Z axis rotation angle with Razor IMU, without magnetometer

Hi,

I have a big problem and I will try to explain it as precisely. In my project IMU is sensing head, I only use it for measure angles (yaw, pitch, roll) in reference to base values, which are set when my device starting. For example I put IMU on the table, and turn on device. This position is base (yaw: 0, pitch: 0, roll:0), then if I move IMU in other place (but without any rotations) i should get (0,0,0) too, but when i rotate this in one of planes I should get measurement of rotation angles. I don’t need North direction, but when I turned off magnetometer there was some kind of drift (value of Z axis grows up in constant time intervals, about 1 degree in 2 seconds), because it’s using to drift compensation. I have to turn off magnetometer, because my device will be use in room, where ceiling, walls and floor are made from steel, and it will measure orientation of metal objects, that always will be place in different places. In this conditions I can’t do compensation of soft iron distortions, it’s completly irregular. So my question is: can I measure Z angle rotation without magnetometer? In few last days i read some articles, and posts on a few discussion forums and I tried to calculate this from accelerations of X and Y axes, but this didn’t solved my problem. I will grateful for help, thank you in advance.

can I measure Z angle rotation without magnetometer?

Only if you have some other directional reference.

All gyros drift, and the drift rate depends on temperature. Some sort of reference is required to counteract that drift.