Error Analysis Of Rotating Accelerometer Based Gravity Gradiometer

Gravity gradiometer with rotate accelerometer is a high-accuracy instrument. Accelerometer is the main sensing element to measure gravity gradient, it takes advantage of rotation- modulation and common mode rejection to offset the deviation of accelerometers, in this way, gravity gradient could be measured. Some theories about gravity gradiometer with rotate accelerometer are studied in this paper:1. Based on physical implications of gravity gradient and the most fundamentals of equation of motion, with the help of Newton second law and relational knowledge of field theory, dynamics. We deduced measuring equation and formed the model of gravity gradiometer with rotate accelerometer. At last, we interpreted the concrete physical meaning of each term in measuring equation.2. Taking error source in the measuring system into account, we derived the propagating equation of the errors. Based on the model of gravity gradiometer with rotate accelerometer, the propagating rule of position error and angle error in screwing accelerometer on the disk, the propagating laws of measurement error in angular velocity are derived. The influence of matching level between acce lerometers is also studied. All studied above lead a guidance to offset the error source’s influence, give assistance in developing gravity gradiometer.3. To demodulate signals with gravity gradient, two methods of demodulation, namely integral demodulation and solve equation set demodulation with method of least squares is put forward. We also proved the important role demodulation methods played in the measuring system.4. With the help of simulink of matlab, the paper analyzed performance of the two methods mentioned above. The result of simulation with matlab shows that integral demodulation works better than solve equation set demodulation. Q uantitative interpreted the effect of higher order terms to the measurement of gravity gradient, and the effect is verified by simulation.