Scene Correlation for North Vector Maintenance
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Solution Overview
Problem
Existing targeting systems for military applications face challenges in maintaining north vector accuracy over time due to high bias drift in gyroscopes, requiring frequent recalibration and loss of directional precision.
Innovation Solution
The scene correlation method ties the north coordinate to a reference feature in the scene, using an inertial measurement unit and image correlation to maintain pixel accuracy, allowing continuous north vector maintenance by comparing target imagery with a reference image, even under changing lighting and weather conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a gyroscope is used to find north, then north direction can be determined, but the north vector loses accuracy over time due to high bias drift
Solution Approach 1:
The patent creates a digital copy of the reference scene (image data) that is tied to the north vector. This copied scene information is stored and used for continuous correlation, replacing the need for continuous gyroscopic measurement and eliminating drift accumulation over time.
Solution Approach 2:
The patent replaces the mechanical gyroscope system with an optical/image-based scene correlation system. Instead of relying on mechanical gyroscopic sensors that drift, the system uses image processing and correlation algorithms to maintain north vector accuracy indefinitely.
2Reliability
If scene correlation is used to maintain north, then continuous accuracy is achieved, but the system complexity increases
Solution Approach 1:
The patent introduces a reference scene image as an intermediary between the gyroscope and the north vector determination. This reference image serves as a stable mediator that connects the initial north finding to continuous north maintenance, simplifying the overall system architecture.
3Measurement precision
If frequent recalibration is performed to maintain north accuracy, then measurement precision is preserved, but productivity decreases
Solution Approach 1:
The patent performs preliminary action by capturing and storing a reference scene image during the initial north finding process. This pre-captured reference is then used for indefinite continuous correlation, eliminating the need for repeated recalibration operations and maintaining high productivity.
Data Source
AI summary
A method for maintaining north comprising the steps of locating north with a north finding gyroscope, tying north to a feature in a scene, correlating the feature to a target in the field of regard of a plurality of cameras, and determining a north factor and translating the north factor into a target vector relative to north.