# US 11,112,229 B2 · Magnetic type azimuth/position measurement device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,112,229 B2 - Document ID: US11112229B2 - Status: Granted - Kind: B2 - Application number: 16/718,192 - Filed: 2019-12-18 - Published: 2020-04-23 - Granted: 2021-09-07 - Earliest claimed: 2017-06-21 - Assignees: Asahi Intecc Co., Ltd. - Applicants: Asahi Intecc Co., Ltd. - Inventors: Yoshinobu Honkura; Shinpei Honkura - Web page: https://patentgrep.com/patent/US11112229B2 ## CPC - G01B 7/003: {for measuring position, not involving coordinate determination (coordinate measuring G01B7/004)} - A61B 1/00: Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes (examination of body cavities or body tracts using ultrasonic, sonic or infrasonic waves A61B8/12; endoscopic instruments for taking cell samples or for biopsy A61B10/04); Illuminating arrangements therefor (for the eyes A61B3/00) - A61B 34/20: Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis - G01B 7/00: Measuring arrangements characterised by the use of electric or magnetic techniques - G01R 33/02: Measuring direction or magnitude of magnetic fields or magnetic flux (G01R33/20 takes precedence) - A61B 5/062: {using magnetic field} - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A magnetic type azimuth/position measurement device is disclosed, comprising: a plurality of coils driven by circuitry, the circuitry and coils configured to selectively generate a uniform magnetic field and an inclined magnetic field in a three-dimensional space; a uniaxial magnetic field sensor configured to measure a strength of a magnetic field formed by the plurality of coils driven by circuitry; and arithmetic operation circuitry configured to receive signals representative of the strength of the magnetic field from the uniaxial magnetic field sensor and calculate a position and an azimuth of the uniaxial magnetic field sensor in the three-dimensional space. ## Claims ### Claim 1 A magnetic type azimuth/position measurement device, comprising: a plurality of coils driven by circuitry, the circuitry and coils configured to selectively generate a uniform magnetic field and an inclined magnetic field in a three-dimensional space; a uniaxial magnetic field sensor configured to measure a strength of a magnetic field formed by the plurality of coils driven by circuitry; and arithmetic operation circuitry configured to receive signals representative of the strength of the magnetic field from the uniaxial magnetic field sensor and calculate a position and an azimuth of the uniaxial magnetic field sensor in the three-dimensional space. ### Claim 2 (depends on 1) The magnetic type azimuth/position measurement device according to claim 1, wherein the circuitry and coils are further configured to: generate the uniform magnetic field sequentially in each of three orthogonal directions and wherein, for each direction, values of the uniform magnetic fields are measured by the uniaxial magnetic field sensor and wherein the arithmetic operation circuitry is further configured to calculate an azimuth vector of the uniaxial magnetic field sensor in the three-dimensional space and direction cosines for the three orthogonal directions of the uniaxial magnetic field sensor using received signals representative of a strength of the uniform magnetic field in each of the three orthogonal directions; generate the inclined magnetic field sequentially in each of the three orthogonal directions and wherein, for each direction, values of the inclined magnetic fields are measured by the uniaxial magnetic field sensor and wherein the arithmetic operation circuitry is further configured to calculate the position of the uniaxial magnetic field sensor using received signals representative of a strength of the inclined magnetic field in each of the three orthogonal directions and the direction cosines for the three orthogonal directions of the uniaxial magnetic field sensor. ### Claim 3 (depends on 1) The magnetic type azimuth/position measurement device according to claim 1, wherein the circuitry and coils are further configured to cancel an external magnetic field to maintain a zero magnetic field in the three-dimensional space before a start of measurement. ### Claim 4 (depends on 1) The magnetic type azimuth/position measurement device according to claim 1, wherein the plurality of coils includes three sets of coil pairs of parallel four wire coils forming an inclined magnetic field and three sets of Helmholtz coil pairs forming a uniform magnetic field. ### Claim 5 (depends on 2) The magnetic type azimuth/position measurement device according to claim 2, wherein when any one of direction cosines for the three orthogonal directions is zero, a generated magnetic field space is rotated by a predetermined angle with a remaining direction perpendicular to a surface formed by a specific direction where the direction cosine is largest and the direction where the direction cosine is zero as a rotation axis, so that a value of the direction cosine for each direction is not zero. ### Claim 6 (depends on 1) The magnetic type azimuth/position measurement device according to claim 1, wherein if in the inclined magnetic field generated by the three-dimensional magnetic field generating device, the strength at a position deviating from a center line of each axis deviates slightly from a position of the axis, a deviation amount is measured preliminarily to perform position calculation with high accuracy using a value of the deviation amount as a correction value. ### Claim 7 (depends on 1) The