Cable-Driven Blade Hoisting for Offshore Motion Compensation
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Solution Overview
Problem
Installing offshore wind turbines is challenging due to the need to lift and assemble components at high heights while compensating for environmental disturbances, and existing motion compensating cranes are heavy, energy-intensive, and have limited range.
Innovation Solution
A hoisting arrangement with a gripper attachment and vessel module connected by cables, controlled by a system that manipulates the spanned length of multiple cables to position and orient the gripper, allowing for lighter and faster motion compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a motion compensating crane is used to compensate for vessel movements, then the load position stability is improved, but the device weight and energy consumption increase
Solution Approach 1:
The motion compensation function is segmented from the main crane structure and implemented as a separate hoisting arrangement with independent cable-driven actuators. This allows the compensation mechanism to be lighter while performing the same stability function, as each cable actuator only needs to compensate for movements in its specific direction rather than the entire crane system moving the full load weight.
Solution Approach 2:
The traditional motion compensating crane uses heavy mechanical structures and rigid linkages to counteract vessel movements. This invention replaces that mechanical system with a cable-driven parallel mechanism that uses tension control in multiple cables to achieve the same motion compensation effect with significantly reduced weight and energy consumption.
2Stability of the object's composition
If a motion compensating crane is used to compensate for vessel movements, then the load position stability is improved, but the energy consumption increases
Solution Approach 1:
The energy consumption is reduced by segmenting the compensation task across multiple lightweight cable actuators rather than using a single heavy mechanical system. Each actuator only needs to provide small forces to maintain cable tension, resulting in lower total energy consumption while achieving the same stability outcome.
Solution Approach 2:
Replacing the heavy mechanical motion compensating crane with a cable-driven system reduces energy consumption because cables are passive elements that require minimal actuation force to maintain tension and control position, compared to the active mechanical drives needed in traditional cranes.
3Adaptability or versatility
If a motion compensating crane is used, then motion compensation capability is improved, but the vertical working range is limited
Solution Approach 1:
The cable-driven hoisting arrangement serves multiple functions: it provides both the primary lifting capability and the motion compensation function through coordinated cable control. This multi-functionality eliminates the need for separate systems and extends the vertical working range by allowing independent cable length adjustment without the geometric constraints of a traditional crane structure.
Solution Approach 2:
The system uses dynamic cable length adjustment to achieve both lifting and motion compensation. By independently controlling the spanned length of each cable, the system can adapt to various vertical positions and compensate for vessel movements simultaneously, providing unlimited vertical working range compared to the fixed geometry of traditional cranes.
4Force
If conventional crane lifting is used, then heavy components can be lifted, but precise positioning and orientation at high heights is difficult due to environmental disturbances
Solution Approach 1:
The system employs feedback control by continuously monitoring the position and orientation of the suspended load and adjusting the spanned length of individual cables in real-time to compensate for environmental disturbances. This closed-loop control enables precise positioning and orientation maintenance even when lifting heavy components subject to wind and wave effects.
Solution Approach 2:
The cable-driven hoisting arrangement simultaneously provides heavy lifting capability and precise motion compensation through coordinated control of multiple cables. Each cable can be independently adjusted to control both the position and orientation of the load, enabling precise assembly operations at height while maintaining the ability to lift heavy wind turbine components.
Data Source
AI summary
A hoisting arrangement for hoisting an offshore wind turbine blade, comprising a gripper attachment 150 arranged to be connected to the wind turbine blade, comprising a set of cable attachment points 191, 192,193 arranged as a first polygon, a vessel attachment module 194 arranged to be connected to a vessel, comprising a plurality of cable guide elements 190 arranged as a second polygon, a plurality of cables 141, 142, 143, 144 spanned between the cable attachment points and the cable guide elements, and a control system for controlling a position and/or orientation of the gripper attachment within a work space by controlling a spanned length of at least two cables of the plurality of cables between the cable attachment points and the cable guide elements.