Ship Fin Stabilizer Deceleration Control for Roll Reduction
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Solution Overview
Problem
Existing ship stabilization systems using rotating fins face inefficiencies due to negative inertial effects during deceleration, which counteract the roll stabilization at zero or low ship speeds, limiting the effectiveness of fin movements within a ±60° range.
Innovation Solution
The method extends the fin rotation angle from ±60° to ±90° and allows continuous 360° rotation, optimizing the deceleration step to align with acceleration and constant speed steps, thereby canceling negative inertial effects and enhancing roll stabilization by ensuring the deceleration step contributes positively to roll reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the fin rotation angle is limited to ±60°, then the device complexity is reduced, but the roll stabilization effectiveness deteriorates due to negative inertial effects during deceleration
Solution Approach 1:
The patent changes the operational parameters of the fin rotation system by extending the rotation angle range from ±60° to ±90° and implementing continuous 360° rotation capability. This parameter change allows the deceleration step to be optimized so that negative inertial effects are canceled, thereby improving roll stabilization effectiveness without significantly increasing device complexity
Solution Approach 2:
The patent introduces dynamic control of the fin rotation process by dividing it into distinct steps (acceleration, constant speed, deceleration) and optimizing each step's characteristics. The deceleration step is specifically designed to align with acceleration and constant speed steps, creating a dynamic system that actively cancels negative inertial effects throughout the rotation cycle
2Reliability
If the fin rotation angle is extended to ±90° with continuous 360° rotation, then the roll stabilization effectiveness is improved, but the device complexity increases
Solution Approach 1:
The patent segments the fin rotation process into distinct phases (acceleration step, constant speed step, deceleration step) and applies specific control characteristics to each phase. This segmentation allows the complex 360° rotation to be managed through standardized, repeatable cycles, reducing the practical complexity of control while achieving superior stabilization
3Reliability
If the deceleration step is optimized to cancel negative inertial effects, then the roll stabilization is enhanced, but the energy consumption increases
Solution Approach 1:
The patent converts the harmful negative inertial effects during deceleration into a beneficial contribution to roll stabilization. By carefully designing the deceleration step to align with the acceleration and constant speed steps, the previously harmful inertial forces are transformed into useful stabilizing moments, improving roll control without requiring additional energy input
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly improves roll stabilization by eliminating negative inertial effects during deceleration, allowing for more efficient control of roll, pitch, and jolt disturbances, even at wider angular excursions, and reduces the size of stabilizing fins required, leading to improved comfort and reduced fuel consumption.
Implementation Method 1
The fin rotation speed generates a force perpendicular to the fin. This force produces a roll moment on the ship which is proportional to the cosine of the fin angle measured with respect to zero.
Data Source
AI summary
A method is described for attenuating the oscillation of a ship, which includes a controller of a drive adapted to move at least one fin to allow stabilizing the ship, when the ship is at zero speed, anchored, wherein the motion of such at least one fin comprises an initial acceleration step, an intermediate step at constant speed and a final deceleration step. In the initial acceleration step, such at least one fin can start from a first angular position, while in the final deceleration step, such at least one fin can reach a second angular position corresponding to minimum or null values of effects opposite to those of the acceleration and constant speed steps of such at least one fin to allow maximizing the useful roll moment generated by such at least one fin.