Mavic flyaway covered by warranty

[Grey Wolf]

Still sounds like operator error.
You really have to know the machine and settings before you fly.

 

[Andrejs]

There was a problem with unexpected GPS lost and changing to ATTI mode.
My friend had the same problem and crash after.
So he didn't have a lot of experience and when he lost GPS and changed to ATTI he completed to flying in wrong way and after that got signal lost. After logs it was seen that Mavic fly till middle of the river than stopped (got back GPS signal) and started to fly back and hit the tree.
Hopefully he found it and get it down. Send it to DJI and wait answer.
So here I see 2 problems -
1) DJI Mavic PRO problem to unexpectedly loose GPS signal and change to ATTI in open clear sky. Hope it was fixed in last firmware.
2) Pilot problem to flying in wrong way in ATTI mode.

What about training etc. Flying Mavic it is like driving Tesla
I had long time ago a simple China Helicopter and there you needed some skills to fly it without all this GPS, IMU and other stuffs
I think also when you fly with all this systems on board make you lazy (if I could say so) and when it is needed you can do some crazy stuff due to stress and don't knowing what to do.
So it could be nice to have opportunity to turn of GPS and fly only in ATTI mode,without IMU etc. Is it possible? I need to check it

 

[Reinheart Damanik]

There was a problem with unexpected GPS lost and changing to ATTI mode.
My friend had the same problem and crash after.
So he didn't have a lot of experience and when he lost GPS and changed to ATTI he completed to flying in wrong way and after that got signal lost. After logs it was seen that Mavic fly till middle of the river than stopped (got back GPS signal) and started to fly back and hit the tree.
Hopefully he found it and get it down. Send it to DJI and wait answer.
So here I see 2 problems -
1) DJI Mavic PRO problem to unexpectedly loose GPS signal and change to ATTI in open clear sky. Hope it was fixed in last firmware.
2) Pilot problem to flying in wrong way in ATTI mode.

What about training etc. Flying Mavic it is like driving Tesla
I had long time ago a simple China Helicopter and there you needed some skills to fly it without all this GPS, IMU and other stuffs
I think also when you fly with all this systems on board make you lazy (if I could say so) and when it is needed you can do some crazy stuff due to stress and don't knowing what to do.
So it could be nice to have opportunity to turn of GPS and fly only in ATTI mode,without IMU etc. Is it possible? I need to check it

It also happent to me, mavic got lost GPS signal in open clear area while it flight, after that Mavic turn off the Satelite Potitioning, and then you know the next it'll turn to ATT mode..

 

[burtg]

This why I recommend all the newbies flying to get the Syma X5C and learn the basics with just stick flying, for $50 it is a tough little bird.
I learn to fly all through the house and, I eventually got good enough to fly without bumping into walls. I moved outside and flew it for months before I went to the phantom 3 pro. It is good to have just the basic flying skills, especially when the gps, etc. doesn't work and you have to get your $1000 plus bird back to home point.


Sent from my SM-G920V using MavicPilots mobile app

 

[Reinheart Damanik]

Its not about learn to fly, its a bout a technology u buy but u cant enjoy it. I think lot of mavic user is not a beginner pilot, they just a need a portable drone with the latest technology and they hope they get what they pay for.

It also an information for another droner who have plan to buy mavic.

 

[m0j0]

I only fly my Tarot T810 hexa in GPS mode when I need to hover at altitude for panos etc. The rest of the time (95%) I fly in Atti. GPS positioning is too un reliable with multirotors. It's just another tool to use when necessary, not all the time. You really need to learn to fly without any GPS aid, then use it when you need to. Far less chance of getting an error and your bird flying off when in Atti mode.

That's interesting I'm new to all of this. I have been flying for only a year and I can say pretty confidently I have a GPS problem 1 time out of a countless number of flights. So GPS has been spot on 299 times out of 300. That is pretty reliable.


Sent from my iPad using MavicPilots

 

[Slantnose79]

It also happent to me on the 2nd day I own my mavic and I almost loose it or make it crash, you may see on flight log screenshot.

I cannot figure out how to produce a flight log map? I see the flight logs, but they are only text. How do I create the flight log map? Does the Mavic have to be linked to the app to make this possible? Or, can I simply generate this map with my phone and no Mavic attached? Using DJIGo4



Sent from my iPhone using MavicPilots

 

[Andrejs]

I cannot figure out how to produce a flight log map? I see the flight logs, but they are only text. How do I create the flight log map? Does the Mavic have to be linked to the app to make this possible? Or, can I simply generate this map with my phone and no Mavic attached? Using DJIGo4



Sent from my iPhone using MavicPilots

You can see it in DJI Go App. You don't need to generate anything.

 

[Slantnose79]

Andre, thanks for the reply. I'm using the DJI-Go4 App. I cannot see how to generate these in it. Can anyone provide the steps to viewing these flight logs within Go4?

Thanks!

 

[Andrejs]

Andre, thanks for the reply. I'm using the DJI-Go4 App. I cannot see how to generate these in it. Can anyone provide the steps to viewing these flight logs within Go4?

Thanks!

At least on Android it is like that.
Open app:

Select Flight records:


And there in list select flight what you want to see.
For more detailed logs advice to use HealthyDrones.com - Innovative flight data analysis that matters

 

[Slantnose79]

Awesome. I didn't think to go back to the main screen. I'm in there - - Thanks Andre

 

[AlanTheBeast]

fschilder, fair question and I did a bit of digging. I am sure I've read that specific conclusion (or heard it in a video) but can't find that information after a reasonable search now. I could be wrong, but I will lay out my reasoning.

