An AHRS (Attitude and Heading Reference System) provides 3D orientation by integrating gyroscopes and fusing this data with accelerometer data and magnetometer data. With sensor fusion, drift from the gyroscopes integration is compensated for by reference vectors, namely gravity and the earth magnetic field. This results in a drift-free orientation, making an AHRS a more cost effective solution than conventional high-grade IMUs (Inertial Measurement Units) that only integrate gyroscopes and rely on a very high bias-stability of the gyroscopes.
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Affordable MEMS AHRSs were introduced just after 2000, when inertial sensors prices dropped and accuracy improved, to enable the mass introduction of ESP, airbags and built-in car navigation. The improved inertial sensors were used by companies such as Xsens to design AHRSs that provide 3D orientation for a broad range of applications from human motion to navigation of unmanned vehicles and the stabilization of antenna and camera systems. The Xsens MTi 10-series and MTi 100-series are proven products in the industrial applications market place.
In order to cope with transient accelerations, magnetic disturbances and vibrations, the sensor fusion algorithm needs to be adapted for specific applications. Xsens offers the best performance by applying filter setting profiles that are optimized for the customer’s application.
To improve the AHRS performance under long-lasting accelerations and under conditions with severe magnetic disturbance, Xsens offers the MTi-G-700 GPS/INS. The MTi-G-700 uses GPS to determine accelerations and velocity, which can be used to make the referencing with gravity more robust, resulting in a robust roll and pitch. Using the heading and course of the GPS, it is also possible to retrieve heading without using the magnetometers.
The MTi-G-700 is often used in applications that are high-dynamic. Test results and testimonials can be found here:
Traditional IMUs (e.g. Honeywell, Sagem and Northrop Grumman/Litef) are used in many applications for navigation, control and stabilization. With the Xsens AHRSs, it is however possible to get similar performance in a smaller package allowing to use them in more applications, such as antenna and camera stabilization, small unmanned vehicles and even hand-held applications.
It also makes the use of orientation sensors possible where an orientation sensor had not been considered before. A few examples can be found at the Xsens website: