Ship Collision Research Articles

Automatic Collision Avoidance Route Planning Method in Complex Navigation Environments

Efficient collision avoidance (CA) route planning is one of the important technologies for ensuring the safety of autonomous ships. Many CA route planning studies have been developed for the open sea, but few studies have been conducted for ships in complex navigation environments. A complex navigation environment refers to water encompassing various factors, such as multiple obstacles, varying water depths, ships collision risk, and other maritime challenges. These factors collectively contribute to the complexity of the environment. CA planning in this type of environment is a special type of route planning. To address CA in complex navigation environments, firstly, the route binary tree algorithm is utilized for conducting global route planning in order to determine the optimal path. Secondly, this paper proposes a dynamic generation of local collision avoidance trajectories along the optimal path, seamlessly integrating global route optimization and local collision avoidance. Finally, a comparative analysis is conducted using classical techniques to verify the effectiveness of the proposed method. Numerical simulation results reveal that when a ship is taken as the object of CA in the open sea, the route generated using the proposed method exhibits a remarkable level of unity with the one generated by the benchmark method of improved Artificial Potential Field (APF), particularly in terms of collision avoidance strategy selection, collision avoidance trends, and the actual trajectory. The former’s computational efficiency is improved by at least 30%. When dealing with CA at sea, with complex navigation obstacles, the proposed method considers static complex navigation obstacles, dynamic ships, and their unpredictable strategies to timeously generate a safe path which considers some key rules from the COLREGS (International Regulations for Preventing Collisions at Sea) (IMO, 1972).

An Improved A-Star Ship Path-Planning Algorithm Considering Current, Water Depth, and Traffic Separation Rules

The influence of the maritime environment such as water currents, water depth, and traffic separation rules should be considered when conducting ship path planning. Additionally, the maneuverability constraints of the ship play a crucial role in navigation. Addressing the limitations of the traditional A-star algorithm in ship path planning, this paper proposes an improved A-star algorithm. Specifically, this paper examines the factors influencing ship navigation safety, and develops a risk model that takes into account water currents, water depth, and obstacles. The goal is to mitigate the total risk of ship collisions and grounding. Secondly, a traffic model is designed to ensure that the planned path adheres to the traffic separation rules and reduces the risk of collision with incoming ships. Then, a turning model and smoothing method are designed to make the generated path easy to track and control for the ship. To validate the effectiveness of the proposed A-star ship path-planning algorithm, three cases are studied in simulations and representative operational scenarios. The results of the cases demonstrate that the proposed A-star ship path-planning algorithm can better control the distance to obstacles, effectively avoid shallow water areas, and comply with traffic separation rules. The safety level of the path is effectively improved.

A COLREGs-Compliant Ship Collision Avoidance Decision-Making Support Scheme Based on Improved APF and NMPC

In this paper, combined with the improved artificial potential field (IAPF) method and the nonlinear model predictive control (NMPC) algorithm, a collision avoidance decision-making support scheme considering ship maneuverability and the International Regulations for Preventing Collisions at Sea (COLREGs) is proposed. First, to comply with the requirements of COLREGs, an improved repulsive potential field is presented for different encounter scenarios when the ship detects the risk of collision, and the coordinated ship domain is applied to provide safety criteria for collision avoidance. Then, by transforming the MMG model to a discrete-time nonlinear system, the NMPC is utilized to predict the future state of the ship according to the current state, and the IAPF method is incorporated to calculate the potential field in each future state as the objective function. Following this approach, the action taken to avoid collision is more effective, the ship motion in avoiding collision is more accurate, and the collision avoidance decision making is more reasonable. Finally, two simulation examples of multi-ship encounter scenarios are applied to illustrate the merits and effectiveness of the proposed collision avoidance decision-making support scheme.

