Reducing interference between Electromagnetic Tracking systems
Inventors
Koole, Thomas • Cameron, Marc • Mccartney, Joel
Assignees
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Publication Number
US-11454810-B2
Publication Date
2022-09-27
Expiration Date
Abstract
A method of reducing a chance of interference between operations of two electromagnetic systems (e.g., AR/VR systems) is provided. The method includes determining one or more first frequencies at which a first electromagnetic system is operating, identifying one or more second frequencies that do not interfere with the determined one or more first frequencies, and setting a second electromagnetic system to operate at the identified one or more second frequencies. Each of the first and the second electromagnetic systems includes a respective magnetic transmitter configured to generate magnetic fields, and a respective magnetic sensor configured to generate signals based on characteristics of the magnetic fields received at the magnetic sensor (e.g., from the respective magnetic transmitter).
Core Innovation
The disclosed techniques address interference between operations of a first electromagnetic system and a second electromagnetic system in electromagnetic tracking (EMT). The first electromagnetic system includes a magnetic transmitter configured to generate magnetic fields and a magnetic sensor configured to generate signals based on characteristics of the magnetic fields received at the magnetic sensor. The method and system determine one or more first frequencies at which the first electromagnetic system is operating and identify one or more second frequencies that do not interfere with the determined first frequencies.
The non-interfering second frequencies are identified in response to determining that the second electromagnetic system operates at a frequency that is within a threshold value of at least one of the first frequencies such that an interference between operations of the first electromagnetic system and the second electromagnetic system would result. In this way, the second electromagnetic system is set to operate at the identified one or more second frequencies. The described process includes frequency selection driven by interference-likelihood when frequency proximity occurs.
The approach further describes using status signals for frequency decision making and, in some implementations, using measurements such as RSSI values and threshold values from status information to determine which frequencies will avoid interference. Frequency-domain processing can be used, including FFT-based scanning to identify interference-related frequency behavior, and repeated switching between identified second frequencies can be performed on a periodic basis. Optionally, the document describes detecting likely interference using IMU-derived pose divergence between a pose derived from magnetic fields and a pose derived at least in part from IMU measurements.
Claims Coverage
The document includes two independent claims: a method claim and a system claim. Together, they define a frequency-interference avoidance framework using determined first frequencies, identified non-interfering second frequencies, and switching or requesting operation of a second electromagnetic system to avoid interference when frequency proximity would otherwise cause it.
Frequency selection to avoid interference by threshold proximity
A method that determines one or more first frequencies of a first electromagnetic system, identifies one or more second frequencies that do not interfere with the determined first frequencies, and sets a second electromagnetic system to operate at the identified second frequencies, wherein the second frequencies are identified in response to determining that the second electromagnetic system operates at a frequency within a threshold value of at least one first frequency such that interference between operations would result.
Status-signal driven frequency selection and request to operate
A system with a status sensor that receives a status signal from a first electromagnetic system and a computing device configured to determine, from the status signal, one or more first frequencies at which the first electromagnetic system is operating; identify one or more second frequencies that do not interfere with the determined first frequencies; and send, to a magnetic transmitter of a second electromagnetic system, a request to operate at the identified one or more second frequencies, wherein the computing device identifies the second frequencies in response to determining that the second electromagnetic system operates at a frequency within a threshold value of at least one first frequency such that an interference between operations would result.
Claim coverage centers on determining first operating frequencies for a first electromagnetic system, identifying second frequencies that will not interfere based on a threshold-value relationship to first frequencies where interference would result, and configuring the second electromagnetic system accordingly either by directly setting operation (method) or by sending an operation request using status-signal information (system).
Stated Advantages
Reduction of interference between operations of a first electromagnetic system and a second electromagnetic system in electromagnetic tracking (EMT).
Documented Applications
Electromagnetic tracking (EMT) environments where interference occurs between a first and a second electromagnetic system, including scenarios where another system is close enough to cause interference.
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