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Obstacle Avoidance Failed

Kevin2735

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I have run active track before and had obstacle avoidance kick in when you would expect it to. On this particular flight, the Mavic started at about 17' and lost altitude as it was following the target for some reason, when it hit the ground it was still showing at 7.5 feet. I did calibrate it earlier that day, but not at this location. After the Mavic was lost, the controller was reporting a magnetic error, but I don't show any such error on the flight log? Curious what I may have done wrong if anyone has any thoughts? The first link is the YouTube vid of the flight, the second is the AirData flight record.

(The notes in the video state 9,000', it was actually 7,800')

Airdata UAV - Flight Data Analysis for Drones
 

lisadoc

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Looks like the downward sensors weren't turned on (you can't tell in Airdata) and by setting the active track to 7.5 feet, the MP did what it was supposed to and maintained 7.5 feet in height from where you initiated active track (hence it reports 7.5 feet at the crash as well). With the gentle slope upwards on the road, the MP maintained 7.5 feet above where it took off and it gradually drove itself into the ground.

Additionally, even if they were turned on, your speed might have prevented the sensors from being able to adjust the height while in active track. Some users have reported it works well when following runners, etc. but the elevated speed might have affected its ability to adjust quickly.
 
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Path Finder

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Looks like the downward sensors weren't turned on (you can't tell in Airdata) and by setting the active track to 7.5 feet, the MP did what it was supposed to and maintained 7.5 feet in height from where you initiated active track (hence it reports 7.5 feet at the crash as well). With the gentle slope upwards on the road, the MP maintained 7.5 feet above where it took off and it gradually drove itself into the ground.

Additionally, even if they were turned on, your speed might have prevented the sensors from being able to adjust the height while in active track. Some users have reported it works well when following runners, etc. but the elevated speed might have affected its ability to adjust quickly.

I have not used active track enough to know but thinking the downward slope should have kept the Mavic "higher"? If you take off from a hilltop then fly lower it reads "-feet" so I agree with the OP, what is up with the crash. . .

Trusting Mavic's less and less the more I read!
 

lisadoc

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I have not used active track enough to know but thinking the downward slope should have kept the Mavic "higher"?
From the video, it appears to be an upward slope, not a downward slope (which would cause it to go lower while maintaining the same relative height to the starting point).
 

Path Finder

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Wow, really, my old eyes must be tricking me already! (Looks like the "road" ran down hill, the Mavic kept dropping from the original height for sure. . .)
 

lisadoc

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Wow, really, my old eyes must be tricking me already! (Looks like the "road" ran down hill, the Mavic kept dropping from the original height for sure. . .)
The OP would have to tell us (whether it went up or down), as it can always be deceiving trying to judge something like that from a video clip.
 

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From the video I am quite certain it was an upward slope. OA doesn't work well for tall grass like that, especially since it was probably going at max OA speed.
 

tcope

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Looks like the downward sensors weren't turned on (you can't tell in Airdata) and by setting the active track to 7.5 feet, the MP did what it was supposed to and maintained 7.5 feet in height from where you initiated active track (hence it reports 7.5 feet at the crash as well). With the gentle slope upwards on the road, the MP maintained 7.5 feet above where it took off and it gradually drove itself into the ground.
While using Active Track, the Mavic will move up and down in altitude in order to maintain the same altitude above ground. Of course, the Mavic needs to be within 30' of the ground. That is, if the Mavic starts at 10' the Mavic will maintain the height above the ground currently under it, even if the ground moves up and down.
 

tcope

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From the video, it appears to be an upward slope, not a downward slope (which would cause it to go lower while maintaining the same relative height to the starting point).
Under Active Track, the Mavic will adjust it's altitude based on the ground under it in order to maintain the same altitude.
 

beach_Dr

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While using Active Track, the Mavic will move up and down in altitude in order to maintain the same altitude above ground. Of course, the Mavic needs to be within 30' of the ground. That is, if the Mavic starts at 10' the Mavic will maintain the height above the ground currently under it, even if the ground moves up and down.
Will it?
As I understand the manual, and experience from little bit of practice, it will only do that in terrain follow mode, not regular active track, and then only to increase height to maintain a minimum distance above ground, it will not decrease height if going down hill.

