Highly erratic IMU

[theseankelly]

Hey Community

Got a crazyflie 2.0 for Christmas and have been playing with it for a few days. All firmware/code is up to date for the radio, client, copter, etc.

I've gotten a couple good stable flight sessions out of it, but the vast majority of the time, the IMU goes way out of whack. Here's a typical flow of operation:
1) Power on the crazyflie, ensuring the copter is sitting flat on a level surface (for the initial IMU calibration)
2) Connect via the client in the VM.
3) Observe the pitch/etc in the graphical display to be pretty level. Slightly off, but nothing abnormal.
4) Take off, fly for a short while (I've gone as long as 45 seconds)
5) Usually, crash land. Sometimes I've set it down moderately gently and seen the same effect. On a few rare occasions, I've seen this seem to materialize mid flight for no apparent reason.
6) IMU is now way out of whack. The GUI shows a pretty consistent drift along all axes, even when the copter is sitting stationary. The speed of the drift is proportional to the degree of impact the copter saw on the landing.
7) Copter is totally unflyable until I power it off and return to step 1.

I understand that some degree of IMU drift can be introduced by impact, but this seems extreme based on the devices I've interacted with before. I essentially have to power cycle the entire copter every single time I want to take off.

This is also observable when flying from the iOS app, though there's obvious no GUI to visually observe the gyro drift. I just see the same erratic takeoff behavior after a landing of any sort. Power cycle required.

Is this normal for the crazyflie or is something wrong with my sensors? I seem to recall a time when I was able to fly a few times in a row without a power cycle, but I'm not positive.

Thanks
Sean

[theseankelly]

I suppose I don't actually know whether the crash landing causes the imu behavior, or whether the imu goes crazy and causes the crash. My crashes are usually a pretty severe dip/flip and I've been assuming it's due to air currents backfiring from nearby objects and walls, but maybe its the imu causing it...

[theseankelly]

Some updates -- I've done some experimenting and I'm now pretty sure the IMU drift/error is the cause for my crashes, not vice versa.

I've taken videos of a few examples.

Exhibit A: https://onedrive.live.com/redir?resid=4 ... ideo%2cmp4
In this video, I connect to my crazyflie and demonstrate that the orientation appears correct according to the GUI and adjusts responsively as I move the copter around. I then hold the copter in my hand and apply thrust. You can see the orientation in the GUI drift quite dramatically. After releasing thrust, the orientation doesn't correct itself and the orientation doesn't seem to change based on the actual motion of the copter.

Exhibit B: https://onedrive.live.com/redir?resid=4 ... ideo%2cmp4
In this video, I perform a thrust-only takeoff (with no trim applied) in a wide open area with no fans, air vents, etc. The copter almost immediately inverts itself and slams into the ground.

Exhibit C: https://onedrive.live.com/redir?resid=4 ... ideo%2cmp4
Same scenario as B. This time the copter dips drastically and slams into the wall (off camera). I made sure to take video of the GUI before and after -- same general effect: Weird IMU drift, and not really responding to real time movements of the copter any longer.

I'm on the latest firmware for everything (2015.08.1 for the copter, 0.53 for the crazyradio PA, latest sync/build of the python client). I was very careful to make sure my props were balanced using the needle method (I found four which didn't require tape) and I've double checked them after these videos; they're all well balanced. Please help -- I fear for my dog's life!

[theseankelly]

Aha! I found the following error output in the console:

"I2CDEV: Error callback nr: 1024"

This error is seen at the exact moment the orientation view starts drifting. Definitely the cause.

Sounds like this is possibly a known soldering defect, as referenced here?? Please help.
viewtopic.php?f=5&t=1162

Also, I realized I posted this on the wrong board. Would love it if someone could move this entire thread to the support forum.

[tobias]

@theseankelly Sent you a PM

[theseankelly]

Thanks, Tobias and Bitcraze, for the quick resolution. Replacement board flies like a dream.