In many applications there is a need to have a complete sensing system to measure rotation, acceleration, … in all 3 axes. The Inertial Measurement Unit (IMU) is a set of gyroscopes and accelerometers (and also possibly magnetometers). The set of sensors are structured in a 3 axes orthogonal system. The set of 3 dimensional Gyroscopes need a special calibration process.
GyrOptics is engaged in an IMU project. Our R&D researchers make some successful first models.