The motivating force in the United Kingdom for the commercialization of unmanned systems is North Sea oil, which is a major national asset. Consequently, systems and subsystems components are developed to assist the offshore oil business. Of a secondary nature would be the support of non-oil requirements, including undersea cable deployment and burial, surveys, waste outfalls, salvage, and others. The driving force to develop scientific unmanned systems is the same as that in the rest of the world -- to acquire information. The water column is always of interest, but one area may be more interested in subsea geological or seismic information, while another may seek information on the fisheries potential.
The major producer of working ROVs in Great Britain is Slingsby Engineering Ltd. (SEL). This small company of 80 people, located in the English countryside between London and Newcastle, has cornered a major portion of the large ROV business. Other ROV-producing companies in the U.K. are no longer in business.
SEL has been in operation since the 1970s. During the earlier years the company designed and fabricated the Submarine Escape and Rescue Vehicles (LR5); the one-atmosphere JIM suit, a carbon-fiber-skin diving suit rated for 1,500 ft operating depth; and Scarab III vehicles with water jet systems for cable burial, bottom crawlers with trenching capabilities, and other heavy duty work systems for ocean use. SEL has also undertaken special design studies, for example, the 10K DOLPHIN project, a 10,000 m ROV system for Japan.
SEL now concentrates on large ROVs. The company first started with the Trojan series, which was redesigned to become the Multi-Role Vehicle (MRV). The market for these vehicles is small. Thirteen Trojans were built, but the last one remains unsold because the first MRV made its debut. Presently SEL is working on MRV number 5. The basic parameters of these two large ROVs are given in Table 5.2.
Basic Parameters of Trojan and MRV ROVs
There is a great deal of similarity between the two vehicle designs, but the basic design philosophy is different. In 1990, SEL surveyed the market place and concluded that the future for large ROVs was a multipurpose vehicle system that would have the power, structure, strength and integrity, and flexibility that other ROVs did not have. The result was the MRV -- a basic core vehicle with the capability of incorporating a variety of payload packages based on customer demand. The modular building-block approach must be cost-effective. The Mobil-FSSL project presented later emphasizes this concept.
SEL only incorporates field-proven components in its vehicles. What is not available, the company designs and builds. Consequently, although SEL has designed a number of special tools, the company is known for its manipulators, namely, TA9, a seven-function master/slave position feedback manipulator; TA16, a five-function rate control manipulator/grabber; and TR33, a nine-function spatially correspondent manipulator. The company also has designed its own hydraulic power packages and thrusters. SEL has the capability to test all of the systems and components at their rated operating depths.
Commercial customers want to purchase complete ROV systems. Consequently, SEL sells a complete ROV system that includes dual manipulators and necessary spares and documentation; a Tether Management System (TMS/garage), a deck-handling winch, and an A-Frame; and a North Sea duty control van with system controls, video displays, and recording capabilities. An auxiliary power generator system is included. For the complete 600 m MRV system, including operator training, the purchase price is £1,230,000, or about $2 million.
Mobil North Sea Limited of Aberdeen, Scotland, is a user of the technology and hardware developed by firms with ocean-related products. Because of the small market, they can direct where the technology should go. The Mobil-FSSL Diverless Intervention System is a prime example of this approach.
The capability requirements of the Mobil-FSSL system are to replace components, operate valves, conduct valve maintenance and pressure testing, and execute control umbilicals and flowline installations in 1,000 m of sea water. To achieve this goal, the company starts with a core ROV, the SEL MRV, and adds peripheral components (see Table 5.3). These components have been or are being designed by Mobil, SEL, and others. It is a multiyear program with defined milestones to assure system reliability and success.
The justifications for this approach to operating and maintaining a subsea completion system are cost savings and reliability. The cost advantage is demonstrated by two examples presented in Table 5.4.
The reliability advantage is exemplified by the trend of removing the human element (diver) from the underwater work tasks and replacing him with a tested, proven, and known work package.
