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

促进深海内部的精确导航持续存在有可能改变海洋学的开展方式。 目前现有技术尚不具备该能力；然而，如果开发成功，将改变水下航行器所开展项目的范围，其航程和续航时间比目前无需研究船支持的部署范围更长。 这项研究开发了一种新型低功耗导航系统，可将导航精度从数千米提高到数百米。 这一进展将使海洋学调查的多个新领域成为可能。 例子包括部署协调滑翔机机队来研究复杂的物理-生物地球化学相互作用；地形诱导混合的深入研究；整个海洋盆地规模的海底生境/生态系统的长期特征描述；更好地解析水下地形陡峭区域的底部边界层过程的尺度。 研究人员将参与外展活动，包括本科生参与我们的研究以及继续与当地高中机器人和环境科学课程建立的合作。这项研究开发并测试了一种低功耗声学定位系统，该系统能够在深海中进行精确的外部辅助导航。 滑翔机（或滑翔机机队）在深处运行，而自主水面机器人（ASV）则在海面跟随。 ASV 定期将其地理参考位置传输给滑翔机。然后，每个滑翔机独立地采用精密时基（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 将此相对位置估计与接收到的数据包中编码的 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。使用滑翔机上已使用的低功耗传感器，可以在 5000m 深度实现 250-400m 的精度。因此，对于深潜滑翔机来说，该方法的定位精度将比当前范例（即不频繁的 GPS 修复）提高 10-100 倍，并且允许飞行器在深度上花费更多时间进行相关观测。这项研究将实现新的操作范式，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。所开发的能力也是多个深潜AUG协调运动控制的先决条件，进一步提高深海观测的密度和节奏，提供更接近深海内部天气的视图。 开发的系统将首先在水箱中进行测试，然后在两次远洋巡航中进行测试，其中包括第 3 年在 Seaglider 上的部署。

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.