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Application of accelerometer in AHRS

Item No.: WLS089
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Application of accelerometer in AHRS
+ 5g to + 15g
Excellent bias stability (less than 0.05% of full scale)
There is no low temperature coefficient under T calibration
Ultra small 20 lead LCC hermetic ceramic package
Package size (8.9mm, x, 8.9mm)
low power consumption
Undervoltage protection
Lead free soldering in line with RoHS standards
The inertial navigation is by self-contained accelerometer and gyroscope to calculate the position and speed of object (e.g. a plane). Attitude and heading reference system, which is AHRS, is to provide direction, multi axis sensor and yaw attitude information, so that the aircraft or any other mobile objects in free space.
The AHRS is designed to replace the traditional mechanical gyroscope flight instrument, and provide superior reliability and accuracy. All three axes are not solid or MEMS (microelectromechanical systems) gyroscope, accelerometer and magnetometer. Using GPS receiver AHRS, to improve the long-term stability of gyroscope. The Calman filter usually from these the source of composite were calculated.
Function of each component
The strapdown inertial navigation system requires an initialization process to establish a body frame and the relationship between the local geographical parameters. This is called the calibration process usually requires the equipment stable, because it takes time to build the initial state. During initialization, the strapdown inertial navigation system by self calibration technique to measure (horizontal) induction the acceleration and speed level, the local level coordinate axis calibration, to determine the initial (azimuth gyro compass). If we can know the initial posture of the aircraft, and provides the perfect reading attitude gyroscope, so the processor can work smoothly. However, little is known about the initial attitude, but also often because of gyroscope when the start-up bias drift and instability provides corrupted data.
Gyroscope and acceleration are also affected by bias and offset drift, as well as misalignment axis error problems, acceleration problems (sensitivity to acceleration g), nonlinear effects (two
The influence of a scale factor error. Magnetometer is also vulnerable to damage by measuring magnetic disturbances in the earth's magnetic field. These errors are calibrated in the final assembly step of the system installation, VRE
The maximum error of AHRS in bias gyroscope. The structure without any filter, separate accelerometer, gyroscope and magnetometer measurements, attitude processors tend to deviate from the true trajectory.
The Calman filter attitude correction component is adopted to support the correction of the trajectory of gyro's attitude processor and
The characteristic deviation state of the gyroscope provides a method of in-flight calibration
To support the attitude benchmark, magnetometer uses the earth's magnetic field vector to provide a heading reference
Application specification
Application of accelerometer in AHRS
In general, the accelerometer's role in AHRS applications is to provide initial attitude reference (horizontal) and provide attitude correction during flight to correct gyro drift
Nowadays, various AHRS solutions are available in the market:
The system with high accuracy using ring laser gyro (RLG) or fiber optic gyroscope (FOG). They need to be very accurate, because they are often used in automatic flight mode, only enough to prevent a collision in precise landing on the ground of large aircraft wing during takeoff and, especially in fog and extreme weather conditions more important. For this type of application, usually need to use the acceleration bias stability is better than 2mg or more in all conditions, including temperature range, linear, two order effect and non alignment error of the axis.
The low end of the AHRS can be used as a common sight of the pilot aid, or as a backup system, usually does not require good performance. Often use AHRS in this type of civil aircraft and some small UAV. In these cases, often using low-end MEMS accelerometer and gyroscope. The scope of application of MEMS on accelerometer in the face. On the performance of high-end and medium AHRS is normally required for 10G to 15g, and often use the 5g sensor for low-end solutions.
Attitude alignment system of COLIBRYS accelerometer
The main parameters of the best AHRS performance is critical to bias stability (1), the scale factor stability, non alignment error of the axis, and the stability of two order nonlinear effect or VRE (vibration correction error). The initial deviation of most of these parameters, from their expected values can be easily calibrated. However, the main problem is repeated and stability, long time working temperature, after the shock and vibration. These effects may lead to unpredictable drift, which will in turn effect at different levels of the accelerometer.
Colibrys is a MEMS accelerometer suppliers, is committed to the military, aerospace market, and to determine the parameters of a large number of.MS9000.D series is the latest generation of products, LCC20 is Colibrys's flagship accelerometer MS8000 products to further improve the.MS9000 provide a smaller package, essentially the same MS8000 performance, but smaller in size.MS9010.D with 4.5mg (1 sigma) scale factors and long-term bias stability is better than 400ppm. This product can be used according to the requirements of 2G, 5g and 10g and 15g AHRS acceleration range.
Working principle
The core of the accelerometer is a silicon sensor.Colibrys large capacity capacitor micromachined accelerometer basic manufacturing technology is three. Three based on the structure of silicon wafer by silicon fusion bonding (SFB) fixed together. The bonding process, not only to ensure that a system of three wafers between the perfect balance, but also makes the to establish a spring mass system in an airtight seal cavity. The bonding process is in high temperature (>1000 DEG C) carried out under low pressure environment, to ensure that air damping and bandwidth control. It also makes the best to avoid any surface pollution, especially water molecules, and relax all the surface bonding material the surface of possible stress.
The measuring range of the system of spring quality "is a strong adaptability. Changes of open-loop measurement range, by changing the thickness of the spring. The moving mass changes caused by the lower electrode and the capacitance value in acceleration or tilt on. This induction differential capacitors change is measured by the interface circuit, which uses the self balancing capacitance bridge to convert the output signal voltage calibration.
Summary Colibrys is one of the best AHRS MEMS capacitive accelerometer.Colibrys has been committed to the development of new products and solutions. The development of manufacturing technology also encouraged MEMS sensor components and assembly process and related electronic products continue to improve, especially for the optimization of the bias stability ("operation" and "run to run" stability), by demand of countless AHRS suppliers.