Adaptive Neural Network Control of Zero-Speed Vessel Fin Stabilizer Based on Command Filter

This paper proposes a zero-speed vessel fin stabilizer adaptive neural network control strategy based on a command filter for the problem of large-angle rolling motion caused by adverse sea conditions when a vessel is at low speed down to zero. In order to avoid the adverse effects of the high-frequency part of the marine environment on the vessel rolling control system, a command filter is introduced in the design of the controller and a command filter backstepping control method is designed. An auxiliary dynamic system (ADS) is constructed to correct the feedback error caused by input saturation. Considering that the system has unknown internal parameters and unmodeled dynamics, and is affected by unknown disturbances from the outside, the neural network technology and nonlinear disturbance observer are fused in the proposed design, which not only combines the advantages of the two but also overcomes the limitations of the single technique itself. Through Lyapunov theoretical analysis, the stability of the control system is proved. Finally, the simulation results also verify the effectiveness of the control method.

BACKSTEPPING CONTROL OF NONLINEAR ROLL MOTION FOR A TRAWLER WITH FIN STABILIZER

A backstepping control design procedure for nonlinear fin roll control of a trawler is presented in this paper. A roll equation consisting of linear and nonlinear damping and restoring moment on the roll response is expressed. Flow analyses are carried out for a scaled model of trawler type fishing vessel including fin stabilizers on both sides of the hull. The fin stabilizer geometry is chosen as NACA 0015 foil section which is widely used in the literature. The flow analyses are performed by using a commercial computational fluid dynamics (CFD) software based on finite volume method. The flow problem is modeled in a 3-dimensional manner while the flow is considered as steady, incompressible and fully turbulent. The numerical model consists of the ship wetted surface and the fin stabilizer in order to investigate the hull-fin interaction. Non-dimensional lift coefficients of the fin stabilizer for different angles of attack are gained. Both controlled and uncontrolled roll motions are examined and simulated in time domain for the maximum lift coefficient. Backstepping controller for roll motion has given a rapid and precise result.

Research on the Hydrodynamic Performance of Zero Speed Fin Stabilizer

Nowadays, zero speed fin stabilizer has been initially applied in ship. Whether zero speed fin stabilizer can generate enough lift moment to resist rolling moment or not, determines the anti-rolling effect of ship at zero speed. In the present paper, numerical model is proposed to calculate the lift force and moment of zero speed fin stabilizer. The results of numerical calculation are verified by model test results and the hydrodynamic performance of zero speed fin stabilizer are studied. The numerical results are in good agreement with the model test results. For different swing angular velocity of a zero speed fin stabilizer, the lift force and moment of zero speed fin stabilizer reach the maximum at the same swing angle. For the same swing angle of a zero speed fin stabilizer, the lift force and moment of zero speed fin stabilizer are proportional to the square of angular velocity.

Analisis Performa Fin Stabilizer untuk menurunkan Rolling pada Perahu menggunakan Software CFD

Penggunaan perahu sering terjadi banyak insiden kecelakaan yang disebabkan oleh cuaca, ombak yang tinggi, rendahnya tingkat kesadaran keselamatan saat berlayar maupun perahu yang tidak memenuhi standar keselamatan dan teknologi pendukung keselamatan dan kenyamanan yang mengakibatkan perahu terbalik dan karam. Tujuan dari penelitian ini adalah untuk melihat pengaruh performa perahu dengan penambahan variasi fin stabilizer untuk menurunkan gerakan rolling. Metode yang digunakan adalah analisis hambatan dan perilaku gerak kapal menggunakan Software CFD (Computational Fluid Dynamics) untuk melihat pengaruh penambahan fin stabilizer, pengaruh variasi bentuk dan sudut fin stabilizer terhadap gerakan rolling pada perahu. Hasil analisa dengan penambahan fin stabilizer pada perahu dengan menggunakan 2 jenis variasi fin stabilizer yaitu fin stabilizer tipe triangle dengan frekuensi gelombang 0.39 Hz, tinggi gelombang 0.2 m, kecepatan arus 1 m/s, kecepatan angin 5 knot dan kecepatan 2 knot lebih efektif mereduksi sampai dengan 5% gaya rolling yang terjadi pada perahu dengan kondisi air laut yang tenang dengan ketinggian gelombang yang tidak terlalu tinggi. Sedangkan hasil analisa dari perahu dengan penambahan fin stabilizer tipe propeller pada perahu dengan frekuensi gelombang 0.76408 Hz, tinggi gelombang 0.4 m, kecepatan arus 2 m/s, kecepatan angin 15 knot dan kecepatan 4 knot lebih efektif mereduksi sampai 7% gaya rolling yang terjadi pada perahu dengan kondisi air laut yang sebenarnya. The use of boats often occurs with many accidents caused by weather, high waves, low levels of safety awareness while sailing or boats that do not meet safety standards and supporting technology for safety and comfort which results in the boat overturning and sinking. The purpose of this research is to see the effect of boat performance with the addition of variations of the fin stabilizer to reduce rolling motion. The method used is the analysis of the resistance and motion behavior of the ship using CFD Software (Computational Fluid Dynamics) to see the effect of adding a fin stabilizer, the effect of variations in the shape and angle of the fin stabilizer on the rolling motion of the boat. The analysis results with the addition of a fin stabilizer on the boat using 2 types of variations of the fin stabilizer, namely the triangular fin stabilizer with a wave frequency of 0.39 Hz, a wave height of 0.2 m, a current speed of 1 m / s, a wind speed of 5 knots and a speed of 2 knots more effectively reducing to with 5% of the rolling force that occurs in boats with calm sea water conditions with not too high wave heights. While the results of the analysis of the boat with the addition of propeller type fin stabilizer on the boat with a wave frequency of 0.76408 Hz, wave height 0.4 m, current speed 2 m / s, wind speed 15 knots and speed 4 knots more effectively reduce up to 7% of the rolling force that occurs at boat with real sea water conditions.

L2-Gain Based Adaptive Robust Heel/Roll Reduction Control Using Fin Stabilizer during Ship Turns

The rolling and heeling experienced by a ship during turning will be more severe under the interference of winds and waves, which will seriously affect the navigation safety of the ship. The fin stabilizer is currently the best active anti-rolling device, which is usually used to reduce the roll of the ship during straight-line sailing. The purpose of this work is to study the use of fin stabilizers to reduce the rolling and heeling during ship turning, considering the non-linearity and uncertainty during the rotation. The 4 degrees of freedom (4-DOF) nonlinear motion model of a multi-purpose naval vessel is established. The forces and moments produced by fin stabilizers, rudders, propellers, and waves are also considered. The nonlinear control model of rotation and roll is derived and established. Given the non-linearity and uncertainty in the ship turning process, an L2-gain based robust adaptive control is proposed to control the fin stabilizers to reduce the turning heel and roll motion. The proof of the stability and the detailed design process of the controller are also given. Simulations are carried out to verify the effectiveness of the proposed control strategy. For comparison purposes, the simulation results under a well-tuned PID controller are also given. The simulation results show that the developed control strategy can effectively reduce the heel and roll during ship turns, and it has good robustness against uncertainty and internal and external interference.