Hey guys,
i'm in australia, brought my mavic which i love 6 days ago. Got about 3 days in and now having hte VPS issues.

Unit just keeps going up and up and up, the VPs show as 0.5-1.0m so it think it's to close to the ground and just keeps going up. :-(
Sometime it works fine, but 4/5 flights are a no go.

Just want to confirm i have done everything that is possible before i take it back to Harvey Norman for a replacement. Australian law, i'm aloud to exchange a DOA unit for a replacement, the end user does not have to deal with the company, that's for the retail i purchased it from.

anyway -
- firmwire upto day
- VPS config done via PC, hadd isues but finally got it working
- compass done
- IMU done
- app uninstalled and reinstalled.

The pic was from my last test flight after the new VPS config done. nothing changed.

DJI chat didn't abmit to anything, but kinda got the idea that i had done everthing possible. Have worked in retail for 10 years so know the steps... I just want to get up and flying again.

Matthew

you can see the VPS is 0.1m and the VS is going up, not touching the controller.

I suppose you could try calibrating the controller, though I'm not very confident it'll help. You could also retrieve and post the DAT file from one of the flights where this occurred and someone will look at it, though that may only confirm the VPS explanation. If you're interested, the instructions for accessing the DAT file are here, and after retrieving it you'll need to upload it to DropBox (or a similar service) and provide a link to it in this thread.

DroneFlying Posted at 2017-6-28 04:44
I suppose you could try calibrating the controller, though I'm not very confident it'll help. You could also retrieve and post the DAT file from one of the flights where this occurred and someone else will look at it, though that may only confirm the VPS explanation. If you're interested, the instructions for accessing the DAT file are here, and after retrieving it you'll need to upload it to DropBox (or a similar service) and provide a link to it in this thread.

https://1drv.ms/f/s!AsUHia4hYIfDhu8mXtRZKeIW5KCvig

If someone would like to have a look, pic and video too
after opening it in the program you can see it drops from reading correctly to nothing (i think)

I presume you mean the Mavic  continues to rise after launch.  Did you use  Auto-Launch?   

Not surprised VPS height reads 0.1 m at that actual height (27 m by barometric measurement). It's not  accurate much above 10 m.  VPS has an optical and ultrasound component. VPS height measurement is ultrasonic. Therefore the condition of the surface under the Mavic can also effect the reading.  For example; if the surface below is grass, you will get a poor ultrasound reflection and erroneous reading.  Did you notice normal VPS height changes initially as the craft rose?  Is it accurate within just a few meters from ground as you're landing?

My impression is that VPS is only used to insure a precise soft landing.  If your drone us just continuing to rise, I'd suspect another problem.  Probably stick.

MDL Posted at 2017-6-28 05:08
https://1drv.ms/f/s!AsUHia4hYIfDhu8mXtRZKeIW5KCvig

If someone would like to have a look, pic and video too

I looked at your DAT files and in particular found FLY034.DAT to be interesting. If you look at the graph below, the green line is the barometer's estimate of your Mavic's height and the red line is VPS's estimate. As you can see, they're reasonably similar at first, but at some point VPS indicates that your Mavic instantaneously went from a height of 6.6 meters to just centimeters above the ground. And this happens while you're still well below the maximum height under which VPS is supposed to be able to function.

Also, once you get beyond the height where VPS is able to work it normally stops estimating your Mavic's height, but the screen shot in your original post shows VPS providing an obviously inaccurate estimate while you're 27 meters above the ground.

So yes, your belief that your ascent problem is related to VPS seems to be correct. I suppose that before sending it in you could try a different firmware version, but I'm guessing that won't help because this problem would probably be more widespread if it was caused by firmware.

DroneFlying Posted at 2017-6-28 05:41
I looked at your DAT files and in particular found FLY034.DAT to be interesting. If you look at the graph below, the green line is the barometer's estimate of your Mavic's height and the red line is VPS's estimate. As you can see, they're reasonably similar at first, but at some point VPS indicates that your Mavic instantaneously went from a height of 6.6 meters to just centimeters above the ground. And this happens while you're still well below the maximum height under which VPS is supposed to be able to function.

Also, once you get beyond the height where VPS is able to work it normally stops estimating your Mavic's height, but the screen shot in your original post shows VPS providing an obviously inaccurate estimate while you're 27 meters above the ground.

In my experience, this is a fairly normal behavior for VPS height.  If you overlay the  vertical scales, I think you'll see almost identical agreement in the 2 measurements.  6 meters is not an unreasonable drop-out point for VPS, especially over a soft  or extremely rough surface.  I wouldn't be too concerned about the VPS reading unless you're experiencing hard landings.
But I believe your original post indicated that the Mavic continues to rise (presumably without stick input). Even if you use auto-takeoff,  VPS should be still accurate up to the hover altitude.  I don't think the Mavic relies solely on VPS in that situation, anyway.

