Crazyflie takes a very long time to lock IMU

[theseankelly]

Sometimes, it takes a very very long time (over a minute) before my crazyflie finishes the IMU init (and the red led starts pulsing faster).

I think, but am not certain, this has to do with when I'm trying to take off from unlevel surfaces like the ground, or a pile of papers on my desk.

[tobbeanton]

This is something that came with improved bias calibration, and I agree, now it is way to conservative. It is the GYRO_VARIANCE_BASE constant that needs to be increased to relax the calibration threshold.