A Rayleigh-Ritz solution for high order natural frequencies and eigenmodes of monopile supported offshore wind turbines considering tapered towers and soil pile interactions

Offshore wind turbines may be exposed to extreme or accidental loads during the service life, such as extreme water slamming, ship collisions, earthquakes, extreme winds, ice loads, etc. Under the action of such loads, they will respond not only in the primary eigenmode, but also high order modes. This paper presents a Rayleigh-Ritz solution for high order natural frequencies and eigenmodes of monopile supported offshore turbines. The model considers explicitly tapered wind turbine towers and soil-pile interactions. Different soil conditions are considered using equivalent cross coupled springs at the mudline. The proposed Rayleigh-Ritz solution is applied to the DTU 10 MW wind turbine mounted on a monopile foundation. The predicted natural frequencies and eigenmodes are compared with nonlinear finite element simulations using USFOS. The results show excellent agreement for the first 3 eigenmodes. Even higher eigenmodes than the 3rd order are also calculated but are not presented. They can be readily obtained if needed.High order natural frequencies and eigenmodes using the proposed Rayleigh-Ritz solution can, together with the Duhamel's integral, be well utilized in the buckling and collapse analysis and design of monopile supported offshore wind turbines in Ultimate Limit States (ULS) and Accidental Limit States (ALS). In addition, the high accuracy of the predicted primary natural frequency makes it a useful design tool to help avoid undesired resonance from external excitation loads and to reduce resonance related fatigue effects in Fatigue Limit States (FLS).

Determining the Proper Times and Sufficient Actions for the Collision Avoidance of Navigator-Centered Ships in the Open Sea Using Artificial Neural Networks

Ship collisions are a major maritime accident; various systems have been proposed to prevent them. Through investigating and analyzing the causes of maritime accidents, it has been established that ship collisions can either caused by delaying actions or not taking the sufficient actions to avoid them. Recognizing the limitations in providing quantitative numerical values for avoiding ship collisions, this study aimed to use Bayesian regularized artificial neural networks (BRANNs) to suggest the proper time and sufficient actions required for ship collision avoidance consistent with the Convention on the International Regulations for Preventing Collisions at Sea. We prepared the data by calculating the proper times and sufficient actions based on precedent research and used them to train, validate, and assess the BRANNs. Subsequently, an artificial neural network controller was designed and proposed. The data of the proposed neural network controller were verified via simulation, validating the controller. This study is limited in cases such as overtaking a ship in front. However, it is expected that this controller can be improved by establishing the criteria for an appropriate overtaking distance after further examining the closest point of approach (CPA) and time to the CPA (TCPA) for overtaking a ship in front and using the method presented herein.

Ship Collision Risk Assessment

Ship collision accidents are one of the most frequent events, and cause serious damages to health, structural safety and the environment [...]

Hybrid causal logic model for estimating the probability of an icebreaker–ship collision in an ice channel during an escort operation along the Northeast Passage

Under severe Arctic ice conditions, escort operations are the most efficient methods for facilitating shipping. Nevertheless, escort operations are among the most dangerous operations, as they may result in icebreaker–ship collisions and/or ship besetting in ice. To mitigate the risk of collisions, it is essential to understand the event sequences of collisions and the risk control options that can be implemented to reduce the occurrence of undesired events. This paper proposes a hybrid causal logic model to estimate the likelihood of an icebreaker–ship collision while considering human factors during an escort operation along the Northeast Passage. The model relies on inputs from four icebreaker captains. Its applicability is demonstrated for a 2018 summer voyage of a cargo ship assisted by an icebreaker. Risk control options are then proposed based on qualitative and sensitivity analyses of the model. The results of this study can assist shipping companies to better understand the sequence of events prior to icebreaker–ship collisions during escort operations in ice-covered waters. This paper provides information on risk reduction measures. In addition, the proposed model can assist in route planning.

Construct Maritime Safety Culture to Reduce Risk Occurrence Through Implement of Balanced Scorecard

_ This study aims to assess navigation safety by enhancing maritime management based on balanced scorecard (BSC). Although the International Safety Management Regulations and the Ship Safety Management System have safety related definitions and provide standard safety regulations, but lack effective management processes. This study used path analysis and regression analysis to analyze the safety outcomes relationship among organization safety culture, work condition, and framework condition sectors. In this study, 173 valid sample questionnaires were collected to answer the influence of organizational culture, working environment, service process, and framework conditions on ship navigation safety. The suggestions mentioned expect to establish a maritime management-based BSC that could pave the way for the application of maritime safety around the organization culture. Introduction Safety management is an important part of organization management process. The purpose of safety management is to prevent accidents, so organizations need to develop, plan, implement, and track risks related to personal, environmental, or property safety in order to minimize risks. The rapid development of China’s economy has promoted the increase of economic, trade, and ship navigation between Taiwan and Chinese mainland, and the number of ships in Taiwan and other countries has also increased. Maritime transportation plays a significant role in the integrated transportation system, especially in international trade system. Safety is a crucial factor due to the fact that various accidents like ship collisions and groundings often result in great economic loss, fatalities, and the environmental contamination. This information shows that Taiwan plays a key maritime role in Asia and the world. Previously, several frameworks for assessing the effects of organizational aspects on risk or safety have been published within different domains (Embrey 1992; Pate-Cornell & Murphy 1996; Oien 2001; Roelen et al. 2003; Mohaghegh et al. 2009) and in the maritime transportation field (Trucco et al. 2008). However, these have not addressed the navigation safety process management through systematic concepts and empirical study, they only emphasized the reducing risk on the maritime safety.

