Mavic mini, unresponsive on forward command, logs for the pros.

[eljefeguero]

Coming from another thread was advised to start a specific one. Drone has done this three times, this is the most recent log of flight. Drone becomes unresponsive on forward command and loses altitude.or.drifts sideways. I will try to find logs from previous flights to look at also. Since this I have updated firmware with PC instead of mobile and will be changing blades before next flight. Thank you all for any input, becoming very frustrated with not having confidence to fly this drone over water or where it is unretrievable.

 

[Fly Dawg]

Drone becomes unresponsive on forward command and loses altitude.or.drifts sideways.

I certainly don't see that in this file. The sideways "drift" as you call it was due to your aileron inputs. The aircraft appears to be responding to all of your inputs. Here is your uploaded flight: DJI Flight Log Viewer - PhantomHelp.com

 

[eljefeguero]

Now that is cool, I need to look that over when I get to a desktop, I guess I am.not saying it did not respond to commands but it acted like it had now power, I will find the log for the first flight I had problems where it slowly descended to the grown, belly flopped and popped right back up, almost like the blades were not getting enough power. Just a quick question beings I'm still.mobile, what are the orange battery voltages listed, is that when cells get off from one another?

 

[Fly Dawg]

is that when cells get off from one another?

Correct. Those are minor deviations and are not related to your issue.

 

[new2mavic]

I have gone through the log and could see that the drone did fail to respond sufficiently to full forward stick. It is clear that the drone was fighting against head wind so low speed is expected but the drone was not giving out all it has got . It can be seen from the chart below that the elevator stick was full forward in this time period but the speed was just around 2 m/s compared with the max speed of 13 m/s in the specification. It was this low speed that made you feel the drone being unresponsive. Despite the full foward stick and the fact that the drone was in sport mode, the pitch angle was just around -11 degrees on average compared with - 30 degrees stated in the spec. At the beginning of the time period covered by the chart, the drone did tilt close to 30 degrees briefly and the speed went up to around 7 m/s which is normal but for the rest the time, the pitch angle was just unreasonably small.

 

[slup]

I have gone through the log and could see that the drone did fail to respond sufficiently to full forward stick. It is clear that the drone was fighting against head wind so low speed is expected but the drone was not giving out all it has got . It can be seen from the chart below that the elevator stick was full forward in this time period but the speed was just around 2 m/s compared with the max speed of 13 m/s in the specification. It was this low speed that made you feel the drone being unresponsive. Despite the full foward stick and the fact that the drone was in sport mode, the pitch angle was just around -11 degrees on average compared with - 30 degrees stated in the spec. At the beginning of the time period covered by the chart, the drone did tilt close to 30 degrees briefly and the speed went up to around 7 m/s which is normal but for the rest the time, the pitch angle was just unreasonably small.

View attachment 89716

IMHO your analyse is wrong as it builds upon a direct headwind scenario ...

This was the wind condition ... just so we can agree of the directions



The head/side wind blow away started here & then continued into the spaghetti like trajectory that ended in a landing beside the road E


As seen in below chart nearly no attempts were made to give any aileron input (light brown), only max elevator (light blue).
The correct stick inputs to properly get out of the escalating blow away situation are shown in above pic by the red crosses.
It's only in 07m44s full aileron input are given together with full elevator ... but this only for 6sec & without any descending,
still keeping 42m altitude. One other good practice had been to yaw directly up into the wind & with full elevator descended
as quickly as possible.



After several later erratic stick movements: yawing, releasing elevator followed again by full elevator + aileron input with the wind, towards the wind ... finally the throttle inputs come which makes the AC descend and luckily can land in one piece.

This is again nothing more then a blow away ... what complicated things was the side wind which I imagine stops the AC to fully utilize the full pitch angle as it also needs to roll to fight the wind. The earlier stated stick unresponsiveness is due to the AC fighting the wind.

Below just a 3D pic to better get an idea about the flight path ... red cross were the blow away started.

