The aim of this article is to present the author’s opinion about possible underwater natural gas pipeline monitoring using Polish Navy resources. Due to the bathymetrical characteristics of the pipeline equatorials the high efficiency and safe for the deck operators systems are expected to support the bottom survey and gas line monitoring. Time and engaged resources reduction are crucial factors in this kind of mission together with high probability of possible dangerous objects detection. The paper describes main threats for the underwater transportation line as a state energetic independence vital object (supplies diversification). An example of a threat caused by lost unmanned platform technologies near Nord Stream was presented and analyzed as well. The rapid development of unmanned maritime technologies (aerial, surface and subsurface) observed in the last decade creates new possibilities in maritime security/surveillance applications. The Polish mine counter measures assets which were equipped with sophisticated AUV’s as a part of the Polish Navy modernization process (new minehunters Kormoran IInd class deployable). The presented autonomous underwater vehicles (AUV) are equipped with advanced sonars and create new possibilities in the issue of effective threats detection/classification/ identification and neutralization. The main advantages of such solutions were pointed in the article with the crucial one based on time reduction as well as human – deck operators threats constraints. The first successes in the operational use of unmanned systems were reached during the military exercises (historical ordnance disposal) conducted on historical mine laying areas. This creates good possibilities to train the unmanned system operators in live objects activity which improves skills and knowledge. Moreover, the double use applications of unmanned technologies both in defense and maritime security has been observed.

In global path planning (GPP), an autonomous underwater vehicle (AUV) tracks a predefined path. The main objective of GPP is to generate a collision free sub-optimal path with minimum path cost. The path is defined as a set of segments, passing through selected nodes known as waypoints. For smooth planar motion, the path cost is a function of the path length, the threat cost and the cost of diving. Path length is the total distance travelled from start to end point, threat cost is the penalty of collision with the obstacle and cost of diving is the energy expanse for diving deeper in ocean. This paper addresses the GPP problem for multiple AUVs in formation. Here, Grey Wolf Optimization (GWO) algorithm is used to find the suboptimal path for multiple AUVs in formation. The results obtained are compared to the results of applying Genetic Algorithm (GA) to the same problem. GA concept is simple to understand, easy to implement and supports multi-objective optimization. It is robust to local minima and have wide applications in various fields of science, engineering and commerce. Hence, GA is used for this comparative study. The performance analysis is based on computational time, length of the path generated and the total path cost. The resultant path obtained using GWO is found to be better than GA in terms of path cost and processing time. Thus, GWO is used as the GPP algorithm for three AUVs in formation. The formation follows leader-follower topography. A sliding mode controller (SMC) is developed to minimize the tracking error based on local information while maintaining formation, as mild communication exists. The stability of the sliding surface is verified by Lyapunov stability analysis. With proper path planning, the path cost can be minimized as AUVs can reach their target in less time with less energy expanses. Thus, lower path cost leads to less expensive underwater missions.