Multiple decision feedback equalizer for satellite AIS coherent detection
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The Automatic Identification System is a universal shipborne system adopted to improve safety at sea and efficiency of navigation. This system allows to identify and localize vessels in a short range for collision avoidance by exchanging messages with navigational information.Keywords:
Automatic Identification System
Identification
선박운항시스템은 첨단화 되고 있으며, 선박충돌회피시스템에 관한 연구가 활발히 진행되고 있다. 그럼에도 선박 충돌사고율은 줄어들지 않는 실정이다. 시스템에 의한 충돌회피 조종에도 불구하고 근접거리로 충돌위험이 계속 존재한다면, 충돌위험 결정 및 판단기준에 있어서 단순히 TCPA, DCPA만의 입력변수 사용은 근접상황에서 충돌위험회피에 도움을 주지 못한다. 최근 5년간 국내 선박충돌사고 상대선 초인거리 조사에 의하면 약 $45\%$ 가 2마일 이하 근거리 초인하는 것으로 분석된다. 이런 요소는 선박조종성능 특성과 행위결정을 위한 시간적 특성의 영향을 많이 받는 근접조우를 유발한다. 따라서 근접상황에서 선박충돌회피동작 결정에 관한 연구는 안전항해의 필수적인 요소라고 할 수 있을 것이다. 본 논문에서는 선박조종성능 특성에 따른 선회조종과 선박의 거동을 분석하여 근접상황에서 신속하고 올바른 층돌회피 조선을 지원할 수 있는 선박충돌회피지원 모델을 제시한다. Up to now a lot of the study on ship collision avoidance systems have proceeded actively. However the rate of ship collision accidents hasn't decreased yet. If there is collision risk in close quarters situation in spite of maneuvering ship for collision avoidance according to the system, only use of TCP A and DCP A as input factor for collision risk decision is not useful to avoiding collision action. For the recent 5 years by the analysis of first observation distance about approaching ship in domestic collision accidents, nearly $45\%$ of accidents is close first observation less than 2 miles. Therefore it is essential part for safety navigations to study for collision avoidance action in close encounter. In this paper, as a fundamental study of supporting collision avoidance maneuvering for navigators, we proposed ship collision avoidance support model in close quarters situation through analysis qf collision accidents to effectively get rid of the causes.
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The automatic collision avoidance for vessels on sea is an important and difficult problem for modern navigation. We propose a new Vessel Automatic Collision Avoidance System (VACAS) based on Multi-agent System (MAS) and Automatic Identification System (AIS). Each ship can be regarded as an agent, and multiple ships which have potential collision danger compose a MAS. The vessels move toward their goals step by step. Before each step, they should reserve the next sea areas. By exploring the functions of AIS, we use Self Organizing Time Division Multiple Access (SOTDMA) to coordinate vessels automatically. The simulation result demonstrates that our system can automatically avoid collision for multiple vessels successfully. And our method is also suitable for other vehicle's automatic collision avoidance.
Automatic Identification System
Collision avoidance system
Fully automatic
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Ship Domain (SD) is an important concept for the navigational safety of ships that can be used to determine the risk of ship collision. In this paper, we propose a method to establish a Ship Safety Domain Oriented to Collision Risk Judgment (CRSD), which considers the quantified collision risk in the process of establishing the ship domain, therefore the CRSD model is more suitable for risk judgment. Firstly, Automatic Identification System (AIS) data of paired ships are analyzed through using the ship collision risk detection model, and the cases with high collision risk are counted. Then, considering the relationship between ship domain and ship's length, the selected cases are classified according to the ship's length of Own Ship (OS), and the angle when OS encounters with Target Ship (TS) is quantified to get the relationship between the radius of the ship domain and ship's length at different angles so that the shape of CRSD can be obtained. Finally, the CRSD is analyzed and the results show that the CRSD model is consistent with the International Regulations for Preventing Collisions at Sea (COLREGs) that is suitable to be applied to ship collision avoidance risk judgment.
Automatic Identification System
Naval architecture
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In recent years, many ships at sea take measures to reduce potential danger of ship collision. In order to analyze ship collision avoidance behaviors, the Automatic Identification System (AIS) data of vessels in the waters near Zhoushan Island is selected, and pre-processing operations such as dynamic and static data matching, data cleaning, data sorting and trajectory interpolation are carried out in the first step. Then, distance to the Closest Point of Approach (DCP A) and Time to the Closest Point of Approach (TCP A) are calculated, and the safety threshold is determined to extract the encounter vessel data. Based on the changes of the encounter vessel's course and speed, collision avoidance operation points are identified. The results show that the method effectively extracts encounter situation information and collision avoidance behavior information from AIS data. The research results can be used for early warning of ship collision risk, provide with data support for ship collision avoidance decisions and further promoting ship navigation safety.
