Sensor Calibration via Steady State Detection and Ellipsoid Fitting
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Solution Overview
Problem
Portable sensor devices, such as magnetometer or accelerometer sensor triads, require calibration to correct for systematic errors like scale factor, biases, and non-orthogonality, which existing methods fail to address effectively due to manufacturing variations and environmental changes.
Innovation Solution
A method and system for calibrating sensor devices by determining steady states through measurement readings, storing data, and fitting an ellipsoid to collected steady points to generate calibration parameters, which involves obtaining measurements in various spatial orientations and using audible notifications for user guidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used, then calibration can be performed quickly, but the accuracy of sensor data is insufficient due to unaddressed systematic errors
Solution Approach 1:
The system performs preliminary detection of steady states before calibration data collection. By using exponential moving average to predict steady states in advance, the system prepares for accurate data collection without unnecessary delays, resolving the contradiction between accuracy and time loss.
Solution Approach 2:
The system continuously monitors sensor readings against exponential moving average predictions and provides feedback to determine when steady states are achieved. This feedback mechanism ensures accurate calibration data is collected only when conditions are optimal, improving measurement precision while maintaining efficient calibration timing.
2Productivity
If calibration data is collected during movement, then calibration can be performed faster, but noise and measurement errors increase
Solution Approach 1:
The system predicts steady states using exponential moving average before actual data collection occurs. This preliminary prediction allows the system to identify optimal calibration moments in advance, ensuring high-quality data collection without sacrificing calibration speed.
Solution Approach 2:
The system uses feedback from comparing current readings with exponential moving average predictions to determine when to collect calibration data. This feedback ensures data is collected only during steady states, maintaining high measurement precision while enabling efficient calibration throughput.
3Measurement precision
If multiple steady points are collected for calibration, then calibration accuracy improves, but data processing complexity increases
Solution Approach 1:
The system performs preliminary identification of steady states using exponential moving average before full calibration processing. This preliminary action filters and organizes potential calibration points in advance, reducing the complexity of subsequent ellipsoid fitting and calibration parameter calculation.
Solution Approach 2:
The system uses feedback mechanisms to validate steady points against calibration criteria before including them in the final calibration set. This feedback-based filtering ensures only high-quality steady points are processed, improving calibration accuracy while managing data processing complexity through intelligent selection.
Data Source
AI summary
A system, method, and computer program product are provided for calibrating a sensor device, such as an accelerometer, gyroscope, and/or magnetometer. The sensor device provides measurements, and a determination if the sensor device is in a steady state is made based at least partly on the measurements. If the sensor device is in a steady state then measurement data is stored in a memory, and the sensor device is calibrated at least partly with the stored data. A set of such steady points is gathered with the sensor device in various spatial orientations, preferably with the steady point orientations spaced appropriately apart to ensure precise calibration throughout the range of possible orientations. Calibration parameters are determined by fitting the set of steady point measurements to an ellipsoid. Active audio and visual guidance may be provided to a user to assist with orienting the sensor device during calibration.