# US 12,014,809 B2 · Calibration of orientations of a gyroscope of a motion tracking system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,014,809 B2 - Document ID: US12014809B2 - Status: Granted - Kind: B2 - Application number: 17/604,671 - Filed: 2020-04-27 - Published: 2022-07-07 - Granted: 2024-06-18 - Earliest claimed: 2019-04-30 - Assignees: Sword Health, S.A. - Applicants: Sword Health S.A. - Inventors: Pedro Henrique Oliveira Santos; Luís Ungaro Pinto Coelho; Marta Maria Ramalho Ferreira; Ana Clara Ferreira Matos; Virgílio António Ferro Bento - Web page: https://patentgrep.com/patent/US12014809B2 ## CPC - G01C 25/005: {initial alignment, calibration or starting-up of inertial devices} - G16H 20/30: relating to physical therapies or activities, e.g. physiotherapy, acupressure or exercising - A61B 5/11: Measuring movement of the entire body or parts thereof, e.g. head or hand tremor or mobility of a limb {(A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721)} - A61B 5/6823: {Trunk, e.g., chest, back, abdomen, hip} - A61B 5/6824: {Arm or wrist} - A61B 2560/0223: of calibration, e.g. protocols for calibrating sensors - A61B 2562/0219: Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches - A61B 2562/0223: Magnetic field sensors - G16H 30/20: for handling medical images, e.g. DICOM, HL7 or PACS - G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S) - G16H: HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract A method for adjusting operation of a motion tracking system at least including first and second sensors and a computing device, each of the sensors at least having a gyroscope. The method includes the following steps: arranging the first sensor on an upper arm of a person, and the second sensor on their chest; measuring orientations each of the first and second sensors while the person performs a predetermined movement. The movement includes the person moving a torso with respect to their hip while keeping the upper arm parallel to the torso and not rotating the upper arm. The method further includes digitally processing, the computing device, the orientations measured so as to digitally compute an orientation difference between the orientations measured by the first sensor and by the second sensor; and adjusting, the computing device, the operation of the motion tracking system based on the orientation difference computed. ## Claims ### Claim 1 A method for adjusting operation of a motion tracking system at least comprising first and second sensors and a computing device, each of the first and second sensors at least comprising a gyroscope, the method comprising: arranging the first sensor on an upper arm of a person, and the second sensor on a chest of the person; measuring orientations each of the first and second sensors while the person performs a predetermined movement; digitally processing, by the computing device, the orientations measured so as to digitally compute an orientation difference between the orientations measured by the first sensor and the orientations measured by the second sensor; and adjusting, by the computing device, the operation of the motion tracking system based on the orientation difference computed; wherein the predetermined movement comprises the person moving a torso thereof with respect to a hip of the person, and during the predetermined movement the upper arm is not rotated with respect to a shoulder of the person connected to the upper arm. ### Claim 2 (depends on 1) The method of claim 1, wherein the adjusting of the operation of the motion tracking system comprises one of: digitally modifying orientations measured by the first sensor or the second sensor; digitally adjusting a physical exercise evaluation procedure; and providing at least one of: at least one user perceptible signal indicative of an incorrect placement of the first sensor on the upper arm and at least one user perceptible signal indicative of an instruction to rearrange the first sensor on the upper arm. ### Claim 3 (depends on 2) The method of claim 2, wherein digitally adjusting the physical exercise evaluation procedure comprises digitally adjusting an algorithm with which the motion tracking system digitally determines whether the person tracked with the first and second sensors performs a physical exercise. ### Claim 4 (depends on 1) The method of claim 1, wherein the digitally processing the orientations measured comprises digitally computing the following: an angular displacement of each of the first and second sensors between a first position in which the person is standing still and a second position in which the person has performed the predetermined movement; axes of rotation of each of the first and second sensors relative to local coordinates of each of the first and second sensors, respectively, based on the respective angular displacements; and the orientation difference by digitally computing an angle between the axes of rotation of the first sensor and the axes of rotation of the second sensor. ### Claim 5 (depends on 1) The method of claim 1, further comprising calibrating the second sensor prior to the measuring of the orientations while the person performs the predetermined movement, and wherein the second sensor further comprises an accelerometer. ### Claim 6 (depends on 1) The method of claim 1, wherein each of the first and second sensors further comprises a magnetometer, and wherein in the measuring of the orientations while the person performs the predetermined movement each of the first and second sensors does not process measurements of the magnetometers in respective sensor fusion algorithms thereof. ### Claim 7 (depends on 1) The method of claim 1, wherein the computing device digitally processes the orientations measured to digitally compute the orientation difference irrespective of a direction in which the person has performed the predetermined movement. ### Claim 8 A motion tracking system comprising: a computing device comprising at least one processor and at least one memory; and first and second sensors, each sensor at least comprising a gyroscope; the at least one processor is configured, together with the at least one memory, to: digitally process orientations measured by the first and second sensors while a person having the first and second sensors arranged on an upper arm and a chest thereof, respectively, performs a predetermined movement, the orientations being processed so as to digitally compute an orientation difference between the orientations measured by the first sensor and the orientations measured by the second sensor; and adjust operation of the motion tracking system based on the orientation difference