4
Priorities for Future Development

This chapter presents the committee's evaluation of the subsystem technologies reviewed in Chapter 2 and identifies the technology investments with the greatest potential for advancing undersea vehicle capabilities for meeting the national needs and opportunities discussed in Chapter 3.

IMPORTANT NEEDS AND OPPORTUNITIES

The quantitative information and physical samples that undersea vehicles enable the nation's scientists and engineers to gather will play a central role in characterizing and protecting the Earth and the human environment; in developing food, fossil fuel, and marine mineral resources; and in enhancing national security and law enforcement.

The scientific challenge is to obtain new kinds of quantitative information about the Earth and its natural systems, sampled over a sufficiently broad range of space and time. This information includes physical, chemical, biological, and geological measurements. Undersea vehicles, with their evolving capabilities, can greatly improve the temporal and spatial resolution of many of these measurements. They can give scientists access to ocean environments not now accessible, such as under ice and at depths below 6,500 meters. Ocean scientists today use a combination of DSVs and ROVs to achieve these goals to a limited degree.

Commercial uses of underwater vehicles (as in support of offshore oil and gas production and fishing operations) are served by a competitive market for vehicles and vehicle services. The next few decades will witness expansion of commercial uses of the oceans. Oil and gas deposits on shore are being increasingly depleted. Fish and other renewable ocean resources require more intensive monitoring and regulation, as commercial fish stocks are more heavily exploited to feed growing world populations; sustainable development requires better knowledge of the fish populations and their ecological relations. Other uses requiring improved knowledge of the ocean environment include renewable energy and communications cable routes.

Commercial and scientific applications are mutually dependent. Fundamental scientific discoveries often lead to new and unexpected opportunities for commercial uses; examples include discoveries such as plate tectonics, high-temperature seafloor vents, methane hydrates, new living resources, and mineral deposits. In turn, scientific investigation is enabled by new vehicle capabilities pioneered in the commercial sector.

ROVs will remain the workhorse vehicles for commercial activities. But an increasing role is foreseen for AUVs, especially in survey, exploration, and environmental monitoring. New and improved sensors, guidance and control of task-performance, navigation, data processing and storage, higher energy density, and improved reliability will be key technology development and improvement goals for long-duration AUVs. ROVs can be expected to be used in tasks of increasing complexity (such as changing chokes in undersea oil production flow lines) in response to industry demands.

Undersea vehicle programs for national defense did not grow as rapidly as was once forecast. However, demand by the military for such systems is likely to grow in the next decade. Reductions in defense spending will place a premium on less expensive systems for underwater tasks involving labor-intensive operations such as surveying. Reductions in the number of military submarines will tend to increase demand for AUVs, which can perform some of the surveillance tasks commonly performed by submarines and can extend their surveillance range. Most undersea vehicles are transportable by aircraft for quick reaction to distant emergencies.

The U.S. Department of Defense has, and will continue to have, special information needs defined by military missions. An understanding of the physical environment, such as the factors affecting sonar performance in support of mine antisubmarine warfare or littoral topography and soil mechanics in support of amphibious assaults, is vital to the military. ROVs and AUVs may play expanding roles in obtaining such information by transporting sensors over a wide area from a single support ship. The military appears to be moving



