Dynamic Stiffness Control for Monopile Installation Safety
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Solution Overview
Problem
Current methods for installing monopiles on the seabed face challenges such as instability in dynamic positioning systems, potential for pile damage or loss during floating installation, and difficulties in maintaining precise verticality and position due to high coupling stiffness with the seabed, leading to safety and accuracy issues.
Innovation Solution
A control system that uses force data to adjust the stiffness and damping of the coupling between the vessel and the monopile, employing impedance or admittance control to stabilize the pile's orientation and position, even under dynamic conditions, and incorporates a combined vessel-monopile controller to manage vessel drift and maintain precise installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If floating installation is used to install monopiles, then installation time is reduced and productivity is improved, but operational safety deteriorates due to potential pile damage or loss during floating installation
Solution Approach 1:
The control system dynamically adjusts the coupling stiffness parameter between the vessel and monopile during installation. By changing the stiffness parameter from high to low, the system enables safe floating installation while maintaining control, thus improving both productivity and operational safety simultaneously
Solution Approach 2:
The system transitions from a static high-stiffness coupling to a dynamic adjustable coupling system. The coupling stiffness can be modified in real-time based on installation phase and sea conditions, enabling the system to adapt between safe operation and efficient installation requirements
2Manufacturing precision
If high coupling stiffness is used between vessel and monopile, then position control precision is improved, but system stability deteriorates due to control instabilities in the coupled dynamic system
Solution Approach 1:
The coupling stiffness is changed from a fixed high value to a dynamically adjustable parameter. The system can switch between high stiffness (for precision) and low stiffness (for stability) based on the installation phase, resolving the contradiction between precision and stability
Solution Approach 2:
The control system modifies the coupling stiffness parameter in real-time. During phases requiring precision (like final positioning), high stiffness is applied. During phases where instability risks are high (like initial contact with seabed), low stiffness is applied to maintain system stability
3Stability of the object's composition
If de-tuning of DP-system is applied to avoid control instabilities, then system stability is improved, but installation accuracy deteriorates due to significant loss of installation accuracy
Solution Approach 1:
Instead of permanently de-tuning the DP-system, the coupling stiffness is dynamically adjusted. This allows the DP-system to maintain its high precision capability while the variable coupling stiffness prevents control instabilities, thus improving stability without sacrificing installation accuracy
Solution Approach 2:
The adjustable coupling acts as an intermediary between the DP-system and the monopile. It buffers the coupling stiffness to prevent instabilities while allowing the DP-system to operate at full precision, eliminating the need for de-tuning
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 enhances operational safety and installation accuracy by actively managing the coupling dynamics, reducing the risk of pile damage and ensuring precise verticality and positioning, even in challenging marine conditions.
Implementation Method 1
employing impedance or admittance control to stabilize the pile's orientation and position
Implementation Method 2
employing impedance or admittance control to stabilize the pile's orientation and position
Implementation Method 3
adjust the stiffness and damping of the coupling between the vessel and the monopile
Data Source
AI summary
A method of controlling a position and/or an orientation of an elongated structure is provided. The method is a method of controlling a position and/or an orientation of an elongated structure connected via a gripper to a vessel. The method comprises the steps of: receiving force data indicative of an interaction force between the structure and the gripper; and controlling a position and/or an orientation of the structure and the vessel, in particular controlling a position and/or orientation of the structure and/or the vessel with respect to each other. The step of controlling a position and/or an orientation of the structure and the vessel comprises controlling the position and/or the orientation of the structure and the vessel on the basis of the force data.