# US 9,435,708 B1 · Devices and methods to enhance accuracy of magnetoelastic torque sensors > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,435,708 B1 - Document ID: US9435708B1 - Status: Granted - Kind: B1 - Application number: 14/741,305 - Filed: 2015-06-16 - Granted: 2016-09-06 - Earliest claimed: 2015-06-16 - Applicants: MagCanica, Inc. - Inventors: Ryan Kari - Web page: https://patentgrep.com/patent/US9435708B1 ## CPC - G01L 25/003: {for measuring torque} - G01L 3/102: {involving magnetostrictive means (magnetostrictive sensors H10N35/101)} - G01L 3/14: wherein the torque-transmitting element is other than a torsionally-flexible shaft - G01L 25/00: Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency - G01L 3/104: {involving permanent magnets} - G01L 3/1435: {involving magnetic or electromagnetic means} - G06F 17/00: Digital computing or data processing equipment or methods, specially adapted for specific functions (information retrieval, database structures or file system structures therefor G06F16/00) - H10N 35/00: Magnetostrictive devices (integrated devices or assemblies of multiple devices H10N39/00) - H10N 35/101: {with mechanical input and electrical output, e.g. generators, sensors} - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR ## Abstract This invention concerns magnetoelastic torque sensor systems and methods that computationally compensate in real-time for magnetic hysteresis in signals output from sense elements that are indicative of a torque parameter sensed from a remanently circumferentially magnetized region of an associated torque-transmitting member when it experiences an applied torque. In preferred embodiments, temperature effects can also be compensated for by such methods and systems. ## Claims ### Claim 1 A computerized method of real-time hysteresis compensation in a signal indicative of a sensed torque parameter experienced by a ferromagnetic member upon application of a torque, the method comprising: (a) using a sense element disposed in sensing relation to a remanently circumferentially magnetized region of a torque-transmitting member to sense a magnetic parameter of the remanently circumferentially magnetized region, wherein the sense element generates a signal indicative of a sensed torque parameter from the torque-transmitting member upon application of a torque to the torque-transmitting member, wherein the signal indicative of the sensed torque parameter exhibits magnetic hysteresis; and (b) using a computer comprising a processor, memory, and power supply to computationally process the signal to compensate in real-time for the magnetic hysteresis in the signal indicative of the sensed torque parameter, wherein the computer processing of the signal indicative of the sensed torque parameter utilizes information for the torque-transmitting member that is correlated with a torque history or a degree of prior magnetic hysteresis compensation for at least one signal indicative of the sensed torque parameter upon prior application of a torque to the torque-transmitting member, thereby compensating for magnetic hysteresis in the signal in real-time. ### Claim 2 (depends on 1) A method according to claim 1 that further comprises compensating for temperature-related magnetic hysteresis variation in the magnetized region of the member. ### Claim 3 (depends on 1) A method according to claim 1 wherein the sensed torque parameter is torque or a rate of change of torque applied to the member. ### Claim 4 (depends on 1) A method according to claim 1 wherein the remanently circumferentially magnetized region comprises a remanently circumferentially magnetized portion of the member or a remanently circumferentially magnetized band coupled to the member, wherein the remanently circumferentially magnetized region has a magnetic hysteresis error of 0.5% to 20% for a loading cycle, and wherein the member is a torque-transmitting shaft. ### Claim 5 (depends on 1) A method according to claim 1 wherein the sense element is disposed proximate to the remanently circumferentially magnetized region in order to output a signal indicative of the torque parameter when the torque-transmitting member experiences or is subjected to a time-varying torque. ### Claim 6 (depends on 5) A method according to claim 5 wherein the magnetic parameter of the remanently circumferentially magnetized region sensed by the sense element is magnetic flux or magnetization orientation. ### Claim 7 An automated, real-time magnetic hysteresis-compensating torque measurement system, comprising: (a) a torque-transmitting member having at least one remanently circumferentially magnetized region; (b) a sense element disposed in sensing relation to the remanently circumferentially magnetized region of the torque-transmitting member to sense a magnetic parameter of the remanently circumferentially magnetized region, wherein the sense element is configured to output a signal indicative of a torque parameter from the torque-transmitting member upon application of a torque to the torque-transmitting member, wherein the signal indicative of the sensed torque parameter exhibits magnetic hysteresis; (c) a processor operatively associated with the sense element and configured to (i) process signals output from the sense element to determine the torque parameter and (ii) compensate in real-time for magnetic hysteresis in the remanently circumferentially magnetized region(s) of the torque-transmitting member; (d) a memory operatively associated with the processor and configured to store data representing a torque history or degree of prior magnetic hysteresis compensation in one or more signals indicative of the sensed torque parameter upon application of a torque to the torque-transmitting member; and (e) a power supply to provide electrical enemy for the torque measuring system. ### Claim 8 (depends on 7) A system according to claim 7 wherein the processor is further configured to compensate for temperature-related magnetic hysteresis variation in signals output from the sense element. ### Claim 9 (depends on 7) A system according to claim 7 wherein the torque parameter is torque or a rate of change of torque. ### Claim 10 (depends on 7) A system according to claim 7 wherein the remanently circumferentially magnetized region comprises a remanently circumferentially magnetized portion of the torque-transmitting member or a remanently circumferentially magnetized band coupled to the torque-transmitting member. ### Claim 11 (depends on 7) A system according to claim 7 wherein the sense element is disposed proximate to the remanently circumferentially magnetized region in order to output a signal indicative of a torque parameter when the torque-transmitting member experiences or is subjected to a time-varying torque. ### Claim 12 (depends on 11) A system according to claim 11 wherein the sense element senses a magnetic parameter of the remanently circumferentially magnetized region, wherein the magnetic parameter is magnetic flux or magnetization orientation. ### Claim 13 (depends on 7) A system according to claim 7 wherein the signal indicative of the sensed torque parameter exhibits a magnetic hysteresis error of 0.5% to 20% for a loading cycle. ### Claim 14 (depends on 7) A system according to claim 7 wherein the torque-transmitting member is a torque-transmitting shaft.