 

[new2mavic]

IMHO your analyse is wrong as it builds upon a direct headwind scenario ...
This was the wind condition ... just so we can agree of the directions

I am not sure if I can agree with that. If there was a side wind component and there was no aileron stick input, the drone should have tilted sideward to fight against the wind to prevent side slipping but such tilting is not seen from the raw data. There are two possibilities : either there was little side wind OR there was indeed some significant sidewind but the drone did not react appropriately :

...... As seen in below chart nearly no attempts were made to give any aileron input (light brown), only max elevator (light blue).

My focus is not so much about whether the OP has done his best. All the analysis given in the replies focus on whether the drone had responded correctly direction wise but my analysis goes deeper to check whether it has responded sufficiently magnitude wise. Unless the pitch angle given in the field OSD.pitch is not in degree so I have interpreted the value incorrectly, the drone clearly did not tilt anywhere close to the maximum achievable angle stated in the specifications ( 30 degrees ) but just about half of that. Had the drone performed according to the spec, the forward speed would have been significantly higher.

This is the flight data of my M2P when flying against wind, also in sport mode. The difference is quite obvious :



To me, the drone seems to have entered some sort of "retarded mode". The response to wind and control inputs became somewhat sluggish.

 

[m80116]

It's not not the first time this happens, kind of (firmware) strategy error, even though expectable the wind resistance is not on par with bigger models the drone seems to fail to acknowledge the wind limit conditions and has a totally inadequate response where it should technically be able with withstand the wind conditions.

 

[BudWalker]

You guys might want to also consider the motor commanded signal in the .DAT. Here it shows that the leftBack was maxed.

I think that has to mean that MM couldn't produce enough thrust. In this case the interval of maxed out thrust was coincident with full elevator (black trace)

 

[sar104]

You guys might want to also consider the motor commanded signal in the .DAT. Here it shows that the leftBack was maxed.
View attachment 89871
I think that has to mean that MM couldn't produce enough thrust. In this case the interval of maxed out thrust was coincident with full elevator (black trace)
View attachment 89873

And to elaborate on that, the left back motor speed was also maxed out:



That makes it fairly clear what is happening here. Even thought the tilt, at this point, is only averaging 13° rather than the maximum of 30° in sport mode, it can only be increased by increasing the rear motor speeds relative to the front motor speeds, and that can't happen if one of the rear motors is already at maximum. Why that would happen so far from the specified performance envelope is still a mystery.

 

[slup]

I am not sure if I can agree with that. If there was a side wind component and there was no aileron stick input, the drone should have tilted sideward to fight against the wind to prevent side slipping but such tilting is not seen from the raw data. There are two possibilities : either there was little side wind OR there was indeed some significant sidewind but the drone did not react appropriately :

View attachment 89840





My focus is not so much about whether the OP has done his best. All the analysis given in the replies focus on whether the drone had responded correctly direction wise but my analysis goes deeper to check whether it has responded sufficiently magnitude wise. Unless the pitch angle given in the field OSD.pitch is not in degree so I have interpreted the value incorrectly, the drone clearly did not tilt anywhere close to the maximum achievable angle stated in the specifications ( 30 degrees ) but just about half of that. Had the drone performed according to the spec, the forward speed would have been significantly higher.

This is the flight data of my M2P when flying against wind, also in sport mode. The difference is quite obvious :

View attachment 89844

To me, the drone seems to have entered some sort of "retarded mode". The response to wind and control inputs became somewhat sluggish.

Went out with my Air today as the winds at last have fallen from 15-16m/s ground to only 4-5m/s ... this to test off my thesis about that with increased roll angle will decrease the pitch angle ... and have some Sport mode fun on lower altitudes

So the setup was flight at roughly 30 meters with a slight tail/left wind of average 5m/s. According the specs the Air can achieve 35 degree tilt in Sport mode.