Automatic Identification System
Interpolation
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In order to avoid collision, ships usually take collision avoidance manoeuvres, such as course alteration. However, the effect of such a manoeuvre is influenced by ship manoeuvrability. This paper proposed an improved danger sector model to identify the collision risk between two encountering ships. The proposed model is improved from the danger sector model, which is based on a course alteration manoeuvre by taking ship manoeuvrability into consideration. To involve ship manoeuvrability in the proposed model, the turning circle of a ship is determined when it calculates the size of the danger sector. For validating the proposed model, the Automatic Identification System (AIS) data in the northern Yellow Sea of China were used to carry out some experiments of different encountering scenarios. The results show that the proposed improved danger sector model can identify the collision risk between two encountering ships effectively and has advantages compared with the original danger sector model. The proposed model can help mariners and maritime surveillance operators have a more accurate and effective assessment of ship collision risk in the water area, which can contribute to the improvement of navigational safety.
Automatic Identification System
Sector model
Course (navigation)
Water area
Maritime industry
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Using electronic chart display and information system(ECDIS)and automatic identification system(AIS)as a credible resource of static and dynamic information and based on the International Regulations for preventing collisions at sea,this paper focused on the techniques of collision avoidance aid. Mathematical model of determining distance for safe meeting was also proposed in detail. A rectangular area model was suggested for searching the information of dangerous underwater obstructions,and the reasoning flow of the decision making system for vessel collision avoidance aid was illustrated. This research administers to the improvement of decision making system for vessel collision avoidance aid practically.
Automatic Identification System
Flow chart
Collision avoidance system
Decision system
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Collision is one of the major accidents threaten the safety of navigation. For avoiding collision, collision risk index is researched and modeled for automatic collision avoidance and collision risk monitoring. This paper proposed a new collision risk index model. The model was based on the collision avoidance manoeuvre of course alteration, which represent the collision risk by calculating the amplitude of alteration that avoid invading ship domain of target ship. Additionally, another collision avoidance manoeuver, which is speed reduction, was incorporated into the model and was combined with course alteration by fuzzy logic. For validating the effectiveness, the AIS data of Northern Yellow Sea were used for experiments. The results showed that the collision risk between ships can be effectively represented by the proposed model. In addition, the advantage of the proposed model was verified by comparing with the danger sector model. The proposed model can be used in automatic collision avoidance system and can provide assistance to maritime surveillance operators in collision risk monitoring, which will make contribution to the navigational safety.
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The objectives of this paper are to describe the development results of the ship collision avoidance support system called HiCASS (Hyundai intelligent Collision Avoidance Support System) and present the real ship voyage test results of the system. This system automatically evaluates the risk of detected objects around ship using the information from AIS (Automatic Identification System), Radar ARPA (Automatic Radar Plotting Aid) and ENC (Electronic Navigational Chart). And if the risk is over the predefined level, it recommends the detour routes according to the COLREGs 1972 (International Regulations for Preventing Collisions at Sea 1972). Its usability has been verified in real round voyages between South Korea and Europe cooperating with HMM (Hyundai Merchant Marine). As a result, it is found that the system gives alarms at proper time and avoidable routes in complicated collision situations but the suggested collision avoidance routes are comparatively larger than the real action of officers.
Automatic Identification System
Collision avoidance system
Radar Systems
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Up to now a lot of the study on ship collision avoidance systems have proceeded actively. However the rate of ship collision accidents hasn't decreased yet. If there is collision risk in close quarters situation in spite of maneuvering ship for collision avoidance according to the system, only use of TCP A and DCP A as input factor for collision risk decision is not useful to avoiding collision action. For the recent 5 years by the analysis of first observation distance about approaching ship in domestic collision accidents, nearly 45% of accidents is close first observation less than 2 miles. Therefore it is essential part for safety navigations to study for collision avoidance action in close encounter. In this paper, as a fundamental study of supporting collision avoidance maneuvering for navigators, we proposed ship collision avoidance support model in close quarters situation through analysis qf collision accidents to effectively get rid of the causes.
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Based on the analysis of the concept of ship domain, starting from the reality of collision avoidance, according to the international rules for preventing collision at sea and the practices of seafarers in collision avoidance, the scope of ship field is quantitatively studied, so that the ships sailing on the sea always keep a safe area in different waters, so as to achieve good collision avoidance effect and reduce the occurrence of collision accidents.
Scope (computer science)
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