A. Gaykovich, PhD in Engineering Science, Deputy General Director,
JSС “NPP PT “OCEANOS”
JSC “NPP PT “Oceanos” has been working on its own initiative since 2011 in collaboration with the State Marine Technical University of St.-Petersburg (SMTU) and other higher academic institutions of the country on building a family of underwater vehicles with predominantly hydrodynamic principles of motion. A number of articles previously published in the journal “New Defense Order. Strategy” described the relevance of such devices in Russia, laid out the history of their appearance in the West (especially in the United States), described the principles of operation of the device and its various subsystems as well as formulated the challenges the development team was facing.
In May 2015 the specialists of JSC “NPP PT “Oceanos” have been specially invited to lecture at the Moscow State Institute of International Relations (MGIMO), at the Department of Ecology; in the course of these lectures the concepts of using robotic vehicles for environmental monitoring, such as gliders have been considered. In July 2015 an experimental prototype of the device was presented at the International Maritime Defence Show in St. Petersburg, where it aroused great interest among the representatives of the Ministry of Defense and commercial companies specializing in the offshore oil and gas production and marine ecology.
Currently, the vehicle continues to undergo field tests, according to the preliminary results of which the design of the glider has been (and continues to be) significantly changed:
- Volume of the fore buoyancy variation mechanism (BVM) and its performance has been increased.
- Initial ballasting of the vehicle has been changed for increasing the margin of subsea stability, especially lateral. It allows to “smooth” the curves of capsizing and righting moments greatly facilitating the work of control algorithms.
- Automatic control system software has been fully updated. The concept of single system time has been introduced, according to which the scale of synchronization of system processes and events is built.
- ACS now has an “Assist autopilot” mode, working on the basis of the predictor algorithms. In fact, the ACS constantly calculates and updates the mathematical model of movement of the vehicle in its path, and in the event of deviation of actual parameters from the tolerance corridor it automatically adjusts the position of the vehicle. This allows pre-empting possible critical situations (stall, spin, “hovering” without moving) in the early stages, based on relatively small deviations in the parameters. These algorithms operate as “assistants” of the main navigation algorithm and increase the efficiency of the ACS.
The latter improvement is crucial, as the experience of working with operators of foreign commercially available gliders (for example, the DOF Subsea company has 3 Slocum type gliders) showed that the problem of loss of control and stalling at low speed has not yet been satisfactorily resolved. It is unacceptable when working in areas with complex hydrology (availability of water lenses with different density/salinity, vertical currents, sharp temperature jumps).
Analyzing the experience accumulated during the tests, given the changing economic and political situation, the development agency believes that only the building of a family of new high-tech vehicles can help find the means to maintain a competitive struggle for economic space of the Arctic seas. It is obvious that with the existing rate of the cost of shipbuilding and construction of ships and vessels, traditional measures of intelligence and surveillance are unable to reliably cover such large and remote areas that often also feature the limited navigability or even are non-navigable.
As can be seen from the published policy document Arctic Roadmap 2020, the main priority of the US Navy is the deployment of a multi-agent system of gathering the intelligence and auxiliary (meteorological, hydrological, oceanographic, geological) information in the Arctic seas. The system consists of bottom stations, drifting buoys, wave and underwater gliders, ice observatories, etc. This system is already being actively built, Figure 3 shows the diagram of the system.
On 11.04.2015 the website Vessel Finder (international reference navigational database) published an article called “US Navy deploys under-ice drones in competition with Russia for Arctic”, which citing the sources in the US Navy stated that in the context of the expected fight with Russia over the Arctic resources, the US Navy has already placed a number of long-term underwater robotic vehicles that are already collecting information about temperature fluctuations and sea conditions, to clarify the operational weather forecasting and build the computer models of Arctic ice melting. In order “to counter the illegal activities” the Europeans have placed a network of hydrophones on the underwater gliders in the project PERSEUS creating a mobile monitoring line of maritime traffic according to the authors of the program. Obviously, the deployed sonar tracking system could do much more than that.
Thus, it is necessary to make decisions in the shortest possible time and start the practical development of a new generation of robotic vehicles. We will need to respond to a broad range of technological and scientific challenges in the development of the new generation vehicles focusing on the following areas:
- Power sources.
We can identify the following among the most promising power sources potentially considered for installation in the next generation of underwater vehicles such as “Glider”:
- Solar panels
- Thermal engines. Gliders trace their history to the first prototypes developed at the Woods Hole Oceanographic Institution, which had thermal drive (Slocum Thermal Glider). Their use is limited mainly by climatic and meteorological characteristics of the application area;
- Radioisotope power sources are also of interest, especially given the wealth of experience of the national industry in this area. Possible arguments “against” include the obviously increased security requirements, unclear legal status and the responsibility of the manufacturer and the user in case of vehicle loss or destruction as well as the need to perform maintenance of the vehicle in specially authorized institutions.
- Phase transfer generators. Recently, the Scripps Institution of Oceanography (the USA) has reported a successful completion of testing the SOLO-TREC device, which is powered by the phase transfer generator. During the phase change of the working fluid, its volume changes, and the impeller of the generator is driven via the second circuit with oil. The device performs a dive to a depth of 500 meters and back, during one dive the generator produces about 1.7 Wh. Unfortunately, no practical information could be obtained on the domestic versions of such generators.
- Communication tools
The need to provide all possible forms of communication became clear in the course of works on the project. In addition to the already available digital radio station apparatus, short-range WiFi unit, 3G communication station (used in debug mode), we added the sonar communication modules (sonar modem with the possibility of underwater navigation), satellite communication. Much interest was aroused by the works going in the United States to create laser and optical submarine channels. The systems are based on blue-green lasers (470-570 nm) that have minimum energy dispersion in seawater (about 0.2 dB/m). Laser communication features high speed (up to 10 Kbps) and has reliably transferred even the streaming video during experiments. Small parcel duration, high stealthiness and high volume of transmitted information makes the optical means of communication the most promising at the relatively short distances.
- Transfer to hybrid motion model
It is necessary to increase the speed of the vehicle up to 2-3 knots and to comply with altitude corridor with sufficiently high accuracy (horizontal flight) to overcome the areas with complex hydrology, as well as to perform areal sonar surveys. Due to the physical nature of the motion mechanism, the traditional-design glider cannot solve these problems. The only way out is to partially sacrifice the energy efficiency and to install a traditional engine with propeller on the vehicle (although alternative propulsion devices, such as bionic, have also been considered). This direction offers great scope for research and development, where we could apply the advanced knowledge accumulated in the USSR and the Russian Federation in the field of fluid dynamics, efficiency and stealthiness of propeller screws.