I have had mavic in regular active track (not terrain follow) hiking down steep path and mavic tried to me in frame, with no reference to ground. I had to cancel active track to stop it crashing into ground, as when I climbed down some rocks, the mavic, which was to side and slightly higher up slope, quickly descended to keep me in frame, and would have crashed into rocks
 

bonzo

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I wish they would make a Mavic pro without any of this automated stuff to save weight and give me more flight time and reduce the price.

I do not trust or ever use any of these flight modes.
 
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Skippy905

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Will it?
As I understand the manual, and experience from little bit of practice, it will only do that in terrain follow mode, not regular active track, and then only to increase height to maintain a minimum distance above ground, it will not decrease height if going down hill.

I have had mavic in regular active track (not terrain follow) hiking down steep path and mavic tried to me in frame, with no reference to ground. I had to cancel active track to stop it crashing into ground, as when I climbed down some rocks, the mavic, which was to side and slightly higher up slope, quickly descended to keep me in frame, and would have crashed into rocks
I agree. I think this is the difference between Active Track and Terrain Follow.

I'm not overly familiar with either, but from my understanding, only Terrain follow will adjust it's height to match hills. I would have to try it myself and also see what sensors turn on and off when you engage Active Track.
There may have been nothing wrong with the Mavic, but simply a matter of the OP not fully knowing how the MP works in that particular condition. Need to wait and see before making final judgement.
 

Kevin2735

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Looks like the downward sensors weren't turned on (you can't tell in Airdata) and by setting the active track to 7.5 feet, the MP did what it was supposed to and maintained 7.5 feet in height from where you initiated active track (hence it reports 7.5 feet at the crash as well). With the gentle slope upwards on the road, the MP maintained 7.5 feet above where it took off and it gradually drove itself into the ground.

Additionally, even if they were turned on, your speed might have prevented the sensors from being able to adjust the height while in active track. Some users have reported it works well when following runners, etc. but the elevated speed might have affected its ability to adjust quickly.
I never turned the sensors off and really not even sure how to do that unless I am in Sport mode? If I was in Sport Mode, Active Track should not work at all. I have used Active Track other times were it stops short of a tree, or an incline on a hill. I wished it would hold steady elevation throughout, but I guess it can't do that. That is the difference with Terrain Follow and AT as I understand it. I wasn't going that fast, probably 15 mph when I rode off. I did run an elevation profile using Google Earth. It is a downward slope from the starting point to the crash point, but the mountain itself actually climbs in altitude. So it is an optical illusion where it appears to be descending, even to the naked eye when I was on site, but it is actually climbing. So I get that part of it, just don't know why the sensors didn't work as they had in the past. I know I shouldn't be dependent on those things I guess, but still they do advertise them to work in this fashion.

The other thing I noted that I didn't mention was that after the crash I inspected the drone, didn't see any damage to the props, and launched it again. I only put it to a about a six foot hover. It showed a great deal of difficulty holding a hover. It was wobbling left and right seemingly trying to compensate. I then packed it up and put it away because I wasn't going to take any chances with it. Later that day back at base camp, I decided to replace all of the props. I could feel that the new props were much stiffer and not as pliable. Once I put the new props on and launched it there was no problem holding a hover. The original props were only about 9 hours flight time old.
 

MAvic_South_Oz

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Under Active Track, the Mavic will adjust it's altitude based on the ground under it in order to maintain the same altitude.
Will it?
As I understand the manual, and experience from little bit of practice, it will only do that in terrain follow mode, not regular active track, and then only to increase height to maintain a minimum distance above ground, it will not decrease height if going down hill.
I'd better both read up about it in the manual and test this, I thought active track maintained height / angle aspect relative to subject it is tracking ??