magnetic type azimuth/position measurement device according to claim 1, wherein the uniaxial magnetic field sensor is a GSR (GHz-Spin-Rotation) sensor. ### Claim 8 (depends on 1) The magnetic type azimuth/position measurement device according to claim 1, wherein the uniaxial magnetic field sensor includes a magnetic detection element with one or more magnetic wires, a detection coil surrounding the one or more magnetic wires and a signal processing circuit configured to convert a detected coil voltage into a signal representing a magnetic field strength, and has performance of measuring the magnetic field with a standard error of 1 mG or smaller. ### Claim 9 A magnetic type azimuth/position measurement device, comprising: a plurality of coils driven by circuitry, the circuitry and coils configured to sequentially generate a uniform magnetic field and an inclined magnetic field along an X axis, a Y axis, and a Z axis in a three-dimensional space; a uniaxial magnetic field sensor configured to measure a strength of the uniform magnetic field and the inclined magnetic field; and arithmetic operation circuitry configured to calculate an azimuth vector of the uniaxial magnetic field sensor in the three-dimensional space, direction cosines for the X axis, the Y axis, and the Z axis and position of the uniaxial magnetic field sensor using signals received from the uniaxial magnetic field sensor that represent a strength of the uniform magnetic field and the inclined magnetic field in each of the X axis, the Y axis, and the Z axis. ### Claim 10 (depends on 9) The magnetic type azimuth/position measurement device according to claim 9, wherein the circuitry and coils are further configured to cancel an external magnetic field to maintain a zero magnetic field in the three-dimensional space before a start of measurement. ### Claim 11 (depends on 9) The magnetic type azimuth/position measurement device according to claim 9, wherein when any one of direction cosines for the X axis, the Y axis, or the Z axis is zero, a generated magnetic field space is rotated by a predetermined angle with a remaining axis perpendicular to a surface formed by a specific axis where the direction cosine is largest and the axis where the direction cosine is zero as a rotation axis, so that a value of the direction cosine for each axis is not zero. ### Claim 12 (depends on 9) The magnetic type azimuth/position measurement device according to claim 9, wherein the uniaxial magnetic field sensor is a GSR (GHz-Spin-Rotation) sensor. ### Claim 13 (depends on 9) The magnetic type azimuth/position measurement device according to claim 9, wherein the uniaxial magnetic field sensor includes a magnetic detection element with one or more magnetic wires, a detection coil surrounding the one or more magnetic wires and a signal processing circuit configured to convert a detected coil voltage into a signal representing a magnetic field strength. ### Claim 14 (depends on 9) The magnetic type azimuth/position measurement device according to claim 9, wherein the plurality of coils includes a parallel four wire coil for at least one of the X axis, the Y axis, and the Z axis. ### Claim 15 (depends on 9) The magnetic type azimuth/position measurement device according to claim 9, wherein the plurality of coils includes two types of coils of a coil forming an inclined magnetic field and a Helmholtz coil generating a uniform magnetic field. ### Claim 16 A method, using circuitry, of measuring azimuth and position comprising: selectively generating, by the circuitry and a plurality of coils driven by the circuitry, a uniform magnetic field and an inclined magnetic field in a three-dimensional space; measuring, by a uniaxial magnetic field sensor, a strength of a magnetic field formed by the plurality of coils driven by the circuitry at a location of the uniaxial magnetic field sensor; receiving from the uniaxial magnetic field sensor, by the circuitry, signals representative of the strength of the magnetic field; and calculating, by the circuitry, a position and an azimuth of the uniaxial magnetic field sensor in the three-dimensional space. ### Claim 17 (depends on 16) The method of claim 16, wherein: the selectively generating step further comprises generating, by the circuitry, the uniform magnetic field and the inclined magnetic field sequentially in each of three orthogonal directions; the measuring step further comprises measuring for each direction, by the uniaxial magnetic field sensor, values of the uniform magnetic field and the inclined magnetic field; and the calculating step further comprises calculating, by the circuitry, an azimuth vector of the uniaxial magnetic field sensor in the three-dimensional space, direction cosines for the three orthogonal directions of the uniaxial magnetic field sensor and the position of the uniaxial magnetic field sensor. ### Claim 18 (depends on 16) The method of claim 16, wherein: when any one of direction cosines, calculated in the calculating step, for the three orthogonal directions is zero, rotating a generated magnetic field space by a predetermined angle with a remaining direction perpendicular to a surface formed by a specific direction where the direction cosine is largest and the direction where the direction cosine is zero as a rotation axis, so that a value of the direction cosine for each direction is not zero. ### Claim 19 (depends on 16) The method of claim 16, further comprising: cancelling an external magnetic field to keep zero external magnetic field in the three-dimensional space before a start of measurement.