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

Abstract

An accelerometer generally has direction gaps between the package and the actual sensors. Conventional accelerometer calibration methods, 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 a parallel linkage 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 counterweights. Therefore, the exciter applies a stable sine wave acceleration to the accelerometer. This method contributes not only to the accuracy of input acceleration but also to the removal of offset noise. In addition, the input acceleration is calculated only by one differential computation, whereas an ordinary mechanism requires a second order differential. From the accelerometer output, a plane including the actual sensor direction is detected by the sine curve profile. The direction of the actual sensor is the line of intersection of two measured planes. For a 3-axis accelerometer, measurement 2 times is enough to determine all actual sensor directions and sensitivities with this method (measurement one time is enough for a 2-axis accelerometer). Actual sensor directions and sensitivities are experimentally examined. The result is consistent with the data sheet of the test accelerometer.11. This paper is the full translation from the transactions of JSME, Series C, Vol.78, No.786, pp. 499-507, 2012.