Underwater Position Estimation Using Magnetic Field Signal Extraction
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Solution Overview
Problem
Current methods for underwater object position estimation, such as the fingerprinting technique and time-of-arrival (ToA) technique, face challenges in accuracy due to the absorption of radio frequency signals and variations in water temperature and pressure, and are not effective when using magnetic field signals, leading to position estimation errors and increased computational complexity.
Innovation Solution
A system using an underwater sensor network with magnetic field sensors that extracts an induced magnetic field signal by removing geomagnetic and noise signals, determines the presence of an underwater moving object, and estimates its position using the extracted signal, employing single or double exponential smoothing algorithms and threshold-based determination methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ToA technique is used to measure position using acoustic signals, then position estimation can be performed in underwater environments, but the position estimation accuracy deteriorates due to variations in water temperature, pressure, and water flow affecting sound propagation speed
Solution Approach 1:
The patent replaces the acoustic signal-based ToA technique with a magnetic field-based detection system. Magnetic field signals are used instead of acoustic waves to detect object position, eliminating the problems associated with sound propagation variations in water. The magnetic field sensors detect changes in magnetic field strength caused by the object's movement, providing accurate position estimation without being affected by temperature, pressure, or water flow conditions.
2Measurement precision
If the fingerprinting technique is used for position estimation, then position can be measured using signal strength, but the technique cannot be applied in underwater environments because it relies on radio waves that are rapidly absorbed in water
Solution Approach 1:
The patent substitutes radio wave-based fingerprinting with magnetic field-based detection. Instead of using electromagnetic radio waves that cannot penetrate water effectively, the system uses magnetic field sensors to detect objects underwater. The magnetic field changes caused by the object's presence and movement are used to estimate position, making the technique adaptable to underwater environments while maintaining measurement precision.
3Measurement precision
If too many anchor nodes are used to improve position estimation performance, then position estimation accuracy improves, but the computational complexity of the system increases making real-time position estimation difficult
Solution Approach 1:
The patent employs a magnetic field sensor on the object itself to perform self-positioning. Instead of relying on multiple anchor nodes to triangulate position, the object's own magnetic field sensor detects changes in the magnetic field environment caused by its movement relative to known sensor positions. This self-service approach reduces the need for numerous anchor nodes and simplifies computational requirements while maintaining position estimation accuracy.
4Device complexity
If a small number of anchor nodes are used, then the computational complexity is reduced, but a great position estimation error occurs according to separation distance between sensor nodes
Solution Approach 1:
The patent replaces the anchor node-based triangulation system with magnetic field-based detection. The magnetic field sensor on the object detects subtle changes in the magnetic field caused by proximity to different sensor locations. This substitution allows for accurate position estimation with fewer nodes because the magnetic field provides continuous spatial information rather than requiring geometric triangulation from multiple anchor points.
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 approach allows for more accurate position measurement of underwater moving objects compared to existing techniques, reducing errors even when sensor distances increase, by selecting appropriate sensors based on magnetic field signal strength and estimating positions effectively.
Implementation Method 1
receiving a magnetic field signal that is emitted from an underwater moving object using an underwater sensor network which is configured with a plurality of magnetic field sensors in the water
Implementation Method 2
extracting an induced magnetic field signal by removing a geomagnetic field and a noise signal from the received magnetic field signal
Data Source
AI summary
A method for object position estimation based on a magnetic field using an underwater sensor network, includes: step of receiving a magnetic field signal that is emitted from an underwater moving object using an underwater sensor network which is configured with a plurality of magnetic field sensors in the water; step of extracting an induced magnetic field signal by removing a geomagnetic field and a noise signal from the received magnetic field signal; step of determining whether or not the moving object enters the underwater sensor network using the induced magnetic field signal; and step of estimating a position of the object using position information of the plurality of sensors that sense the object if it is determined that the object enters the underwater sensor network.