移动平台超短基线阵实现水下目标高精度定位

High-precision acoustic localization of underwater target for mobile platform using ultra-short baseline array

针对自主式水下航行器如AUV(Autonomous Underwater Vehicle)等水下移动平台,提出了一种超短基线多元阵的快速收敛的高精度声定位方法。通过对比超短基线多元阵定位误差的克拉美罗下界,对阵型结构和阵元数目进行了优化,确定优化的阵列为9元立方阵;融合移动平台行进过程中的多次定位结果,进一步降低定位误差;并利用梯度下降法实现平台轨迹优化,使得系统最快收敛到需要的定位精度。仿真结果表明,在1000 m距离内,利用优化轨迹可以将定位均方根误差快速收敛至预设的0.2%以内.此外,对于海试实验采集数据的目标定位结果显示,对距基阵约700 m及400 m的目标,5元阵定位标准差相较4元阵缩小了约2 m及1 m,验证了多元阵定位方法在实际海洋环境中的有效性.

Based on underwater mobile platform like AUV(Autonomous Underwater Vehicle),a fast convergence and high accuracy acoustic localization method using ultra-short baseline multi-element array was proposed.The CramerRao Lower Bounds(CRLBs)of different USBL multi-element arrays were compared to optimize the array structure the number of elements,which achieves that a 9-element cubic array should be optimal.Multiple localization results of the moving platform were combined to further decrease the localization deviation.And the gradient descent method was used to optimize the trajectory of the platform so that the system can converge to the required localization accuracy as soon as possible.The simulation results showed that the Root-Mean-Square(RMS)error of localization can be fast reduced to a required value of 0.2%within a distance of 1000 m by using optimal trajectory.Moreover,the effectiveness of the localization method using multi-element array in practical oceanic enviroment were verified by sea trials results which showed that for the targets about 700 m and 400 m away from the array,the standard deviations of localization with a 5-element array are 2 m and 1 m lower than that of a 4-element array respectively.