Submersible Frame Design for Precise Fall Pipe Rock Installation
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Solution Overview
Problem
Existing fall pipe ROVs face challenges in achieving accurate and qualitative subsea rock installation due to increased fuel consumption and decreased productivity, primarily caused by the need to rotate the ROV about its own axis using thrusters, which reduces thrust available for positioning and requires high power consumption.
Innovation Solution
A submersible frame with integrated propulsion and survey equipment, featuring a rotation system that allows the survey equipment to rotate independently from the propulsion system, using an actuator to adjust orientation without thrusters, enabling precise positioning and inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the vessel is positioned head seas to reduce fuel consumption, then fuel consumption is reduced, but the thrusters must be used to rotate the ROV about its own axis, reducing thrust available for positioning and decreasing positioning accuracy
Solution Approach 1:
The invention divides the ROV into two independent rotational segments: the submersible frame and the survey equipment. The survey equipment can rotate independently about the vertical axis relative to the submersible frame through a dedicated rotation system with an actuator, while the submersible frame maintains its positioning using thrusters. This segmentation allows positioning and orientation functions to be decoupled, resolving the contradiction between fuel consumption and positioning accuracy.
Solution Approach 2:
The invention introduces a dynamic rotation system that allows the survey equipment to change its orientation independently from the submersible frame's position. The actuator enables the survey equipment to rotate about the vertical axis, providing dynamic adaptability in orientation without affecting the positional stability maintained by the thrusters, thus resolving the trade-off between energy loss and positioning precision.
2Ease of operation
If the thrusters are used to rotate the ROV about its own axis, then the correct orientation of the inspection arms is achieved, but the thrust available for positioning is reduced, leading to decreased accuracy of positioning
Solution Approach 1:
The invention segments the orientation control function from the positioning function by introducing a dedicated rotation system. The actuator controls the rotation of survey equipment relative to the submersible frame, while the thrusters exclusively handle positioning. This functional segmentation ensures that orientation adjustments do not compromise positioning accuracy, resolving the contradiction between ease of operation and positioning precision.
Solution Approach 2:
The submersible frame serves multiple functions: it provides the platform for both propulsion (positioning) and survey operations. The independent rotation system allows the survey equipment to achieve correct orientation for inspection while the frame maintains accurate positioning, enabling the system to perform multiple functions simultaneously without trade-offs.
3Ease of operation
If rotation of the ROV is performed by means of the thrusters, then the correct orientation is achieved, but a high amount of thrust force is required, thus contributing to an increased power consumption
Solution Approach 1:
The invention segments the rotation function from the propulsion function. A dedicated actuator with a rotation system handles the rotation of survey equipment, while the thrusters are reserved for positioning. This segmentation eliminates the need for high-power thruster operation during orientation adjustments, significantly reducing power consumption while maintaining ease of operation.
Solution Approach 2:
The invention introduces an intermediary rotation system between the submersible frame and the survey equipment. This intermediate mechanism, driven by a relatively low-power actuator, enables orientation adjustments without requiring the high-thrust thrusters to be engaged, thus reducing power consumption while preserving full orientation capability.
4Manufacturing precision
If the ROV position is adjusted accurately by means of the ROV's own propulsion means, then positioning accuracy is improved, but the vessel may need to deviate from head seas position, leading to increased fuel consumption
Solution Approach 1:
The invention segments the control functions by allowing the submersible frame to maintain accurate positioning through thrusters while the survey equipment independently adjusts its orientation. This enables the vessel to maintain optimal head seas position for fuel efficiency while the ROV achieves accurate positioning and orientation through its independent propulsion and rotation systems, resolving the energy-precision trade-off.
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 solution enhances rock dumping precision, reduces fuel consumption, and increases productivity by maintaining thrust for positioning while allowing correct orientation of the survey equipment, even in misaligned vessel conditions.
Implementation Method 1
the actuator being adapted to convert an energy input into a rotation of the second element when holding the first element, the rotation being about a vertical axis
Implementation Method 2
propulsion equipment adapted for moving the submersible frame in a horizontal plane, thereby controlling the position of the submersible frame independently from the vessel
Data Source
AI summary
An arrangement for positioning a fall pipe end (414) during subsea rock installation includes a submersible frame (400) adapted to be lowered towards an underwater structure. The submersible frame has a first (401) frame structure carrying propulsion equipment (415) and a second frame structure (402) carrying survey equipment (406, 407), a channel structure (410), and a rotation system with an actuator (403). The actuator (403) has a first (411) and a second element (412) and being adapted to convert an energy input into a rotation of the second element (412) when holding the first element (411). The second element (412) is connected to the second frame structure (402), such that in suspended condition of the submersible frame (400), the survey equipment (406, 407) can be rotated about a vertical axis (409) by energizing the actuator (403), without using the propulsion equipment (415).