I leave for Europe on Monday and am taking my drone but I replaced all 8 propellers and now the drone flies wonky. It takes off no problem but then moves on its own ... forward mostly, but doesn't respond to joysticks as it should. I've checked the "ridges" (Front right, back left" and it really looks like they are all installed securely and in their proper locations.

Help!


Thanks!

You've probably already done this, but.... IMU calibration?

No Original Thought Posted at 5-17 12:19
You've probably already done this, but.... IMU calibration?

I'm newish to droning and honestly had never heard of that until just now. That seems to have fixed it and you are a rockstar! Thanks so much!

Adronaline Junkie Posted at 5-17 12:45
I'm newish to droning and honestly had never heard of that until just now. That seems to have fixed it and you are a rockstar! Thanks so much!

Hi, Adronaline Junkie. We're glad that the issue has been resolved by performing the IMU calibration. In case you don't have the manual yet, you may download this PDF file: (https://dl.djicdn.com/downloads/ ... _Manual_v1.4_en.pdf). Should you need further assistance, don't hesitate to reach us here. Have a safe flight.

Adronaline Junkie Posted at 5-17 12:45
I'm newish to droning and honestly had never heard of that until just now. That seems to have fixed it and you are a rockstar! Thanks so much!

No problem. Glad it's fixed it for you.

No Original Thought Posted at 5-18 00:31
No problem. Glad it's fixed it for you.

Just curious, if the problem was not evident before the blade change why would an IMU calibration fix this and how/why would a blade change 'disturb' the IMU?

Were the installations A and B adhered to?

No Original Thought Posted at 5-18 00:31
No problem. Glad it's fixed it for you.

Seems like that was an original thought!!  : ). Great diagnosis from over the internet!

Sean-bumble-bee Posted at 5-18 04:33
Just curious, if the problem was not evident before the blade change why would an IMU calibration fix this and how/why would a blade change 'disturb' the IMU?

My understanding is that the blades are paired, but that does not mean that every pair is equal to every other pair.

If one pair is generating very slightly more lift /thrust than another that would result in the drone drifting.

As iI understand it it is the job of the IMU to identify when the drone is moving when it is not expected to be moving (and that it is moving in the direction relative to itself expected when it is supposed to be moving). Ie detecting movement via calhanges in inertial forces.

BUT, I cannot explain how IMU calibration actually works because that is done with the drone static and with the blades not spinning, so you are absolutely right to ask how it helps in a blade change situation.

All I know is that it has fixed similar srift problems before and makes sense when considering what the IMU measures .

I'd love to know how the IMU calibration actually works though, in relation to the drone in flight rather than the static drone with changed props.

No Original Thought Posted at 5-18 12:38
My understanding is that the blades are paired, but that does not mean that every pair is equal to every other pair.

If one pair is generating very slightly more lift /thrust than another that would result in the drone drifting.

Cheers, I think you'd need Dr in your name ( honorific ? )  to fully understand the workings of the IMU. Lol. Us poor numpties will just have to be satisfied with "It's

Sean-bumble-bee Posted at 5-18 13:08
Cheers, I think you'd need Dr in your name ( honorific ? )  to fully understand the workings of the IMU. Lol. Us poor numpties will just have to be satisfied with "It's https://www.youtube.com/watch?v=c2_xWTSyCuU

Hehehe....

Thinking about it, all that the IMU calibration can possibly be doing is teaching the done how it 'feels' to be static in the three positions (level, most up, and sleeping on its side).

If, when the drone expects to be stationary and level it finds it "feels'different then it knows it is moving out fighting movement through attitude changes.  .

So how's on earth does that feeling change when you change props...

Hmmmm ...

TonyPHX Posted at 5-18 09:55
Seems like that was an original thought!!  : ). Great diagnosis from over the internet!

I wish it was, but alas it's once again proof that there really is no such thing as original thought.

I'm only repeating advice I had read somewhere else for a similar problem. And as you can see from the diffusion that follows, I'm even now questioning why it works.

My understanding is that when you calibrate the IMU, you are actually resetting the stored parameter that keep the drone steady in lock position. By changing the blades, those stored parameter, were no longer true, so now the IMU is trying to keep the drone in the same place by applying the same parameters and it senses the movements, but it doesn't know that those movement are created by it own stored parameter, so he tries to compensate like it would do when things like the wind come into play... Problem is, every time it tries to go back to the stored parameters, there were once the good starting points, it starts to move again...

Practically the IMU or Gyro is blind. You need to calibrate it once to give him the understanding of what the object neutral positions are. Changing the blade it is like taking the IMU from one drone and installing into another drone, and expecting it to work like before... It can't do that...

Hope it makes sense...

Adronaline Junkie, could you post the log of a wobbily flight before the IMU calibration and stable flight after the IMU calibration?
Even better, if you do not sync your logs with DJI can you post the DAT flight logs from the screen device for those flights?  
The DAT flight logs from the drone itself are likely to be encrypted and unreadable but the DAT flight log from the screen device is readable.

Burt37 Posted at 5-19 00:42
My understanding is that when you calibrate the IMU, you are actually resetting the stored parameter that keep the drone steady in lock position. By changing the blades, those stored parameter, were no longer true, so now the IMU is trying to keep the drone in the same place by applying the same parameters and it senses the movements, but it doesn't know that those movement are created by it own stored parameter, so he tries to compensate like it would do when things like the wind come into play... Problem is, every time it tries to go back to the stored parameters, there were once the good starting points, it starts to move again...

Practically the IMU or Gyro is blind. You need to calibrate it once to give him the understanding of what the object neutral positions are. Changing the blade it is like taking the IMU from one drone and installing into another drone, and expecting it to work like before... It can't do that...

That makes sense.  Good to reason through it!

TonyPHX Posted at 5-19 13:17
That makes sense.  Good to reason through it!

With Gyros in helicopters there is always one calibration every start of a flight. I would have thought that the DJI gyro (or IMU) would have done the same, but perhaps because of the 4 rotors instead of one it is a different start up... Not sure