Study on the Classification Perception and Visibility Enhancement of Ship Navigation Environments in Foggy Conditions

Based on ship navigational requirements and safety in foggy conditions and with a particular emphasis on avoiding ship collisions and improving navigational abilities, we constructed a fog navigation dataset along with a new method for enhancing foggy images and perceived visibility using a discriminant deep learning architecture and the EfficientNet neural network by replacing the SE module and incorporating a convolution block attention module and focal loss function. The accuracy of our model exceeded 95%, which meets the needs of an intelligent ship navigation environment in foggy conditions. As part of our research, we also determined the best enhancement algorithm for each type of fog according to its classification.

Modeling Human Encounter Situation Awareness Results Using Support Vector Machine Models

This study constructs a support vector machine model based on supervised learning to model the results of situation awareness for ship collision avoidance. To explain the model, collision risk situations were defined, and human situation recognition results were collected in the specified cases. Moreover, it was used to build predictors and outcome variables. Finally, the constructed variable was applied to the classification model. This model provides insight into the results of the navigator’s encounter situation awareness when collision avoidance is required. The results indicate that the proposed model can be used to predict human situation awareness outcomes in given cases.

Effects of ship domain shapes on ship collision risk estimates considering collision frequency and severity

This study aims to estimate ship collision risk considering the occurrence frequency and severity simultaneously, as well as to explore the influence of ship domain shapes on estimation results in the Yangtze River estuary waterway. In contrast to the circular ship domain, the elliptical domain may result in an overestimate for head-on collisions and overtaking collisions, while it may underestimate the small-angle and large-angle crossing collision frequency. Conversely, the sector domain may underestimate the occurrence frequency of all collision types. Results also reveal that overtaking encounters are the most common type with a relatively low severity degree, while large-angle crossing collisions are associated with a lower frequency but a higher potential for causing serious consequences. The collision occurrence likelihood and severity are a little higher for the passenger ship type. Furthermore, two high-risk areas are found to be located between longitudes of 121°33′E and 121°46′E, 121°50′E and 121°58′E, respectively. The results of this study are beneficial for a better understanding of the overall collision risk in the Yangtze River estuary waterway.

TOWARDS THE ISSUE OF INTERNATIONAL LEGAL ASPECTS OF A MARITIME AUTONOMOUS SURFACE SHIP OPERATION

The article discusses the international legal aspects related to the operation of maritime autonomous surface ships (hereinafter - MASS) that do not require the presence of a crew on board. It is highlighted that the current «maritime» conventions do not mention MASS as a category of sea vessels, however, some doctrines and soft law acts deal with the issues of international legal regulation of the operation of MASS. These sources are revealed in the article. Problematic issues related to the operation of MASS are considered, including the shipping safety, compliance with international shipping standards to avoid ship collisions, cyber security, the status of the person responsible for safety on board and environmental protection. Due to the introduction of MASS, it was taken note of the feasibility to improve the UN Convention on the Law of the Sea (1982) in terms of regulating the rules for the peaceful passage of MASS through the territorial sea. In addition, the need to eliminate legal conflicts with the International Convention on Salvage (1989) is stated, since the possibility of an autonomous vessel to perform rescue operations remains unclear. In summary, it is needed to develop mandatory international standards in order to regulate the operation of MASS, including requirements for the design of MASS, technical regulations, minimum requirements for MASS operators. It is proposed to extend the international legal status of the captain to the operator of the remote control center, however, excluding his responsibility for violations that occur directly on board the ship (e.g. fire safety, smuggling). It is advisable to entrust the responsibility for the proper technical condition of the ship’s mechanisms to the specialists who will carry out the maintenance of the autonomous ship. The remote control center should be considered like both the wheelhouse and the central control point of the engine room.