The first flight was full ahead both elevator+aileron ... The Air screamed nicely away in a 45 degree angle over the field & maxed out on 19,1m/s.
The second flight started from the same spot & were directed in the same direction that the first flight. Again it screamed (really nice sound I might add ) away but this time only full elevator were applied. it maxed out on 18m/s.

Later back home the DAT file showed me that:

For the diagonal flight the pitch forward reached a max of -24 degrees when at the same time the roll reached +13 degrees --> 19,1m/s heading speed
For the straight forward flight the pitch forward reached a max of -34,5 degrees when at the same time the roll reached -6 degrees (due to a slight side wind) --> 18m/s heading speed

So this leads me to believe that with increasing roll angle available pitch angle will be reduced ... if so, a flight in side winds with only elevator input (and the firmware taking care of aileron like inputs due to side forces coming from winds) will not give access to the full spec tilt angle.

This phenomenon of course becomes more pronounced when engines are maxed out as both @BudWalker & @sar104 points out ...

 

[BudWalker]

Went out with my Air today as the winds at last have fallen from 15-16m/s ground to only 4-5m/s ... this to test off my thesis about that with increased roll angle will decrease the pitch angle ... and have some Sport mode fun on lower altitudes

So the setup was flight at roughly 30 meters with a slight tail/left wind of average 5m/s. According the specs the Air can achieve 35 degree tilt in Sport mode.

The first flight was full ahead both elevator+aileron ... The Air screamed nicely away in a 45 degree angle over the field & maxed out on 19,1m/s.
The second flight started from the same spot & were directed in the same direction that the first flight. Again it screamed (really nice sound I might add ) away but this time only full elevator were applied. it maxed out on 18m/s.

Later back home the DAT file showed me that:

For the diagonal flight the pitch forward reached a max of -24 degrees when at the same time the roll reached +13 degrees --> 19,1m/s heading speed
For the straight forward flight the pitch forward reached a max of -34,5 degrees when at the same time the roll reached -6 degrees (due to a slight side wind) --> 18m/s heading speed

So this leads me to believe that with increasing roll angle available pitch angle will be reduced ... if so, a flight in side winds with only elevator input (and the firmware taking care of aileron like inputs due to side forces coming from winds) will not give access to the full spec tilt angle.

This phenomenon of course becomes more pronounced when engines are maxed out as both @BudWalker & @sar104 points out ...


View attachment 89881

If you can supply the .DAT I'll give you back a .csv that has tilt and tilt heading. Those are in the next version.

I suspect @sar104 is already computing this with Igor Pro - in which case you can just wait for him.

 

[slup]

If you can supply the .DAT I'll give you back a .csv that has tilt and tilt heading. Those are in the next version.

I suspect @sar104 is already computing this with Igor Pro - in which case you can just wait for him.

Attached ...

Please explain tilt heading ... is it the combined pitch/roll angle ?

 

[BudWalker]

Attached ...

Please explain tilt heading ... is it the combined pitch/roll angle ?

20-01-05-12-33-11_FLY069.5599789.csv

Shared with Dropbox

www.dropbox.com

tiltHeading is the heading in the earth frame. If tiltHeading == 90° then the MM is tilted towards the east regardless of the MM's heading.

 

[sar104]

Attached ...

Please explain tilt heading ... is it the combined pitch/roll angle ?

This is what that flight looks like in terms of sticks, pitch, roll, tilt and speed:



That's completely consistent with the specifications for the Mavic Air in sport mode. You commanded periods of full elevator, full aileron, and full elevator and aileron. All resulted in almost exactly 35° tilt. The achieved speed varied due to the wind out of the east - and also notice that flying diagonally appears to be slightly faster than flying directly forwards. Sideways is slower, as expected, since the larger cross-sectional area will produce more drag.

FYI, tilt is the angle between vertical and the aircraft z-axis. It's computed from pitch and roll by:

tilt = arccos(cos(pitch)*cos(roll))

 

[slup]

OK, so ... think I understand the concept of "tilt" vs. pitch & roll (perhaps or not )

@sar104 Am I right by then think (just as my attached try out flight suggest) that when no roll is going on in a forward flight, the pitch (AC angle from horizon forward direction) is equal to the tilt (angle from vertical Z-axis)? But as soon roll comes in to play the angles of pitch/roll always will be less then the tilt angle ... but the tilt angle will still be constant (in theory)?

