Method of taking into account the ship’s dynamics in the process of the ship’s safe trajectory calculation

Dynamika statku w procesie manewru zmiany kursy zależy od aktualnego kąta wychylenia płetwy steru, aktualnej prędkości statku oraz stanu załadowania. W pracy przedstawiono metodę tworzenia rodziny charakterystyk czasu realizacji manewru w funkcji zmiany kursu dla różnych wartości kąta wychylenia steru oraz prędkości liniowych statku, dla wybranych typów statków. Właśności dynamiczne przykładowych statków obliczane są przy wykorzystaniu oprogramowania MATLAB. Na podstawie obliczeń próby cyrkulacji otrzymywania jest wartość średnicy cyrkulacji ustalonej statku. Następnie obliczana jest prędkość kątowa statku oraz wyznaczane są charakterystyki czasu realizacji manerwu w funkcji zmiany kursu. W dalszej części pracy przedstawiono sposób uwzględniania czasu realizacji manewru w obliczeniach realizowanych przez algorytm wyznaczania bezpiecznej trajektorii statku.Dynamics of a ship in the process of a course change manoeuvre depends on the current rudder angle, the ship’s speed and loading condition. A method of calculating a family of characteristics, presenting the manoeuvre time as a function of the course change for different values of the rudder angle and the ship’s speed, for different types of vessels is presented in this paper. Dynamic properties of a ship are calculated using the MATLAB software. Based upon the turning circle calculation, a value of the steady turning radius in obtained. Then, the angular velocity of the ship is calculated and characteristics of the manoeuvre time as a function of the course change are determined. After that, a method of taking into account the manoeuvre time in the ship’s safe trajectory determination algorithm is presented and its successful application is proved by results of simulation tests. A heuristic Ant Colony Optimization based algorithm and a deterministic Trajectory Base algorithm were used for the dynamic properties application and evaluation tests, but the method can easily be applied in other algorithms utilizing different optimization methods

Verification of a deterministic ship's safe trajectory planning algorithm from different ships’ perspectives and with changing strategies of target ships

The paper presents results of a ship's safe trajectory planning method verification - the Trajectory Base Algorithm, which is a deterministic approach for real-time path-planning with collision avoidance. The paper presents results of the algorithm’s verification from different ships’ perspectives and with changing strategies of target ships. Results prove the applicability of the algorithm in the Collision Avoidance Module of the Autonomous Navigation System for Maritime Autonomous Surface Ships

Swarm intelligence approach to safe ship control

This paper presents an application of the Ant Colony Optimization (ACO) technique in a safe ship control system. The method developed solves the problem of path planning and collision avoidance of a ship in the open sea as well as in restricted waters. The structure of the developed safe ship control system is introduced, followed by a presentation of the applied algorithm. Results showing the problem-solving capability of the system are also included. The aim of the system developed is to increase automation of a safe ship control process. It is possible to apply the proposed method in Unmanned Surface Vehicles (USVs) control system, what will contribute to the enhancement of their autonomy

A nature inspired collision avoidance algorithm for ships

Nature inspired algorithms are regarded as a powerful tool for solving real life problems. They do not guarantee to find the globally optimal solution, but can find a suboptimal, robust solution with an acceptable computational cost. The paper introduces an approach to the development of collision avoidance algorithms for ships based on the firefly algorithm, classified to the swarm intelligence methods. Such algorithms are inspired by the swarming behaviour of animals, such as e.g. birds, fish, ants, bees, fireflies. The description of the developed algorithm is followed by the presentation of simulation results, which show, that it might be regarded as an efficient method of solving the collision avoidance problem. Such algorithm is intended for use in the Decision Support System or in the Collision Avoidance Module of the Autonomous Navigation System for Maritime Autonomous Surface Ships

Verification of ship's trajectory planning algorithms using real navigational data

