Research On Calibration Table Of Three Axis Accelerometer

In basic scientific research, the sensor plays an important role. Almost every modern project can’t be separated from a wide variety of sensors.The calibration of the three axis accelerometer is of great significance to the research and development of the accelerometer. At the present stage, there is no exact standard for the calibration of the three axis accelerometer. At the present stage, the three axis accelerometer is calibrated by the calibration method of the single axis accelerometer. This method can only get single axis direction of the three axis accelerometer. The coupling sensitivity between three shafts can’t get, and the method needs to be carried out three times, which is not only time consuming, but also has the installation error. So it is of great significance to study a test rig which can calibrate three axes of three axes simultaneously.According to the production standards of the three axis accelerometer at the present stage, the design requirements of the calibration table are determined. According to the relationship between the different sensors and their transverse sensitivity, two different vibration exciter installation schemes are designed: a fixed mounting base and an adjustable mounting base. According to the working conditions at the present stage, the fixed installation method can meet the design requirements of the calibration table when the transverse sensitivity of the sensor is greater than 2%. when the transverse sensitivity of the tested sensor is less than its geometric sensitivity 2%, adjustable mounting base can meet the design requirements of calibration station.In order to realize the simultaneous vibration of the three axes of the three axis calibration table, and without mutual influence, a mechanical decoupling structure based on the plane air bearing is designed. Through the Adams motion simulation, the three directions of motion are independent of each other, which proves the decoupling of the structure. Through the analysis of the stress and strain by the ANSYS, the rationality of the design is proved. According to the result of the modal analysis and the design requirements of the calibration stage, it is showed that the calibration table does not appear resonance in the work.In order to reduce the friction force in the mechanical decoupling structure and to prevent the damage caused by fatigue damage, the static pressure support is applied to the mechanical decoupling structure. By analyzing the difference between the gas film stiffness and bearing capacity of different throttle forms, a new type of porous throttle with large stiffness and uniform pressure distribution is chosen. According to the design requirements of the three axis calibration table, a suitable plane air bearing is chosen.According to the basic principle of the absolute calibration and the comparison calibration, the calibration methods of the parameters in the static calibration and dynamic calibration of the sensor are described. In the calibration of accelerometers, because of the installation error and bias effect, an error model of three axis accelerometer calibration is built. An error model is established based on coordinate transformation method. And by using the least squares coefficient, the installation error and sensor sensitivity matrix is obtained.Through the research on the calibration method of the three axis accelerometer, two different design schemes are discussed for different standards of the sensor to be measured. A mechanical decoupling structure based on the plane air bearing is designed. And its rationality is verified. According to the bearing capacity of air bearing, a plane air bearing is selected. The error model of the calibration of the three axis accelerometer is established. The installation error coefficient and sensitivity matrix of the sensor are obtained. The above research results has laid a theoretical foundation for the experiment of the three axis accelerometer calibration table.