At least that's what it did (or seemed to do) on a desert trip recently when tracking vehicles over dunes as high as 20m or so.
I certainly don't recall adjusting anything on those flights except that I could use yaw to change view aspect and hover around as much as I liked (with backwards flight allowed), or adjust height to change that view, the active track kept auto following.

I've never had much luck with follow me mode (seems to only follow at walking speeds), though haven't tried more than a couple of times, so probably just need to muck around with that some more.
 

ThorDar

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Optical and ultrasonic sensors have a lot of limitations. While they help reduce the risk of collision, they certainly don't make the Mavic crash-proof. I'm sticking to flying as though it has no collision avoidance.
 

tcope

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I have used Active Track other times were it stops short of a tree, or an incline on a hill. I wished it would hold steady elevation throughout, but I guess it can't do that. That is the difference with Terrain Follow and AT as I understand it. I wasn't going that fast, probably 15 mph when I rode off. I did run an elevation profile using Google Earth. It is a downward slope from the starting point to the crash point, but the mountain itself actually climbs in altitude. So it is an optical illusion where it appears to be descending, even to the naked eye when I was on site, but it is actually climbing. So I get that part of it, just don't know why the sensors didn't work as they had in the past. I know I shouldn't be dependent on those things I guess, but still they do advertise them to work in this fashion.
Active Track does hold it's altitude based on the terrain under it, as long as the Mavic is at 30' or lower. For example, let's say you start AT at 10' and walk up a hill. If you have it in Profile mode (for example), the Mavic will follow you and increase it's high relative to the starting 10' in order to maintain it's height at 10' at all times. if you walk up the hill, it will flow and climb to maintain 10'. If you walk down, it will lower to maintain 10'.

I've done a lot of testing on this and am almost done with my video demo of this (I was 90% done a few weeks ago but lost all of that work). I can also say, it's not perfect. One time I started to walk up the hill. The Mavic lagged a little behind and once it realized I was walking away, it sped up to follow me. It was about 30' away and _quickly_ closed the gap. Since AT follows it's subject and I was the subject... it came right at me like a crazy bat! I moved out of the way and it came within about 5' of hitting me. I can only hope that the forward sensors would have stopped it. I did get a yellow warning but that was all. It was coming right at me and I quickly stopped to avoid it.

upload_2017-9-12_22-10-59.png
 

tcope

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I'd better both read up about it in the manual and test this, I thought active track maintained height / angle aspect relative to subject it is tracking ??
Is that not the same thing? in AT the Mavic is only moving because the subject it's following is moving. So if the subject moves up and down, so does the Mavic. But if the Mavic is 100' in the air and tracking an object, it won't move up and down when the object does.
 

MAvic_South_Oz

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Is that not the same thing? in AT the Mavic is only moving because the subject it's following is moving. So if the subject moves up and down, so does the Mavic. But if the Mavic is 100' in the air and tracking an object, it won't move up and down when the object does.
That's what i have experienced, but a couple of comments above say otherwise . . . eg. post 10 and 12.
 

tcope

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That's what i have experienced, but a couple of comments above say otherwise . . . eg. post 10 and 12.
You can see what other people say in this thread who have tested it:

Active Track mode WITH Terrain Follow mode now?

The video I'm putting together has the Mavic in AT and flying up and down a hill as it follows me. It maintains it's height based on the ground under it, not based on where I'm at in the frame (the camera moves up and down to do this). It does this pretty good but it's not great or perfect.
 
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flightmike

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Is that not the same thing? in AT the Mavic is only moving because the subject it's following is moving. So if the subject moves up and down, so does the Mavic. But if the Mavic is 100' in the air and tracking an object, it won't move up and down when the object does.
100 foot is too high. I think there is a max altitude you have to stay at to work.