【作者】 成怡；

【导师】 郝燕玲；

【作者基本信息】 哈尔滨工程大学 ， 导航、制导与控制， 2008， 博士

【摘要】 研究融合多源重力数据构建高精度海洋重力图是重力辅助导航系统的关键技术之一,海洋重力数据库是水下重力导航系统的基本依据。重力场局部特征是否明显、重力数据的精度和位置分辨率是否满足要求直接决定着重力辅助导航系统能否正常工作。卫星测量、航空测量及船上测量三种重力测量方式产生的重力数据,它们有其各自的优点和适用范围,反映着不同频段的重力信息,联合多种数据源建立重力数据库可弥补单一测量方式测量范围有限的不足,同时也引出了不同测量方式下的数据融合问题。本文的研究目标就是分析如何融合卫星、航空、船上重力测量数据获得高精度、高分辨率的海洋重力图。论文的主要内容有:总结了地球重力场的特性及其中各扰动量的定义,分析了三种海洋重力测量方式各自的测量原理和海洋重力数据的计算方法,即卫星测量的原理及卫星测高数据反演海洋重力异常的方法,航空重力测量的基本框架及向下延拓技术,船测海面重力的特点和其解算方法。这些是研究融合多源海洋重力数据融合的前提。对移去—恢复技术进行了详细的剖析,在移去-恢复技术的通式的基础上研究了它的两个基本原理:梅森原理和Helmert压缩原理,即对移去-恢复中的重力场模型贡献和地形的直接影响和间接影响的解算。讨论了移去-恢复技术在卫星测高数据反演海洋重力场及航空重力数据向下延拓中的应用,并通过航空重力数据向下延拓为例详细地分析了移去-恢复技术的作用。研究测量高度和地形效应对向下延拓的影响,提出有效的解决方案,并分析了它对测量误差的适应程度。针对海洋重力场这一特殊的应用环境,分析了水深对海洋重力场的影响,提出用船测重力数据结合先验水深特性,通过最小二乘配置过程估计局部水深模型的思想。提出由重力数据计算的协方差函数作为经验协方差函数,用局部逼近的方法逼近最小二乘配置中用到的协方差函数,从而计算其相应的协方差矩阵,估计局部水深模型。提出将估计水深模型的RTM改正应用到移去—恢复技术中去,代替传统的Helmert方法。并通过大量的试验评价估计的局部水深模型对局部水深特性的描述情况,以及RTM改正在移去—恢复技术中的应用效果。研究卫星测高的重力数据、航空向下延拓的重力数据、海面直接测量的重力数据融合方法。通过对球谐函数的分析,并在利用残差重力异常计算球谐函数系数改正项的基础上,提出了修正局部重力场的球谐函数系数的融合算法。并通过实验评价了该融合算法的效果。分析局部重力数据网格间距和水深RTM改正对融合多源重力数据的影响,并将融合后的重力图应用到重力辅助导航的匹配算法中去,在实验海区内对比于船测重力数据,分析融合后的重力图匹配效果。实验结果表明,既使在局部重力数据网格间距相对较大时,融合后重力图对比船测重力图在匹配上包含更多的局部特征。更多还原

【Abstract】 Research on combining heterogeneous gravity data to construct high accuracy marine gravity map is a key techqiue of gravity aided navigation system, marine gravity map is the basic of gravity aided navigation system. Whether the local characters of gravity field is obvious and whether the accuracy and resolution of gravity data meet the demand directly decides if the gravity navigation method works well. There are three kinds of gravity data: satellite altimetry data, airborne gravity data and shipboren gravity data, but they have their own advantadges and applying area, describe different frequency gravity information. Combination heterogeneous gravity data can make up the only measurement area limitation, however, which arise the problems in how to combine the gravity data from different measurent manners. In this paper, how to combine satellite altimetry data, airborne and shipborne gravity data is studed.The geopotential characteristics and the definition of disturb vectors are summaried, meanwhile, the survey principles and computation method of three marine gravity measurement manner are introduced. That is, the principle of satellite measurement and the method of using satellite altimetry derive marine gravity anamoly, basic rule of airborne gravity measurement system and the downward continuation technique, ship-borne measurement characteristics and its computation method. These are the preconduction of the research on the herogeneous marine gravity combination.The remove-restore technique is analysised in detail. Based on the general formula, the two basic principles Meissl scheme and Helmert condensation scheme are studied. They are used to compute the geopotential model attribution and the terrain directive and indirective influence. The application of remove-restore technique to the satellite altimetry derived gravity and downward continuation of airborne gravity is researched. By the example of airborne gravity, the performence of remove-restore is demonstrated. To analysis the influence of height and terrain to the downward continuation, the effective method is presented to resolve the influence. And its adaptive ability to the noise data is also studied.For the marine gravity field is a special application, the relationship between depth and gravity is studied. The ideal that using ship-borne gravity data and the pri-depth information to estimatie local depth model by least squares collocation (LSC) is presented. Set the covariance computed by gravity data to be the experience covariance to approach the covariance used in the LSC, and to compute the corresponding covariance matrix for estimating depth model. The RTM correction of the estimated model is applied to the remove-restore technique to substitute the Helmert method. In the paper, a lots of experiments is performed to value the estimated depth model and the performance of its RTM correction in the remore-restore technique.The combination method to combine satellite altimetry and airborne gravity and shipborne gravity is researched. With the spherical harmonics analysis, based on the idea that using residue gravity data to compute the spherical harmonic corrected coefficients and add to the original coefficients, an iteration method is presented to correct the local gravity model. The performance of this method is demonstrated by the simulations.The effect of gravity data grid distance and depth RTM correction to the combination results is studied, meanwhile, the combination gravity map is applied into gravity navigation system. In the experiment area, the navigation result is contrasted to the registration result on the shipborne gravity map. According to the results, even the local gravity data has large grid distance, using the combination methods also can achieve better registioan result.更多还原