Attitude and Heading Reference Systems
From Wikipedia, the free encyclopedia
Attitude and Heading Reference Systems (AHRS) are 3-axis sensors that provide heading, attitude and yaw information for aircraft. AHRS are designed to replace traditional mechanical gyroscopic flight instruments and provide superior reliability and accuracy.
AHRS consist of either solid-state or MEMS gyroscopes, accelerometers and magnetometers on all three axes. Some AHRS use GPS receivers to improve long-term stability of the gyroscopes. A Kalman filter is typically used to compute the solution from these multiple sources. AHRS differ from traditional inertial navigation systems by using magnetometer and/or GPS data to correct the raw gyroscopic data.
AHRS have proven themselves to be highly reliable and are in common use in commercial and business aircraft. Recent advances in MEMS manufacturing have brought the price of FAA certified AHRS down to below $15,000. AHRS are typically integrated into Electronic Flight Information Systems (EFIS), which are the central part of so-called glass cockpits. AHRS are often combined with air data computers to form an "air data, attitude and heading reference systems" (ADAHRS), which provide additional information such as airspeed, altitude and outside air temperature.
