Three-position characterization for the adjustment of MEMS accelerometer scale factor

Abstract

Up/down static and the six-position least squares calibration methods are commonly used in research conducted on adjustment of the micro-electromechanical systems (MEMS) accelerometer scale factor (or sensitivity). When applying these methods, it is difficult to adjust the accelerometer measuring axis parallel to the gravity direction, causing an error in the accelerometer scale factor. In this paper, a three-position scale factor characterization that does not require corrections of the precise coincident of the measuring axis with the direction of gravity is studied. The method uses the up/down calibration method to obtain the coarse scale factor and bias. The coarse adjustment coefficient is then used to convert the accelerometer output data in the horizontal, up, and down positions into acceleration. The horizontal acceleration is used to estimate the scale factor error. Next, the estimated scale factor error is used to modify the coarse scale factor, producing a more accurate scale factor. The adjustment results from simulation and experiments on triaxial MEMS accelerometers show that the proposed method can effectively correct the scale factor error caused by inability to align the accelerometer measurement axis parallel to the gravity line, with a relative scale factor error of 0.07%, improving the accuracy of the accelerometer scale factor.