Towed Sidescan Sonar Position Correction via Feature Matching
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Solution Overview
Problem
Current sidescan sonar systems struggle to accurately correct the position of towed sensors when using different types and frequencies of sensors, as they typically only correct horizontal offsets and do not effectively match features between various sensor types and resolutions.
Innovation Solution
A system comprising a towing vessel, a sidescan sonar, a multibeam echosounding sonar, and an ultrashort baseline navigation system, which transmits pulses of different frequencies and processes backscattered data to create error vectors for updating and correcting the position and orientation of the sidescan sonar, using pattern matching algorithms to determine similar features between the data sets from both sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feature matching is performed between different sensor types with different frequencies and resolutions, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses an intermediary processing system that receives data from both the vessel-mounted sensor and the towed sensor, performs feature matching between them, and generates correction factors. This intermediary processing layer enables precise position correction by bridging the two different sensor types, allowing them to work together effectively despite their different frequencies and resolutions.
Solution Approach 2:
The system implements a universal feature matching algorithm that can handle multiple sensor types with different characteristics. The algorithm is designed to be adaptable to various sensor configurations and resolutions, making the position correction system versatile and applicable to different survey scenarios while maintaining high precision.
2Adaptability or versatility
If multiple sensor types with different frequencies and resolutions are used, then adaptability is improved, but measurement precision deteriorates
Solution Approach 1:
The patent applies local quality by performing feature matching at the level of individual features rather than attempting to match entire datasets from sensors with different resolutions. Each feature is matched locally between the vessel-mounted sensor data and the towed sensor data, allowing precise correction factors to be derived for each specific feature location, thereby maintaining accuracy despite sensor differences.
3Device complexity
If only horizontal offsets are corrected using the same sensor type, then device complexity is reduced, but measurement precision is limited
Solution Approach 1:
The patent extends position correction from simple horizontal offset correction to three-dimensional correction by incorporating vertical position correction as well. The system derives correction factors that account for errors in multiple dimensions (horizontal and vertical) by performing feature matching between the vessel-mounted sensor and the towed sensor, thereby achieving comprehensive position accuracy.
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 enables accurate correction of the sidescan sonar's position and orientation, allowing for the creation of a detailed topographic image of the seabed by matching features between different sensor types and resolutions, improving the accuracy and completeness of underwater surveys.
Implementation Method 1
Sidescan sonars (SSS) are used for surveying large areas of the seafloor or seabed. SSS uses a device that emits sonar pulses down toward the seabed across an angle perpendicular to the path of the sensor through the water. Backscatter from the seabed is recorded
Implementation Method 2
Backscatter from the seabed is recorded and stitched together along the direction of motion. This forms an amplitude image of the seafloor within the coverage of the beam
Data Source
AI summary
Aspects of the subject technology relate to a method of correcting sensor position. The method comprises transmitting one or more first pulses of a first frequency range towards a first portion of a seabed and one or more second pulses of a second frequency range towards a second portion of the seabed, and receiving a first set and second set of backscattered data. The method further includes processing the first and second set of backscattered data to form a first and second set of image data and comparing the first set and second set of image data. The method further includes creating one or more error vectors between the first set and second set of image data, and updating the first set of backscattered data based on the one or more error vectors to produce an updated set of image data.