Collaborative Research: Persistent Presence in the Ocean Interior: Developing a Low-power, Autonomous System for Geo-referenced Navigation

促进深海内部精确导航的持续存在有可能改变海洋学的开展方式。现有技术目前还没有提供这种能力；然而，如果研制成功，将改变水下航行器所承担的项目范围，与目前在没有研究船支持的情况下部署的水下航行器相比，它的航程和续航时间更长。本研究开发了一种新的低功耗导航系统，将导航精度从1000米提高到100米。这一进展将使多种新的海洋学调查成为可能。例子包括部署协调的滑翔机舰队，以调查复杂的物理-生物地球化学相互作用；地形诱导混合的深入研究；在整个海洋盆地尺度上海底生境/生态系统的长期特征；在水下地形较陡的地区，对底边界层过程的尺度分辨率较高。研究人员将参与拓展活动，包括本科生参与我们的研究，并继续与当地高中机器人和环境科学课程建立合作关系。本研究开发并测试了一种低功率声学定位系统，该系统可以在深海中实现精确的外部辅助导航。一架滑翔机（或一队滑翔机）在深海作业，而一架自主水面机器人（ASV）在海面上跟随。ASV每隔一段时间将其地理参考位置传送给滑翔机。然后，每个滑翔机独立地使用精确时基（由芯片级原子钟提供）和阵列处理来确定其相对于ASV的位置。每个ASV将这个相对位置估计值与接收数据包中编码的ASV位置相结合，以计算其地理参考位置。系统性能取决于许多因素，包括车辆姿态传感器的精度。使用已经在滑翔机上使用的低功率传感器，在5000米深度可以达到250-400米的精度。因此，对于深潜滑翔机，这种方法将提供10-100倍的定位精度比目前的范例（即，不频繁的GPS定位），并将允许车辆花更多的时间在深度进行相关的观察。这项研究将实现新的操作范例，提高观测能力，并促进比以前可能的更密集的空间观测。此外，新系统还将提高估计平均深度洋流的能力。发展的能力也是多个深潜aug协调运动控制的先决条件，进一步增加深海观测的密度和节奏，提供更接近深海内部的天气视图。开发的系统将首先在水箱中进行测试，然后在两次海洋巡航中进行测试，其中包括在滑翔机上进行第3年的部署。

Facilitating an accurately navigated persistent presence for the interior of the deep ocean has the potential to transform how oceanography is conducted. This capability is currently not provided by existing technologies; however, if developed would transform the scope of projects undertaken by underwater vehicles with longer range and endurance than can currently be deployed unsupported from research ships. This research develops a new low power navigation system that improves navigational accuracy from 1000s of meters to 100s meters. This advance will enable multiple new lines of oceanographic investigation. Examples include deployment of coordinated glider fleets to investigate complex physical-biogeochemical interactions; deep studies of topographically induced mixing; long-range characterization of seafloor habitats/ecosystems at the scale of entire ocean basins; and better resolution of the scales of bottom-boundary-layer processes in regions with steep underwater terrain. The researchers will engage in outreach activities including undergraduate participation in our research and continuation of established collaborations with local high school robotics and environmental science classes. This research develops and tests a low-power acoustic positioning system that enables accurate externally aided navigation in the deep ocean. A glider (or fleet of gliders) operates at depth while an autonomous surface robot (ASV) follows on the sea surface. The ASV transmits its geo-reference position to the gliders at a regular interval. Each glider then independently employs a precision time base (provided by chip-scale atomic clocks) and array processing to determine its position relative to the ASV. Each ASV combines this relative position estimate with the ASV's position encoded in the received packet to compute its geo-referenced position. System performance depends on a number of factors including the precision of vehicle attitude sensors. Accuracies of 250-400m are possible at 5000m depth using low-power sensors already in use on the glider. Hence, for deep-diving gliders, this method will provide a 10-100 fold improvement in positioning accuracy over the current paradigm (i.e., infrequent GPS fixes) and would allow vehicles to spend more time at depth making relevant observations. This research will enable new operating paradigms, advance observational capabilities and facilitate spatially denser observations than were previously possible. Furthermore, the new system will also improve the ability to estimate depth-averaged ocean currents. The developed capability is also a prerequisite for coordinated motion control of multiple deep-diving AUGs, further increasing the density and cadence of deep ocean observations, providing an ever closer-to-synoptic view of the deep ocean interior. The developed system will be tested first in the tank and then in two ocean cruises including a Year 3 deployment on a Seaglider.