Magnetic Transmitter Calibration Using Multi-Sensor Reference
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Solution Overview
Problem
Magnetic transmitter calibration in Electromagnetic Tracking (EMT) systems for Augmented Reality (AR) and Virtual Reality (VR) is often inaccurate due to improper positioning and orientation, leading to incorrect position and orientation data for sensors and transmitters.
Innovation Solution
A calibration device with multiple magnetic sensors at known locations and orientations is used to generate magnetic fields, allowing a computer system to determine position and orientation data, and apply calibration correction factors to ensure accurate representation of sensor positions and orientations relative to the transmitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic transmitter is calibrated using traditional methods with complex translation systems, then positioning accuracy can be improved, but device complexity and calibration time increase significantly
Solution Approach 1:
The calibration device is segmented into multiple independent magnetic sensors positioned at known locations, each sensor providing individual measurements that collectively enable accurate transmitter calibration without requiring complex mechanical translation systems
Solution Approach 2:
The patent replaces complex mechanical translation systems with a static calibration device containing multiple magnetic sensors. The system uses magnetic field measurements from multiple fixed sensor positions to calculate transmitter position and orientation, eliminating the need for mechanical movement while maintaining calibration accuracy
2Measurement precision
If multiple sensors are positioned at various known locations in a calibration device, then calibration accuracy improves, but the time required to process signals and determine positions increases
Solution Approach 1:
The magnetic sensors are pre-positioned at known locations with predetermined coordinates stored in the system. This preliminary setup allows the processor to directly compare measured magnetic field positions with pre-stored reference positions, significantly reducing calculation time while maintaining high calibration accuracy
Solution Approach 2:
The system transforms raw magnetic field signals into position and orientation parameters by comparing them against pre-stored reference data. This parameter transformation approach enables rapid processing of multiple sensor signals without sacrificing measurement precision
3Measurement precision
If calibration correction factors are calculated using a calibration algorithm, then positioning accuracy improves, but computational complexity and processing requirements increase
Solution Approach 1:
The system calculates calibration correction factors by comparing measured magnetic field positions with pre-stored reference positions. These correction factors are then applied as feedback to adjust subsequent position calculations, improving accuracy while using iterative refinement rather than complex computational algorithms
Solution Approach 2:
The system applies calibration correction factors selectively to correct specific positioning errors rather than performing exhaustive computational analysis. This partial correction approach achieves sufficient accuracy for practical applications without requiring excessive computational resources
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
This method enables quick and accurate calibration of multiple transmitters, eliminating the need for complex translation systems and simplifying the calibration process, resulting in improved accuracy and efficiency in EMT systems.
Implementation Method 1
The transmitter can generate one or more magnetic fields, and the plurality of sensors spaced at known locations of the calibration device receive the generated magnetic fields
Data Source
AI summary
A calibration device comprising: a plurality of magnetic sensors positioned at the calibration device, the plurality of magnetic sensors defining a space; a controller configured to be positioned in the space defined by the plurality of magnetic sensors, wherein the controller includes a magnetic transmitter; and one or more processors configured to: cause the magnetic transmitter to generate magnetic fields; receive signals from the plurality of magnetic sensors that are based on characteristics of the magnetic fields received at the plurality of magnetic sensors; calculate, based on the signals received from the plurality of magnetic sensors, positions and orientations of the plurality of magnetic sensors relative to a position and orientation of the magnetic transmitter; and determine whether the calculated positions and orientations of the plurality of magnetic sensors are within one or more threshold limits of known positions and orientations of the plurality of magnetic sensors.