AUV Support Cable With Sinker-Floating Body Motion Isolation
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Solution Overview
Problem
Existing AUV support systems face difficulties in maintaining stable docking due to the transmission of surface ship movements through cables, which can displace the underwater station, making docking challenging.
Innovation Solution
The system incorporates a sinker and a floating body in the cable configuration, adjusting weights and volumes to ensure the underwater station remains suspended and stable, even when the surface ship moves, by satisfying specific force balance conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the underwater station is suspended from the surface ship through a cable, then electric power can be supplied to the AUV, but the movement of the surface ship is transmitted to the underwater station making docking difficult
Solution Approach 1:
A floating body is introduced as an intermediary element between the surface ship and the underwater station. The floating body absorbs ship movements through its own motion on the water surface, preventing these movements from being transmitted to the underwater station via the cable. This mediator approach allows power supply to continue while isolating the underwater station from destabilizing movements.
Solution Approach 2:
A sinker is attached to the cable to provide a counterbalancing downward force. This sinker creates a stable equilibrium point in the water column, anchoring the cable configuration and reducing the transmission of horizontal movements from the surface ship to the underwater station, thereby improving docking stability.
2Force
If the cable is stretched tight by the own weight of the underwater station, then the station remains suspended, but movement of the surface ship displaces the underwater station
Solution Approach 1:
The cable system is segmented into multiple sections with different functional elements. The cable is divided into a first cable portion (from surface ship to floating body) and a second cable portion (from floating body to underwater station). This segmentation allows each section to perform its specific function: the first portion handles surface movements while the second portion maintains stable suspension of the underwater station.
Solution Approach 2:
The cable configuration is changed from a simple vertical suspension to a three-dimensional structure involving a floating body at the water surface. This dimensional change allows the system to absorb horizontal movements at the surface level while maintaining vertical suspension stability for the underwater station, effectively decoupling the two movements.
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 configuration effectively suppresses the transmission of surface ship movements to the underwater station, ensuring stable docking and preventing the floating body from floating on the water surface.
Implementation Method 1
a value obtained by subtracting a buoyant force acting on the underwater station based on the volume of the underwater station in the water from a gravitational force acting on the underwater station based on the weight of the underwater station
Implementation Method 2
a value obtained by subtracting a gravitational force acting on the floating body based on the weight of the floating body from a buoyant force acting on the floating body based on the volume of the floating body in the water
Data Source
Figure 1
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AI summary
An AUV support system includes: a surface ship; an underwater station configured to support an AUV which autonomously sails in water; and a cable connecting the surface ship and the underwater station. The cable includes: a first cable portion extending downward from the surface ship through a water surface when the underwater station is suspended in the water by the cable from the surface ship that is in a stop state on the water; a second cable portion extending upward from a lower end portion of the first cable portion when the underwater station is suspended as above; and a third cable portion extending downward from an upper end portion of the second cable portion and connected to the underwater station when the underwater station is suspended as above.