Magnetometer Heading Error Estimation Using Magnetic Maps
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Solution Overview
Problem
Magnetometer measurements for determining device heading can be inaccurate due to environmental magnetic interference, leading to incorrect pose computation and impaired augmented reality experiences.
Innovation Solution
Estimate the error in magnetometer heading measurements by comparing the measured vertical component to an expected vertical component using a magnetic map, and adjust the heading estimation based on this error to improve pose determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetometer measurements are used to determine device heading, then pose computation can be performed, but measurement accuracy deteriorates due to environmental magnetic interference
Solution Approach 1:
The patent introduces an intermediary correction mechanism that uses magnetic map data as a mediator between the magnetometer readings and the final heading computation. The magnetic map provides expected vertical component values that serve as reference standards, allowing the system to detect and correct deviations caused by environmental magnetic interference without directly eliminating the interference source.
Solution Approach 2:
The system implements feedback by comparing the measured vertical component against the expected value from the magnetic map and using this difference to correct the heading measurement. This closed-loop approach continuously monitors measurement accuracy and adjusts the pose computation based on detected errors, thereby maintaining reliability despite environmental interference.
2Measurement precision
If environmental magnetic interference is present, then magnetometer readings become inaccurate, but adding correction mechanisms increases device complexity
Solution Approach 1:
The patent applies preliminary action by pre-loading magnetic map data that contains expected vertical component values for various locations before the actual measurement process. This pre-prepared reference data allows the system to perform error correction without requiring complex real-time analysis, thereby improving measurement precision while limiting the increase in computational complexity during operation.
Solution Approach 2:
The system creates a simplified representation of the magnetic field environment by using a magnetic map that copies the essential characteristics of Earth's magnetic field at different locations. This copy serves as a reference model that simplifies the correction process, avoiding the need for complex real-time magnetic field modeling while still achieving accurate heading measurements.
3Ease of operation
If magnetometer measurements are used for AR content overlay, then virtual content can be positioned, but positioning accuracy deteriorates due to magnetic interference
Solution Approach 1:
The magnetic map serves as an intermediary reference that mediates between the magnetometer's raw measurements and the final virtual content positioning. By comparing measured vertical components against expected values from the magnetic map, the system corrects positioning errors before they affect AR content overlay, thereby maintaining both ease of operation and positioning precision.
Solution Approach 2:
The system implements feedback in the AR positioning pipeline by continuously monitoring the consistency of magnetometer readings against magnetic map expectations and adjusting virtual content positions accordingly. This ensures that AR content remains accurately positioned even when environmental magnetic interference affects the raw sensor data.
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
Enhances the accuracy of pose estimation for augmented reality applications by compensating for environmental magnetic interference, ensuring precise overlay of virtual content on real-world imagery.
Implementation Method 1
Magnetometer measurements may include heading data, data that describes the direction the client device is pointing
Data Source
AI summary
A client device estimates an error in a heading component of a magnetometer measurement based on an error in a vertical component of the magnetometer measurement. The client device receives a three-dimensional measurement from a magnetometer including a heading and a vertical component. The client device identifies an expected vertical component based on a position of the client device and a magnetic map. The client device generates an error estimate based on the vertical component of the three-dimensional measurement and the expected vertical component. The client device compares the error to an error threshold and, in response to the error estimate being less than an error threshold, determines a pose of the client device based on the heading. The client device displays augmented reality content to the user using the pose.