computed; wherein the predetermined movement comprises the person moving a torso thereof with respect to a hip of the person, and during the predetermined movement the upper arm is not rotated with respect to a shoulder of the person connected to the upper arm. ### Claim 9 (depends on 8) The motion tracking system of claim 8, wherein the at least one processor is configured to adjust the operation of the motion tracking system by one of: digitally modifying orientations measured by the first sensor or the second sensor; digitally adjusting a physical exercise evaluation procedure; and commanding means for providing user perceptible signals to provide at least one of: at least one user perceptible signal indicative of an incorrect placement of the first sensor on the upper arm and at least one user perceptible signal indicative of an instruction to rearrange the first sensor on the upper arm. ### Claim 10 (depends on 9) The motion tracking system of claim 9, wherein the at least one processor is configured to digitally adjust the physical exercise evaluation procedure by digitally adjusting an algorithm with which the motion tracking system digitally determines whether the person tracked with the first and second sensors performs a physical exercise. ### Claim 11 (depends on 8) The motion tracking system of claim 8, wherein the at least one processor is configured to digitally process the orientations measured by digitally computing the following: an angular displacement of each of the first and second sensors between a first position in which the person is standing still and a second position in which the person has performed the predetermined movement; axes of rotation of each of the first and second sensors relative to local coordinates of each of the first and second sensors, respectively, based on the respective angular displacements; and the orientation difference by digitally computing an angle between the axes of rotation of the first sensor and the axes of rotation of the second sensor. ### Claim 12 (depends on 8) The motion tracking system of claim 8, wherein the second sensor further comprises an accelerometer, and wherein the at least one processor is further configured to at least one of calibrate the second sensor and command the second sensor to start a calibration procedure. ### Claim 13 (depends on 8) The motion tracking system of claim 8, wherein each of the first and second sensors further comprises a magnetometer, and wherein each of the first and second sensors is configured to not process measurements of the magnetometers in respective sensor fusion algorithms thereof at least when measuring the orientations while the person performs the predetermined movement. ### Claim 14 (depends on 8) The motion tracking system of claim 8, wherein the at least one processor is configured to digitally process the orientations measured so as to digitally compute the orientation difference irrespective of a direction in which the person has performed the predetermined movement. ### Claim 15 A computer-readable storage medium comprising instructions which, when executed by a computing device, cause the computing device to perform operations comprising: digitally processing orientations measured by first and second sensors of a motion tracking system while a person having the first and second sensors arranged on an upper arm and a chest thereof, respectively, performs a predetermined movement, the orientations being processed so as to digitally compute an orientation difference between the orientations measured by the first sensor and the orientations measured by the second sensor, the first and second sensors each comprising a gyroscope; and adjusting operation of the motion tracking system based on the orientation difference computed; wherein the predetermined movement comprises the person moving a torso thereof with respect to a hip of the person, and during the predetermined movement the upper arm is not rotated with respect to a shoulder of the person connected to the upper arm. ### Claim 16 (depends on 15) The computer-readable storage medium of claim 15, wherein the instructions cause the computing device to adjust the operation of the motion tracking system by one of: digitally modifying orientations measured by the first sensor or the second sensor; digitally adjusting a physical exercise evaluation procedure; and providing at least one of: at least one user perceptible signal indicative of an incorrect placement of the first sensor on the upper arm and at least one user perceptible signal indicative of an instruction to rearrange the first sensor on the upper arm. ### Claim 17 (depends on 16) The computer-readable storage medium of claim 16, wherein the instructions cause the computing device to adjust the operation of the motion tracking system by digitally adjusting the physical exercise evaluation procedure, and wherein the adjustment of the physical exercise evaluation procedure comprises digitally adjusting an algorithm with which the motion tracking system digitally determines whether the person tracked with the first and second sensors performs a physical exercise. ### Claim 18 (depends on 15) The computer-readable storage medium of claim 15, wherein the instructions cause the computing device to digitally process the orientations measured by digitally computing the following: an angular displacement of each of the first and second sensors between a first position in which the person is standing still and a second position in which the person has performed the predetermined movement; axes of rotation of each of the first and second sensors relative to local coordinates of each of the first and second sensors, respectively, based on the respective angular displacements; and the orientation difference by digitally computing an angle between the axes of rotation of the first sensor and the axes of rotation of the second sensor. ### Claim 19 (depends on 15) The computer-readable storage medium of claim 15, wherein the instructions cause the computing device to digitally process the orientations measured so as to digitally compute the orientation difference irrespective of a direction in which the person has performed the predetermined movement. ### Claim 20 (depends on 15) The computer-readable storage medium of claim 15, wherein each of the first and second sensors further comprises a magnetometer, and wherein the instructions cause the computing device to command each of the first and second sensors not to process measurements of the magnetometers in respective sensor fusion algorithms thereof at least when measuring the orientations while the person performs the predetermined movement.