水下不确定性环境中广义秩信源凸优化稳健波束形成与方位估计研究

Currently, long-distance underwater target sensing based on conventional beamforming and direction of arrival estimation has been approaching bottleneck and how to improve the performance of array processing in uncertain underwater environment is an urgent task for the researchers all around the world. Based on the National Natural Science Fund Key Project Group for underwater communication and detection, this research project aims to meet the increasing need on long-distance underwater target sensing in complex ocean environment, and is about to introduce general-rank source model and convex optimization to the robust adaptive beamforming and direction of arrival estimation in the uncertain underwater environment. And thus, some novel spatial spectrum matching based robust adaptive beamforming techniques are proposed, while several new methods of direction of arrival estimation are studied based on signal self-nulling and delay snapshot. By this way, the constraints of conventional target sensing in uncertain underwater environment are expected to overcome, and meanwhile the practical application of long-distance underwater target sensing is enhanced. The proposed methods will be verified and improved by tank tests (or lake experiments). The signal processing software and hardware systems of robust adaptive beamforming and direction of arrival estimation for underwater general-rank signal models will be founded and investigated, and the systems can provide powerful support to research deeply. The achievements of this project will be used to sonar, underwater navigation, geological exploration and other fields. And also, these results can be extended for radar, communications, navigation and other related fields.

当前，基于传统波束形成和方位估计的水下目标远程感知技术受诸多瓶颈制约，如何进一步提高水下不确定性环境下的阵列处理性能是当前迫切需要突破的重要研究方向。本课题密切结合复杂海洋环境水下远程目标感知的迫切需求，并结合“水下通信与探测”国家自然科学基金重点项目群的研究内容，率先开展水下不确定性环境中广义秩信源凸优化稳健波束形成与方位估计研究，拟提出基于空间功率谱匹配、信号自消以及延迟快拍的水下远程目标凸优化稳健阵列处理新方法，以期突破复杂海洋环境对水下目标远程感知能力的制约，提升水下目标远程感知方法的实用化水平。同时拟通过水池（或湖上）试验研究对所提方法加以验证和完善，并研制方法先进和功能完善的广义秩信源凸优化稳健波束形成与方位估计软硬件系统，为该方向研究工作的深入开展提供有力工具。该项目的研究成果可应用于声纳、水下精确制导、海洋地质勘探等领域，也可推广用于雷达、通信和导航等相关领域。

本课题针对复杂不确定性水下环境以及阵列自身存在的诸多不确定性因素，深入开展了水下不确定性环境中广义秩信源凸优化稳健波束形成与方位估计的理论方法研究。主要研究成果包括：（1）水下介质随机性和非均匀性引起的波前扰动，以及相干或非相干局部散射使得点源信号模型不再适用。同时，阵列通道幅相误差、阵元位置误差、波束指向误差、阵元各向异性与不一致性引起的响应灵敏度误差、阵元间耦合等诸多阵列自身非理想因素也导致波束形成器性能急剧下降。为此，本课题提出了水下不确定性环境中广义秩信源凸优化稳健波束形成方法，实现了秩一信源凸优化稳健波束形成以及高阶秩信源凸优化稳健波束形成。（2）水下目标远程感知系统需要在极低信噪比、强干扰、小快拍数等复杂不确定性海洋环境下仍能有效工作，而已有方位估计方法通常不能达到实用要求。针对水下不确定性环境，本课题利用导向向量失配，提出了基于Capon波束形成器信号自消的高精度方位估计方法。同时还提出了延迟快拍方法，增强了现有高分辨方位估计方法在水下不确定性环境中的分辨能力和稳健性。（3）建立和完善了复杂不确定性海洋环境中广义秩信源凸优化稳健波束形成与方位估计的仿真和实验系统，利用实验数据进一步验证与完善了水下不确定性环境广义秩信源凸优化稳健波束形成与方位估计方法。本课题研究在一定程度上突破了复杂海洋环境对水下目标远程感知能力的制约，较好地提升了水下目标远程感知方法的实用化水平。目前，本课题组已发表高水平学术论文6篇、发表教学改革论文1篇、申请发明专利2项（已授权1项）、申请并授权实用新型专利1项、出版专著1部、完成博士学位论文1篇。本课题取得的研究成果可应用于声纳、水下精确制导、海洋地质勘探等领域，也可推广用于雷达、通信和导航等相关领域。