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Analysis and Comparison of the Vibration Correction Accuracy of Different Optimization Objectives for the Classical Absolute Gravimeter

Accurate absolute gravimeters are important instruments in applications, such as metrology, geophysics, and geological exploration. Vibration is one of the limiting factors that cause deterioration in measurement accuracy, which includes trueness and precision. The vibration correction method, in which a seismometer is used to record the vibration, provides an effective method to deal with the disturbances. The theoretical analysis shows that the ultimate correction accuracy is limited by the inherent frequency performance of the seismometer. The correction algorithm is an optimization problem to achieve this ultimate accuracy. The selection of the optimization objectives affects the correction accuracy dramatically. Although the real gravitational acceleration is unknown before the measurement is taken, minimization of the standard deviation of the fitting residual for a single drop (SDFRSD) is proven to realize better trueness. Enhanced precision is achieved through minimization of the Type A uncertainty of gravitational accelerations for all drops (UGAAD). Simulations and experimental measurements with the T-1 absolute gravimeter verify the theoretical analysis results. In addition, the results also show that the SDFRSD correction contains the real gravitational acceleration value, while the UGAAD correction exceeds the valid range. Therefore, the SDFRSD correction approach provides better comprehensive accuracy than the UGAAD correction method.