ROV Tether Winch Tension Control for Drag Reduction
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Solution Overview
Problem
Remotely operated underwater vehicles (ROVs) face issues with cable tension increasing as they move away from the support ship, leading to potential damage and communication failures due to excessive drag forces from thick, heavy cables.
Innovation Solution
The ROV emits a thin optical cable that is stored on a spool and released at a rate controlled by tension and speed sensors, maintaining minimal tension and reducing drag, allowing the cable to remain stationary in the water while the ROV moves, using a system with a tension sensor, microprocessor, and cable release mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick cable with electrical conductors is used to provide power and communication to the ROV, then power transmission and communication reliability are improved, but cable weight and drag increase, requiring more propulsion thrust
Solution Approach 1:
The patent extracts the power transmission function from the mechanical cable and relocates it to wireless power transfer systems or onboard energy storage (batteries/fuel cells). The cable is retained only for communication and control signals, dramatically reducing its weight and drag while maintaining power supply reliability through alternative means.
Solution Approach 2:
The patent replaces the mechanical cable-based power transmission system with wireless power transfer technology or onboard energy storage systems. This substitution eliminates the need for heavy electrical conductors in the cable, reducing drag and weight while maintaining reliable power delivery to the ROV.
2Length of moving object
If the ROV travels farther from the support ship, then operational range is improved, but cable tension increases due to drag, risking cable damage
Solution Approach 1:
The patent removes the heavy electrical conductors from the cable, retaining only lightweight communication fibers. This extraction reduces cable drag and tension, enabling the ROV to operate at greater distances from the support ship without risking cable damage from excessive tension.
Solution Approach 2:
The patent changes the cable composition from heavy electrical conductors to lightweight optical fibers, fundamentally altering the cable's physical parameters. This parameter change reduces drag and tension forces, extending the operational range while maintaining communication reliability.
3Speed
If more thrust is produced to overcome cable tension, then ROV mobility is improved, but energy consumption increases
Solution Approach 1:
The patent extracts the power transmission function from the cable system, eliminating the need for the ROV to overcome heavy cable drag. This reduces the thrust required for mobility and consequently lowers energy consumption while maintaining operational speed and maneuverability.
Solution Approach 2:
By changing the cable from heavy electrical conductors to lightweight optical fibers, the patent reduces the drag force that the propulsion system must overcome. This parameter change directly reduces energy consumption while preserving the ROV's mobility and speed capabilities.
4Weight of moving object
If a thin optical cable is used instead of a thick electrical cable, then cable drag and weight are reduced, but power transmission capability is lost
Solution Approach 1:
The patent extracts the power transmission function from the cable and implements it through alternative systems (wireless power transfer or onboard energy storage). The cable itself is reduced to a thin optical fiber for communication only, achieving dramatic weight reduction while maintaining power transmission capability through the extracted alternative systems.
Solution Approach 2:
The patent substitutes the mechanical cable-based power transmission with wireless power transfer technology or onboard energy storage. This allows the use of thin optical cables for communication while maintaining full power transmission capability through the substituted system.
Data Source
AI summary
A cable containing an optical fiber is used to transmit data between an underwater remotely operated vehicle (ROV) and a support vessel floating on the surface of the water. The ROV stores the cable on a spool and releases the cable into the water as the ROV dives away from the support vessel. The ROV detects the tension in the cable and the rate that the cable is released from the ROV is proportional to the detected tension in the cable. After the ROV has completed the dive and retrieved by the support vessel, the cable can be retrieved from the water and rewound onto the spool in the ROV.