声速不确定条件下的运动水下航行器自定位

Moving underwater vehicle localization with uncertain sound speed

传统利用水下声学定位系统的航行器自定位存在两方面问题,一方面没有考虑测量周期内航行器的运动,另一方面没有考虑水声声速的不确定。为解决上述问题,构建了航行器运动状态下的时间测量定位模型,并对声速不确定性进行建模。分别推导了基于加权最小二乘的运动航行器定位方法和基于最大似然估计的声速更新方法。利用所提模型和时间测量,不仅可以估计航行器位置,还可以更新声速。仿真结果验证了本文所提方法在各种参数设置下均优于现有方法,并且在时间测量噪声不大时可以达到克拉美罗下界(Cramer-Rao lower bound, CRLB),在时间误差不大时,声速更新结果显著提高。

The traditional localization of vehicle using an underwater acoustic positioning system has two problems.One is the motion of the vehicle during observation period is ignored,and the other is that the uncertainty of underwater sound speed is not taken into account.A time measurement model for localization is constructed for the vehicle in motion,and the uncertainty of sound velocity is modeled to solve the above problems.A localization method for the moving vehicle is derived based on weighted least squares estimator,and a sound speed update method based on maximum likelihood estimator is proposed as well.Apart from estimating the vehicle position,the proposed model and the time mesurement are able to update the sound speed.The simulation results verify that the proposed methods outperform the existing methods for various parameter settings and achieve Cramer-Rao lower bound(CRLB)when the time measurement noise is not large.Moreover,the performance of the sound speed update is significantly improved when the time error is not large.