Toroidal Shape Recognition for Automatic Compass Calibration
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Solution Overview
Problem
Conventional compass calibration methods are time-consuming, expensive, and prone to inaccuracy, especially in changing environmental conditions, and require manual intervention, which is not feasible for continuous operation in dynamic situations like ship motion at sea.
Innovation Solution
An automatic compass calibration system that uses a magnetometer, gyroscope, and accelerometer to measure angular velocities and linear accelerations, correlating these with local magnetic field measurements to develop a robust calibration parameter space, eliminating the need for manual calibration and allowing continuous correction without user intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional manual calibration methods are used, then calibration accuracy can be achieved in controlled environments, but the process becomes time-consuming and requires expensive equipment
Solution Approach 1:
The system performs automatic self-calibration by detecting the toroidal shape of magnetic field measurements and extracting calibration parameters without human intervention. The mobile structure autonomously identifies valid measurement portions and computes calibration data, eliminating the need for manual calibration procedures while maintaining accuracy in varying environmental conditions.
Solution Approach 2:
The system continuously collects and stores magnetic field measurements in advance, building up a data set that forms the toroidal shape. This preliminary data accumulation allows the calibration process to be performed automatically when sufficient data is available, rather than requiring time-consuming manual procedures at the moment calibration is needed.
2Reliability
If conventional calibration methods are used, then initial calibration can be achieved, but the calibration rapidly becomes inaccurate under changing environmental conditions and uncontrolled motion
Solution Approach 1:
The calibration system is designed to be dynamic and adaptive, continuously updating calibration parameters based on newly acquired magnetic field measurements. The system automatically detects when a sufficient toroidal data set is available and performs recalibration, allowing it to adapt to changing environmental conditions and maintain heading accuracy during uncontrolled motion and varying operational scenarios.
Solution Approach 2:
The system continuously monitors magnetic field measurements and uses feedback from the detected toroidal shape to automatically adjust calibration parameters. This closed-loop approach ensures that calibration remains accurate under changing conditions by continuously comparing new measurements against the established calibration model and making corrections as needed.
3Extent of automation
If automatic calibration is implemented, then continuous operation without manual intervention is achieved, but the system must process and validate complex toroidal shape data
Solution Approach 1:
The system extracts only the valid portions of the toroidal shape data that are suitable for calibration processing, separating useful calibration information from irrelevant or invalid measurements. By identifying and extracting only the necessary data portions, the system reduces processing complexity while maintaining automation, focusing computational resources on the most valuable calibration inputs.
4Ease of operation
If GPS-based heading estimation is used, then heading information can be provided, but accuracy deteriorates over short linear distances and quick heading changes
Solution Approach 1:
The system combines magnetic field-based compass calibration with other sensing capabilities to provide comprehensive heading information. By merging the automatically calibrated magnetic compass data with additional sensor inputs, the system overcomes the limitations of GPS-based estimation, maintaining high accuracy during short-distance travel and quick heading changes while retaining the ease of automatic operation.
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
The system provides accurate and adaptive compass calibration, continuously compensating for hard and soft iron disturbances, and other motion-related errors, ensuring reliable heading information across varying environmental conditions without the need for manual calibration processes.
Implementation Method 1
a magnetometer to measure angular velocities and linear accelerations of the mobile structure and provide a local magnetic field
Implementation Method 2
a magnetometer, gyroscope, and accelerometer to measure angular velocities and linear accelerations
Implementation Method 3
a magnetometer, gyroscope, and accelerometer to measure angular velocities and linear accelerations
Data Source
AI summary
Techniques are disclosed for systems and methods to provide automatic and substantially continuous calibration for compasses mounted to moving structures. A compass calibration system may include a logic device configured to receive one or more sensor signals and determine a corrected magnetic field based, at least in part, on a measured local magnetic field. The logic device may be configured to receive the measured local magnetic field comprising a series of magnetic measurements associated with a mobile structure; determine a valid portion of a toroidal shape of the series of magnetic measurements that is available for further processing; and determine the corrected magnetic field based, at least in part, on calibration parameters derived from at least the valid portion of the toroidal shape.