Inconsistent Acceleration / Top Speed

[E-N]

I had noticed this previously but attributed it to not understanding the collision avoidance algorithm or my garbage flying skills. Now that I am (slowly) improving, I'm not sure what the inconsistencies are are actually related to.

When I accelerate, occasionally the drone increases slowly up to about 17-18mph, then plateaus there for a few seconds before accelerating normally (more quickly) the rest of the way to 30ish mph. The whole acceleration takes 10+ seconds in this case.

When I try to recreate the same exact start position and path acceleration scenario, sometimes the drone accelerates normally (at least what I think it's normal) up to 30ish mph within a few seconds.

I have tried turning off the anti collision, checking to make sure it's all current software and even trying different locations, proximity to obstacles, different batteries, warm up, pre-run, yet I keep getting random results. I have the smart controller and everything else seems to be working perfectly. Tsunami Trial 4k.mp4 In this clip, my buddy slowly pulled away from the drone until the drone "woke up" and accelerated to top speed just as he's about to turn the final corner.

Any ideas on where to start would be greatly appreciated.

 

[sar104]

Start with the flight logs.

 

[Meta4]

When I accelerate, occasionally the drone increases slowly up to about 17-18mph, then plateaus there for a few seconds before accelerating normally (more quickly) the rest of the way to 30ish mph. The whole acceleration takes 10+ seconds in this case.

What you describe is not normal.
Flight data might help shed light on the mystery.

 

[E-N]

Start with the flight logs.

Ok, Thanks

 

[E-N]

What you describe is not normal.
Flight data might help shed light on the mystery.

Ok, thanks

 

[E-N]

Ok, Thanks

Start with the flight logs.

I misread your Mavic Flight Log Retrieval and Analysis Guide initially. It took me a few re-reads of your post to realize that I could actually pull the logs from the M 2. Thanks for the nudge to look at it again. I believe I am looking at the right parameters. My take is this:

1. I slowly increased RC:elevator to max positive value around 136s
2. I realize the drone is not accelerating normally, so I pump the elevator controls twice to see if that might wake it up 140s.
3. No change. Drone accelerates slowly and plateaus just above 8 m/s between 146 and 152s.
4. Drone begins to accelerate normally after dramatic pitch change at 152s.
5. Max speed is reached 159s.

If I'm looking at the flight log correctly, it appears there's nothing obvious that is causing the drone to change it's pitch and begin accelerating normally. Is there a CTRL + ALT + Delete for these that I should try?


Thanks to everyone for taking a peek.

 

[boblui]

There is definitely something wrong with the drone. If I push the elevator fully forward in P mode, the pitch angle of my M2P will change from 0 to -24 deg in less than a second and then keep it steady at about -18 deg afterwards. In the flight you have posted, there was not much wind but the pitch angle under full elevator input varied from -7 to - 20 deg.

It seems that some of the motors required some kicking before they could reach the commanded speed. Apparently such kicking can be done by applying aileron input as shown the following example . The pitch angle changed from the abnormally low value of about -7 deg to the normal value of about -18 deg after a pumping in aileron control was applied.




Posting the .DAT file will help to identify the reason more precisely.

 

[E-N]

There definitely does seem to be some correlation between the aileron and full activation of the drone pitch. Thanks for pointing that out.

It took me a while to realize that I already had the .dat files. The naming is not quite the same as the Flight Records, but this one seems to have the same time stamp. It looks like the guy that made CsvView has the .dat viewer as well, so down the rabbit hole I go!

Thanks for looking into this so far

 

[boblui]

This is probably the most challenging case I have come across so far ....

As observed by the OP, with full-forward elevator applied, the drone would occasionally accelerate much slower than expected at the beginning and all of a sudden, it would abruptly increase the pitch and pick up speed more quickly . This is an example :



With full-forward elevator applied, the pitch angle stayed abnormally low ( around - 7 deg ) at the beginning but at 257.5 sec, the pitch suddenly changed from -7 deg to -18 deg followed by a rapid increase in speed to about 14 m/s which is the maximum speed in P mode as stated in the spec. The pitch change was real because both IMU0 and IMU1 detected the same amout of pitch change and the subsequent speed increase. The speed change also matches that detected by the GPS :



The pitch change was commanded by the flight controller and the motors just followed the command faithfully so the propulsion system seems to be working fine.



I could not see any sensor outputs that could have triggered such action by the flight controller. There was also no logged events of any kinds around this point of time in the .DAT file.

In short, I cannot offer any explanation. Hope the other flight log analysts here can shed some light on this interesting case.

 

[slup]

This is probably the most challenging case I have come across so far ....

As observed by the OP, with full-forward elevator applied, the drone would occasionally accelerate much slower than expected at the beginning and all of a sudden, it would abrouptly increase the pitch and pick up speed more quickly . This is an example :

View attachment 109567

With full-forward elevator applied, the pitch angle stayed abnormally low ( around - 7 deg ) at the beginning but at 257.5 sec, the pitch suddenly changed from -7 deg to -18 deg followed by a rapid increase in speed to about 14 m/s which is the maximum speed in P mode as stated in the spec. The pitch change was real because both IMU0 and IMU1 detected the same amout of pitch change and the subsequent speed increase. The speed change also matches that detected by the GPS :

View attachment 109568

The pitch change was commanded by the flight controller and the motors just followed the command faithfully so the propulsion system seems to be working fine.

View attachment 109569

I could not see any sensor outputs that could have triggered such action by the flight controller. There was also no logged events of any kinds around this point of time in the .DAT file.

In short, I cannot offer any explanation. Hope the other flight log analysts here can shed some light on this interesting case.

