by Lev KISELEV, Dr. Sc. (Tech.), chief research fellow of the Institute of Marine Technologies, RAS Far-Eastern Branch (Vladivostok)

Studies of oceans and seas at great depths is impossible without complicated equipment and, in particular, unmanned underwater apparatuses. Today such intelligent robots suitable for the widest range of scientific, commercial, military and other purposes are no longer a curiosity, as two or three decades ago, but each of them is unique in its own way, and its creation requires solution of many intricate scientific and engineering problems.

OCEAN DEPTHS-INVITING TERRA INCOGNITA

The first generations of underwater robots created in the 1970s were intended, first of all, for accomplishment of survey and exploratory missions, in particular, provision of echolocation and photographic surveying of the bottom to detect objects, which had an accident at sea. The later models were developed for other needs, for instance, for geological prospecting or topographic survey of bottom relief (for example, the autonomous underwater apparatus Hugin, built in the Norwegian Center of Marine Technologies in 1995-1998 and designed for work at depths up to 3,000 m). Such apparatuses can be of paramount importance in mineral exploration in areas of seas and oceans, which are notable for exceptional diversity of the bottom relief and processes of volcanic activity. They can also be used for detailed studies of hydrothermal systems, located on the slopes of underwater volcanoes and in the Earth crust fractures. Extensive works are carried out in this field, in particular, in the Republic of Korea. The specialists used the OKRO-6000 autonomous unmanned underwater apparatus developed under a joint (with DAEWOO company) Russian-Korean project.

Practical experience in development of underwater robots for the said needs is still rather modest, and com-

plex engineering experiments are required. Apart from the discussed objectives, automatic equipment can be helpful in studies of active processes in the areas of colossal accumulation of gas hydrates, for example, in the Sea of Okhotsk. At present it is one of the priorities both with regard to geological prospects for production of energy resources imperative for the mankind and in respect of ecological monitoring of water environment.

The most labor-intensive missions of unmanned underwater apparatuses include oceanographic research objectives connected with large-scale measurements of parameters of the medium in a water column and near the bottom. Today a wide range of all-purpose robotized complexes already exists for such needs both on the shelf and at great depths. Among them there are the following devices created in the USA in 1990-2000: Odyssey (Massachusetts Institute of Technology), Ocean Voyager, Ocean Explorer (Florida Oceanographic University), REMUS (Woods Hole Oceanographic Institution), which were used in studies conducted in the Gulf of Mexico, near the Antarctic Continent, and also for military purposes, in particular, in search of mines in the Persian Gulf. In the long run, it is assumed to study active near-bottom (including hydrothermal) sources and to carry out monitoring of water environment.

Recently the first experiments were implemented in the USA, which involved joint use of several devices for studies of tidal processes, in-depth convection and a number of other dynamic phenomena in the ocean. Meanwhile, the heads of the listed operations note that, due to spatial and temporal variability of the ocean and a large scope of the studied phenomena, it is impossible to obtain their overall picture and also to make forecasts in this way. That is why it is urgent to establish large-scale systems of survey and global long-term ecological monitoring, which provides, in particular, for measurement of hydrobiological, hydrochemical and hydro-physical parameters of water medium with subsequent data mapping. When collecting such information, automatic vehicles are most efficient in near-bottom layers, including measurements by sensors of such parameters, as oxygen content, water salinity, temperature, electric conductivity, turbidity and chlorophyll concentration. It is obvious that to perform various listed functions, underwater robots should be equipped with a multiprocessor on-board computer network capable to change its configuration depending on the set task. They can include also military ones: foreign publications give facts of development of appropriate robotized complexes by large corporations of the USA and Europe.

