Electromagnetic tracking and position measurement system having interference reduction from nearby instrumentation by filtering time-division multiplexed signal via step function
Inventors
Ashe, Westley S. • Petrow, William
Assignees
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Publication Number
US-12616390-B2
Publication Date
2026-05-05
Expiration Date
Abstract
An electromagnetic tracking (EMT) system is configured for determining a frequency for generating at least a portion of a magnetic field signal using a transmitter coil of a plurality of transmitter coils. The EMT system configures a time-division multiplexed (TDM) control signal configured to cause the transmitter coil to transmit bursts of the magnetic field signal at the frequency. The EMT system configures a filter for filtering the TDM control signal, the filter configured to shape each burst to reduce or eliminate a harmonic artifact of the bursts. The EMT system causes the transmitter coil to generate the shaped bursts of the magnetic field signal. The EMT system receives, from a sensor, a sensor signal that corresponds to the magnetic field signal, the sensor including the output response indicative of the location of the sensor relative to the transmitter.
Core Innovation
A tracking and position measurement system uses a transmitter configured to generate a magnetic field signal and a receiver configured to generate a signal representing an output response indicative of a location of the receiver relative to the transmitter based on the magnetic field signal. A computing device communicates with the transmitter and the receiver and configures a control signal for controlling transmissions, where the control signal causes the transmitter to periodically transmit bursts of the magnetic field signal. The computing device configures a filter for filtering the control signal to prepare each burst for transmitting, and each prepared burst reduces or prevents a harmonic artifact at the receiver.
The filtering uses a windowing filter that prepares a burst by reducing a rate of change of an excitation signal applied to the magnetic field signal. The filter is configured based on a determined threshold or based on a determined signal strength of a harmonic artifact for the magnetic field signal transmitted by the transmitter. In this way, burst generation and excitation are shaped so that the harmonic artifact is reduced or prevented at the receiver during tracking and position measurement.
The receiver includes a receiver-coil core having relative magnetic permeability greater than 1, and the core can be made from ferrite or permalloy. In additional embodiments, transmitter coil magnetic field signals are at distinct frequencies compared with magnetic field signals generated by other transmitter coils. The receiver may be associated with sensor types including hall-effect sensors, magnetoresistive sensors, magneto-optical sensors, or fluxgate magnetometers.
Claims Coverage
The document includes two independent claims, one directed to a system and one directed to a method. Across these independent claims, the coverage centers on configuring burst transmissions and preparing each burst with a windowing filter to reduce or prevent harmonic artifacts using threshold or harmonic-artifact signal-strength information.
Burst transmission with filtered control signal to reduce harmonic artifacts
The computing device configures a control signal for periodically transmitting bursts of a magnetic field signal, and configures a filter for filtering the control signal to prepare each burst for transmitting, where each prepared burst reduces or prevents a harmonic artifact at the receiver.
Windowing filter based on rate-of-change reduction and threshold or harmonic-artifact signal strength
The filter comprises a windowing filter that prepares a burst by reducing a rate of change of an excitation signal applied to the magnetic field signal, and the filter is configured based on a determined threshold or based on a determined signal strength of a harmonic artifact for the magnetic field signal transmitted by the transmitter.
Tracking and position measurement with prepared bursts and received location-indicative response
The computing device causes the transmitter to periodically generate the prepared bursts based on the control signal and receives, via the receiver, a signal representing an output response indicative of a location of the receiver relative to the transmitter.
The independent claims focus on adaptive burst transmission in a magnetic tracking system, where each burst is prepared by a windowing filter that reduces rate-of-change of an excitation signal and is configured based on a determined threshold or a determined signal strength of harmonic artifacts, thereby enabling the receiver to generate a location-indicative output response.
Stated Advantages
Reduces or prevents harmonic artifacts of the respective burst at the receiver.
Reduces a rate of change of an excitation signal applied to the magnetic field signal (as part of harmonic-artifact mitigation).
Configures filtering based on determined threshold or determined signal strength of a harmonic artifact for the magnetic field signal transmitted by the transmitter.
Documented Applications
Not explicitly described in patent.
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