Katsuro Kijima

Automatic collision avoidance system using the concept of blocking area

Abstract The authors propose an algorithm for automatic collision avoidance system for ships. The automatic collision avoidance system is one of important functions comprised in automatic navigation system. The concept of inherent blocking area is introduced as a parameter to evaluate collision risk among ships. Contents of blocking areas is defined with the parameters of ship length, breadth, relative speed and relative angle between courses. Numerical simulations using proposed algorithm were carried out with three types of ship such as container ship, VLCC and general cargo ship which have different principal particulars. Results of the simulation show that the proposed system works well for head-on, crossing and overtaking conditions for combination of these ships

Design of Automatic Collision Avoidance System Using Fuzzy Inference

Abstract Automatic collision avoidance system is one of important function comprised in automatic navigation system. The authors propose algorithm for the automatic collision avoidance system using fuzzy inference in this paper. The authors also utilized fuzzy inference to obtain a steerage angle required in order to change course. Numerical simulations were carried out for some scenarios which represent different encounter situation of plural ships risked in collision respectively. It was shown by the simulation study that the system works properly for the scenarios.

The Manoeuvring Characteristics on Tug-Towed Ship Systems

Abstract Ships disabled from marine disasters are generally towed by tug-boat. Concerning safe towing operations, we examined the course stability of the tug and towed ship taking into account some factors such as the length of towing ropes, the location of towing points and the condition of the disabled ship. By using of the numerical simulations, we estimated manoeuvring performance of the ships, and examined how those factors would affect the course stability for tug-towed ship systems.

Design of a Dynamic Positioning System for Self-Propulsive Barge under External Disturbances

Abstract A dynamic positioning system (DPS) is used in order to keep the specified position. By using the inverse linear quadratic (ILQ) optimal servo theory, it will be able to construct a control system of DPS which has no interaction among the controlled variables. In ILQ optimal servo theory, time constant T i as the design parameters have much influence on the performance of the control system. In this paper, we applied the ILQ optimal servo theory to design the control system of DPS for a self-propulsive barge. We designed the system with T i defined automatically in response to the dimensions of state variables. We examined the characteristics of the control system using T i which is defined automatically.

Shallow Water Effects on Longitudinal Components of Hydrodynamic Derivatives

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Development of automatic course modification system using fuzzy inference

Abstract Navigational safety is highly demanded in order to prevent marine accidents. The authors had already proposed collision avoidance systems using fuzzy inference to evaluate the risk of collision and to define countermeasures in order to avoid collision with other ships. In this paper, the authors introduce experimental system which was built for evaluation of automatic navigation system. As the first step of model experiment of the automatic navigation system, results of model test for course modification activated by steering control using fuzzy inference is shown. The results represent that the automatic rudder control system for course modification works well for model ships.