A full-time deep learning-based alert approach for bridge–ship collision using visible spectrum and thermal infrared cameras

With the rapid development of transportation infrastructure and the growing water transportation industry, many bridges have been constructed across navigable rivers. However, collisions between ships and bridges remain a frequent occurrence, particularly under low illumination conditions. To address this issue, this paper proposes a full-time bridge–ship collision alert approach based on the combination of visible spectrum and infrared cameras. This approach includes the following steps: (1) capturing and identifying ships in the channel using a single visible spectrum camera is challenging in low illumination environments such as nighttime. To overcome this limitation, we propose the use of infrared thermal imaging technology, which can monitor ships at night due to their inherent emissivity of ship thermal radiation. By comprehensively analyzing factors such as the real-time lighting environment and comparing the advantages of visible spectrum cameras and thermal infrared cameras in object recognition under various illuminance levels, we determine the effectiveness of the decision-making method of the dual-channel camera for ships under different illumination conditions. (2) To detect and track ships in the channel, a deep learning-based automatic detection and tracking method is designed using visible spectrum and infrared thermal imaging cameras, providing early warning of dangerous trajectories of ships that threaten the piers. To address the real-time identification and positioning of ships by dual-channel cameras in different light environments, we adopt a target detection network and a displacement calculation algorithm for multi-target tracking. Analysis results demonstrate that this method can automatically assign visible spectrum and thermal imaging cameras as effective input sources in different illumination environments to detect and warn ships with dangerous trajectories, contributing to the safety of navigable ships and bridges in low illumination conditions.

Numerical Study on Ductile Failure Behaviours of Steel Structures under Quasi-Static Punch Loading

A reliable finite element procedure to simulate shear-dominated ductile fractures in large-scale, thin-walled steel structures is still evolving primarily due to the challenges in determining the failure criterion of metal materials under complex stress states. This paper aims to examine the accuracy of the modified Gurson–Tvergaard–Needleman (GTN) model considering the shear failure in simulating the ductile fracture of steel plate structures under quasi-static punch loading. The modified GTN damage models are performed by the ABAQUS user-defined material subroutine (VUMAT). The void-related parameters and shear damage parameters of Xue’s and the N-H modified GTN models are calibrated from test specimens with various geometries corresponding to different stress triaxiality and shearing conditions. The damage evolution associated with shearing of voids in the modified GTN models has strong influences on the stress triaxiality versus plastic strain under complex stress states, especially for the shear-dominated loading conditions. Based on the original GTN model, Xue’s and the N-H modified GTN model with calibrated material parameters, a numerical comparative study examines the ductile fracture of steel non-stiffened plates and stiffened plates under punch loading. Benchmarked against the experimental studies, the numerical simulations demonstrate that the shear-driven void evolution in the modified GTN model imposes significant effects on the load–displacement responses as well as the onset and extension of ductile fractures in steel plates under punch actions. The N-H modified model with calibrated shear damage parameters shows a better correlation with the ductile fractures in steel plates observed in the experiment than the original GTN model and Xue’s modified GTN model. As a result of this study, the modified GTN model considering shear action can be applied for practical applications in the crashworthiness assessment of ship collision and grounding.

Optimized APF-ACO Algorithm for Ship Collision Avoidance and Path Planning

The primary objective of this study is to investigate maritime collision avoidance and trajectory planning in the presence of dynamic and static obstacles during navigation. Adhering to safety regulations is crucial when executing ship collision avoidance tasks. To address this issue, we propose an optimized APF-ACO algorithm for collision avoidance and path planning. First, a ship collision avoidance constraint model is constructed based on COLREGs to enhance the safety and applicability of the algorithm. Then, by introducing factors such as velocity, position, and shape parameters, the traditional APF method is optimized, creating a dynamic APF gradient for collision avoidance decision making in the face of dynamic obstacles. Furthermore, the optimized APF method is integrated with the ant colony optimization algorithm, the latter modified to overcome the inherent local optimality issues in the APF method. Ultimately, validations are conducted in three areas: static avoidance and planning in restricted sea areas, avoidance under conditions of mixed static and dynamic obstacles, and avoidance in situations of multiple ship encounters. These serve to illustrate the feasibility and efficacy of the proposed algorithm in achieving dynamic ship collision avoidance while simultaneously completing path-planning tasks.