IDEAS EMBODIED IN METAL

The national experience in creation of autonomous unmanned underwater apparatuses is indicative as an example of solution of a scientific and technical problem, which emerged at the junction of the control system theory, robotics, oceanography and marine technologies. Works in this field started at the Institute of Automatics and Management Processes, Far-Eastern Scientific Center of the USSR Academy of Sciences in 1972. Based on the department headed by Mikhail Ageev, Dr. Sc. (Tech.), Academician since 1992, the Institute of Marine Technology Problems, RAS Far Eastern Scientific Center, was established in 1988. For the past 40 years over 20 types of robots were put into operation, which

could perform various operations in the ocean, under ice, on the shelf and in coastal areas. The difficult road of scientific search from mockup specimens to deepwater complexes is presented in works prepared by our scientists, for example, in the monograph Autonomous Underwater Robots. Systems and Technologies, edited by Mikhail Ageev (M.: Nauka, 2005, 398 p.).

At the initial stage (world experience in creation of similar equipment was very meagre at that time) we planned to develop the simplest facilities for using them at offshore depths as carriers of instruments for collection and accumulation of information on the environment. In the course of work on this problem, specialists of our institute created the first national Skat automatic unmanned underwater apparatus (1974). It was used in the hydrochemical survey on Lake Baikal in an area adjacent to the pulp and paper plant. During this ecological experiment we developed also methods of trajectory measurements of local physical fields and carried out survey of the bottom relief.

The acquired experience proved useful later in the design of Skat-geo apparatus (1976) intended for geodetic measurements and photo survey of the sea bottom on the shelf. Preliminary estimates showed that with a high-accuracy gravimeter* installed on that apparatus it was possible to improve several times accuracy of measurements taken from boards of ships or submarines. The final tests of Skat-geo took place in the summer of 1978 on a geodetic testing area in the White Sea, and they confirmed all assigned parameters. Later on the apparatus was at the disposal of the Central Research

* Gravimeter is an instrument for measurement of gravity force acceleration. Gravimetric survey is used for solving of geophysical and geological objectives.–Ed.

Institute of Geodesy, Aerial Survey and Cartography. After reconstruction, in 1991-1992 it was used for surveying of marine culture resources near the Pacific Ocean coast in the Far East.

The main achievement of the next stage (1976-1985) was introduction of a modular technology implying unification of subassemblies and components of different-purpose apparatuses and creation on its basis of a deep-water (up to 6,000 m) robotic complex at our institute. Testing of an apparatus taken in tow and two L-1 and L-2 autonomous vehicles, which were a part of the complex with a submergence depth of 2,000 and 6,000 respectively, and also of navigation and auxiliary equipment took place in the Sea of Japan and the Philippine Sea in 1979-1980. Since then they were intensively used in practice in different regions of the World Ocean; in a number of cases it was connected with tragic events. For example, in 1982-1983 they took part in a detailed survey in the region of wreck of the Soviet K-8 nuclear submarine at a depth of over 5,000 m in the northern part of the Atlantic and then at a site of crash of the South Korean aircraft near the Sakhalin Island. In 1987, they examined K-219 nuclear submarine, which had an accident in the Sargasso Sea near the Bermudas. In the spring of 1989, the deep-water complex thoroughly examined Komsomolets nuclear submarine, which had sunk in the Norwegian Sea. Besides, due to lack of reliable information on its location, the apparatus, equipped with a side-scanning hydrolocator and a radiometer and taken in tow by a surface vessel, was used at the start of the search operation. At the second stage, the place of the accident was examined by Mir-1 and Mr-2* manned vehicles, which were stationed on the Academician Mstislav Keldysh research vessel, where they passed on all initially obtained information. At the final stage, L-2 autonomous unmanned apparatus was used, which made 17 deep-water submersions and helped obtain about 1,000 informative photos.

In 1986, the institute started to design another unique Tiflonus underwater robot with account of increased self-sufficiency to perform geophysical studies in the Arctic conditions. It was used for development of new onboard systems and conducting of experimental acoustic and gravimetric measurements. In particular, it was proved that measurement inaccuracy of vertical accelerations taken from the robot board made units of percent of the target value, which was an order higher than in the case of using ships and submarines.

