Flexible Fluid-Current Sensor Tether for Deep-Ocean Positioning
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Solution Overview
Problem
Underwater vehicles (UVs) face significant navigation uncertainties due to the lack of Global Navigation Satellite System updates underwater, leading to large position errors from ocean currents, which current navigation systems struggle to accurately measure and correct.
Innovation Solution
A fluid current and position sensing instrument using an elongate structure with organic sensor increments (OSIs) to measure drag force, tension, deformation, and rotation, combined with a processing module to determine fluid flow characteristics and UV position relative to a surface or subsurface expression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sonar systems are used to track the seafloor for position estimation, then position accuracy can be improved in shallow waters, but the system becomes inoperable in deep ocean environments and requires extensive infrastructure deployment
Solution Approach 1:
The patent replaces acoustic sonar systems with a mechanical/optical tether-based system. The tether connects the UV to a surface or subsurface expression and uses drag force measurements, tension sensing, and optical curvature measurement to determine position, eliminating the need for acoustic propagation and seafloor transponders required by conventional sonar systems.
Solution Approach 2:
The patent introduces a tether as an intermediary physical connection between the UV and the surface/subsurface expression. This tether serves as a mechanical mediator that transmits force and position information, replacing the need for acoustic intermediaries and infrastructure-based positioning systems.
2Device complexity
If inertial navigation systems are used for underwater navigation, then the system remains simple and lightweight, but position uncertainty accumulates rapidly due to unmeasured ocean currents
Solution Approach 1:
The tether acts as a physical intermediary that provides absolute reference measurements of ocean current effects. By measuring drag force and tension in the tether, the system obtains external reference data that corrects inertial navigation drift without requiring complex onboard sensors or infrastructure.
Solution Approach 2:
The patent implements feedback by continuously measuring tether drag force and tension, processing these measurements to determine UV position and current characteristics, and using this information to correct navigation estimates. This closed-loop feedback prevents position uncertainty accumulation.
3Measurement precision
If a tether with embedded sensors is used to measure drag force and position, then measurement capability is improved, but the tether becomes more complex and difficult to manufacture
Solution Approach 1:
The patent segments the sensing function into discrete Organic Sensor Increments (OSIs) distributed along the tether length. Each OSI is a simple sensor element that measures local drag force, and multiple OSIs are distributed along the tether, simplifying the manufacturing of individual components while achieving comprehensive measurement coverage.
Solution Approach 2:
The patent changes the measurement parameter from requiring complex embedded sensor arrays to using simple tension and drag force measurements at the tether ends combined with optical curvature measurement. This parameter change simplifies manufacturing while maintaining measurement precision.
4Measurement precision
If multiple sensors are distributed along the tether to measure drag force at multiple points, then current profile measurement accuracy is improved, but the device complexity and cost increase
Solution Approach 1:
The patent divides the tether into multiple segments with OSIs at discrete locations. Each OSI measures local conditions, and the segmented measurements are processed to reconstruct the continuous current profile, achieving high measurement precision through spatial segmentation rather than continuous sensing.
Solution Approach 2:
The patent makes the tether multi-functional by using it simultaneously as a mechanical connection element, a communication medium, and a distributed sensing array. This universality reduces overall system complexity compared to separate dedicated sensing systems.
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
Accurately determines UV position and fluid flow dynamics, reducing navigation uncertainties to kilometers, enabling precise underwater operations even in deep ocean environments.
Implementation Method 1
The elongate structure can have a first end and a second end. The instrument can include a sensor system. The sensor system includes different sensors including plural Organic Sensor Increments (OSI). The plural OSI can function to sense drag force, tension, deformation, deflection, and/or rotation experienced by the elongate structure
Implementation Method 2
The elongate structure is capable of flexible movement and deflection due to fluid flow within a fluid column the elongate structure is immersed
Implementation Method 3
The elongate structure can be covered with a coating. In some embodiments, the coating includes a protective material that is a high-strength cladding material or a high-strength braided material. In addition, or as the alternative, the coating can include a buoyant material
Data Source
AI summary
Embodiments can relate to a fluid current and position measurement instrument. The instrument can include an elongate structure (having a first end and a second end) capable of flexible movement and deflection. The instrument can include a sensor system having plural organic sensor instruments (OSIs) configured to: sense drag force, tension, deformation, deflection, and/or rotations experienced by the elongate structure; and generate sensor signals representative of the same. The sensor system can include a communication medium in communication with the plural OSI and configured to transmit the sensor signals to the first end and the second end. The instrument can include a processing module (having a processor and a memory) configured to receive the sensor signals and determine: i) flow rate, flow direction, and fluid density of one or more fluid flow currents of the fluid column, ii) position and/or velocity of the second end relative to the first end.