A novel method for ship trajectory prediction in complex scenarios based on spatio-temporal features extraction of AIS data

Ship trajectory prediction plays a key role in the early warning and safety of maritime navigation. Ship pilots must have a complete grasp of the future trajectories of ships within a certain period of time when moving the ship to effectively avoid collisions. However, the accuracy of ship trajectory prediction is a significant issue that needs to be resolved at present. In this paper, we propose a ship trajectory prediction model covering spatio-temporal awareness graph attention network (GAT) based on long short-term memory network (LSTM) to predict the future trajectories of ships in complex scenarios, named STPGL model, which adopts the design of encoder–decoder structure. The historical encoder uses an LSTM to extract the kinematic sequence features of each ship from historical trajectories in the temporal dimension. The interactive encoder summarizes the interaction features between different ships through GAT in the spatial dimension. Then, the two features are fused and fed into the decoder module to infer the future trajectories of ships. The experimental results demonstrate that STPGL model can effectively improve the prediction accuracy of short-term, medium-term and long-term ship trajectory. It has excellent performance and has a certain reference value for the advancement of unmanned ship collision avoidance.

Анализ безопасности плавучего энергоблока при столкновениях

The article considers a possible navigational accident associated with the ramming of a modernized floating power unit (MFPU) by another ship. The authors suggest an approach to determine the consequences of a collision using the finite element method. The finite element model has been developed for modeling the destruction of ship hull structures, to determine the energy intensity of ship hull structures during ramming, and to calculate the critical velocity of ramming ships. The study results provide the following conclusions: 1) the use of the finite element method in the analysis of collisions of nuclear ships helps removing excessive conservatism characteristic of engineering approaches that underestimate the energy intensity of structural elements during destruction. 2) when determining the volume of destruction of the hull structures of colliding ships and the critical velocity of ramming ships, it is necessary to use the model of the deformable bow of a ramming ship. 3) ramming the floating power unit by an icebreaker does not lead to radiation consequences at icebreaker velocity of less than 18 knots. The ramming of an unfastened floating power unit with a similar one caused by extreme natural impacts during its mooring does not lead to radiation consequences, since the critical velocity of the floating power unit of 10.4 knots cannot be achieved. Thus, it is shown that the modernized floating power unit has a high level of safety in case of navigation accidents associated with collisions.

A Novel Ship Domain-oriented Parameter of Ship Collision Risk Considering the Ship Maneuverability and Encounter Situation

The identification of ship collision risks is an important element in maritime safety and management. The concept of the ship domain has also been studied and developed since it was proposed. Considering the existing trend that the ship domain is increasingly widely used in collision risk-related research, a new domain-oriented collision risk factor, i.e., the current state of domain (CSD), is introduced in this paper, which can effectively reflect the current state and show a certain predictability of collision risk from the perspective of the ship domain. To further prove the rationality of the CSD, a series of different simulations consisting of three typical encounter scenarios were conducted, verifying the superiority of the proposed parameter.

Survey on Cooperative Collision Avoidance Research for Ships

Communication among the ships can provide additional information that assists ships in negotiating and collaborating with others to take effective actions. This paper provides a review on ship collision avoidance methods proposed during the last decade from the perspectives of communication and cooperation. Two innovatively indices are defined, i.e., the communication index and the cooperation index. The overview of the existing research shows that collision risks are the most often exchanged information, while weak cooperation based on predefined protocols or rules, like COLREGs, is the majority. Competition and high-level cooperation are rarely studied in the past, but these topics have attracted increasing attention. Moreover, the analysis of the two indices reveals that communication is the premise of cooperation. Higher-level cooperation requires detailed information, which means higher communication requirements. The main challenges for future research are identified, including cooperation among heterogeneous ships considering various autonomous levels and cooperation levels, the stability of the communication network and the reliability of the exchanged information, methods for obtaining the required information, and quantitative interpretations of COLREGs and seamanship.

Quantitative assessment of ship collision risk influencing factors from worldwide accident and fleet data

Quantitative assessment of ship collision risk influencing factors from worldwide accident and fleet data