Abstract
Fin stabilizers are very effective devices for controlling the ship roll motion against external wave-generated moments. Lift forces due to flow around fin with an angle of attack produce anti - roll moment. Therefore control of attack angle plays important role in reducing roll of ships. This paper presents results of using a combined neural network and PID for roll control of ship with small draught. Numerical results are given of around-fin flow analysis with considering free surface effect modelled by neural network and imposed to controlling loop. Hydraulic machinery constraints are also considered in the modelling. The obtained results show good performance of the controller in reducing roll amplitude in random seas. The approach can be used for any irregular sea conditions.
Highlights
The aim of using roll stabilizing systems on ships depends on requirements of their mission such as the preventing against damage of cargo, increasing the effectiveness of crew or accuracy of positioning and handling weapons on naval vessels.Roll motion is one of the most important ship motions
The PID controller is used as a main controlling tool
For considering complex behaviour of roll moment in function of roll angle in case of large angles and forward speed, an inverse neural network model is trained by using the Error Back Propagation technique (EBP) based on the results achieved from the introduced ship dynamic model
Summary
The aim of using roll stabilizing systems on ships depends on requirements of their mission such as the preventing against damage of cargo, increasing the effectiveness of crew or accuracy of positioning and handling weapons on naval vessels.Roll motion is one of the most important ship motions. In this paper the results of flow field analysis around fin stabilizer including free surface, presented by the authors [7], are used for modelling the fin in the controlling loop. There are analytical equations for calculating the lift force of fins in function of angle of attack, but in the present work numerical results accounting for the free surface effects, were used.
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