分布式海洋声学网络传感理论与实验研究

Effective measurement techniques for ocean temperature and current distribution have been of great interest in ocean observations. As the main tool for ocean remote-sensing, acoustic wave has been exploited via ray travel time measurements to invert and map large-area ocean disturbance, i.e., the so-called ocean acoustic tomography. However, it has a limited spatial resolution and the system realization is rather complex. In recent years, the concept of underwater acoustic sensing network has attracted great attention, aiming to obtaining high-resolution and accurate regional measurements. The network consists of a large number of low-cost, low-power, and small-size nodes distributed according to certain spatial topology; as such, its sensing function realization has different design considerations from the conventioanl methods. Currently there is no systematic design methodology and performance evaluation theory similar to that described by sonar equation for conventioanl sonar systems. Aiming to realizing effective temperature and current measurements, this project studies underwater acoustic sensing network of multiple distribued nodes inclduing mobile nodes. Specifically we will develop node and network design and performance evaluation methods for environmental sensing function implementation, and conduct experimental studies of the developed theory via a self-built experimental system. On the basis of establishing a systematical set of performance evaluation metrics, we will focus on a number of key problems inclduing network topology optimization, efficient signaling mechanism design, and local low-complexity environmental inversion algorithms. Through this project, we expect to make significant progresses on network sensing theory, which will form a solid foundation for future applications of the underwater acoustic sensing network in practical ocean environment observations.

温场、流场作为海洋动力环境要素，其有效测量技术一直受到关注。声波是水下遥感遥测的主要手段，通过声线传播时间测量发展了海洋声学层析技术，然而其系统复杂度高，分辨尺度有限。近年来针对区域高分辨环境测量的水声传感网络概念迅速发展。由大量低成本、低功耗、小型节点组成具有一定空间拓扑结构的传感网，其传感功能实现有着与传统方法不同的考虑，目前尚未建立类似于传统声纳方程的系统设计、评估理论体系。项目以温场、流场测量为目标，以包含移动节点的多节点分布式水声传感网为研究对象，系统发展环境测量功能实现的节点及网络设计理论和性能评估方法，并通过构建实验系统，开展水声网传感理论的实验研究。在建立水声传感网络性能评估体系的基础上，重点解决网络拓扑结构优化、高效信号体制设计、节点低复杂度环境反演算法等关键问题。通过本项目研究实现网络传感理论的突破，为水声传感网络在实际海洋环境监测中的推广应用奠定基础。

项目以流场测量为目标，分布式水声传感网络(Underwater Acoustic Sensor Network, UWSN)为研究对象，发展环境测量功能实现的网络设计理论和性能评估方法，并研制节点，构建实验系统，开展水声网传感理论的试验研究。具体内容包括分布式声学探测网络设计研究、UWSN框架下低复杂度节点处理算法研究、水下声学传感系统平台研制、分布式目标探测的理论与方法研究等。取得了若干特色研究成果：(1)发展了分布式传感网络框架下的参数估计理论，提出了基于时空演化Kalman滤波与传播时延差声学层析的海洋流场估计与跟踪方法；(2)创新发展了UWSN分布式估计方法，实现基于一致新息的分布式流速场估计；(3)针对分布式海洋环境参数测量的需求与特点，研发了UWSN试验系统，并成功开展了海上试验；(4)开展了面向分布式UWSN应用的声源目标探测理论与技术研究，提出了能量测量模型下的伯努利随机有限集序贯目标检测跟踪算法。通过本项目分布式网络声学探测研究，丰富了分布式传感网络框架下的信息处理理论，为UWSN在实际海洋环境监测中的推广应用奠定基础，为实现大范围、高分辨海洋环境参数测量和目标探测提供新的途径。