Quantitative Analysis of the Effects of Environmental Magnetic Field in Gravity Gradient Sensing

Magnetic field affects the sensing performance of rotating accelerometer gravity gradient instrument (RAGGI) used for airborne mineral exploration and gravity-aided navigation. This article studies the error introduction mechanism of the RAGGI measurement platform caused by the environmental magnetic field. It clarifies the inseparable function relationship between gravity gradient and magnetic gradient based on the magnetic-feedback-accelerometer RAGGI measurement principle. The RAGGI gravity gradient sensing output with environmental magnetic field quantitative analysis model is proposed and established. The experimental verification scheme of moving a ferromagnetic gravitational source for generating the gravity gradient anomaly and magnetic gradient anomaly simultaneously is set up. The experimental results witness that by lowering the magnetic sensitivity coefficient of the four accelerometers from >10 to < 0.1 V/T, the proportion of RAGGI output caused by magnetic gradient anomaly is successfully decreased from >56% to < 1% and verifies the effectiveness of the proposed error correction output model.