Abstract: A magnetic tracking device includes a sensor configured to generate a sensor electromotive force (EMF). The device includes a mechanism configured to select between a first operating mode in which the sensor generates the sensor EMF when receiving the magnetic field and a second operating mode in which the sensor generates a reduced amount of the sensor EMF when receiving the magnetic field. An interconnecting circuit generates a parasitic EMF in each of the first operating mode and the second operating mode. The interconnecting circuit connects to a processing device which receives a first measurement for the first operating mode, the first measurement representing the sensor EMF and the parasitic EMF, receives a second measurement for the second operating mode, the second measurement representing the parasitic EMF, compares the first measurement and the second measurement, and determines an approximate value of the sensor EMF.

Abstract: A magnetic tracking device includes a sensor configured to generate a sensor electromotive force (EMF). The device includes a mechanism configured to select between a first operating mode in which the sensor generates the sensor EMF when receiving the magnetic field and a second operating mode in which the sensor generates a reduced amount of the sensor EMF when receiving the magnetic field. An interconnecting circuit generates a parasitic EMF in each of the first operating mode and the second operating mode. The interconnecting circuit connects to a processing device which receives a first measurement for the first operating mode, the first measurement representing the sensor EMF and the parasitic EMF, receives a second measurement for the second operating mode, the second measurement representing the parasitic EMF, compares the first measurement and the second measurement, and determines an approximate value of the sensor EMF.

Abstract: An electromagnetic tracking system includes a magnetic transmitter configured to output magnetic fields, a receiver responsive to the magnetic fields, an electronics assembly having conductive elements that cause distortion to the magnetic fields, and an output mechanism configured to output a position of the receiver relative to the magnetic transmitter, wherein the magnetic transmitter has at least one winding disposed around a hollow ferromagnetic core comprised of conductive material through which current is made to flow by the electronics, wherein the electronics assembly is at least partially contained within the hollow portion of the hollow ferromagnetic core. Methods of manufacturing include shaping walls into a hollow shell to surround an electronics assembly, covering the hollow shell with ferromagnetic material, inserting the wrapped hollow shell into a plastic bobbin, and winding the plastic bobbin with coil wire to produce three orthogonal windings.

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.

Abstract: A system is configured to model a magnetic field by measuring a first value for characteristics of a magnetic field at a first position in the magnetic field. The system measures a second value characteristics of the magnetic field at a second position in the magnetic field. The system determines a distance between the first position and the second position. The system estimates a distortion component of the magnetic field at approximately the second position in the magnetic field based on each of the distance, the first value for each of the one or more characteristics, and the second value for each of the one or more characteristics. The system outputs a model of at least a region of the magnetic field.

Abstract: A magnetic tracking device includes a sensor configured to generate a sensor electromotive force (EMF). The device includes a mechanism configured to select between a first operating mode in which the sensor generates the sensor EMF when receiving the magnetic field and a second operating mode in which the sensor generates a reduced amount of the sensor EMF when receiving the magnetic field. An interconnecting circuit generates a parasitic EMF in each of the first operating mode and the second operating mode. The interconnecting circuit connects to a processing device which receives a first measurement for the first operating mode, the first measurement representing the sensor EMF and the parasitic EMF, receives a second measurement for the second operating mode, the second measurement representing the parasitic EMF, compares the first measurement and the second measurement, and determines an approximate value of the sensor EMF.

Abstract: 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.

Abstract: An electromagnetic tracking system includes a magnetic transmitter configured to output magnetic fields, a receiver responsive to the magnetic fields, an electronics assembly having conductive elements that cause distortion to the magnetic fields, and an output mechanism configured to output a position of the receiver relative to the magnetic transmitter, wherein the magnetic transmitter has at least one winding disposed around a hollow ferromagnetic core comprised of conductive material through which current is made to flow by the electronics, wherein the electronics assembly is at least partially contained within the hollow portion of the hollow ferromagnetic core. Methods of manufacturing include shaping walls into a hollow shell to surround an electronics assembly, covering the hollow shell with ferromagnetic material, inserting the wrapped hollow shell into a plastic bobbin, and winding the plastic bobbin with coil wire to produce three orthogonal windings.

Abstract: An electromagnetic tracking system includes a magnetic transmitter configured to output magnetic fields, a receiver responsive to the magnetic fields, an electronics assembly having conductive elements that cause distortion to the magnetic fields, and an output mechanism configured to output a position of the receiver relative to the magnetic transmitter, wherein the magnetic transmitter has at least one winding disposed around a hollow ferromagnetic core comprised of conductive material through which current is made to flow by the electronics, wherein the electronics assembly is at least partially contained within the hollow portion of the hollow ferromagnetic core. Methods of manufacturing include shaping walls into a hollow shell to surround an electronics assembly, covering the hollow shell with ferromagnetic material, inserting the wrapped hollow shell into a plastic bobbin, and winding the plastic bobbin with coil wire to produce three orthogonal windings.

Abstract: 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.

Abstract: A system is configured to model a magnetic field by measuring a first value for characteristics of a magnetic field at a first position in the magnetic field. The system measures a second value characteristics of the magnetic field at a second position in the magnetic field. The system determines a distance between the first position and the second position. The system estimates a distortion component of the magnetic field at approximately the second position in the magnetic field based on each of the distance, the first value for each of the one or more characteristics, and the second value for each of the one or more characteristics. The system outputs a model of at least a region of the magnetic field.