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4 Priorities for Future Development This chapter presents the committee's evaluation of the subsystem technologies reviewed in Chapter 2 and identifies the technology investments with the greatest potential for advancing undersea vehicle capabilities for meeting the national needs and opportunities discussed in Chapter 3. IMPORTANT NEEDS AND OPPORTUNITIES The quantitative information and physical samples that undersea vehicles enable the nation's scientists and engineers to gather will play a central role in characterizing and protecting the Earth and the human environment; in developing food, fossil fuel, and marine mineral resources; and in enhancing national security and law enforcement. The scientific challenge is to obtain new kinds of quantitative information about the Earth and its natural systems, sampled over a sufficiently broad range of space and time. This information includes physical, chemical, biological, and geological measurements. Undersea vehicles, with their evolving capabilities, can greatly improve the temporal and spatial resolution of many of these measurements. They can give scientists access to ocean environments not now accessible, such as under ice and at depths below 6,500 meters. Ocean scientists today use a combination of DSVs and ROVs to achieve these goals to a limited degree. Commercial uses of underwater vehicles (as in support of offshore oil and gas production and fishing operations) are served by a competitive market for vehicles and vehicle services. The next few decades will witness expansion of commercial uses of the oceans. Oil and gas deposits on shore are being increasingly depleted. Fish and other renewable ocean resources require more intensive monitoring and regulation, as commercial fish stocks are more heavily exploited to feed growing world populations; sustainable development requires better knowledge of the fish populations and their ecological relations. Other uses requiring improved knowledge of the ocean environment include renewable energy and communications cable routes. Commercial and scientific applications are mutually dependent. Fundamental scientific discoveries often lead to new and unexpected opportunities for commercial uses; examples include discoveries such as plate tectonics, high-temperature seafloor vents, methane hydrates, new living resources, and mineral deposits. In turn, scientific investigation is enabled by new vehicle capabilities pioneered in the commercial sector. ROVs will remain the workhorse vehicles for commercial activities. But an increasing role is foreseen for AUVs, especially in survey, exploration, and environmental monitoring. New and improved sensors, guidance and control of task-performance, navigation, data processing and storage, higher energy density, and improved reliability will be key technology development and improvement goals for long-duration AUVs. ROVs can be expected to be used in tasks of increasing complexity (such as changing chokes in undersea oil production flow lines) in response to industry demands. Undersea vehicle programs for national defense did not grow as rapidly as was once forecast. However, demand by the military for such systems is likely to grow in the next decade. Reductions in defense spending will place a premium on less expensive systems for underwater tasks involving labor-intensive operations such as surveying. Reductions in the number of military submarines will tend to increase demand for AUVs, which can perform some of the surveillance tasks commonly performed by submarines and can extend their surveillance range. Most undersea vehicles are transportable by aircraft for quick reaction to distant emergencies. The U.S. Department of Defense has, and will continue to have, special information needs defined by military missions. An understanding of the physical environment, such as the factors affecting sonar performance in support of mine antisubmarine warfare or littoral topography and soil mechanics in support of amphibious assaults, is vital to the military. ROVs and AUVs may play expanding roles in obtaining such information by transporting sensors over a wide area from a single support ship. The military appears to be moving