In 1988, the institute worked out, on its own initiative, MT-88 autonomous apparatus, whose design incorporated improved on-board unified modules and a multiprocessing control system based on a local computer network. Its deep-water testing took place in the Pacific Ocean in the Clarion-Clipperton fracture zone (northern subequatorial region of the North-Eastern Depression between 7° and 18° N) and was combined with the examination of bottom areas with deposits of ferro-manganese nodules. The examination was carried out under a scientific-and-technical cooperation agreement concluded by the institute with InterOceanMetal International Organization.

In 1991-1995, our staff members in cooperation with Chinese partners from the Institute of Automatics of the Chinese Academy of Sciences (city of Shenyang) created CR-01 unmanned apparatus designed for oceanographie studies and mineral exploration at depths of up to 6,000 m. It included water medium gauges, a side-

* See: A. Lisitsyn, A. Sagalevich, "Underwater Dimension of the Academy", Science in Russia, No. 2, 1997; "The Main Discovery in the Ocean", Science in Russia, No. 1, 2001.–Ed.

scanning hydrolocator, a video system and acoustic profile recorder of sea bottom. In 1995, it was successfully tested in the Pacific Ocean and then used as a research platform. Later on Chinese and our specialists designed and built CR-02 similar in design to the previous one. The international projects with the participation of our institute included also thes above-said OKRO-6000 Russian-Korean vehicle.

Apart from the discussed "big" underwater robots (mass over 1,000 kg), the institute workers developed and built a number of "small" ones (mass below 500 kg). Among them there is TSL autonomous fastened apparatus for studies of long-distance waterways (tunnels), capable of operating in the modes of independent and supervisory (with the participation of an operator) control; a remotely piloted fastened apparatus (with an optical fiber cable and a manipulator) (1996); a "solar" vehicle (SUNPA), i.e. solar battery-powered (1998-2000). The latter was developed under a contract with the Autonomous Underwater Systems Institute (AUSI), USA. The same is true of towed vehicles for deep and shallow waters and also MMT-3000 autonomous underwater robot, i.e. a small sea technologist for depths of up to 3,000 m, built in 2007 and designed for a wide range of operations (surveying and mapping of sea relief with a view of planning to lay pipelines and cables, exploration of mineral resources at the bottom and in soil column, ecological studies, and exploratory operations), refer to the same category of vehicles.

The "solar" apparatus arouses a special interest of specialists. It is notable for increased (in principle, unlimited) independence and is designed in the form of a measuring platform of a long-term performance in a global autonomous network of oceanographic measurements. The development of the latter started by efforts of international community 15 years ago, and at present it expands within the framework of coordinated programs. Scientists had been handling the problem of increased independence of underwater robots based on new power technologies already for many years, but only recently tangible progress was reached in this area. The idea of using of inexhaustible energy of the environment for such tasks looks extremely attractive. Academician Mikhail Ageev was one of the first, who voiced such an idea in the middle of the 1990s. Thus, there appeared a concept, according to which unmanned vehicles, which utilize energy of sun light, wind and sea waves, are fit to accomplish the set goals. This idea was supported abroad, and constructive contacts were established between Mikhail Ageev and AUSI head Richard Blidberg, which resulted in creation of "solar" vehicle models, almost similar in configuration, under their guidance.

As a result of accumulated experience, specialists of our institute reached a world level and acquired invaluable experience of cooperation with leading national research and design organizations. So, autonomous underwater vehicles MT-98 and Clavesin, created not long ago, accumulated a number of modern achievements in electronics, power engineering, modular architecture of systems, navigation and control. Academician Ageev headed this research work and was chief designer of projects and supervisor of studies until the last days of his life (2005). Leonid Naumov, Dr. Sc. (Tech.), succeeded him as director.

