2. UNDERWATER ROBOTICS
2. UNDERWATER ROBOTICS
IFREMER has very actively pursued the large scale projects presented in last year report (VICTOR 6000, ARAMIS, SWIMMER) and started the development of ANTARES, an international very large science endeavor.
The following four sections briefly describe the status of those projects and the main results already obtained.
2.1. ROV: VICTOR 6000
This new deep underwater ROV (Remote Operated Vehicle) developed by IFREMER with the French Company ECA, is used for the exploration of the ocean floors. Victor 6000 is a cabled vehicle which is controlled from a support vessel. It is designed to make optical surveys and to carry out local assignments for imagery, implementing instrumentation and sampling water, sediments or rocks. In the field of operational development, the deep sea ROV VICTOR 6000 has been launched in operational conditions. A first significant at sea operation has been conducted in polar region (Spitzberg-Greenland) on the German RV Polarstern for the Alferd Wegner Institute In Germany (Campaign ARK XV/1). VICTOR and the new Ultra Short Base Line Posidonia (Thomson) has been used by 5500m of water , non stop during 24 hours. Since, Victor has established up to date records: 2500m depth for 36 hours continuously and 6000m depth for 20 hours.
Photo 1 : VICTOR on the RV Vessel Polarstern, tools deployment.
On this basis, a new R&D project has been launched at the European level on new scientific modules development for VICTOR. This is in particular done in the field of the ARAMIS European project, with Technomare in Italy, Heriot Watt University, Challenger Oceanic In UK, IAN Genoa in Italy, UPC from Spain, and University of Galway In Ireland.
2.2. ARAMIS
ARAMIS is intended to be easily integrated with typical mid class existing ROV's, providing a highly automated scientific tool to carry out multidisciplinary missions. Capabilities include samples from the water column and sediments, multidirectional instrument profiling and quantifiable imaging.
The ARAMIS system consists of two parts:
The resulting system (ARAMIS+ROV) allows the pilot/scientist to command easily in real time both the ROV and the scientific instruments/tools and thus to carry out the scientific mission in an efficient, reliable and repeatable way. In more detail, the system capabilities include:
This prototype, with its associated functionalities, has been tested with VICTOR, and will lead to the building of an operational module for sea floor mapping and measurements.
Photo2: VICTOR and the ARAMIS toolsled.
2.3. AUV: SWIMMER
In the AUV field after the success of the SIRENE prototype demonstration a new program, SWIMMER, has been launched with the Cybernetix company.
The Swimmer Vehicle is a EU funded project to develop an autonomous vehicle capable of transporting existing work-class ROVs around sub-sea installations - removing the need for the surface support vessels and long umbilical cables.
As offshore exploration and production moves to increasingly larger water depths, the greater becomes the need to rely on remote intervention using ROVs (Remotely Operated Vehicles). This means that any technology that can reduce the cost of deploying and using such vehicles could produce considerable savings.
The aim of EU-MAST funded Swimmer project is to construct an AUV (Autonomous Underwater vehicle) prototype capable of carrying a standard work-class ROV to a seabed installation. This AUV will actually act as an autonomous deployment platform. This would have three immediate benefits:
Remove the need for a permanent support vessel, with subsequent cost savings.
Remove the long tether / umbilical with consequent improvement in vehicle dynamics and energy usage.
Once docked, the work-class ROV can completely be conventionally operated via a sub-sea fibre optic communications network and short (~100s metres) umbilical. This allows the ROV pilot to be stationed ashore (in theory anywhere in the world).
Fig. 1: Computerised Mock-up of the Swimmer Sled and Payload Vehicle on Final Approach
A typical mission scenario might be as follows. The Swimmer AUV is to be deployed from an FPSO (Floating Production Storage Offloading) vessel. The work-class ROV is mounted on the Swimmer AUV. The ROV has a short 200m umbilical that is wound round a self-contained winch mounted on the Swimmer. The ROV is un-powered for the duration of the transit to the seabed. The Swimmer AUV is tetherless and powered from onboard batteries. The combined Swimmer / ROV vehicle is launched using a crane on the FPSO. A low-speed acoustic data link is established to the Swimmer, final system checks are done and the command to begin the deployment mission is sent via the acoustic link.
During the Transit Phase, the Swimmer uses its LRPS (Long Range Positioning System based on a Long Baseline Sonar network) to fix its position, and autonomously decide on its heading, speed and dive rate. Periodically, navigational fixes are sent via the acoustic data link (part of the LRPS system). The dive could reach a depth as high as 1000 m to 3000 m, combined with a horizontal displacement of several kilometers.
The Approach Phase commences when the vehicle is 50m above the Docking Station and within 10m radius. Based on a novel technique developed at Liverpool, the SRPS (Short Range Positioning System) uses CAD information to derive a 3D map (profile) of the Docking Station on the seabed and automatically manoeuvres the vehicle from 50m to within 0.2m. The close quarters approach is illustrated in figure 1.
The final alignment in the Docking Phase is aided by the mechanical design of the Docking Station. The sloping members on the top of the rig help the Swimmer align correctly and allow the wet connectors (carrying power and communications) to mate.
Once docked the Swimmer AUV is powered down (the onboard batteries are recharged). The work-class ROV is now connected, via the seabed fibre optic communication network, to the pilot ashore somewhere in the world. The ROV can be detached from the Swimmer, and operated around the seabed installation completely conventionally.
The ROV could stay deployed for months without further need of a surface support vessel. The Swimmer "concept" envisages a network of Docking Station nodes fitted across a whole production field. If the ROV is required elsewhere, the ROV is docked back onto the Swimmer and powered down. The Swimmer is then given commands to make its way autonomously to the Docking Station nearest the work site (using the LRPS and SRPS), recharging at immediate stations as necessary.
The Swimmer vehicle is designed to carry a work-class ROV as a payload. This is achieved by the Swimmer mounted as a tool-skid under the ROV. The Swimmer has computer-controlled clamps that allow the ROV and the Swimmer to be disengaged remotely while on the seabed. While docked, power and communications are fed from a seabed network to allow the Swimmer to recharge and the ROV to be remotely controlled. This is shown schematically in figure 2.
Fig 2: Schematic of Swimmer (with payload ROV) Docked to the Seabed Station
2.4. ANTARES
The goal of the project, set in a large European scientific cooperation, leaded by the French CNRS Centre des Particules de Marseille (CPPM-IN2P3-CNRS) and the DAPNIA Saclay Laboratory (CEA-DSM) is to demonstrate that it is possible to built a detector capable of studying high energy cosmic neutrinos. The study has important features relevant of advanced marine technology and Robotics.
The detector is a tridimensional matrix of light sensors (photomultiplier tubes) covering an effective volume on the order of 1 km3.
The system will be installed off Porqueroles in the Mediterranean sea, and the matrix will be moored by big depth.
Data processing will be done on shore and the antennas are linked to the data center through a cable.
Fig 3: Artist view of the Antares field (CPPM)
IFREMER is involved in the marine operation on three kinds of marine operation tasks: