UDT 2020 UDT Extended Abstract Presentation Lightweight influence mine sweeping system for the future Norwegian unmanned MMCM concept R. Fardal 1 and M. Nakjem 2 1 Principal scientist, FFI, Horten, Norway 2 Project manager, FFI, Horten, Norway Contact author: Rune Fardal, rune.fardal@ffi.no Abstract — The Royal Norwegian Navy (RNoN) Alta class mine sweepers are close to the end of their lifetime and Norway has an overall plan to replace the capability in the timeframe of 2025 – 2030. An increased focus on reduced cost, flexible scalable solutions and a desire to remove personnel from the minefield, have resulted in a future mine sweeping concept based on unmanned surface vehicles (USV). The Norwegian Defence Research Establishment (FFI), the RNoN, the Norwegian Defence Material Agency (NDMA) and the industry have started to investigate in future concepts with use of a mothership, positioned outside the minefield, and forward deployed autonomous unmanned maritime mine countermeasures (MMCM) systems. Several tests have been performed and this paper will give an overview of the concept, technology and testing of a USV-based magnetic, electric and acoustic light weight influence mine sweeping system. 1 Introduction Both the Oksøy and Alta class have identical hull mounted mine hunting sonars and Kongsberg’s Minesniper One- Effective MMCM requires a combination of mine Shot Mine Disposal Weapon. This enables the Alta class sweeping, mine hunting and clearance diving. Hunting, to perform complete mine sweeping and mine hunting sweeping and clearance diving are complementary operations. The Mine Diver Command (MDK) techniques and it is absolutely necessary to master all three supplement the Naval Mine Warfare Service with an in order to handle all mine threats and operate effectively additional capability for clearing mines from the MCM in all areas with varying environmental conditions. vessels and in very shallow water and surf zone where the Extensive bottom profiling and mapping shows that more vessels cannot operate. The MDK is also equipped with than 50% of Norwegian areas relevant for mine clearance small Remus100 AUVs. operations are unsuitable for mine hunting and a robust mine sweeping capability is necessary. The RNoN Alta 3 Future Norwegian MCM class mine sweepers were built for a lifetime of 25 years in the period 1994 to 1997. Towards the end and past the In 2015 the Norwegian Ministry of Defence (MoD) issued designed lifetime, a significant increase in the maintenance the order for start-up of the conceptual phase for the cost is expected to sustain operational availability. planned replacement of the current Norwegian MMCM Assessment about the future of Norwegian MMCM is capability. The order stated the conceptual phase to focus therefore needed and FFI have several projects related to on the possibilities of using unmanned systems in the technological risk reduction for the future mine sweeping future capability to get the “man out of the minefield” concept. when possible. This statement was based on the successful experiences from operational testing of the Hugin AUV, 2 Current Norwegian MCM giving the Navy great confidence in the use of unmanned systems for MMCM operations. The current Norwegian MMCM forces consist of two Oksøy class mine hunters, two Alta class mine sweepers The conceptual phase is finalized and it states that the and mine divers. The Oksøy class is equipped with hull future MMCM capability will be based on use of mounted sonar and a remotely operated vehicle for mine unmanned systems. Further, the conceptual phase disposal. In addition, the Navy has a contract with recommend that the preferred future MMCM solution Kongsberg for delivery in 2020 of four new Hugin should consist of unmanned systems operating from a autonomous underwater vehicles (AUV). Two of them manned ship located outside the mined area. This is also in operated from the Oksøy class and two containerized line with the new long-term plan for the Norwegian Armed systems operated from ship of opportunity. The Hugin Forces. Table 1 shows the timeline for the transition to the AUV is equipped with Synthetic Aperture Sonar and next generation MMCM capability. optical camera with strobe lights. The Alta class has the ELMA cable sweep and AGATE acoustic system for magnetic and acoustic influence sweeping. The sweepers are also capable of performing mechanical sweeping.
UDT 2020 Presentation UDT Extended Abstract Table 1. Timeline for the Norwegian MMCM capability 4.1 Concept for Future Norwegian Unmanned procurement program. Mine sweeping capability Phase Year The Norwegian unmanned influence mine sweeping Conceptual phase 2015-2019 concept will use USVs to tow magnetic, acoustic and Definition Phase 2020-2021 electric sweep sources in various configurations. The USVs will be transported by a dedicated supporting vessel Project Phase 2021-2028 or by other military transportation (air/sea/land), and they Initial operational capability 2025 will be operated from the supporting vessel or a mobile land station. Full operational capability 2028 The sources will be towed behind the USVs in order to get 3.1 Concept for Future Norwegian MMCM the required field distribution and prevent the USV from Capability damage after a mine explosion. The sweep sources will most likely be launched from the manned ship outside the The Norwegian Navy future MMCM concept will be mined area and then transferred as a “clip-on” sweep to the based on use of USV, AUV and clearance divers as shown USV before the USV leaves the mother ship rather than in Figure 1. The unmanned MCM components are having the sweep systems integrated onboard the USV. transported on- and operated from a manned ship placed This clip-on solution will remove the complexity of outside the mined or assumed mined area. AUVs will be unmanned launch and recovery of the sweep from the used for detection, localization and identification of the USV, and will also allow for a smaller USV size. The USV mines, while an operator controlled mine disposal weapon with the lightweight influence sweep deployed will transit (MDW) will be used for classification and neutralization. into the operation area and start the mine sweeping The USV will have a multi role function including towing operation in a predefined pattern. When the operation is of the influence sweep and control platform for the MDW. completed or when the USV needs refueling the USV will The USV can also be used for AUV transportation and transit back to the supporting vessel. deployment, and as a communication relay station between the operator and the AUV. FFI has two 35-feet boats with 600 hp and water jets for use as test and development platforms as shown in figure 2. The boats are equipped with relevant sensors and used for autonomy development related to obstacle detection and avoidance, track planning and GPS-independent navigation. The boats are also used for all USV-based development and testing at FFI. Fig. 1. Future Norwegian MMCM concept (figure: NDMA). USV based influence mine sweeping has a key role in the future concept and the following sections of this paper will focus on how the mine sweeping operations and the related technological development at FFI. 4 Norwegian Influence Mine Sweep Fig. 2. FFIs test USV “Odin” (picture: FFI). The current Norwegian Alta class mine sweepers have The following influence sweep sources and con- ELMA cable sweep and AGATE acoustic system for figurations will be described in this section of the paper: magnetic and acoustic influence sweeping. The influence - Acoustic sweep sweeps are used in Mine Setting Mode (MSM) which - Open electrode magnetic cable sweep means that they have sufficient energies to satisfy the - Closed loop magnetic and electric cable sweep triggering logic of mines. They are also used in Target Simulation Mode (TSM) where the idea is to emulate the ship to protect and then the mine logic set for the specific 4.1.1 Acoustic Sweep ship will trigger. ELMA and AGATE can emulate ship signatures for large civilian merchants. The Alta class is A traditional acoustic sweep source can be used to mimic also capable of performing mechanical sweeping. the acoustic ship signature, but it has to be a light weight
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