Present Position. SEL is undoubtedly the major large ROV supplier in Great Britain. On the world market, the possible competition SEL has is Perry Tritech, a Florida- based company owned by the French company Coflexip, with its RECON, Triton, and Scorpion vehicles, and International Submarine Engineering Ltd. (ISE), of Port Moody, B.C., Canada, and its series of large ROVs -- Hysub, Hydra, and others.
Cost Advantage of Diver and ROV
Trends. SEL identifies customer needs and designs the hardware accordingly, for example, the MRV ROV. Where needed, the company continues to improve the components. SEL will remain a small organization because the customer market is small and more user/service companies are fabricating their own special purpose ROVs.
The Mobil-FSSL project is a typical example of a major oil company working with equipment suppliers toward a common goal. It also exemplifies the trend toward removing the human element from the ocean. Twenty years ago, the offshore oil market was serviced by manned submersibles and divers. Now, there is not a single manned submersible in operation for the offshore oil companies, and diver tasks are continually being reduced in depth and function. The reliability of a diver versus a proven and tested work system is considered to be low, and the cost and potential liabilities extremely high. This trend will continue.
A major ongoing program to develop unmanned systems for the scientific community is the Autosub project. This project is being led by the Institute of Oceanographic Science Deacon Laboratory, located in Godalming, Surrey, south of London. The project seeks to use the most appropriate experience and skills available in the United Kingdom's science and technology communities. Consequently, university departments, industry, and laboratories of the Defence Research Agency have been directly involved.
The Autosub program envisions two operational vehicles, DOLPHIN and DOGGIE. The DOLPHIN, or Deep Ocean Long Path Hydrographic Instrument vehicle, is a long-path undulator for hydrographic work to full ocean depths. The vehicle would quantify the vertical ocean profile with spatial and temporal sampling of the ocean volume to determine the distribution of heat and fresh water, carbon dioxide content, air-sea fluxes, plankton distribution and nutrients, and others, surfacing every 30 km to fix its position via global positioning satellite and return data to appropriate shore facilities. The motivation for the development of DOLPHIN is the automation of routine data gathering, for example in the North Atlantic Ocean. It has been estimated that the North Atlantic heat flux, which is vital for maintaining the mild climate for the United Kingdom and Europe, could possibly be monitored and predicted with data obtained from 10 transocean DOLPHIN sections carried out routinely at specific times yearly. This data would be of great interest to programs like Global Ocean Observing System (GOOS) and Global Climate Observing System (GCOS).
Information on the deep sea floor gathered from surface platforms, though of excellent quality, is on a large scale. Scientists need higher resolution data obtainable only from higher frequency instruments mounted on deep towed, or autonomous, platforms deployed much closer to the sea floor. The DOGGIE vehicle would cover the ocean bottom at 5 to 6 kt with 5 to 6 km side scan swaths with 1 m resolution. The vehicle would also support subbottom profiler, magnetometer, and chemical sensors. All data would be temporally and spatially recorded.
The Autosub program, begun in 1988, incorporates four phases over a ten-year period, as shown in Table 5.5.
Four Phases of Autosub Project
Presently, the dual propulsion motors have been designed and tested under load at full operating depth. A one-half scale of the laminar flow hull for DOLPHIN has been built and tested in water depths to 1,000 m. The hull design is underway. Sea water exhibits compression of 2.8 percent between the surface and a depth of 6,000 m. Any material that is less compressible (steel exhibits 1/70 the compressibility of sea water) must be compensated or counteracted to maintain a neutrally buoyant system. The search for proper materials, both metallic and nonmetallic, and structural design is ongoing. Control logic for autonomous vehicle operations is being studied. Autosub is at the halfway point, and the demonstration test vehicle is behind schedule. The goals are ambitious, but the real issue is the availability of funds to complete the program.
Heriot-Watt University is located in Edinburgh, Scotland. The university is greatly influenced by the needs of the North Sea oil industries. In the 1970s, Heriot-Watt developed the Angus class of ROVs. Angus-1 was the first deep operating (300+ m) ROV in Europe. Angus-2 and Angus-3 were improved versions of the original design. Angus-3 incorporated Rover, a small ROV. Angus-4 was designed but never built. A lack of funds was the main reason, but the changing nature of the underwater service industry required rethinking the ROV's design. Angus-4 was to be powered from the surface but diver operated, and was to act as a staging and power source platform from which divers would operate.
