Parallel Hoisting Cable Heave Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing heave compensation systems for hoisting systems on moving structures, such as floating vessels, are complex, energy-intensive, and prone to wear, with limitations in control accuracy and efficiency, particularly when dealing with heavy loads.
Innovation Solution
A method and apparatus utilizing two hoisting cables connected in parallel, where one cable provides a spring force and the other adjusts its lifting force and length to compensate for variations, allowing for precise control of the load's position and movement by distributing the load weight and reducing the need for strong, bulky systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If passive heave compensation relying on spring devices is used, then energy dissipation is provided, but the system cannot provide accurate and fast control over load position
Solution Approach 1:
The hoisting cable is divided into two separate cables: a first hoisting cable with passive spring-based heave compensation and a second hoisting cable with active length adjustment. This segmentation allows each cable to specialize in one function (passive energy dissipation vs. active control), resolving the contradiction between energy dissipation and control accuracy.
Solution Approach 2:
The patent combines passive spring-based heave compensation and active cable length adjustment into a unified parallel cable system. The spring mechanism provides continuous energy dissipation while the active adjustment mechanism provides precise control, merging both approaches to simultaneously achieve energy dissipation and control accuracy.
2Measurement precision
If active heave compensation with single hoisting cable is used, then control accuracy is improved, but the cable and system must be bulky and consume significant power
Solution Approach 1:
The load support function is segmented between two cables: the first cable with spring mechanism handles a portion of the load weight passively, while the second cable handles active adjustments. This segmentation reduces the burden on any single cable, allowing for lighter system components while maintaining control accuracy.
Solution Approach 2:
The active length adjustment applies only partial force to compensate for heave motion rather than fully supporting the load. Since the spring mechanism already supports part of the load, the active adjustment only needs to provide incremental compensation, reducing power consumption and system size.
3Reliability
If reeling in and paying out hoisting cable is used, then heave compensation is achieved, but cable wear accelerates and strong engines are required
Solution Approach 1:
The cable system is segmented into two functions: the first cable provides passive spring-based compensation that reduces dynamic loads, while the second cable provides active adjustment. This segmentation reduces the stress and wear on individual cables compared to single-cable active reeling systems.
Solution Approach 2:
The spring mechanism automatically provides passive heave compensation without requiring active control systems or engines. This self-service mechanism reduces cable wear by naturally absorbing dynamic loads and reduces the burden on active adjustment components.
4Reliability
If passive and active actuation of hydraulic systems are combined, then heave compensation is provided, but the system becomes complex and requires strong hydraulic pumps and bulky conduits
Solution Approach 1:
The hydraulic system is segmented into two independent parts: a passive spring mechanism requiring no hydraulic actuation and an active cable length adjustment mechanism. This segmentation eliminates the need for complex combined hydraulic systems while maintaining heave compensation functionality.
Solution Approach 2:
The complex combined hydraulic actuation system is extracted and replaced with a simpler parallel cable system where one cable uses passive spring mechanics and the other uses active adjustment. This extraction removes unnecessary complexity while preserving the essential heave compensation function.
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 enables more accurate and efficient control of load movement with reduced wear and energy consumption, allowing for lighter and smaller active heave compensation systems, while maintaining precise positioning and minimizing relative motions between the load and the platform.
Implementation Method 1
the first hoisting cable exerts a first lifting force on the load including a spring force
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A method for compensation movements and/or force variations of a load is provided, in particular of a load suspended from a moving structure, more in particular a load suspended from a floating vessel, comprising the steps of: connecting a first hoisting cable (11) and a second hoisting cable (13) with the load in parallel; suspending the load from the first and second hoisting cables, wherein the first hoisting cable exerts a first lifting force on the load including a spring force, and wherein the second hoisting cable exerts a second lifting force on the load; wherein the method comprises the step of controlling a position and/or movement of the load by compensating, in particular reducing, at least part of the spring force by adjusting the second lifting force and/or a length of the second hoisting cable. An apparatus for performing the method is also provided.