Griffith Posted at 2017-6-28 07:13
In my experience, this is a fairly normal behavior for VPS height.  If you overlay the  vertical scales, I think you'll see almost identical agreement in the 2 measurements.  6 meters is not an unreasonable drop-out point for VPS, especially over a soft  or extremely rough surface.  I wouldn't be too concerned about the VPS reading unless you're experiencing hard landings.
But I believe your original post indicated that the Mavic continues to rise (presumably without stick input). Even if you use auto-takeoff,  VPS should be still accurate up to the hover altitude.  I don't think the Mavic relies solely on VPS in that situation, anyway.

The behavior he's seeing isn't normal unless DJI has significantly changed the behavior of VPS in a recent firmware release, but if they did I hadn't heard about it. And I didn't mean to imply that there's a specific fixed height threshold below which VPS always functions, only that there is some (possibly fluctuating) point beyond which it stops providing meaningful estimates of height.

Normally when the aircraft gets to a height where VPS is no longer usable the VPS height display disappears from within the Go app. But if you look at the screen shot in the OP's initial post, it still shows a (meaningless) VPS height even when his aircraft's actual height is about 27 meters -- well beyond VPS's range, even in the best of conditions. Likewise, most of that almost-unbroken plot of (again meaningless) VPS heights you see in the graph I attached shouldn't be there, but for some reason the OP's Mavic thinks its VPS height is still valid and meaningful even when it clearly isn't.

Given all that, it seems very likely that the OP's speculation about a VPS problem being the cause of his uncontrolled ascent is correct, and it probably is also the cause of at least some of the other similar reports of this behavior that we've seen reported by others.

Thanks guys. The issue is, because the vps show red and 0.1 when flying you can't descend because it Thinks its at ground level. I have put the .05 firmwire on there and will confirm this morning other wise I will take it back and swap it over.

And I don't believe I suggested that there's a specific fixed height threshold below which VPS always functions, only that there is some (possibly fluctuating) point beyond which it stops providing meaningful estimates of height.

This is true.   I've seen examples and experienced them myself where VPS fails to provide ANY accurate information.  In my case, I wasn't using auto-takeoff, I just lifted up from a sloping grass hillside to about 10 ft to check systems and wait for Home Position confirmation.  VPS was very unstable but no problems with run-away altitude.

Normally when the aircraft gets to a height where VPS is no longer usable the VPS height display disappears from within the Go app.

I'm guessing that's the point where the ultrasound receiver no longer receives a return signal, or the return signal is below a threshold.

So what could be causing the consistent low VPS altitude?   Here are a few hardware-related possibilities:  
The US system consists of a pulsed transmit element and a receive element - the two larger disks nearer the center on the bottom of the Mavic.  The system measures time between a transmit pulse and the time the receiver detects a reflected signal - the longer the time, the longer the distance. Factors that influence the received signal are absorbance of the reflecting surface and scattering by the surface.  Thus a variable usable range.

The observation that the VPS is reading an very low altitude when it shouldn't indicates that the reflection is coming back very fast. So it's seeing some obstruction (tape, grass, dirt)  - or - (more likely) there is unintended sound coupling through the bottom heat sink.  Normally, the transmit transducer (maybe both) is insulated from the heat sink, but if it becomes loose - pops in or out - it may contact  the frame and conduct sound directly. Another possibility is electronic noise, providing an instantaneous false echo signal and keeping the receive signal above it's turn-off threshold.

So, first I would recommend insuring the two US transducers are clean and free of debris, and lightly touch then to insure they are firmly attached to the heat sink.  Failing those tests, I recommend seeking a repair.

Having said that (and back to the problem at hand).  The manual states that (if the aircraft status is green) auto-takeoff hover should be 1.2 meters,, However, if status indicator is blinking rapidly (I think that means no GPS lock), the hover is stabilized by the downward visual system and the aircraft can rise up to 13 meters.

If OP can't suffer through a repair experience, he could just shut off VPS - assuming that may be responsible for takeoff problem.   VPS just makes landings nice and provides added stability for low-level 'tripod' shots, but is not useful in 90 % of flying.

Just my 2 cents worth :-)

MDL Posted at 2017-6-28 11:17
Thanks guys. The issue is, because the vps show red and 0.1 when flying you can't descend because it Thinks its at ground level. I have put the .05 firmwire on there and will confirm this morning other wise I will take it back and swap it over.

Thanks guys.

