Ocean Current Measurement Using Multi-GNSS Buoy Attitude Correction
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Solution Overview
Problem
Current surface drifting buoys have limited positioning accuracy and cannot measure instantaneous flow velocity, flow direction, or sea surface elevation with high precision, failing to meet high-precision ocean current measurement requirements.
Innovation Solution
The method involves using four GNSS positioning modules and an attitude sensor to acquire and correct three-dimensional coordinates, optimize them, and convert them into precise latitude and longitude coordinates, enabling the calculation of instantaneous flow velocity, flow direction, and sea surface elevation by employing specific correction, optimization, and conversion formulas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single GNSS antenna is used for positioning, then the device complexity is low, but the positioning accuracy is limited to 10 m
Solution Approach 1:
The patent divides the positioning function into four separate GNSS modules instead of using a single module. Each module independently measures three-dimensional coordinates, and the results are integrated through coordinate transformation and optimization algorithms to achieve higher positioning precision (better than 0.6 m) compared to the conventional 10 m accuracy
Solution Approach 2:
The patent transitions from two-dimensional horizontal positioning to three-dimensional positioning by incorporating vertical coordinate measurements from multiple GNSS modules. The attitude sensor further adds orientation dimensions (roll, pitch, yaw angles), creating a multi-dimensional measurement system that transforms spatial coordinate data into precise position and orientation information
2Measurement precision
If only average flow velocity is measured, then the measurement system is simple, but instantaneous flow velocity and flow direction cannot be provided
Solution Approach 1:
The patent performs preliminary coordinate correction using attitude data before calculating flow parameters. The three-dimensional coordinates from four GNSS modules are corrected based on buoy attitude (roll, pitch, yaw angles) to establish an earth-centered fixed coordinate system, enabling subsequent calculation of instantaneous flow velocity and direction with high resolution
Solution Approach 2:
The patent replaces traditional mechanical current measurement methods with a satellite-based GNSS positioning system combined with attitude sensing. By using electromagnetic signals from GNSS satellites and electronic attitude sensors instead of mechanical current meters, the system achieves non-contact, high-resolution measurement of instantaneous flow velocity and direction
3Measurement precision
If four GNSS modules are used with coordinate correction and optimization, then positioning precision improves to better than 0.6 m, but the processing complexity increases
Solution Approach 1:
The patent implements a feedback-based optimization process where the measured three-dimensional coordinates are continuously corrected using attitude sensor data, then optimized by comparing with mounting position information. The coordinate transformation and optimization algorithms provide feedback loops that iteratively improve positioning precision from 10 m to better than 0.6 m
Solution Approach 2:
The patent transforms the coordinate system parameters from the GNSS module reference frame to the earth-centered fixed coordinate system through mathematical transformation involving attitude angles (roll, pitch, yaw). This parameter transformation, combined with optimization algorithms, converts raw coordinate data into precise position information while accounting for buoy orientation and mounting variations
Data Source
AI summary
An ocean current measurement method, includes: acquiring three-dimensional coordinates measured by four GNSS (Global Navigation Satellite System) positioning modules on the surface drifting buoy and attitude data of the surface drifting buoy measured by an attitude sensor; correcting the three-dimensional coordinates measured by the four GNSS positioning modules based on the attitude data; optimizing the corrected three-dimensional coordinates of the four GNSS positioning modules according to the mounting positions; converting the optimized three-dimensional coordinates of the four GNSS positioning modules into latitude and longitude coordinates; and calculating coordinates of the surface drifting buoy, an instantaneous flow velocity and flow direction of ocean current and sea surface elevation through the latitude and longitude coordinates of the four GNSS positioning modules. The coordinates with higher precision can be obtained, and the flow velocity, flow direction and sea surface elevation of the sea area where the buoy is located can be measured.