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

促进对深海内部的准确导航的持续存在有可能改变海洋学的开展方式。 现有技术目前还不能提供这种能力;但是，如果开发出来，将改变水下航行器所进行的项目的范围，这些水下航行器的航程和续航力将比目前在没有研究船支持的情况下部署的水下航行器更长。 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。 这一进展将使多个新的海洋学调查路线成为可能。 例如，部署协调一致的滑翔机队，调查复杂的物理-地球化学相互作用;深入研究地形引起的混合;在整个海洋盆地的尺度上对海底生境/生态系统进行远程定性;以及更好地分辨水下地形陡峭区域的底边界层过程的尺度。 研究人员将参与外展活动，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。该研究开发并测试了一种低功率声学定位系统，该系统能够在深海中进行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，而一个自主表面机器人（ASV）在海面上跟随。ASV定期向滑翔机发送其地理参考位置。然后，每个滑翔机独立地使用精确的时基（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将该相对位置估计与在接收到的分组中编码的ASV的位置组合以计算其地理参考位置。系统性能取决于许多因素，包括飞行器姿态传感器的精度。使用滑翔机上已经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，这种方法将提供比当前范例（即，不频繁的GPS定位），并将使车辆在深度上花费更多的时间进行相关观测。这项研究将促成新的操作模式，提高观测能力，并促进比以前更密集的空间观测。此外，新系统还将提高估计深度平均洋流的能力。开发的能力也是多个深潜AUG协调运动控制的先决条件，进一步增加了深海观测的密度和节奏，提供了更接近于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，包括在海上滑翔机上进行第三年的部署。

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.