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generally toward buying commercial equipment and using available technologies. Law enforcement and regulation are government functions that hold important opportunities for undersea vehicles to contribute in the future. The USCG's missions of patrol and law enforcement include interdiction of drugs, pollution detection and control, and fisheries regulation enforcement. Innovative use of undersea vehicles could make the most of USCG assets by performing hull inspections for damage and contraband, searching for contraband on the seafloor, detecting and mapping pollution fields, and conducting reconnaissance and surveillance. Undersea vehicles will also help other law enforcement agencies, which often need to conduct accident investigations or recover bodies and evidence underwater. Many of the investigative needs of the USCG and other law enforcement and regulatory agencies can generally be met by commercial and defense-derived undersea systems. SETTING PRIORITIES FOR UNDERSEA VEHICLE DEVELOPMENT Summary of Potential Performance Improvements Chapter 2 describes the current state of undersea vehicles and the potential for performance improvements as a result of technical advances across the range of subsystem technologies, including the following: DSVs of the present generation have reached a mature state of development. The next generation of smaller, lighter, and, perhaps, less complex DSVs will be based on advances in new materials, power, and pressure-tolerant electronics, when and if they are required. ROVs are widely used in undersea commercial activities and are increasingly used by the oceanographic scientific community. Incremental improvements in most of the subsystems of ROVs can be anticipated. AUVs require the most significant improvements in subsystems to enable their anticipated major contributions to national needs. Focused development in key subsystem areas should result in significant enhancement of overall system performance and capability. Development Projects to Support Undersea Vehicle Advances Identifying Development Priorities Table 4-1 lists the key vehicle subsystems reviewed in Chapter 2 and summarizes the committee's evaluation of how improvements in each subsystem technology are likely to affect the overall performance of each of the three major classes of vehicle. The committee classified the subsystem technologies as "critical" (improvement would enable important new vehicle capabilities), "incremental" (improvement would benefit overall vehicle capability in an evolutionary sense), or "mature" (improvement would only marginally enhance vehicle performance). The committee then ranked the critical subsystem technologies by priority: greatest potential (highest probability of benefiting from research to improve vehicle performance) and high potential (significant, but not quite as high, probability of benefiting from research to improve overall performance). The committee considered many factors in constructing these rankings. The most important of these are (1) criticality of each subsystem's performance to the total system performance, (2) cogency of application to the three vehicle types (DSV, ROV, and AUV), (3) range of potential uses, TABLE 4-1 Technology Assessment Summary by Subsystem Subsystem DSVs ROVs AUVs Sensors Incremental Critical Critical Communications Incremental Mature Critical Mission and Task- Performance Control Mature Incremental Critical Energy Incremental Mature Critical Navigation and Positioning Incremental Incremental Critical Data Processing Incremental Incremental Critical Signal Processing Mature Incremental Incremental Data Management and Storage Incremental Incremental Critical Work Subsystems and Sampling Devices Incremental Incremental Critical Launch/Recovery/Docking Incremental Incremental Critical Materials and Structures Incrementala Incrementala Incrementala Propulsion Mature Mature Mature Total System Integration Mature Mature Critical NOTE: Shaded areas indicate critical subsystems with greatest potential for vehicle performance improvement and total system integration. a Critical for deepest applications.

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and (4) degree of innovation required (which ranged from incremental improvement to radical innovation). Other factors, such as agency mission priorities, are likely to influence the allocation of funds in practice. The committee's intent was to set broad priorities among the major vehicle subsystem technologies to provide general guidance for the allocation of research and development funds. Results: Critical Subsystems with the Greatest Potential for Improving Vehicle Performance The committee finds that three subsystem technology development areas offer the greatest potential for significantly improving the most-needed undersea vehicle data-gathering capability and task-performance over the coming 5 to 10-year period: ocean sensors, undersea communications, and mission and task-performance control. Ocean Sensors. Ocean sensors are needed in several areas that will enhance undersea vehicle performance: Acoustic. Further development of a variety of acoustic sensors will improve undersea vehicle performance. These efforts should include sensors for more efficient and detailed seafloor and subseafloor mapping, assessment of plants and animals in the seafloor and in the water column, and tomographic mapping of the interior of the ocean. Development efforts should focus on the following: miniaturization (to permit use of more sensors per vehicle) reduction of power consumed in propulsion (to permit more on-board sensors and longer missions) combine different sensor types into single integrated systems (interdisciplinary advice—from biological, chemical, physical, and geological oceanography—is necessary for understanding data fields and processes) sensors for biological reconnaissance Visual Imaging. Further development, miniaturization, and reduction of power consumption of optical, laser, and structured light sensors will allow existing capabilities to be integrated into smaller, less expensive vehicles. Improvements in resolution and data storage will allow closer matches between acoustical and optical surveys of underwater areas. On-board scene analysis will permit real-time remote control of AUVs at the task level, with tasks executed by the control subsystems. Chemical. The development of chemical sensors is central to a number of scientific and environmental applications, including studies of gradient and plume phenomena. Continued progress will determine the usefulness of undersea vehicles in these areas. The field is developing rapidly, but more work needs to be done in several areas: In situ chemical analyzers capable of analyzing a variety of chemical species (including methane, organic contaminants such as polycholorinated biphenyls and hydrocarbons, helium, and specific radioisotopes), which cannot now be detected by technology appropriate to vehicles, must be developed. A method for accurate on-board long-term calibration of chemical sensors is needed. Sensors of low power and small size, which will permit incorporation of a variety of sensors on a single vehicle, must be developed. Sensor Applications. Improved in situ sensing can greatly increase scientists' ability to determine the character and the temporal and spatial distributions of oceanic phenomena. Nearly 20 years ago, the CTD instrument provided greatly increased sampling density over reversing thermometers and Nansen bottles. The CTD data revealed important, previously unsuspected features. The committee believes that similar revelations are likely with regard to a variety of crucial oceanographic parameters, including nutrients, chemical species, hydrocarbons, and anthropogenic inputs. The prospect of integrating these multiple sensor modalities with arrays of fully mobile, intelligent vehicles provides a logical route to filling crucial gaps in the scientific understanding of the oceans from a multidisciplinary perspective. Fisheries managers are among the potential beneficiaries. They must make decisions based on sparse data from a handful of stations, using techniques such as individual CTD casts and net tows. In the future, arrays could be used to improve forecasts based on simultaneous measurements of water temperature and salinity; nutrients; and the distribution of plant biomass, zooplankton, and fish on unprecedented scales of time and space. Despite recent progress, many parameters, such as oil and many organic chemical pollutants, cannot today be measured in situ. Sensor development needs to proceed on a broad front so that new types of sensors, based on new technologies, can be incorporated into vehicles. Development of sensors will also be driven by the progress of scientific understanding of oceanographic phenomena. As long-duration undersea vehicles are developed, anti-fouling technology will be required to extend sensor usefulness and improve the reliability of long-term calibration. Communications. The rapid advance of the technology of communications holds great promise. Fiber-optics provides a new medium for control and communications with tethered vehicles, with vastly greater bandwidth than conventional coaxial cables offer. Acoustic communication, on which DSVs and AUVs rely, has benefited substantially from the development of data compression techniques. A valuable and challenging research goal is to devise an acoustic modem with enough bandwidth to let human operators control a vehicle from a moving platform in reverberant and dynamic acoustic environments found in shallow water and at long horizontal ranges. Achieving that goal will allow human operators to remain in the vehicle control loop for some AUV operations. Communications between vehicles