I think this have to do with that the OD sensors sense something ... nearly every time the AC passes below marked area OA:vertLowLimit becomes true (Pink background in the chart further down). As seen from the pic. the flight route is downhill from the HP & pretty low to ground.



As seen in the chart the ultrasonic sensor just lose track (Black), then a second later OA:vertLowLimit = False (Pink area) ... then again a second later the tilt inclination increases (Angle combining Roll & Pitch from the vertical axis, Green dotted) & the speed (Red dotted) picks up.


My advice is to test a flight much higher up ... also try not to use all 4 stick movements as you did most of the time in this attached flight, as ascending/descending+Rolling+Yawing+Pitching usually give a different tilt & speed than stated in the spec.

I misread your Mavic Flight Log Retrieval and Analysis Guide initially. It took me a few re-reads of your post to realize that I could actually pull the logs from the M 2. Thanks for the nudge to look at it again. I believe I am looking at the right parameters. My take is this:

1. I slowly increased RC:elevator to max positive value around 136s
2. I realize the drone is not accelerating normally, so I pump the elevator controls twice to see if that might wake it up 140s.
3. No change. Drone accelerates slowly and plateaus just above 8 m/s between 146 and 152s.
4. Drone begins to accelerate normally after dramatic pitch change at 152s.
5. Max speed is reached 159s.

If I'm looking at the flight log correctly, it appears there's nothing obvious that is causing the drone to change it's pitch and begin accelerating normally. Is there a CTRL + ALT + Delete for these that I should try?


Thanks to everyone for taking a peek.



View attachment 109438

The same OA:vertLowLimit (Pink area) here also ...

 

[boblui]

I think this have to do with that the OD sensors sense something ...

I think this have to do with that the OD sensors sense something ...
...., then a second later OA:vertLowLimit = False (Pink area) ... then again a second later the tilt inclination increases (Angle combining Roll & Pitch from the vertical axis, Green dotted) & the speed (Red dotted) picks up .....

This is not quite my experience with the M2P. I have flown it at full speed in P mode at 1 meter above water surface and the acceleration was normal :

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[slup]

This is not quite my experience with the M2P. I have flown it at full speed in P mode at 1 meter above water surface and the acceleration was normal :

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It can't be a coincidence that every time the not expected tilt angle occurs the OA:vertLowLimit=True & everything is back to normal when it goes =False ... this together with that it happens in the same place on the flight path.

 

[boblui]

Just noticed that VPS was turned off but the log file has the IR-sensed height data there. This is not seen in my M2P's log file. May be the speed restriction at low height ( < 8 meters ) is the behavior of old-version firmware ? Can't find the firmware version in the log file, just the Andriod version.

 

[slup]

Just noticed that VPS was turned off but the log file has the IR-sensed height data there. This is not seen in my M2P's log file. May be the speed restriction at low height ( < 8 meters ) is the behavior of old-version firmware ? Can't find the firmware version in the log file, just the Andriod version.

Don't know if this is the plain true FW version for the AC or something else ...

 

[boblui]

Don't know if this is the plain true FW version for the AC or something else ...

View attachment 109599

I think it is the Andriod version of the phone .... I use iphone on my M2P and this field is blank

 

[E-N]

Don't know if this is the plain true FW version for the AC or something else ...

View attachment 109599

I'm using the smart controller. Maybe that is the difference It hasn't shown any updates required recently.

 

[E-N]

Before I originally posted, I had noticed this delayed acceleration/top speed and tried to narrow down when/why it was occurring. I am definitely flying it in confined spaces when compared to, for example, 100m up with no obstacles; however, there are times when I have placed it in "exactly" the same confined location and it seems to respond normally at least part of the time.

I am heading out now to try a few different scenarios: no obstacles anywhere nearby and only elevator forward instead of multiple stick commands. I do think that I have tried this, but I want to be sure.

I greatly appreciate everyone who has given ideas in this thread.

Thank you again.

 

[E-N]

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I've been enjoying a few days of COVID-19, but I finally managed to take a look at a recent flight that I tested a few different scenarios. At high altitude without any surrounding obstacles, the drone accelerates normally every time. At lower altitude, it's hit or miss. occasionally I can accelerate normally, but other times it won't immediately reach max pitch. This is one example of normal acceleration after hesitation in a confined corridor of trees with multiple stick inputs and very low relative altitude and OA:vertlowlimit true the entire time.

I have been unable to find the usonic display option to see if that is also affected.



I did by chance run into a possibly related issue. After I turned on the drone, I received a battery not secure message and found the "overall status" section on the smart controller. When I selected it, I saw that even though there is no other notification of a problem, it shows up hidden in this menu. I plugged the drone into the computer, but no matter what I did, I cannot get it to calibrate.

 

[boblui]

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.... At lower altitude, it's hit or miss. occasionally I can accelerate normally, but other times it won't immediately reach max pitch.

There seems to be a strong correlation indeed. What is the firmware version of your craft ?

I have been unable to find the usonic display option to see if that is also affected.

Scroll to the very bottom and you will see it



It seems that OA: vertLowLimit = true if the ground is within the range of the IR sensor at the bottom, ie, about 9.5 meters. May be it's worth trying to fly with obstacle avoidance and VPS turned off and see under what combination of settings the behaviour will go away.

 

[boblui]

I have just tried to fly my M2P over water at various height from > 10 m to 1.7 m above the water surface. P-mode used, all obstacle avoidance sensors on, VPS on, craft firmware version is .670 ( latest ). No acceleration issues was found. The craft always tilted to -24 deg upon applying full-forward elevator ( indicated as throttle in the chart because I was using mode 1 )



I don't have the .DAT file because my controller ( model RC1B ) does not produce any.