Question on MPU6050

Hi,

I tried to use MPU6050 for motion detection. But when I setup the device and use the Jeff's library, there are some offset(acceleration x,y,z and gryo x,y,z) I need to set for each MPU6050.

I tried the value comes with the library, tried the auto calibration code and tried random numbers, all of them finally give me the same number for world acceleration value. I am a little confused: Does the offset really matter?

Another thing about the world acceleration. For my understanding, if I don't move the device, the x, y, z value of world acceleration should be close to 0. That is the good value I got when I put the device flat( the chip face up). However, when I turn the device vertical, I got error on z value, constant error around 800, and the error is affected by the angle of the device. I am guessing it is the compensation of the gravity not absolutely accurate. How can I adjust it?

Any other device recommended for world acceleration?

Thanks

catccaatt: For my understanding, if I don't move the device, the x, y, z value of world acceleration should be close to 0.

No. Accelerometers actually measure FORCE, not acceleration. Therefore, if the device is sitting still it will show you a non zero value in the direction normal to the face of the Earth due to the FORCE of gravity.

P.S. What does "world acceleration" mean?