磁力计3轴不共点对水下磁定位精度的影响

Effect of three no-co-point axes in a magnetometer on underwater geomagnetic localization precision

水下磁异常定位新算法是将水下地磁异常等效为一个偶极子磁性目标,由测得的目标磁场大小及梯度确定水下载体相对于目标的位置,再运用同时定位与构图算法实现载体定位的方法.根据10磁力计测量目标磁场大小及梯度的计算公式,分析了水下磁定位异常算法中目标磁场大小、梯度及载体定位等固有误差,理论分析与数值仿真给出了其与测量基线长LX间的关系,分析和仿真结果均表明此固有误差与LX的平方成正比,当LX趋于零时可忽略.σ1及σ2是描述实际磁力计3个轴线不共点的参数,给出了10磁力计的2种放置方式,理论分析和数值仿真了目标磁场大小、梯度及载体定位误差与σ1和σ2的关系,分析和仿真结果均表明在第2种放置方式下误差比较小,与固有误差相当,载体定位精确;而在第1种放置方式下,误差较大.因此,在水下磁异常定位中应选用10磁力计的第2种放置方式.

In new underwater localization method based on geomagnetic anomaly,the position relative to targets of underwater vehicles is determined by magnetic field magnitude and gradients of targets.Then the exact position of the vehicles scan be achieved by SLAM （simultaneous location and mapping） algorithm.According to the equations of magnetic field magnitude and gradients measured by ten magnetometers,the inherent errors of magnetic field localization algorithm are analyzed.The relationship between the errors of magnetic field magnitude,gradients,position of vehicle and LX are studied theoretically and simulated numerically.The results all show that the inherent errors increase rather linearly with L2X,but they can be ignored when LX is close to zero.The parameters 蟽1,蟽2 are used to describe the distances among adjacent sensitive axes of magnetometer.Two kinds of configuration modes about ten magnetometers are given,and the relationship between the errors of magnetic field magnitude,gradients,vehicle localization and 蟽1,蟽2 are analyzed theoretically and simulated numerically.The results show that these errors are bigger in the 1st placement mode compared to the 2nd one,however,these errors are only inherent errors in the 2nd one and the position of vehicle can be determined precisely.So,it is reasonable that the 2nd configuration mode of ten magnetometers is selected.