It appears that the university is redirecting its goals from complete vehicles to specific underwater vehicle functions, for example, autonomous interaction control for two seven-function manipulators using video, very high resolution sonar and laser triangulation sensors to provide reliable motion control in the manipulator work volume.
Marconi Underwater Systems, located in Waterlooville, is an operating company within GEC-Marconi, a large, primarily defense-oriented firm. Eighteen months ago, Marconi started the Ocean Data Acquisition System (ODAS) vehicle, an autonomous vehicle based on technology developed for a number of heavy torpedo projects. Marconi representatives believe that most of the ODAS vehicle is a totally new design.
The basic vehicle is the same size and weight as a heavy torpedo. It has an operating depth of 300 m. The propulsor used is the Deacon Laboratory propulsor design single shaft version. The power source is a sodium-sulphur battery, a high temperature (300 deg. C) battery developed by the Germans for use in an electric car. The 37 kWh battery, divided 65 percent for propulsion and 35 percent for payload, enables the vehicle to travel just under 5 kt for 36 hours, resulting in an operating range of 300 km. Payload is 45 kg wet and 90 kg dry. System sensors include a Chelsea instrumentation package, an upward looking side scan sonar, and an echosounder (reconfigurable to be downward looking). Marconi has developed a novel launch-and-recovery system that is simple, is low cost, can operate in high sea states, and appears to be reliable. Marconi suggests that the ODAS system should be priced in the $100,000 to $200,000 range.
The Institut Francais de Recherche pour L'Exploitation de la Mer, or IFREMER, is in the process of designing a science-dedicated ROV. The vehicle would have major ocean depth capability (6,000 m), use fiber optics for high data rate transfer for communications with other surface entities, and would operate from a garage (TMS) from a 300 m tether. The payload would be three interchangeable packages: biological, geological, and other sensors, and two manipulators. Propulsion would be from 25 hp (five 5 hp) thrusters. The system would be tracked via ultrashort baseline and long baseline systems. IFREMER estimated the cost of the ROV to be $7 million without labor. The program began in 1993 with conceptual studies. Subsystem designs are scheduled for 1994, and the vehicle will be assembled and tested in 1995. To minimize risk, VORTEX (Versatile Ocean Subsea Robot for Technical Experiments), a testbed ROV for validating hardware and concepts, has been built and is operational.
Present Position. Relative to the Western world, the United Kingdom is equal to or slightly behind in scientific unmanned systems, but only because of funding constraints. The Autosub project is very ambitious; it will take five or more years to see the results. However, with low-cost obstacle avoidance and navigation systems, the inexpensive Marconi ODAS vehicle could be of great interest to the scientific community.
Trends. Universities are taking a narrower view of technology development because of funding constraints. Long-term projects like Autosub may survive. What is interesting is the cooperative nature of technology development, not just within the country, but within the European Community. A prime example is the European Community Marine Science and Technology (MAST) research programs. Recently, two new MAST programs have been initiated with a goal of furthering autonomous underwater vehicle technology, namely:
The first project concentrates on generic AUV technology in direct support of individual major vehicle projects at the British and French national oceanographic research institutes. The participants in this project include the Institute of Ocean Sciences Deacon Laboratory, Defence Research Agency (DRA) from the United Kingdom, IFREMER, Societe ECA, and Institut National de Recherche en Informatique et en Automatique (INRIA) from France, National Technical University of Athens from Greece, and Instituto Hidrográfico (IH) from Portugal. The second project, DRA, is actually building a vehicle, MARIUS, or Marine Utility Vehicle System, for coastal seabed and environmental surveys. The key participants in this program are from Portugal, Denmark, and France. The MARIUS vehicle is designed for seabed inspections and environmental surveys in coastal water less than 600 m deep. The vehicle is capable of hovering and retrieving bottom samples. The hull has been completed and initial sea trials are expected off Portugal in late 1993. It is planned to be fully operational in 1994.
The major point to bring forth is the trend toward international cooperation on major projects. There may be something to learn from this mode of technology development, especially in a tight money environment.