[SamcFuchs]

Originally Posted by GeeTwo

short answer: wheels slip.

Once the wheels have slipped against the carpet/floor/obstacle and you don't know how much, you can't reliably use the encoders (by themselves) to determine orientation. Gyros have more drift, but are not subject to this sudden loss of calibration.

Good point. I'm used to encoders because we use them for motion profiling, which you couldn't really do with a gyro.