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AHRS, so-called Attitude Heading and Reference Systems, is said to be a 3-axis Inertial Measurement Unit (IMU) which is shared by a 3-axis magnetic sensor and an on-board processor to make a 3-axis sensor which is capable to measure yaw, pitch and roll of any moving object in a 3D space. Actually AHRS are designed to eliminate the need of heavyweight and traditional flight instruments of mechanical gyroscopic aircrafts and they also are reliable and flexible and provide better accuracy. The typical AHRS system contains either FOG fiber optic or 3-axis MEMS angular rate gyro triad, MEMS 3-axis accelerometer or a 3-axis magnetometer which is a magnetic sensor. By using these measurements, the orientation solution is calculated by an onboard filter. GPS is also used on some AHRS sensors in order to stabilize a drift of gyroscopes. On the basis of which, it provides more accurate calculations of inertial acceleration vector. How AHRS is made? The inertial measurement unit (IMU) is the calibration of AHRS. And this is available as a part or even a single drop in some cases and single-axis accelerometers and separate gyros are used to make this. In a sensor package, magnetic sensors are added which are capable to calculate the magnetic field vector. In addition, DSP or a 32-bit processor is included so that attitude estimation algorithm can get a platform. AHRS Systems at low cost Many companies in the market which provide low cost AHRS systems and sensors in the market like AHRS 500 and AHRS-8 and all of them use accelerometers, magnetometers and gyroscopes of MEMS. The types of algorithm of attitude calculation they use on their sensor make their AHRS systems low cost. Gyroscopes The typical gyros are used mainly on AHRS systems because the quality makes the big difference on overall performance of the sensor and its price. The AHRS of tactical grade uses fiber optic gyros so that it can provide most stable angular rate measurements. Due to low cost and power requirements, MEMS gyros are mostly used by AHRS manufacturers these days. The low end fiber optic gyros are comparable with higher performance levels with MEMS gyros. The latest automotive accelerometers are utilized by low cost AHRS sensors these days. Accelerometer: the solid-state silicon accelerometers are highly used in high end AHRS systems. In addition, the accelerometers are exceptionally very good for the long term. The tactical grade 2mg accelerometers also work better in operational conditions. Magnetometer: They are typically flux-gate magnetometers used on AHRS high-end applications and MEMS Anisotropic Magneto-Resistive (AMR) sensors. The high accuracy and flexibility are provided on exceptionally low non-linearity flux-gate magnetometers. Bottom Line Typically AHRS is used typically in one of three ways. First thing first, they can be used to provide recording of flight data as an instrument of the platform and orientation can be provided as the function of time. Secondly, they can work as platform stabilization. And finally, it can also be used as attitude control system. AHRS provides benefits to helicopters, aircraft, blimps, quad-rotors and even underwater unmanned submarines. Visit inertiallabs.com to know more about AHRS.
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