crash could happen. No large crowds under and a very robust structure I was taking shots of.
Your 3D model looks pretty much like mine, except from a different direction. Yes, I'm now leaning towards radio interference, which has possibly dropped the visuals. However it's seriously mind boggling how the drone has managed to end up hitting the lower outdoor deck. Based on the physical damage, I can see how it has smashed into something, but dunno about two hits.The major difference now was that the drone was momentarily behind the radio structures. I admit to that being an error on my behalf as my flight planning had missed some details regarding the tower. As for RTH, I assumed it would maintain the current altitude, if it's higher than the setting? Or does it really ascend to it? If so, then I certainly have to change the setting.
As for those who will probably find me being a loony, I just point out that this was the second flight in the same location and I had taken into account where a possible crash could happen. No large crowds under and a very robust structure I was taking shots of.
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Yes, you are correct. If your current altitude is Higher than your Failsafe Altitude...it will maintain its current altitude on its flight home. If current is lower, it will climb to Fail Safe. So...in your case, no climb would've occurred...just a turn, so the bird was pointing at you...then direct line back. Had you set your Failsafe to 150M rather than 50... All would've been good, likely, as it would've climbed over it.
Based in the flight, I don't think it hit the tower itself...more likely the spire. Doubly unfortunate cause it looks like it returned (the big circular arc) to hit it again. Had your first (seemingly minor strike) not damaged something that eventually led it t circle around and strike it again, causing it to fall out of the sky, you may have perhaps been allowed to pilot it back.
I do note you question some altitude discrepancies in previous comments (jumping meters). I'm not seeing that, but there's lots of data there. Can you point me to the weird altitude readings you're seeing?
RTH will maintain current altitude if current altitude is higher than RTH setting then head directly back...
no crowds, but there's like 200 cars parked down there your crashed phantom could have damaged!
no crowds, but there's like 200 cars parked down there your crashed phantom could have damaged!
@TAZ: Indeed, now I get your point with the RTH height being higher. If it hit the spire, then heck, that's like hitting a needle in the haystack. It's narrow and the course was never even set towards it. So the RTH was really unlucky. Too bad DJI hasn't yet come up for vertical protection. The sonar is just horizontal.
Overall a sum of some very unfortunate circumstantial occurrences. Radio signal distortion and a stupid shortest path home. That's how I currently see it. Well, will send it to DJI for their interest and see what their conclusion is. It's always good to give them real crash data to chew.
None of them were in my flight path. The elevation makes it harder to grasp the circumstances. Furthermore who doesn't fly over stationary objects that someone else might own? Erm, so everyone is flying above lakes, beaches, forests and other public property only? Okay, noted.
You always take a risk when you fly and it includes a responsibility related to any property damage you cause. So no need to be my aunt. Better just forbid all UAVs and forbid even thinking of them. What a heinous crime to fly a drone.
Overall a sum of some very unfortunate circumstantial occurrences. Radio signal distortion and a stupid shortest path home. That's how I currently see it. Well, will send it to DJI for their interest and see what their conclusion is. It's always good to give them real crash data to chew.
None of them were in my flight path. The elevation makes it harder to grasp the circumstances. Furthermore who doesn't fly over stationary objects that someone else might own? Erm, so everyone is flying above lakes, beaches, forests and other public property only? Okay, noted.
You always take a risk when you fly and it includes a responsibility related to any property damage you cause. So no need to be my aunt. Better just forbid all UAVs and forbid even thinking of them. What a heinous crime to fly a drone.
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@Rasbelin "If it hit the spire, then heck, that's like hitting a needle in the haystack. It's narrow and the course was never even set towards it. So the RTH was really unlucky." Needle in haystack yes, but not 100% by chance. It makes perfect sense that if the tower is broadcasting interfering RFs (or physically blocked the signal), you would have positive signal connection to the remote, up until you were directly in the interference "shadow". So natural the straight line RTH would guide your bird straight into it.
Rather then a collision avoidance system (would be additional cost, and might also be technically fallible)...I'd like to see an option to have "REWIND in case of RC signal Loss".
I'm sure you're not the first person that lost a bird due to a straight line return to home directing the bird into the obstruction that caused the signal loss in the first place (without an appropriate RTH altitude set). A rewind feature, in this case (given it already has the data on board that records exactly how it arrived at the "No RC Connection")...might allow the bird to reverse travel to a safe location where it "knew" it once could positively communicate with the remote controller and try again. Then if that failed, normal RTH. In your case, it looks like a rewind of only a few seconds could have solved the whole situation. For sure it'd take additional development and testing (but no additional hardware), but DJI is making the birds smarter all the time. Perhaps in the future.
Rather then a collision avoidance system (would be additional cost, and might also be technically fallible)...I'd like to see an option to have "REWIND in case of RC signal Loss".
I'm sure you're not the first person that lost a bird due to a straight line return to home directing the bird into the obstruction that caused the signal loss in the first place (without an appropriate RTH altitude set). A rewind feature, in this case (given it already has the data on board that records exactly how it arrived at the "No RC Connection")...might allow the bird to reverse travel to a safe location where it "knew" it once could positively communicate with the remote controller and try again. Then if that failed, normal RTH. In your case, it looks like a rewind of only a few seconds could have solved the whole situation. For sure it'd take additional development and testing (but no additional hardware), but DJI is making the birds smarter all the time. Perhaps in the future.
Rasbelin, the pictures come back with a Forbidden message on your server.
Can't view them.
You might need to change the permissions on them.
(I can reach the server and even the images folder but not the images in the images folder)
Can't view them.
You might need to change the permissions on them.
(I can reach the server and even the images folder but not the images in the images folder)
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@TAZ: Yeah, that rewind feature makes probably more sense. Not even sure how well the sonar of the VPS actually works as it's new stuff.
Will be trying to link up the RC and drone later today to see if it powers up and what the engines do. I'm currently out of props, so can't do a test fight in a secure open location. Or even attempt it. Also awaiting for my insurance company to respond.
I did a CHMOD now. Any luck now?
Will be trying to link up the RC and drone later today to see if it powers up and what the engines do. I'm currently out of props, so can't do a test fight in a secure open location. Or even attempt it. Also awaiting for my insurance company to respond.
I did a CHMOD now. Any luck now?
Glad you have it back The only reason the bird stayed together was that the battery poped out early in the fall. Without the battery it came down like a heavy kite so the impact was minimal.I would not be surprised if the bird survived the crash.But what brought it down in the first place
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