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Modeling of performance of a AUV vehicle towards limiting the hydro-acoustic field

Gerigk M. K.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2018

Vol. 12, no. 4

687--692

Some results of research devoted to the modeling of a AUV-Stealth vehicle performance towards limiting its hydro-acoustic field are presented in the paper. At the beginning the AUV-Stealth autonomous underwater vehicle concept is described. Then the method of research is introduced. Next the key design drivers of the AUV-Stealth vehicle are presented. Between them are the AUV-Stealth hull form, arrangement of internal spaces, materials, hull covers, energy supply and propulsion system, etc. Some results of the hydrodynamic and stealth characteristics of the AUV-Stealth vehicle are briefly described. It is presented in the paper that the hull form, construction materials including the covers may affect the AUV-Stealth vehicle boundary layer and wake. This may create some problems of identification of the AUV-Stealth vehicle using a sonar or hydrophone. The final conclusions are presented.

Risk Assessment for an Unmanned Merchant Ship

Rødseth Ø.J., Burmeister H.-C.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2015

Vol. 9, no. 3

357--364

The MUNIN project is doing a feasibility study on an unmanned bulk carrier on an intercontinental voyage. To develop the technical and operational concepts, MUNIN has used a risk-based design method, based on the Formal Safety Analysis method which is also recommended by the International Mari-time Organization. Scenario analysis has been used to identify risks and to simplify operational scope. Systematic hazard identification has been used to find critical safety and security risks and how to address these. Technology and operational concept testing is using a hypothesis-based test method, where the hypotheses have been created as a result of the risk assessment. Finally, the cost-benefit assessment will also use results from the risk assessment. This paper describes the risk assessment method, some of the most important results and also describes how the results have been or will be used in the different parts of the project.

Consistently Trained Artificial Neural Network for Automatic Ship Berthing Control

Ahmed Y., Hasegawa K.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2015

Vol. 9, no. 3

417--426

In this paper, consistently trained Artificial Neural Network controller for automatic ship berthing is discussed. Minimum time course changing manoeuvre is utilised to ensure such consistency and a new concept named ‘virtual window’ is introduced. Such consistent teaching data are then used to train two separate multi-layered feed forward neural networks for command rudder and propeller revolution output. After proper training, several known and unknown conditions are tested to judge the effectiveness of the proposed controller using Monte Carlo simulations. After getting acceptable percentages of success, the trained networks are implemented for the free running experiment system to judge the network’s real time response for Esso Osaka 3-m model ship. The network’s behaviour during such experiments is also investigated for possible effect of initial conditions as well as wind disturbances. Moreover, since the final goal point of the proposed controller is set at some distance from the actual pier to ensure safety, therefore a study on automatic tug assistance is also discussed for the final alignment of the ship with actual pier.