Inertial Unit Reset via Viewfinder Angular Alignment
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Solution Overview
Problem
Inertial navigation units in means of transport face challenges in long-term accuracy due to errors in gyroscopes, such as drift, scaling factors, and axis alignment, necessitating recalibration, which often relies on distance measurements and telemetry instruments that can be detectable.
Innovation Solution
A method and device for resetting an inertial unit using information from a viewfinder that calculates errors without distance measurements, employing a viewfinder to align the inertial unit by determining the angle between the horizontal speed vector and the line of sight, and using a Kalman filter for correction, thus avoiding detectable telemetry instruments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If distance measurements using radar or telemetry instruments are used to recalibrate the inertial unit, then the calibration accuracy is improved, but the detectability of the means of transport increases
Solution Approach 1:
The patent extracts the distance measurement capability from the recalibration process entirely. Instead of using radar or telemetry instruments that measure distance, the method uses only angular measurements from the viewfinder combined with inertial data to calculate position and velocity errors, thereby eliminating the harmful electromagnetic emissions while maintaining calibration accuracy
Solution Approach 2:
The viewfinder, originally designed for visual target acquisition, is given the additional function of providing angular measurement data for inertial unit recalibration. This multi-functional use allows the system to perform calibration without dedicated distance measurement equipment, reducing detectability while maintaining accuracy
2Measurement precision
If recalibration is performed frequently to maintain accuracy, then the navigation precision is improved, but the time required for recalibration operations increases
Solution Approach 1:
The system performs self-calibration by using its own existing sensors (viewfinder for angular measurements and inertial unit for motion data) to detect and correct its own errors. This eliminates the need for external calibration equipment and personnel, allowing frequent recalibration without time loss
Solution Approach 2:
The recalibration process is designed to be continuous rather than periodic interruptions. The system continuously compares viewfinder angular measurements with inertial unit predictions and applies real-time corrections, maintaining navigation precision without stopping operations for recalibration
Data Source
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AI summary
The invention relates to a method and to a device for resetting an inertial unit of a transport means on the basis of information delivered by a viewfinder of the transport means. According to the invention, a horizontal velocity vector of the transport means (MT) and coordinates of the transport means are obtained from the inertial unit (110), a horizontal line of sight of the viewfinder (120) is obtained on at least one landmark, coordinates of at least one landmark are obtained (130), an angle between the horizontal velocity vector and the horizontal line of sight is computed, the computed angle is drifted, an error is computed on the basis of the obtained coordinates, the angle and its computed drift, the computed error is transferred to a Kalman filter for filtering the error and resetting the inertial unit (110).