Autonomous Underwater Explorer-:-Jaffe Laboratory for Underwater Imaging

Project Goals:

Currently there are very few ways of obtaining both sufficient spatial and sufficient temporal resolution when collecting ocean data. Of these methods, none are cost effective. Moorings can give high temporal resolution, but do not give good spatial resolution. Satellite analysis cannot give 3D information. Water samples can give either good temporal or spatial resolution, but are too timely and costly to provide both. The idea behind the drogue project is to build a system that can give both temporal and special resolution in a cost effective manner. One of the applications for this type of system is the study of small scale circulation, such as coastal or river circulation, and processes, such as dynamics of planktonic communities, oil spill expansion, and sewage outlets that exist on and are affected by such scales.

AUEs in the Ocean: Computer rendering of several AUEs in the water column. AUEs in the Ocean: Computer rendering of several AUEs in the water column.

General Specifications:

The system we will build comprised of small drogues that are buoyancy controlled, acoustically tracked, contain sensors for data collection and are part of an adhoc network for relaying data to surface stations for analysis. The buoyancy control allows the drogues to collect data from various depths in the ocean. Propulsion is not needed as the drogues will be moving with the flow and obtaining data on circulation patterns. Eliminating the need for propulsion cuts down on energy cost which means we can have longer deployment periods.

Networking the drogues with acoustic modems gives us a greater range for data collection. As long as the drogues are acoustically linked to each other, they can relay their data back to drogues which are closer to a fixed mooring. The fixed mooring can then send the data to a surface station. Without the network to relay data, all drogues would have to stay within range of the fixed mooring, or be recovered frequently for data download. Staying within the range of a fixed mooring would not give enough spatial resolution and frequent recovery would not be time or cost effective.

AUE GPS Communications

Since the drogues will be at various depths underwater GPS is not a viable tracking system. Thus we will build an acoustic tracking system to give us needed location information. The drogues will track the relative position of other drogues and send this information back to a surface station. On the surface, the data can be analyzed and absolute location can be extrapolated.

Various sensors can be put on the drogues depending on the system application. For instance, temperature and pressure sensors will be useful for almost any application. Flourometers will be useful for studies needing chlorophyll concentration data. Other possible sensors include dissolved oxygen, salinity, pH and turbidity sensors.

Below is a rendering of one of the mini-AUE's