Identification Method of Sensor Directions and Sensitivities in Multi-Axis Accelerometer (Actual Measurement of Direction Tensor and Sensitivity Tensor)

概要

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An accelerometer has direction gaps between the package and the actual sensors in general. Conventional calibration methods of accelerometer, e.g. ISO standard, do not consider this direction gap. This study proposes a new calibration method. The method uses a new examination system with parallel link exciter mechanism. The exciter rotates a target accelerometer in a uniform circular motion and the posture of the accelerometer is kept constant against external coordinates. The required torque for the rotation is small and constant because the rotation components are balanced with counter weights. Therefore, the exciter applies a stable sine wave acceleration to the accelerometer. This method contributes not only the accuracy of input acceleration but also removing offset noise. In addition, the input acceleration is calculated only by one differential computation whereas ordinary mechanism requires second order differential. From the accelerometer output, a plane including actual sensor direction is detected by the sine curve profile. The direction of actual sensor is the line of inter section of two measured planes. For a 3-axis accelerometer, 2 times measurement is enough to determine all actual sensor directions and sensitivities with this method (1 time measurement is enough for a 2-axis accelerometer). Actual sensor directions and sensitivities are experimentally examined. The result is consistent with the data sheet of test accelerometer.