The AHRS, called the Attitude Reference System, consists of a number of axial sensors that provide heading, roll and rollover information for the aircraft. These systems are used to provide accurate and reliable attitude and navigation information for the aircraft.
The attitude reference system includes a MEMS-based three-axis gyroscope, accelerometer and magnetometer. The difference between the attitude reference system and the inertial measurement unit IMU is that the attitude reference system (AHRS) contains embedded attitude data solution. Unit and heading information, the inertial measurement unit (IMU) only provides sensor data, and does not have the function of providing accurate and reliable attitude data. The currently used azimuth solution for multi-sensor data fusion using the internal attitude reference system (AHRS) The unit of calculation is a Kalman filter.
The heading attitude reference system can provide attitude information such as heading, roll and rollover. High-precision inertial navigation devices such as mechanical gyroscopes and fiber optic gyroscopes are expensive and difficult to be popularized. Currently, MEMS sensors are widely used in consumer electronics. However, the MEMS angular rate gyroscope has serious zero drift and random error. In the strapdown inertial navigation solution, integral error will be generated, which is difficult to achieve the accuracy of the application. The accelerometer and the magnetic field meter can measure the gravity acceleration and the geomagnetic field respectively. An uncorrelated three-dimensional vector can be used as an observation vector of the platform pose to calibrate the gyroscope. At the same time, the extended Kalman filter can combine the characteristics of these sensors to predict the update of the angular rate measured by the gyroscope, with gravitational acceleration and magnetic field. The observation is updated to obtain more accurate attitude angle information.
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