Abstract: An electromagnetic tracking system includes a magnetic transmitter configured to output magnetic fields, a receiver responsive to the magnetic fields, an electronics assembly having conductive elements that cause distortion to the magnetic fields, and an output mechanism configured to output a position of the receiver relative to the magnetic transmitter, wherein the magnetic transmitter has at least one winding disposed around a hollow ferromagnetic core comprised of conductive material through which current is made to flow by the electronics, wherein the electronics assembly is at least partially contained within the hollow portion of the hollow ferromagnetic core.

Abstract: A system comprising: a transmitter that includes at least three coils, the transmitter configured to generate magnetic fields; a sensor that includes at least three coils, the sensor configured to provide sensor signals that correspond to the magnetic fields generated by the transmitter; and a computing device in communication with the transmitter and the sensor, the computing device configured to compare a first sensor signal and a second sensor signal, and based on the comparison, determine whether any of the sensor coils are locked to a corresponding frequency out-of-phase.

Abstract: A system comprising: a transmitter that includes at least three coils, the transmitter configured to generate magnetic fields; a sensor that includes at least three coils, the sensor configured to provide sensor signals that correspond to the magnetic fields generated by the transmitter; and a computing device in communication with the transmitter and the sensor, the computing device configured to compare a first sensor signal and a second sensor signal, and based on the comparison, determine whether any of the sensor coils are locked to a corresponding frequency out-of-phase.

Abstract: An improved system for magnetic position tracking of a device includes a magnetic transmitter, a magnetic sensor, a computing system and a polarity inverter. The magnetic transmitter includes at least one transmitter coil that outputs a transmitted magnetic field having a time derivative component. The magnetic sensor includes at least one sensor coil that has coil terminals having a polarity, and the sensor coil is responsive to the time derivative component of the transmitted magnetic field and outputs a sensor signal. The computing system computes position and angular orientation data of a device based on the sensor signal and the polarity inverter is configured to connect to the coil terminals and to cause the polarity of the coil terminals to be reversed according to a switching signal.

Abstract: An improved system for magnetic position tracking of a device includes a magnetic transmitter, a magnetic sensor, a computing system and a polarity inverter. The magnetic transmitter includes at least one transmitter coil that outputs a transmitted magnetic field having a time derivative component. The magnetic sensor includes at least one sensor coil that has coil terminals having a polarity, and the sensor coil is responsive to the time derivative component of the transmitted magnetic field and outputs a sensor signal. The computing system computes position and angular orientation data of a device based on the sensor signal and the polarity inverter is configured to connect to the coil terminals and to cause the polarity of the coil terminals to be reversed according to a switching signal.

Abstract: Among other things, the disclosure features a system comprising a sensor, a DC magnetic field source, an AC magnetic field source, and a receiver. The sensor has an aspect ratio of 10:1 or higher and comprises a ferromagnetic material. The ferromagnetic material has a non-linear magnetization response, and the response contains a maximum point of non-linearity. The DC magnetic field source is adjustable for providing a magnetic excitation field to excite a magnetic field within the sensor. The provided magnetic excitation field has a range such that the excited magnetic field within the sensor is near the maximum point of non-linearity. The AC magnetic field source is configured to generate an AC magnetic field to cause the sensor to generate even harmonics. The receiver is configured to receive the even harmonics from the sensor for determining a position of the sensor.

Abstract: Among other things, the disclosure features a system comprising a sensor, a DC magnetic field source, an AC magnetic field source, and a receiver. The sensor has an aspect ratio of 10:1 or higher and comprises a ferromagnetic material. The ferromagnetic material has a non-linear magnetization response, and the response contains a maximum point of non-linearity. The DC magnetic field source is adjustable for providing a magnetic excitation field to excite a magnetic field within the sensor. The provided magnetic excitation field has a range such that the excited magnetic field within the sensor is near the maximum point of non-linearity. The AC magnetic field source is configured to generate an AC magnetic field to cause the sensor to generate even harmonics. The receiver is configured to receive the even harmonics from the sensor for determining a position of the sensor.

Abstract: A magnetic field sensor assembly includes a hollow cylindrical core, conductive material and at least first and second lead wires. The hollow cylindrical core is made of ferromagnetic material and has a proximal end and a distal end. The conductive material is disposed around the hollow cylindrical core and forms at least one turn of a coil that has at least one start terminal and at least one finish terminal. The first and second lead wires pass through the center of the hollow cylindrical core and the first lead wire is connected to the start terminal thereby forming a first termination and the second lead wire is connected to the finish terminal thereby forming a second termination. The first and second terminations are positioned within the hollow cylindrical core.

Abstract: A magnetic field sensor assembly includes a hollow cylindrical core, conductive material and at least first and second lead wires. The hollow cylindrical core is made of ferromagnetic material and has a proximal end and a distal end. The conductive material is disposed around the hollow cylindrical core and forms at least one turn of a coil that has at least one start terminal and at least one finish terminal. The first and second lead wires pass through the center of the hollow cylindrical core and the first lead wire is connected to the start terminal thereby forming a first termination and the second lead wire is connected to the finish terminal thereby forming a second termination. The first and second terminations are positioned within the hollow cylindrical core.