Determination of the Last Moment Manoeuvre for Collision Avoidance Using Standards for Ships Manoeuvrability (original) (raw)
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A Mathematical Model for Analysis on Ships Collision Avoidance
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Ship domain is often used in marine navigation and marine traffic engineering as a safety condition. The basic idea behind those applications is that an encounter of two or more ships can be considered safe if neither of ship domains is intruded by other ships. Research utilising this approach has been documented in numerous works, including publications on optimising collision avoidance manoeuvres performed to fulfil domain-based safety conditions. However, up to this point there has been no method, which would apply ship's domain to determine the last moment when a particular collision avoidance manoeuvre can still be successfully performed. This issue is addressed here. The proposed method uses a model of ship's dynamics to assess the time and distance necessary for a manoeuvre resulting in avoiding domain violations in give-way situations. The model and the method are described in detail and illustrated in a series of simulation results. The simulations cover full spectrum of typical give-way encounters in various circumstances: head-on, crossing and overtaking situations; manoeuvres limited to course alteration and those combining turns with speed reduction; open or confined waters and finallyin good and restricted visibility.
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In this paper, safe ship trajectory in collision situation is presented as multistage decision-making in a fuzzy environment*. The model of process takes under consideration the Collision Avoidance Regulations, the manoeuvrability parameters of ship and the navigator's subjective assessment in making a decision. The time of taking the observation of an object and the time of collision avoidance manoeuvre are determined on the membership function of the fuzzy set of a collision risk. The algorithm has been worked out with regard to an on-line control status. A situations of a multiship encounter have also been simulated.
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In constructing a collision avoidance system, it is important to determine the time for starting collision avoidance maneuver. Many researchers have attempted to formulate various indices by applying a range of techniques. Among these indices, collision risk obtained by combining Distance to the Closest Point of Approach (DCPA) and Time to the Closest Point of Approach (TCPA) information with fuzzy theory is mostly used. However, the collision risk has a limit, in that membership functions of DCPA and TCPA are empirically determined. In addition, the collision risk is not able to consider several critical collision conditions where the target ship fails to take appropriate actions. It is therefore necessary to design a new concept based on logical approaches. In this paper, a collision ratio is proposed, which is the expected ratio of unavoidable paths to total paths under suitably characterized operation conditions. Total paths are determined by considering categories such as action space and methodology of avoidance. The International Regulations for Preventing Collisions at Sea (1972) and collision avoidance rules are considered to solve the slower ship's dilemma. Different methods which are based on a constant speed model and simulated speed model are used to calculate the relative positions between own ship and target ship. In the simulated speed model, fuzzy control is applied to determination of command rudder angle. At various encounter situations, the time histories of the collision ratio based on the simulated speed model are compared with those based on the constant speed model.
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This work highlights the problem of planning the movement of a maritime robot, in an unstructured environment, to avoid collision. The motion planning algorithm for Unmanned Surface Vehicles (USVs) addresses stationary and moving obstacle avoidance. The algorithm takes into account the International Regulations for the Prevention of Collisions at Sea (COLREGS). To determine the dimensions of the obstacles and the Kinematic and dynamic constraints of the robot we will apply the principle of Velocity Change Space (VCS), using the changes of velocity and direction of the USV. The COLREG handling rules will be considered: crossing, overtaking, orientation. Also, to consider the velocity of the obstacles (non-stationary), the principle of the Velocity Obstacles (VO) will be applied, which generates a cone of the velocity space.
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Since the rise of intelligent control and multi-sensor integration technology, the development of autonomous ships has been significantly growing over the last decade. This advancement has painted a picture of extreme change with a radical alteration of human factors and new operating models. Inherent with the development of such ships, some concerns regarding their safe operation and integration into the maritime regulatory framework arose. Although the introduction of autonomous vessels is not an impending factor, it is the future, and one day will come into application. The primary concern inherent in the development of autonomous ships is compliance with the current International Regulations for Preventing Collisions at Sea (COLREGS) 1972. This paper uses an interdisciplinary approach to examine autonomous vessel seaborne interactions. The results show that we should actively support the modernization of the maritime industry and integrate it with other autonomous industries in the world.
IEEE Journal of Oceanic Engineering, 2000
Experimental evaluations on autonomous navigation and collision avoidance of ship maneuvers by intelligent guidance are presented in this paper. These ship maneuvers are conducted on an experimental setup that consists of a navigation and control platform and a vessel model, in which the mathematical formulation presented is actually implemented. The mathematical formulation of the experimental setup is presented under three main sections: vessel traffic monitoring and information system, collision avoidance system, and vessel control system. The physical system of the experimental setup is presented under two main sections: vessel model and navigation and control platform. The vessel model consists of a scaled ship that has been used in this study. The navigation and control platform has been used to control the vessel model and that has been further divided under two sections: hardware structure and software architecture. Therefore, the physical system has been used to conduct ship maneuvers in autonomous navigation and collision avoidance experiments. Finally, several collision avoidance situations with two vessels are considered in this study. The vessel model is considered as the vessel (i.e., own vessel) that makes collision avoidance decisions/actions and the second vessel (i.e., target vessel) that does not take any collision avoidance actions is simulated. Finally, successful experimental results on several collision avoidance situations with two vessels are also presented in this study.
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This paper introduces the concept of Collision Avoidance Dynamic Critical Area (CADCA) for onboard Decision Support Systems (DSS). The indicator proposed is derived via identification of a minimum required maneuvering zone in an encounter between two vessels. The CADCA model accounts for ship maneuvering dynamics and associated hydrodynamic actions emerging from different rudder angles and forward speed effects. The method presented is novel as it considers the variability of a critical area due to dynamic changes in operational parameters for both vessels. Results of the simulations carried out in negligible weather conditions confirm that computed zones may differ significantly in terms of shapes and limits. It is demonstrated that the size of the CADCA depends on the rudder angle, forward speed, as well as the dimensions of the vessels.