Mavic Air Fly Away -- and recovery.

[sar104]

But my initial post is #2, and I can’t see his #1 post???

Did you accidentally put the OP on "ignore"?

 

[ac0j]

Maybe he has an “invisible post”.

 

[InvisibleName]

Did you accidentally put the OP on "ignore"?

Ah, that would be it - didn’t want to get into a spat after a private message he sent me!

 

[Miksterr]

Yes - but aside from one anomalous speed excursion that had little effect on the overall flight, I'm not sure what he thinks happened. Without a more detailed description than "trouble" I'm not sure what to focus on.

When it hit the 60mph it definitely wasn’t a stick command to do so.

99% of the flight was fine, just the part where it beers off on the map. From the video it is apparent that it is doing quite high speed and on more than 25degrees.

Not sure if there is more information that can be extracted from the Mavic?

 

[MavicCF]

When it hit the 60mph it definitely wasn’t a stick command to do so.

99% of the flight was fine, just the part where it beers off on the map. From the video it is apparent that it is doing quite high speed and on more than 25degrees.

Not sure if there is more information that can be extracted from the Mavic?

Are you saying that in reference to the logs? I haven’t looked at them myself, but if sar104 says it was responding to stick input appropriately and never really exceeded the 25* pitch limit imposed by GPS mode, than I would believe him.

 

[MavicCF]

I'm not quite sure exactly what you are asking about - is it just the brief high-speed excursion? The aircraft appears to have responded appropriately to stick inputs throughout the flight, with mostly normal flight characteristics. There were a number of "attitude too large" warnings, but those were marginal - for almost all of the flight the pitch and roll values were within the 25° maximum imposed in P-GPS mode. Have you altered any of the gain values?

The velocity excursion to 29 m/s (65 mph) at 454 seconds is recorded in both the IMU velocity measurements and position data, but is probably not correct since neither pitch nor roll were excessive at that time.

You got me again, where are you seeing the IMU velocities? I would have thought OSD_xSpeed_m/s and OSD_ySpeed_m/s second would have been them, but how are you calculating the end result of 29 m/s from that? Horizontal speed at 454 seconds appears to have been only 2.86 m/s.

 

[sar104]

You got me again, where are you seeing the IMU velocities? I would have thought OSD_xSpeed_m/s and OSD_ySpeed_m/s second would have been them, but how are you calculating the end result of 29 m/s from that? Horizontal speed at 454 seconds appears to have been only 2.86 m/s.

The x and y speeds are the appropriate values. But at 454 s those are 13.5 and -25.2 m/s respectively; squaring, adding and taking the square root gives 28.6 m/s, not 2.86 m/s. You lost a factor of 10 somewhere.

That value is also computed in the "CUSTOM_hSpeed__m_s_" field. It is also in the "CALC_hSpeed__m_s_" field, although there is something wrong with those data.

 

[sar104]

When it hit the 60mph it definitely wasn’t a stick command to do so.

99% of the flight was fine, just the part where it beers off on the map. From the video it is apparent that it is doing quite high speed and on more than 25degrees.

Not sure if there is more information that can be extracted from the Mavic?

Even if you retrieve the Mavic DAT file, I'm not sure that it will reveal much more. As I mentioned - that excursion is odd, whether real or not. The aircraft doesn't achieve a pitch/roll at that time consistent with 29 m/s:



As for the remainder of the flight, the pitch and roll values are consistent with the stick inputs so I'm not clear what you are saying; below are the pitch and roll responses. Note that you are in Mode 1, and so the elevator input is in the data log RC_throttle field.

 

[MavicCF]

The x and y speeds are the appropriate values. But at 454 s those are 13.5 and -25.2 m/s respectively; squaring, adding and taking the square root gives 28.6 m/s, not 2.86 m/s. You lost a factor of 10 somewhere.

That value is also computed in the "CUSTOM_hSpeed__m_s_" field. It is also in the "CALC_hSpeed__m_s_" field, although there is something wrong with those data.

Ah, thank you. I got the 2.86 from the CALC_hSpeed__m_s_ and was baffled by the difference between that and your results.
Now that I know how this value is supposed to be computed, it makes much more sence.
I also missed that he was in Mode 1 (I have never even considered that before!). Thanks for your continued willingness to teach me about all this, I really appreciate it!

 

[MavicCF]

Actually now that I'm thinking about it, I can't believe I didn't think of using the good old Pythagorean Theorem to get the velocity. Part of it was I was unsure if those were the correct values...

 

[Miksterr]

I have uploaded the video to YouTube... it shows the time where it goes a little crazy.

Mike.

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[JDawg]

Did you happen to notice the power lines you were flying near?
You parked in the middle of a road and landed your drone on the road?
You see it all here.

 

[Cheech Wizard]

There’s no way an MA can do over 100kph on its own, must have either been a tail wind at altitude that you hadn’t measured, of it was in a nose down dive!

Ps With reference to your terse “genius” comment, he was trying to help! If you don’t want help, don’t come on here!

Yeah, the name calling is rude, seems mostly from new members. Or young members.

 

[Cheech Wizard]

Did you happen to notice the power lines you were flying near?
You parked in the middle of a road and landed your drone on the road?
You see it all here.

Ha... that was crazy, not 100 kph crazy.

 

[Cheech Wizard]

I have uploaded the video to YouTube... it shows the time where it goes a little crazy.

Mike.

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Were you in follow mode? Or just trying to fly from your truck?

 

[MavicCF]

According to the video, the problem started at about 439s. The roll data right at that point just doesn't seem right to me (maybe I'm just paranoid). To me it doesn't appear to have responded appropriately to input and it even hits 32.5˚ of roll without designated input. Here's what I'm talking about.
@sar104

 

[sar104]

According to the video, the problem started at about 439s. The roll data right at that point just doesn't seem right to me (maybe I'm just paranoid). To me it doesn't appear to have responded appropriately to input and it even hits 32.5˚ of roll without designated input. Here's what I'm talking about.
@sar104
View attachment 41122

Comparison of the flight data with the video demonstrates a significant compass error at the time of the excursion. Before that started, the recorded yaw was 40°, but the video in post #31 clearly shows that the actual yaw was approximately 0°. Then, during the excursion to the west, the video shows that the aircraft completes a full CCW rotation, but the IMU yaw data do not show anything other than a 30° CCW turn.

 

[sar104]

We really need to see the mobile device DAT file for this flight to figure out how the IMU yaw became so incorrect.

 

[Miksterr]

We really need to see the mobile device DAT file for this flight to figure out how the IMU yaw became so incorrect.

sar104,

Happy to upload this - not sure where to find the .dat file however?

To Cheech - Not in follow mode, Pilot was outside - not in view. Also, apologies for the frustration at first - for all the doubters who kept questioning what I was saying. As mentioned, it was on the screen, the video and what I witnessed.

Also, yes, I saw the powerlines. Was the first time at the location so they certainly may be the culprit.

Mike.

 

[sar104]

sar104,

Happy to upload this - not sure where to find the .dat file however?

Mike.

How to retrieve a V3.DAT from the tablet