Ship Roll Stabilisation via Dynamic Damping Element Orientation
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Solution Overview
Problem
Existing active stabilisation systems for ships, based on the Magnus effect, are limited to use when the ship is stationary due to increased frictional resistance and mass inertia when sailing, requiring constant reversal of stabilisation element direction.
Innovation Solution
The method involves sensing ship motion and sailing speed to adjust the stabilisation elements' angle relative to the ship's longitudinal axis, varying the rotational speed and pivoting motion based on sailing speed to minimize frictional resistance, and using a wing-shaped stabilisation element to reduce water resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stabilisation element rotates at high speed to generate Magnus effect for roll stabilisation, then the roll damping effect is improved, but the frictional resistance from water increases significantly
Solution Approach 1:
The stabilisation element's angular position is dynamically adjusted based on sailing speed. At low speeds, the element rotates to generate Magnus effect for roll stabilisation. At high speeds, the element is feathered (aligned with flow direction) to minimize frictional resistance. This dynamic repositioning allows the system to optimize between stabilisation effectiveness and energy loss across different operating conditions.
Solution Approach 2:
The system changes the operational parameters of the stabilisation element based on sailing speed. The angular position parameter is varied: at low sailing speeds, the element operates at angles that generate strong Magnus effect (e.g., 90 degrees to flow); at high sailing speeds, the element is positioned at feathered angles (e.g., 0-30 degrees to flow) to minimize drag. This parameter adaptation resolves the contradiction between stabilisation effectiveness and frictional resistance.
2Force
If the stabilisation element is positioned perpendicular to ship's direction of movement to maximize Magnus effect, then the roll damping capability is improved, but the frictional resistance and energy consumption increase
Solution Approach 1:
The angular position of the stabilisation element is made dynamic rather than fixed. The control system continuously adjusts the element's angle relative to the ship's longitudinal axis based on real-time sailing speed data. This dynamic positioning enables the system to achieve maximum Magnus effect force when sailing slowly, and minimum frictional resistance when sailing quickly, thereby resolving the contradiction between force generation and resistance reduction.
3Reliability
If the stabilisation element direction is constantly reversed to counteract roll in both directions, then the roll stabilisation is improved, but the mass inertia of the system becomes a limiting factor when sailing
Solution Approach 1:
The system dynamically adjusts not only the angular position but also the rotational speed and direction of the stabilisation element based on sailing conditions. At high speeds, the element may rotate in one direction to generate stabilising force, while at low speeds, it may rotate in the opposite direction. This dynamic control strategy, combined with angular position adjustment, allows the system to overcome inertia limitations and maintain effective roll stabilisation across varying sailing conditions.
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 allows for continuous active roll stabilisation with minimal water resistance across varying sailing conditions, enabling effective roll stabilisation while sailing without the limitations of stationary systems.
Implementation Method 1
Under the influence of the rotational movement of the stabilisation element and the water flowing past as a result of the stabilisation element moving relative to the stationary ship, a correction force perpendicular to the direction of rotation and the ship's direction of movement is generated. This physical phenomenon is also referred to as the Magnus effect
Implementation Method 2
The resistance from the water is further minimised by using a stabilisation element having a wing shape. Such a wing-shaped stabilisation element will experience a minimum amount of resistance in the 'feathering' (i.e. non-rotating) position at high sailing speeds
Data Source
Figure 1~4
Figure 5~5(d)
Figure 6~6(c)
AI summary
The invention relates to a method for actively damping a ship's motion while the ship is sailing by driving at least one first rotatable damping element that extends from the ship's hull, below the water line, on a side of the ship. The invention also relates to a device for actively damping a ship's motion, comprising at least one first rotatable damping element extending from the ship's hull, below the water line, on a side of the ship. Accordingly it is an object of the invention to provide a method and an active system for stabilising a ship's motion as described in the introductory paragraph which can only be used with ships while sailing. According to the invention, the method is characterised by the steps of: i) sensing the ship's motion and sailing speed, ii) generating and delivering control signals on the basis of step i), iii) rotatably driving the stabilisation elements on the basis of step ii), iv) determining, on the basis of step i), the current frictional resistance experienced by the stabilisation elements at the sensed motion and sailing speed of the ship, v) setting the stabilisation element at an angle relative to a longitudinal axis of the ship on the basis of the determined current frictional resistance and a desired minimum frictional resistance.