The paper presents results of ship's safe trajectory planning algorithms verification. Real navigational data registered from a radar with an Automatic Radar Plotting Aid on board the research and training ship Horyzont II were used as input data to the algorithms. The algorithms verified in the presented research include the Ant Colony Optimization algorithm (ACO), the Trajectory Base Algorithm (TBA), the Visibility Graph-search Algorithm (VGA) ant the Discrete Artificial Potential Field algorithm (DAPF). Details concerning data registration and exemplary results obtained with the use or real navigational data are introduced and summarized in the paper. Presented results prove the applicability of proposed algorithms for solving the ship's safe trajectory planning problem

Decision support system for collision avoidance at sea

The paper presents design and realization of computer decision support system in collision situations of passage with greater quantity of met objects. The system was implemented into the real ship electro-navigational system onboard research and training ship m/v HORYZONT II. The radar system with Automatic Radar Plotting Aid constitutes a source of input data for algorithm determining safe trajectory of a ship. The article introduces radar data transmission details. The dynamic programming algorithm is used for the determination of safe optimal trajectory of own ship. The system enables navigational data transmission from radar system and automatic determining of safe manoeuvre or safe trajectory of a ship. Further development of navigator’s decision support system is also presented. Path Planning Subsystem is proposed for the determination of global optimal route between harbours with the use of Ant Colony Optimization algorithms

Multi-criteria ACO-based algorithm for ship’s trajectory planning

The paper presents a new approach for solving a path planning problem for ships in the environment with static and dynamic obstacles. The algorithm utilizes a heuristic method, classified to the group of Swarm Intelligence approaches, called the Ant Colony Optimization. The method is inspired by a collective behaviour of ant colonies. A group of agents - artificial ants searches through the solution space in order to find a safe, optimal trajectory for a ship. The problem is considered as a multi-criteria optimization task. The criteria taken into account during problem solving are: path safety, path length, the International Regulations for Preventing Collisions at Sea (COLREGs) compliance and path smoothness. The paper includes the description of the new multi-criteria ACO-based algorithm along with the presentation and discussion of simulation tests results

Temperature evolution of the luminescence decay of Sr0.33Ba0.67Nb2O6 : Pr3+

This article presents a spectroscopic investigation of Sr0.33Ba0.67(NbO2)(3), doped with 1 mol% of Pr3+. Photoluminescence and luminescence kinetics were measured at different temperatures at ambient (ferroelectric phase) and 76 kbar pressures (paraelectric phase). The photoluminescence spectrum is dominated by D-1(2)-> H-3(4) transition of Pr3+ in both phases. At ambient pressure when the system is excited with UV radiation, the intensity of dominant D-1(2)-> H-3(4) emission evidently increases in the 200-293 K temperature range. This effect is attributed to enhancement of the excitation of the D-1(2) state through the praseodymium trapped exciton state, which at higher temperatures does not populate the higher lying P-3(0) state. Additionally, under UV radiation the material exhibits afterglow luminescence activated by temperature that can also have an impact on the increase of the D-1(2) emission. We propose that the afterglow luminescence is related to the existence of electron traps. At a pressure of 76 kbar the depth of the electron traps decreases in comparison to the ones observed at ambient pressure. However, the phase transition does not change the number of electron traps

Pressure evolution of luminescence in SrxBa 1-x(NbO2)3:Pr3+ (x=1/2 and 1/3)

The contribution presents a spectroscopic investigation of Sr xBa1-x(NbO2)3 (SBN), (x=1/2 and 1/3) doped with 1 mol% of Pr3+. Photoluminescence and luminescence excitation spectra were measured. Spectroscopic experiments were performed at room temperature at different hydrostatic pressures up to 260 kbar. The emission spectra depend on the excitation wavelength and applied pressure. It was found that pressure causes quenching of the Pr3+ luminescence. This effect was attributed to the existence of praseodymium trapped exciton (PTE) states. Specifically the pressure induces increasing energies of Pr3+ states with respect to the energies of band edges and energy of PTE. \ua9 2013 Elsevier B.V