Spud Force Limiting Control for Cutter Suction Dredgers
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Solution Overview
Problem
Cutter-suction dredgers face challenges in simultaneously minimizing freedom of movement between the spud and hull to prevent damage from high waves while maintaining optimal operation, as existing solutions either restrict movement too much or react too slowly to changing forces.
Innovation Solution
A vessel with positioning means and a control unit that measures forces and predicts future force directions, adjusting the hull's position and orientation proactively to reduce maximum forces exerted on the spud, ensuring a rigid connection without freedom of movement unless necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the spud is rigidly fastened to the hull to minimize freedom of movement, then the cutter head operation is optimized, but the spud or fastening construction can be damaged by high wave forces
Solution Approach 1:
The control unit proactively adjusts the positioning means before the wave forces reach their peak, based on measured force values and predicted future force directions. This preliminary action prevents the harmful forces from being transmitted to the spud fastening, thereby protecting it while maintaining rigid connection during normal operation
Solution Approach 2:
The system continuously measures the force exerted by the hull on the spud using measuring means, feeds this information to the control unit, which then adjusts the positioning means accordingly. This closed-loop feedback system enables real-time adaptation to changing wave conditions
2Reliability
If a fastening construction with freedom of movement is used to prevent damage from high forces, then the spud is protected, but the operation of the cutter head is greatly reduced
Solution Approach 1:
The system dynamically adjusts the rigidity of the spud fastening connection by actively controlling the positioning means. During normal operation, the connection remains rigid for optimal cutter head performance. When wave forces are detected and predicted to exceed threshold values, the system proactively adjusts to reduce force transmission, thereby maintaining reliability without sacrificing productivity
3Device complexity
If a reactive fastening system is used that responds to forces already occurring, then the system is simpler, but the response is too slow and high forces still occur
Solution Approach 1:
The control unit uses measuring means to detect current force values and determines the future direction of forces based on these measurements. It proactively adjusts the positioning means before the harmful forces fully develop, rather than reacting after they occur. This timing is critical - the adjustment is made in advance to prevent peak forces from being transmitted to the spud
Data Source
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AI summary
Vessel (1) with a hull (7) and a spud (2), that is provided with positioning means (9, 16, 22) to set the mutual position and/or orientation of the hull (7) and the spud (2), that is provided with a control unit (14) and measuring means (12) for the force or the pressure exerted by the hull (7) on the spud (2), whereby the control unit (14) is arranged to control the positioning means (9, 16, 22), to make a prediction of the future magnitude of the force or the pressure, and to make an adjustment to the said mutual position and/or orientation.