Multi-Frequency Magnetic Tracking Distortion Correction
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Solution Overview
Problem
Electromagnetic Tracking (EMT) systems used in Augmented Reality (AR) and Virtual Reality (VR) face inaccuracies in determining the position and orientation of magnetic sensors due to distortions caused by metallic and magnetic objects in the tracking environment, leading to erroneous measurements.
Innovation Solution
The system employs techniques to determine and compensate for distortion terms by generating magnetic fields at different frequencies, using optical data, and inertial measurement units to correct positional errors, allowing for accurate determination of sensor position and orientation relative to the transmitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If electromagnetic fields are generated at high frequency for real-time tracking, then tracking speed and responsiveness are improved, but measurement precision deteriorates due to increased distortion effects from metallic and magnetic objects
Solution Approach 1:
The system performs preliminary calibration by generating magnetic fields at multiple frequencies and determining distortion terms before actual tracking begins. These pre-computed distortion terms are stored and applied during real-time tracking to correct measurement errors, allowing high-frequency operation without sacrificing precision
Solution Approach 2:
The system changes the frequency parameter of magnetic field generation to determine distortion characteristics. By analyzing responses at multiple frequencies (including a second frequency that produces reduced distortion), the system identifies distortion terms that can be compensated for during high-frequency operation
2Measurement precision
If distortion compensation is performed by generating magnetic fields at multiple frequencies, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The complex task of multi-frequency distortion analysis is performed as a preliminary calibration step rather than during real-time operation. Once distortion terms are determined during calibration, the system can use these pre-computed values during normal tracking, avoiding the need for continuous complex calculations
Solution Approach 2:
The system creates a mathematical model (distortion term) that represents the distortion effects. This model serves as a copy of the distortion characteristics and can be applied to correct measurements without requiring the actual complex multi-frequency generation to occur during tracking operations
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 approach ensures accurate position and orientation measurements by minimizing the effects of environmental distortions, providing reliable tracking in environments with conductive or magnetic objects, and enabling precise tracking for AR and VR applications.
Implementation Method 1
a magnetic transmitter configured to generate magnetic fields
Implementation Method 2
a magnetic sensor configured to generate signals based on characteristics of the magnetic fields received at the magnetic sensor
Data Source
AI summary
A system comprising: a magnetic transmitter configured to generate magnetic fields; a magnetic sensor configured to generate signals based on characteristics of the magnetic fields; and one or more computer systems configured to: cause the magnetic transmitter to generate a first plurality of magnetic fields at a first frequency; receive a first plurality of signals from the magnetic sensor; determine data indicative of a position and orientation of the magnetic sensor at a first position of the magnetic sensor; determine a distortion term that corresponds to a first position of the magnetic sensor; cause the magnetic transmitter to generate a third plurality of magnetic fields at the first frequency; receive a third plurality of signals from the magnetic sensor; and determine a second position and orientation of the magnetic sensor relative to the magnetic transmitter, wherein the first frequency is greater than the second frequency.