Normally, there are several types of sensors available, but most use 9DOF packages (3-axis gyroscope, accelerometer, and magnetometer) gyroscope: fast over-sam

Normally, there are several types of sensors available, but most use 9DOF packages (3-axis gyroscope, accelerometer, and magnetometer) gyroscope: fast over-sampled low-pass filter, but slowly drifts compounding heading errors accelerometer: relatively stable, but dead-reckoning errors compound quickly magnetometer: best stability, but low-sample rate and vulnerable to metal/magnets fooling/blinding the sensors The fusion algorithms usually weights which data is consistent with the motion path, and attenuates the estimated pose errors. Notably, not all sensors are equal quality, but there are probably better options now. =3