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and shore via radio frequency/high-frequency is another area of concern for certain missions. Mission and Task-Performance Control. High-level mission logic and guidance for fault-tolerant AUV operation in a variety of applications in environments with wide levels of uncertainty would allow AUVs to become reliable tools and would encourage acceptance by users in industry, science, and the military. Further, development of sophisticated user interface systems and techniques for control of ROVs and AUVs will improve human, high-level, real-time supervision of undersea vehicles and allow these vehicles to offer some of the in situ advantages of DSVs, including drawing directly upon human perception in near real-time. The remote operator, for example, can use a light pen or mouse to augment the computer model of a televised scene and to instruct it. For example, the operator may designate a specific feature of the televised scene (such as an isolated organism) for the vehicle or camera to follow automatically. Task-performance control encompasses the operation of work systems and physical sampling devices, which is discussed later in this chapter. As an integral part of the total human-vehicle manipulator control system, the vehicle and its manipulators or sampling devices can move in concert to carry out tasks specified graphically at the object level through a graphical user interface. This coordination can be done in real-time, even by an AUV, due to the much smaller communication bandwidth required by high-level instruction, combined with improvements in acoustical bandwidth now becoming available. These efforts should include fault-tolerant mission logic, layered control architecture, virtual presence operator interfaces, and object-based, task-level control. Results: Other Critical Subsystems with High Potential for Improving Vehicle Performance The committee has also determined that there are other critical areas of ocean-unique technology with high potential for improving undersea vehicle performance. Energy. Continued development of high-performance energy storage technologies will expand the scope of undersea vehicle applications. Current energy technology, however, is adequate for AUVs to be applied in some applications. Technology programs applicable to this challenge can be found in the automobile industry's electric vehicle programs (which are assisted by the federal government), and in the programs of other nations, such as Canada's aluminum-oxygen battery development program. Navigation and Positioning. Integrating inputs from a variety of navigation sensors can create navigation systems that are repeatable and can operate independently of emplaced seafloor references. These developments will improve the performance of AUVs in particular, especially for applications requiring missions of long-durations and distances. This integration should include inertial packages, bottom-lock sonars, and bottom-lock optical and video subsystems. Data Processing. Greater data processing capability will be required by the vastly increased on-board data production of new sensor suites and control systems. This capability will permit real-time interaction with the data to provide an ongoing quality control during the vehicle's mission. Data processing algorithms for the automatic recognition of targets and features in real-time will bring high-level inputs into AUV mission logic, enabling the vehicle to react better to its environment and reducing data storage requirements. Signal Processing. Related to data processing, on-board signal processing will be particularly important for AUVs, because navigation and target detection will be critical to mission performance. Data Management and Storage. New techniques for storing massive amounts of data (up to 1 gigabit) on chips as small as 16 cubic centimeters (1 cubic inch) need to be adapted to undersea vehicles to greatly increase on-board data storage capacity. The accompanying reduction in the space required for storage and lower energy consumption are additional benefits. In addition to on-board storage, systems need to be developed for uploading data during missions, perhaps by burst transmission to satellites or by physically plugging into a data transfer network on the seafloor. For longer duration missions such systems would enable the vehicle to regain previously used storage capacity after each transfer. Work Systems and Physical Sampling Devices. Work systems include all external (i.e., bolt-on) on-board devices that permit doing physical tasks at the work site. They include manipulators, tool packages, and "end-effectors," such as cutters, drills, and probes. Physical sampling is the removal of living and nonliving materials from the ocean for study at a remote site. While the development of sensors and on-board in situ analytical devices will greatly reduce the need to take some types of physical samples, there will still be a need for specialized sampling devices. Some requirements for these devices are as follows: external and internal water samplers, free of all trace element contaminants, that are gas tight (capable of holding pressure even if samples are supersaturated with gas) devices for capturing and maintaining live marine organisms at ambient temperatures and pressures tools for boring, coring, and cutting rock samples and methods for uncontaminated storage of samples devices for collecting seafloor sediment samples and maintaining them uncontaminated at in situ pressure Materials and Structures. For the deepest ocean applications, new materials and design strategies will enable new capabilities and applications for all three vehicle types. These

