​Orientation of the IMU in space
​Among the derived quantities, modifying the orientation of the IMU in space requires merging the information coming from the accelerometer and gyroscope within so-called "Sensor Fusion" methods.
However, due to errors due to the intrinsic noise of the components, the orientation calculated by sensor fusion methods is also noisy and subject to "drift". To overcome this, an additional sensor is normally used, the magnetic one, which allows the drift to be compensated over time. The magnetic sensor is similar to a 3D digital compass which is able to sense where the Earth's magnetic north is at any time. In this way this north becomes a constant reference for the IMU.
Electromagnetic disturbances
​Unfortunately, the magnetic sensor solves one problem but generates another. In fact, in order to function accurately, the magnetic sensor must not be in the presence of magnetic sources or in any case metal parts that are capable of modifying the magnetic field. It is difficult to describe a typical area of ​​our daily life that is free of metal, be they small screws or metal beams.
Mag-free algorithm
​Despite efforts in terms of algorithms and other tricks, there is no way to eliminate this problem completely, unless we completely remove the problem at the source: the magnetometer.
For this reason, in recent years Turingsense has developed and patented a so-called "mag-free" algorithm which does not use the magnetometer at any time to calculate the orientation of the IMU.
You can read the article below.
