Qian Xuewu, Zhao Liye, Liu Weiming, Sun Jianqiang
School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China.
School of Automation and Electrical Engineering, Linyi University, Linyi 276000, China.
Sensors (Basel). 2021 Mar 9;21(5):1925. doi: 10.3390/s21051925.
The output model of a rotating accelerometer gravity gradiometer (RAGG) established by the inertial dynamics method cannot reflect the change of signal frequency, and calibration sensitivity and self-gradient compensation effect for the RAGG is a very important stage in the development process that cannot be omitted. In this study, a model based on the outputs of accelerometers on the disc of RGAA is established to calculate the gravity gradient corresponding to the distance, through the study of the RAGG output influenced by a surrounding mass in the frequency domain. Taking particle, sphere, and cuboid as examples, the input-output models of gravity gradiometer are established based on the center gradient and four accelerometers, respectively. Simulation results show that, if the scale factors of the four accelerometers on the disk are the same, the output signal of the RAGG only contains (4k+2)ω (ω is the spin frequency of disc for RAGG) harmonic components, and its amplitude is related to the orientation of the surrounding mass. Based on the results of numerical simulation of the three models, if the surrounding mass is close to the RAGG, the input-output models of gravity gradiometer are more accurate based on the four accelerometers. Finally, some advantages and disadvantages of cuboid and sphere are compared and some suggestions related to calibration and self-gradient compensation are given.
采用惯性动力学方法建立的旋转加速度计重力梯度仪（RAGG）输出模型无法反映信号频率变化，对RAGG进行校准灵敏度和自梯度补偿效应研究是其发展过程中不可省略的重要阶段。本研究通过在频域中研究周围质量对RAGG输出的影响，建立了基于RGAA圆盘上加速度计输出的模型，以计算对应距离处的重力梯度。以质点、球体和长方体为例，分别基于中心梯度和四个加速度计建立了重力梯度仪的输入输出模型。仿真结果表明，若圆盘上四个加速度计的比例因子相同，RAGG的输出信号仅包含(4k + 2)ω（ω为RAGG圆盘的自旋频率）谐波分量，其幅值与周围质量的方位有关。基于三种模型的数值模拟结果，若周围质量靠近RAGG，基于四个加速度计的重力梯度仪输入输出模型更精确。最后比较了长方体和球体的优缺点，并给出了与校准和自梯度补偿相关的建议。