@BudWalker Can I then with the tilt heading in theory say that it's in that direction the AC will fly (if no wind or nothing is maxed out)?
From your earlier attached csv file how do I visualize the tilt & tiltheading from my flight ... through CsvViewer (can't find those signals there) ... or just try to open the csv in excel & find them there?

 

[BudWalker]

OK, so ... think I understand the concept of "tilt" vs. pitch & roll (perhaps or not )

@sar104 Am I right by then think (just as my attached try out flight suggest) that when no roll is going on in a forward flight, the pitch (AC angle from horizon forward direction) is equal to the tilt (angle from vertical Z-axis)? But as soon roll comes in to play the angles of pitch/roll always will be less then the tilt angle ... but the tilt angle will still be constant (in theory)?

@BudWalker Can I then with the tilt heading in theory say that it's in that direction the AC will fly (if no wind or nothing is maxed out)?
From your earlier attached csv file how do I visualize the tilt & tiltheading from my flight ... through CsvViewer (can't find those signals there) ... or just try to open the csv in excel & find them there?

It's also true that if pitch == 0.0 then tilt == roll. And, tilt will always be greater than or equal to either pitch or roll. I'm not sure what you mean by tilt will be constant, but there are an infinite number of pitch/roll combinations that will yield the same tilt value.

Those tilt signals are in the next version of CsvView that should be out later today or tomorrow. In the interim you'll have to use something like Excel.

Yes, absent any wind the AC will fly in the direction specified by tiltHeading.

 

[slup]

... I'm not sure what you mean by tilt will be constant, but there are an infinite number of pitch/roll combinations that will yield the same tilt value.

Those tilt signals are in the next version of CsvView that should be out later today or tomorrow. In the interim you'll have to use something like Excel.

Yes, absent any wind the AC will fly in the direction specified by tiltHeading.

Yeah @BudWalker ... my try to put word on my thoughts made it perhaps a bit vague, but what you wrote is exactly what I mean... by maintaining the tilt, pitch/roll will be smaller, my feeling said that from the beginning but my brain needed to catch up.

Think this generally is what people misread from the specs (I did it also in the beginning), tilt isn't the same as pitch & the spec clearly says "Tilt", so with some roll the pitch will be smaller than the specified Tilt degrees. Great that we got that right ... waiting eagerly for the next CsvView version, log decoding to understand the event has become half the fun with drone flying

 

[BudWalker]

Yeah @BudWalker ... my try to put word on my thoughts made it perhaps a bit vague, but what you wrote is exactly what I mean... by maintaining the tilt, pitch/roll will be smaller, my feeling said that from the beginning but my brain needed to catch up.

Think this generally is what people misread from the specs (I did it also in the beginning), tilt isn't the same as pitch & the spec clearly says "Tilt", so with some roll the pitch will be smaller than the specified Tilt degrees. Great that we got that right ... waiting eagerly for the next CsvView version, log decoding to understand the event has become half the fun with drone flying

The tilt calculations are now in CsvView 3.7.0 which is available for download at
CsvView Downloads
DatCon 3.7.0 also contains the tilt calculations.

The tilt info is in the IMU record. The signal names were changed. IMU_ATTI(0):tiltInclination is the angle between the Z axis and vertical. IMU_ATTI(0):tiltDirection is the direction of the tilt in the earth reference frame - it's independent of the AC's heading.


The tilt calculations also work for .txt logs

 

[BudWalker]

@slup for your particular flight it can be seen that wind was from 180° At time 214 secs the MM was hovering (velH = 0.0) Yaw was -65° and tiltDirection was ~180°


and at time 153 secs the tiltDirection was also ~180° even though the MM Yaw had changed to 122°