AUV Passive Buoyancy Bladder for Seabed Coupling
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Solution Overview
Problem
Existing autonomous underwater vehicles (AUVs) for seismic surveys have complex and expensive active buoyancy systems, which pose safety hazards when operating at extreme depths due to high-pressure compressed gas requirements.
Innovation Solution
A passive buoyancy system using a bladder with air at elevated pressure, housed in a container with water inlet ports, allows the AUV to maintain neutral or negative buoyancy without changing gas mass, relying on propulsion systems for thrust forces and avoiding the need for compressed gas or processors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an active buoyancy system with compressed gas is used to control AUV buoyancy at extreme depths, then the AUV can achieve positive buoyancy for recovery, but the system becomes complex and expensive with safety hazards from high-pressure gas
Solution Approach 1:
The patent removes the complex processor and active control elements from the buoyancy system, extracting only the essential passive buoyancy control mechanism using a bladder that responds automatically to depth changes without requiring active management
Solution Approach 2:
The buoyancy system operates autonomously through passive physical principles where the bladder automatically expands or contracts in response to ambient pressure changes, eliminating the need for external control signals or power sources
2Reliability
If compressed gas at very high pressure (e.g., 30MPa) is used for buoyancy control at extreme depths, then the AUV can achieve neutral and positive buoyancy, but safety hazards increase
Solution Approach 1:
The patent changes the pressure parameter of the gas in the bladder to operate at much lower pressures (e.g., 0.3MPa gauge pressure) compared to conventional systems, thereby maintaining buoyancy control functionality while dramatically reducing safety hazards associated with high-pressure gas
3Measurement precision
If water is introduced into the buoyancy chamber to achieve negative buoyancy for seabed coupling, then seismic signal quality improves, but the buoyancy system complexity increases
Solution Approach 1:
The patent extracts the processor and active control mechanisms from the buoyancy system, relying instead on passive physical principles where the bladder's automatic expansion/contraction provides the necessary buoyancy changes for both seabed coupling and signal quality improvement
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 simplifies and cost-reduces the buoyancy control, eliminates safety hazards from high-pressure gas, and ensures stable data acquisition by anchoring the AUV to the seabed, while allowing for efficient deployment and recovery at various depths.
Implementation Method 1
A passive buoyancy system using a bladder with air at elevated pressure... allowing the AUV to maintain neutral or negative buoyancy without changing gas mass
Implementation Method 2
The upward thrust force and the downward thrust force are typically generated by a propulsion system of the AUV... The upward thrust force and the downward thrust force may be generated by creating a stream of water directed away from the AUV with the propulsion system of the AUV
Implementation Method 3
After the AUV has ascended through the body of water and become neutrally buoyant, the AUV may stop ascending and remain at a neutrally buoyant depth... the negative buoyancy of the AUV during data acquisition is beneficial for two reasons: firstly it ensures that the AUV is stable and not disturbed by currents, and secondly it couples the AUV strongly to the bed
Data Source
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AI summary
A method of obtaining data with a sensor of an autonomous underwater vehicle (AUV), the AUV comprising a bladder which contains a gas and is exposed to ambient water pressure. A downward thrust force is generated which causes the AUV to descend through a body of water, wherein the bladder contracts as the AUV descends due to an associated increase in the ambient water pressure, the contraction of the bladder causing the gas to compress and the AUV to become negatively buoyant. Next the AUV lands on a bed of the body of water. After the AUV has landed on the bed, the sensor is operated to obtain data with the AUV stationary and negatively buoyant and a weight of the AUV supported by the bed. After the data has been obtained, an upward thrust force is generated which overcomes the negative buoyancy of the AUV andcauses the AUV to ascend through the body of water, the ascent of the AUV causing the bladder to expand due to the associated decrease in the ambient water pressure, the expansion of the bladder causing the gas to decompress and the AUV to become neutrally buoyant.