Calibrating nonlinearity coefficients of a nano-g accelerometer by dual-frequency excitation on a shaker

Abstract

Nano-g accelerometers are utilized extensively in high precision applications, such as gravity measurements on moving bases, which often face strong motion disturbances. Accurately-calibrated coefficients are crucial for suppressing their high-order error effects, but challenging to measure using conventional calibration methods. This paper presents an investigation into calibration of the nonlinearity coefficient of nano-g accelerometers on a horizontal shaker driven by a dual frequency signal. A nonlinear output component occurring at the low difference frequency, with a high signal-to-noise ratio, is utilized. The calibration principle and strategy are investigated, along with an analysis of the potential experimental error sources. Two critical accompanying systematical errors, arising from shaker’s movement distortion along the primary vibration direction and gravity coupling of input acceleration caused by the guide rail deflection, are identified and eliminated through a proposed procedure. Experimental tests demonstrate an uncertainty level two orders of magnitude better than the traditional method based on the dividing head.