Of special importance at that period were works connected with development of the Arctic continental shelf, as lately the interest to resources hidden in the depths of the seabed was growing abruptly. Practice proves that utilization of underwater robotic equipment, operating from boards of icebreakers, is most promising for studies of bathymetrie, physical and geomorphological characteristics of the Arctic Ocean bottom in the conditions of complete ice cover over a large area. The first such experience was accumulated in 2007, when the expedition on the Rossiya nuclear icebreaker used Clavesin apparatus to carry out studies of geological characteristics of the sea bottom in the region of the Lomonosov Range* over an area of more than 50 sq. km at depths of 1,400-1,600 m in a short period of time. Besides, this apparatus proved its efficiency even before, i.e. in 2005-2007, during tests in the Sea of Japan, Sea of Okhotsk and Barents Sea. At the same time new methods of the development of a robotized complex were suggested to implement large-scale marine exploration works, ground shaping, information on the underwater situation, inspection and protection of aquatic areas and marine infrastructures in coastal and deep-water regions of the ocean and under ice. Groups of underwater robots based on hydro-acoustic, fiber-optic and satellite communication can interact in the said complex. At the present time our institute carries out broad-spectrum research in this field in cooperation with a number of leading scientific and production organizations of the country.

TECHNOLOGIES OF THE FUTURE

Let us discuss some priorities, which determine the design of future underwater technologies.

First of all, as already mentioned above, it is deployment of large-scale surveying and global long-term monitoring systems of offshore zones, bottom relief, geological formations, biological objects and hydro-physical fields.  Practice proves that independent or

* See: Yu. Leonov, "Important Phase of Polar Studies", Science in Russia, No. 1, 2010.–Ed.

The CLAVESIN apparatus in the Arctic-2007 polar expedition: 1-launching of an apparatus from board of the ROSSIYA nuclear icebreaker; 2-a fragment of the temperature field map in a benthic area; 3-a fragment of the bathymetric map prepared by means of route area surveying on the Lomonosov Range; 4-a photo of an arctic bottom of one of the sites of the Lomonosov Range with big biological objects in a silt stratum; 5, 6-a fragment of hydrolocation surveying of the bottom and artificial objects at one of the sites of the Lomonosov Range; 7, 8-a fragment of an acoustic profilogram of the bottom in the coastal area of the Great Ainov Island in the Barents Sea.

remote-control underwater robots, equipped with a complex of systems for hydrolocation, photo-, tele-, magnitometric and hydrophysical surveying, are unique means for solving such problems. The information obtained with their help can be used for on-line control of underwater conditions, compilation of maps and chart cases, forming of specialized databases for consequent generalization and drawing up of scientific and engineering recommendations.

Development of the said direction implies working out of models and methods of intelligent control and spatial orientation, which provide safety and "survivability" of independent underwater robots in uncertain and extreme conditions of the environment. It is also required to increase possibility of navigation and control for guaranteed delivery of an underwater robot to the given point or region of space. In this connection, development of a simulation complex is urgent too. It helps generate virtual environment, visualize movement of the apparatus and maintain work of sensory devices in an imitation mode. Besides, it is intended to solve a more complicated problem, namely, volumetric reconstruction of underwater environment, which is necessary, for example, for on-line planning of a spatial route of the robot by its own intellect.

In recent years a tendency is observed to draw together functional properties of autonomous and remote control underwater robots and also to form universal infor-mationally interacting groupings of relatively simple, reliable and efficient vehicles. Probably, some of the problems under consideration will arrive at their solution in the near future. For instance, creation of small autonomous apparatuses with energy-intensive and renewable energy sources will allow to realize an automated network of oceanographic measurements and to show underwater conditions on the vast expanses of the World Ocean. Similar achievements can be attained in case of creation of high-precision integrated systems of underwater navigation based on on-board autonomous hydroacoustic and satellite technologies.

As to creation of "intelligent" underwater robots with adaptive behavior under conditions of information ambiguity and spatial orientation, progress in this field can be especially tangible taking into account development rates typical of electronics and computer technology in general. The autonomous underwater vehicles built in recent years can already serve as prototypes for technology of a new generation.