Marine Micronavigation Fusion for Long-Term Position Accuracy
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Solution Overview
Problem
Existing navigation systems, particularly those using Doppler-aided inertial navigation systems with high-grade accelerometers and gyrocompasses, face challenges in achieving accurate long-term navigation due to assumptions and simplifications that lead to measurement biases and position drift.
Innovation Solution
The proposed navigation aiding method and apparatus integrate micronavigation displacement measurements from sonar systems with inertial navigation measurements, using advanced processing techniques such as Kalman filters to accurately model and correct displacement measurements, handle non-orthogonal measurements, and account for different coordinate frames and times of validity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simplified integration methods are used to combine micronavigation with INS, then device complexity is reduced, but measurement accuracy deteriorates due to unaccounted roll and pitch angles
Solution Approach 1:
The patent performs preliminary coordinate transformations and angle compensations before integrating the micronavigation measurements with the INS system. By pre-calculating the roll, pitch, and yaw corrections and transforming the displacement measurements into the correct navigation frame beforehand, the system eliminates the need for complex real-time compensation algorithms, thus reducing overall integration complexity while maintaining high measurement accuracy.
2Loss of time
If direct integration of micronavigation displacement measurements is performed without coordinate frame transformation, then processing time is reduced, but navigation accuracy deteriorates due to frame misalignment
Solution Approach 1:
The patent performs the coordinate frame transformation as a preliminary step that is computationally efficient. By transforming the micronavigation displacement measurements from the sensor frame to the navigation frame using pre-calculated rotation matrices based on roll, pitch, and yaw angles, the system establishes correct frame alignment once per measurement cycle. This preliminary transformation enables subsequent fast integration with the INS system without repeated complex calculations, thus maintaining both speed and 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 significantly enhances long-term position accuracy, reduces measurement biases, and minimizes position drift, providing a more robust and accurate navigation solution, especially in GPS-denied environments.
Implementation Method 1
the technique of synthetic aperture sonar (SAS) imaging was first disclosed in U.S. Pat. No. 3,484,737 A (Walsh, 1968), where the technique of synthetic aperture radar was adapted to operate on the comparatively slowly propagating acoustical waves in water
Implementation Method 2
the imaging performance achievable using acceleration measurements of an inertial navigation system (INS)
Implementation Method 3
state-of-the-art Doppler-aided INS systems with high-grade accelerometers and gyro compasses
Data Source
AI summary
Navigation aiding method and apparatus for enhanced navigation of a marine platform over a seafloor, wherein using micronavigation displacement measurements and an estimator to improve the navigation data of the marine platform.