Flight logs can someone check them

[BudWalker]

I’ve done a imu calibration and still having errors, another thing is my MM only does 7 metres a second in sport mode surely this isn’t right? My buddy has a mini brand new and it does 13 metres a second in sport mode so not sure what’s happening

Please provide a .DAT from after the IMU calibration.

The reason that the speed is limited is likely because the FC limits the pitch angle. Since there is a 12° pitch down bias the amount of pitch down that can be added is limited.

 

[boblui]

I don't actually know what the IMU calibration accomplishes. Maybe my view that a calibration won't fix this is a sublimated form of confirmation bias. I've not seen a case where there is compelling evidence that a calibration fixed a problem. This is the first time I've seen an accelerometer bias this large. It's be interesting to see if that bias is removed or reduced.

About 4 years ago I did some experiments with my P3A. At the time many people thought an absolutely level surface was required for calibration. In my experiments the calibration was performed on a surface that was 5° off level. The subsequent flight tests did not show any drifting or erratic flight. With present day Mavics it's hard to even know what an absolutely level orientation would be.

Some accelerometer bias shouldn't be a problem. E.g., hovering isn't achieved by getting the X and Y accelerometers to show 0.0. The present flight illustrates this. Not withstanding the wind calcs problem there was no drifting, erratic flight, etc. The uncommanded altitude changes are a bit suspicious though.

It's possible that a calibration determines the noise profile of the accelerometers. Knowing this could be used to set the gains in the Kalman filters being used by the Flight Controller.

For my self-built FPV drones, it is actually necessary to have the accelerometer calibration done on a level surface. The remaining bias has to be trimmed out manually via the controller when flying. I am really curious about how it is done automatically in DJI's drone. In ATTI mode, my M2P hovers perfectly level without any drift and the flight log indicates that the pitch and roll are absolutely zero.

 

[Ryanmini]

Please provide a .DAT from after the IMU calibration.

The reason that the speed is limited is likely because the FC limits the pitch angle. Since there is a 12° pitch down bias the amount of pitch down that can be added is limited.

You want me to upload the day file from today’s flight?

 

[boblui]

I’ve done a imu calibration and still having errors, another thing is my MM only does 7 metres a second in sport mode surely this isn’t right? My buddy has a mini brand new and it does 13 metres a second in sport mode so not sure what’s happening

Likely because the flight controller was wrongly led to believe that the tilting limit is reached so it did not accelerate further. The log will tell why.

 

[Ryanmini]

heres my flight records from today not sure which one you need i flew a couple times different locations i shall add both times, there was no wind maybe on second flight a little but on my buddys mini no wind warnings but i got my normal errors lol

 

[BudWalker]

heres my flight records from today not sure which one you need i flew a couple times different locations i shall add both times, there was no wind maybe on second flight a little but on my buddys mini no wind warnings but i got my normal errors lol

Thank you, It would appear that the X accelerometer bias was reduced some but is still significant. It went from -0.21 to -0.15. Inspecting the .DAT where the calibration was performed would be interesting. Can you provide that? It'll be a .DAT between FLY038.DAT and FLY046.DAT inclusive.

At this point it seems that your MM is not going to be fixed with an IMU calibration. You should consider sending it to DJI for repairs.

 

[Ryanmini]

sounds expensive lol, it flys ok not great just be nice to have it working perfect, I bought it second hand and I reckon the previous guy crashed it but never told me, not sure what files I’m looking for if I was honest

 

[BudWalker]

sounds expensive lol, it flys ok not great just be nice to have it working perfect, I bought it second hand and I reckon the previous guy crashed it but never told me, not sure what files I’m looking for if I was honest

The .DATs I'm requesting are just like the
2020-12-11_12-53-55_FLY046.DAT
you provided earlier. Except that these files will have names that end with FLY038.DAT, ..., FLY046.DAT

 

[Ryanmini]

I only have DATS 047,046,045
027-035

 

[Ryanmini]

this is when i turned it on the do a imu calibration yesterday but didnt fly the drone

 

[BudWalker]

sounds expensive lol, it flys ok not great just be nice to have it working perfect, I bought it second hand and I reckon the previous guy crashed it but never told me, not sure what files I’m looking for if I was honest

I've heard of pilots striking the AC to unstick an accelerometer. I wouldn't do that but you might want to. Since the X accelerometer is stuck on the negative side I think that means a sharp whack from the rear is required. The strike needs to be aligned with the X axis - not from above or side. If this breaks your MM even more I'm really sorry and hope you can fix it.

 

[Ryanmini]

So what give it a hit with my hand on the bottom of the drone lol ie where the battery goes in?

 

[BudWalker]

So what give it a hit with my hand on the bottom of the drone lol

No, not on the bottom - from the rear. Striking it from below will affect the Z accelerometer. You want to strike it in such a way that the MM will move forward along the X axis.

Using your hand is a relatively soft blow and likely not provide the acceleration required. That's the problem. Imparting enough acceleration to unstick the accelerometer, like a whack with a hammer, may crack the case or cause internal damage.

Let me repeat. I wouldn't do this. If this breaks your MM even more I'm really sorry and hope you can fix it.

 

[Ryanmini]

What if I was to do a imu calibration but tilt the drone so it’s a few degrees from flat on the back part?

 

[Ryanmini]

When I look on the top on the mini looks like it has taken a hit on the front left on top on the drone like the plastic has a little like plastic mark where you can tell it’s had a hit

 

[BudWalker]

@Ryanmini
take a look at this post
Unable to calibrate IMU
and also this one
Unable to calibrate IMU

 

[Deleted member 103366]

I have done the 'jar the drone' thing with a P3adv that had a stuck accelorometer and it did work but from memory I used the heel of my hand either open handed or with a clenched fist.
If you can work out which way it is stuck orientate it so that gravity aids your attempt, I seem to remember doing that with the P3 but it might have been limited to fore & aft vs side to side.

 

[Ryanmini]

So from a previous post, it’s found that my x axis one is out by -0.15, is that a lot? So do I face the mini towards the floor and give it a hit with my hand at the back where the battery gets inserted? Then redo a imu calibration and it could fix my issues?

 

[BudWalker]

So from a previous post, it’s found that my x axis one is out by -0.15, is that a lot? So do I face the mini towards the floor and give it a hit with my hand at the back where the battery gets inserted? Then redo a imu calibration and it could fix my issues?

Yes, 0.15 is a lot. It doesn't matter what the orientation is. But, when it's jarred, hit, whacked, etc it has to be along the x axis. Striking the battery from above or side won't do it. The strike has to be such that the MP1 would move forward along it's x axis if you let it.

Another method would be to hold the MP1 vertically in your hand and then strike a desk top by bringing the MP1 straight down. Try a light tap and see what that gets you.

No need to do a calibration. Just start the Go App and look at the IMU Accel values.

 

[Ryanmini]

Where do I find the imu accel values?
I’ve got a Mavic mini, and use the fly app