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efforts should include (1) glass ceramic pressure hull materials for extreme depths, (2) lower cost long-filament fiber-optic links, and (3) marine biofouling coatings for long-duration submersibles. Launch, Recovery, and Docking. Virtually any undersea vehicle operation requires a launch and recovery system provided by a mother vessel. The system is basically an elevator, often including a cage housing the vehicle. Vehicle operations are generally limited by the sea-state conditions under which launch and recovery can be conducted. Operational delays due to high sea states are costly and can considerably degrade productivity at the dive site. Progress has been made in these systems, but improvements are still needed, particularly for handling ROV tethers. Total System Integration. The goal of the system integration process is to bring together subsystems technologies to prove the system's level of technical maturity, assess its potential for commercial or scientific application, and establish a basis for cost-effective design—all in the context of a specific mission or missions. During the last two decades of government-sponsored development, much emphasis has been placed on the subsystem or component level. Where advanced concepts and technologies have been integrated into a system, the objective has generally been to respond to achieving a specific Navy application or mission; cost objectives have not been a high-priority, and potential commercial uses have not been a consideration. System integration emphasizes the process of transferring technology to mature systems—a process involving elements, such as safety, handling, personnel support, and cost performance—as well as vehicle design concerns, such as the use of modular subsystems and payload integration. Integration will not develop new technologies, but it is the step to commercial and cost-effective use that is most often avoided by those engaged in development. Many of the vehicle system integration activities that have occurred have been classified, because they have been mission specific. In the committee's view, the result is that engineers and scientists in industry and academia have become aware of advances in technology, but they have seldom been exposed to the problems and successes of the integration process or the costs of the system and subsystems and their operation. Since the end of the Cold War, with reduced military budgets and increased openness about sharing in development, there have been attempts to foster dual-use development. Advanced technology demonstrations have focused on systems integration and making technologies available to the private sector users. However, military specification requirements still prevail and severely constrain the cost-effectiveness of vehicle development. Transfer of government-sponsored, vehicle-related development to the private sector for wide-range, reasonably priced, applications must entail a balanced development program of technology advancement and systems integration. For example, fuel cells, advanced battery chemistries, closed-cycle internal and external combustion engines, and numerous other concepts have been funded at the technology level, but few of these concepts have moved to the private sector because of lack of integration and the resulting high cost. Table 4-1 summarizes the probable impact upon vehicle performance of technical developments in each of these subsystems. The table suggests that AUVs offer the greatest potential improvements in return for investments in development. In every case, it is necessary to be sensitive to the need for total system design and integration. FINDINGS Finding. Undersea vehicles present an unusual confluence of technical opportunities with national needs. The human needs for data-gathering and work under the oceans are growing steadily. The technologies of information processing, microelectronics, and communications are evolving just as quickly, offering improved vehicle capabilities. With these capabilities, oceanographic, hydrographic, and environmental information could be obtained at lower cost, with higher accuracy and reliability. The development and integration of the technologies involved are relatively straightforward. Finding. The committee has found that the subsystem technologies with the greatest potential for significant improvements in performance are sensors (acoustic, visual, and chemical); communications (both acoustic and digital fiber-optic techniques); and advanced guidance and control methods that then enable task-level direction of vehicles and even fully automated operation. Finding. These advances will enhance all classes of vehicles to some degree. AUVs, however, are likely to benefit most from further investments in development. AUVs are emerging from the research stage and have enormous potential for a wide variety of missions in support of science, industry, and government. The main development goals are improved sensors, guidance and control, navigation, and data processing, as well as higher reliability. Rapid advances in the technology of data processing and control raise the important possibility of hybrid AUVs, with communication links (either acoustic or fiber-optic) that carry control signals. The main burden of developing AUVs, perhaps for the next 5 to 10 years, will fall on government; the technology is not commercially mature. For that reason, and because many of the AUV applications are highly specialized and the vehicle technologies must be developed or adapted for undersea use, the development and integration of most AUV systems are too risky for industry and users to carry forward without help.