That said, it appears DJI uses the u-blox line of GPS processing chips, as they're popular and well-integrated. The first package that supports GLONASS at all seems to be the u-blox NEO-7 line, and I dug into the technical specifications datasheets for NEO-7 and NEO-8. The datasheet does not support my statement above that it would ignore GLONASS if satisfied by GPS, but it doesn't deny it either. Further, it has a nice summary of the technical differences in GLONASS:



https://www.u-blox.com/sites/defaul...verDescrProtSpec_(GPS.G7-SW-12001)_Public.pdf

As I work with embedded systems quite a bit, I understand that when there are two sensors or two data sources, there has to be a strategy to select which input to trust, and which input to combine, and what math would be used to combine, those signals from different sources. Everything I have seen in the datasheets shows that you would calculate a position from GPS, and you would calculate a separate position from GLONASS, given their distinct timing methodologies. Given that GLONASS is seen as (1) less accurate than GPS, and (2) has to account for leap seconds in UTC which are informed from the GPS system, we can see that it is currently a second-tier less-desirable source of information. The datasheets for the u-blox NEO-7 and NEO-8 chipsets do not specify the selection strategy between GPS and GLONASS. They likely see this as an uninteresting internal detail, or a competitive secret.

So at this time I can't find the DJI's preference for GPS over GLONASS specifically in the datasheets. It stands to reason (my reasoning at least) but it's not backed up by any evidence I could find this morning.

Since the GPS/GLONASS is managed by a single system, I'd suspect they have an over-determined solution using both sources. (No, I don't know for a fact).

How they are "mixed" is hard to say since each has a different reference datum. But it's feasible to come up with a ECEF solution for each and then mathematically merge the result before converting to L/L/Alt. It's even mathematically plausible to determine the PR from the GLONASS sats to the receiver in the GPS ECEF before determining the receiver ECEF.

Heretical thought: The origin of ECEF for GPS and GLONASS are a mere 40 cm apart. So one could bypass reconciliation and simply brute force the GLONASS PR's with GPS PR's and the resultant error would be nearly an order of magnitude less than the error of either system.

The GPS status shows some 16-18 satellites when I fly - that's impossible with either system alone. It also may mean "that's what's available" but not "what's being used".

The most positive thing about the chipset that the Mavic is using (per various sources) is that it does use SBAS. So accuracy in North America, Europe and Japan is better even with GPS alone.

Added detail:
uBlox MAX "8" comes in two versions. One separates the RF from GPS and GLONASS and processes them concurrently and then comes up with a solution based on both. The other version selects one or the other and comes up with one solution based on one source.

However, the NEO-7 datasheet (what is suspected to be in the Mavic) makes no distinction about how it processes GLONASS or GPS - only that it can do both. Again, the display shows 16-18 sats ... consistent with receiving both systems (and WAAS and/or EGNOS thrown in for good measure) but that doesn't mean it's computing position with both...

I guess we have to be content to be a bit in the dark ...

 

[erkme73]

Since the GPS/GLONASS is managed by a single system, I'd suspect they have an over-determined solution using both sources. (No, I don't know for a fact).

How they are "mixed" is hard to say since each has a different reference datum. But it's feasible to come up with a ECEF solution for each and then mathematically merge the result before converting to L/L/Alt. It's even mathematically plausible to determine the PR from the GLONASS sats to the receiver in the GPS ECEF before determining the receiver ECEF.

Heretical thought: The origin of ECEF for GPS and GLONASS are a mere 40 cm apart. So one could bypass reconciliation and simply brute force the GLONASS PR's with GPS PR's and the resultant error would be nearly an order of magnitude less than the error of either system.

The GPS status shows some 16-18 satellites when I fly - that's impossible with either system alone. It also may mean "that's what's available" but not "what's being used".

The most positive thing about the chipset that the Mavic is using (per various sources) is that it does use SBAS. So accuracy in North America, Europe and Japan is better even with GPS alone.

Added detail:
uBlox MAX "8" comes in two versions. One separates the RF from GPS and GLONASS and processes them concurrently and then comes up with a solution based on both. The other version selects one or the other and comes up with one solution based on one source.

However, the NEO-7 datasheet (what is suspected to be in the Mavic) makes no distinction about how it processes GLONASS or GPS - only that it can do both. Again, the display shows 16-18 sats ... consistent with receiving both systems (and WAAS and/or EGNOS thrown in for good measure) but that doesn't mean it's computing position with both...

I guess we have to be content to be a bit in the dark ...

I tell ya, it's posts like this that make me feel pretty uneducated. Reading this makes me feel the same way when I watch this:

 

[AlanTheBeast]

I tell ya, it's posts like this that make me feel pretty uneducated. Reading this makes me feel the same way when I watch this:

I've been indirectly or directly involved in GPS receiver development since there were only a few sats in the sky and you had to sched your observation to coincide with there being 4 in view... Didn't happen often (2x per day). The early constellations were in fact set up so that receiver testing could occur with 4 sats visible in North America, periodically. So you'd get an hour or so to test your receiver. Don't feel uneducated - feel ignorant - the blessed state needed to learn!

 

[AlanTheBeast]

I tell ya, it's posts like this that make me feel pretty uneducated. Reading this makes me feel the same way when I watch this:

Hogwash. Not to pick that apart, but the differential girdle spring alone is known to be a failure prone power limiting modulation device. I could go on and on ...