Does anyone know how the Invensense's 9x fusion algorithm works? I found that in the code there is a parameter which represents the accuracy of the magnetometer data and it is in the range between 0 to 3(from lowest accuracy to highest accuracy). And I can't get the absolute orientation when the accuracy is 0, 1 or 2. In that case, the MPU only gives me the relative orientation, which means I can only know how many degrees it passes from the initial position. Is this a problem?
In my opinion, it looks like the MPU only uses a 6x fusion algorithm when the accuracy of magnetometer is not 3. I don't if it is my code's problem or that's how the MPU works.