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Finding. ROVs are likely to remain the "workhorses" of commercial activities. They will see increasingly wide applications, paralleling the increasing human dependence on the ocean and its resources. These applications will include offshore oil and gas development and support of operations, telecommunications cable work, and search and recovery missions. ROVs will also serve defense, law enforcement, and regulatory missions, such as underwater surveillance, fisheries monitoring, and pollution detection. Some oceanographic and hydrographic studies will also be carried out using ROVs. The manufacturers and users of these vehicles can be relied on to develop the technology and to adapt to special noncommercial needs. Finding. The technology of DSVs is generally mature. Improvements in performance and cost will come with advances in materials, power systems, and electronics. The market for these one-of-a-kind systems is small (mainly government) and will be served by specialized engineering firms. The current fleet of DSVs, although aging, will continue to serve military and scientific needs. Finding. The U.S. Department of Defense, and in particular the U.S. Navy, has perhaps the broadest requirements for undersea vehicles for a variety of missions, including search and retrieval, surveillance, mine detection, and exploration of the operational environment (such as sonar performance and coastal topography). ROVs, including those from commercial sources, and AUVs will become increasingly important additions to the military fleet and will justify a government-funded program of development and technology integration. Regulatory and law enforcement agency requirements can be met through the adaptation of commercial and defense vehicle systems. The committee has devoted much attention in this report to individual subsystem technologies, assessing their near-term potential contributions in practical vehicles. The reader should not be misled by this focus on subsystems. Vehicles consist of integrated systems. The challenge of system integration is more difficult, and surely more important, than technology development at the subsystem level.