You're welcome.

you can't descend because it Thinks its at ground level

Yes, and as I believe you already guessed, that's probably why it kept ascending on takeoff -- because it was trying to reach a certain height above the ground, but perpetually believed the ground to be just below.

I have put the .05 firmware on there and will confirm this morning other wise I will take it back and swap it over

Please let us know how your test with the older firmware turns out.

MDL Posted at 2017-6-28 11:17
Thanks guys. The issue is, because the vps show red and 0.1 when flying you can't descend because it Thinks its at ground level. I have put the .05 firmwire on there and will confirm this morning other wise I will take it back and swap it over.

Thanks guys. The issue is, because the vps show red and 0.1 when flying you can't descend because it Thinks its at ground level.

Turn VPS off!

Doesn't matter. The camera is also out of focus on the side as well lol. There a video in the same one drive folder.

Also thanks for the constructive comment Griffith

DroneFlying - .05 firmware. On dust at the moment. Just took it out the back, VPS is 0.2 at the ground which is the same. Goes to about 2-3m and then goes WHITE and VPS n/a . Just went for a 5 min flight and no issue. I'm wondering if it's a weird heat issue or something to do with lighting???? It's going to get a work out today and see it's a firmware issue or a hardware issue.

Thing is, take it for one flight and it will be fine. Take it for another 5 in a row and it will fail.

Have to understand i want to be able to leave it on. Maybe a $2000 drone but being about to put it in beginner mode or tripod mode and give it to my son in an open enviroment he loves it.

Thanks for the help byt the way, DJI online chat was no help at all.

If a DJI tech see this please check the dat file and your emails. (lol)

MDL

Griffith Posted at 2017-6-28 11:21
And I don't believe I suggested that there's a specific fixed height threshold below which VPS always functions, only that there is some (possibly fluctuating) point beyond which it stops providing meaningful estimates of height.

This is true.   I've seen examples and experienced them myself where VPS fails to provide ANY accurate information.  In my case, I wasn't using auto-takeoff, I just lifted up from a sloping grass hillside to about 10 ft to check systems and wait for Home Position confirmation.  VPS was very unstable but no problems with run-away altitude.

I'm guessing that's the point where the ultrasound receiver no longer receives a return signal, or the return signal is below a threshold.

I suspect you're probably right about that.

There's certainly no harm in checking for some sort of obstruction / debris in the sensors, but I'm guessing that's not the case only because we've seen a cluster of these recently, and I remember that checking for something like this was recommended once or twice and found not to be the problem.

MDL Posted at 2017-6-28 12:28
DroneFlying - .05 firmware. On dust at the moment. Just took it out the back, VPS is 0.2 at the ground which is the same. Goes to about 2-3m and then goes WHITE and VPS n/a . Just went for a 5 min flight and no issue. I'm wondering if it's a weird heat issue or something to do with lighting???? It's going to get a work out today and see it's a firmware issue or a hardware issue.

Thing is, take it for one flight and it will be fine. Take it for another 5 in a row and it will fail.

I'm wondering if it's a weird heat issue or something to do with lighting????

I doubt it. We've seen a handful of reports of this problem from different people in recent weeks, so I suspect that a bad batch of Mavics was produced around the same time that all had this problem.

i want to be able to . . . give it to my son in an open enviroment

I understand, and I'm sure you'd hate for him to be soured on it by having it malfunction, so I'd definitely pursue an exchange. Even if I'm right about there being a bad batch, it's probably not happening with all Mavics produced around that time or we'd be seeing this reported a lot more, so the odds are that if you get a replacement that it'll work fine.

Droneflying - saw somewhere about reading the build date. Just can't remember where. Any ideas?

MDL Posted at 2017-6-28 14:00
Droneflying - saw somewhere about reading the build date. Just can't remember where. Any ideas?

Here's a link to the web site that'll tell you your Mavic's build date when you enter its serial number:

http://djiserialdecoder.x10host.com/

I'll have a look.
Go figure this out. Firmware .05 is working fine..... camera lense on the left is out of focus. But vps seems to be working fine.

MDL Posted at 2017-6-28 16:07
I'll have a look.
Go figure this out. Firmware .05 is working fine..... camera lense on the left is out of focus. But vps seems to be working fine.

Interesting. Even though I suggested trying it I'm still surprised that it made a difference. Though I suppose a firmware change would make sense in a way.

By the way, I should have thought to ask this sooner and was reminded of it by something I saw in a different thread: did you have any sort of landing gear extension attached when you encountered the VPS problems?

Ok. Just took it out again. Mid day. Yep vps still playing up. Flying along fine. Then you can see it start flashing red and then red all the time. Oh well was hope a trick.

The landing ext was the other guy