# US 12,000,476 B2 · Method of correcting angular transmission error for reducer and robot system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,000,476 B2 - Document ID: US12000476B2 - Status: Granted - Kind: B2 - Application number: 17/588,647 - Filed: 2022-01-31 - Published: 2022-08-04 - Granted: 2024-06-04 - Earliest claimed: 2021-02-01 - Assignees: Seiko Epson Corporation - Applicants: Seiko Epson Corporation - Inventors: Naoto Murakami - Web page: https://patentgrep.com/patent/US12000476B2 ## CPC - B25J 9/1628: {characterised by the control loop} - F16H 61/12: Detecting malfunction or potential malfunction, e.g. fail safe (in control of hydrostatic gearing F16H61/4192) {; Circumventing or fixing failures} - B25J 9/1694: {characterised by use of sensors other than normal servo-feedback from position, speed or acceleration sensors, perception control, multi-sensor controlled systems, sensor fusion} - G01B 21/22: for measuring angles or tapers; for testing the alignment of axes - G01C 19/00: Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects - F16H 2061/1232: {Bringing the control into a predefined state, e.g. giving priority to particular actuators or gear ratios} - F16H 2061/1256: {characterised by the parts or units where malfunctioning was assumed or detected} - B25J: MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES ({manipulators specially adapted for use in surgery A61B34/70; manipulators used in cleaning hollow articles B08B9/04}; manipulators associated with rolling mills B21B39/20; manipulators associated with forging machines B21J13/10; {manipulators associated with picking-up and placing mechanisms B23P19/007}; means for holding wheels or parts thereof B60B30/00; {vehicles with ground-engaging propulsion means, e.g. walking members B62D57/02, B62D57/032; devices for picking-up and depositing articles or materials between conveyors B65G47/90, B65G47/91; manipulators with gripping or holding means for transferring packages B65H67/065}; cranes B66C; {manipulators used in the protection or supervision of pipe-line installations F17D5/00; walking equipment adapted for nuclear steam-generators F22B37/006}; manipulators specially adapted for, or associated with, nuclear reactors G21C; {apparatus used for handling wafers during manufacture or treatment of semiconductor H10P72/50}) - F16H: GEARING - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - 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) ## Abstract A method of correcting an angular transmission error for a reducer of creating correction data for correction of an angular transmission error of the reducer in a robot system including an arm, the reducer having an input shaft and an output shaft, a motor, an encoder, and an inertial sensor, includes rotating the arm in an input rotation angular range smaller than a necessary input rotation angular range, measuring and recording the angular transmission error, determining whether or not an accumulated value of measurement times is equal to or larger than a predetermined value, when the accumulated value is smaller than the predetermined value, measuring the angular transmission error of the reducer and updating a record, and, when the accumulated value is equal to or larger than the predetermined value, creating the correction data based on the recorded angular transmission error of the reducer. ## Claims ### Claim 1 A method of correcting an angular transmission error for a reducer of creating correction data for correction of an angular transmission error of the reducer in a robot system including an arm, the reducer having an input shaft and an output shaft coupled to the arm, a motor coupled to the input shaft and generating power for rotating the arm via the reducer, an encoder detecting a rotation angular position of the input shaft, and an inertial sensor provided in the arm and detecting a rotation angular velocity of the arm, the method comprising: rotating the arm in an input rotation angular range smaller than a necessary input rotation angular range of the input shaft necessary for creation of the correction data; when the arm rotates in the input rotation angular range, measuring and recording the angular transmission error of the reducer based on an output value from the encoder and an output value from the inertial sensor; using a time when the angular transmission error of the reducer is measured or an angular range in which the angular transmission error of the reducer is measured as an index, determining whether or not an accumulated value of the indexes is equal to or larger than a predetermined value; when the accumulated value of the indexes is smaller than the predetermined value, measuring the angular transmission error of the reducer and updating a record; and when the accumulated value of the indexes is equal to or larger than the predetermined value, creating the correction data based on the recorded angular transmission error of the reducer. ### Claim 2 (depends on 1) The method of correcting the angular transmission error for the reducer according to claim 1, wherein when the input shaft is operated at a constant rotation angular velocity, the angular transmission error of the reducer is measured. ### Claim 3 (depends on 2) The method of correcting the angular transmission error for the reducer according to claim 2, wherein a time taken for measurement of the angular transmission error of the reducer is calculated based on the input rotation angular range of the input shaft and the rotation angular velocity of the input shaft and reported. ### Claim 4 (depends on 1) The method of correcting the angular transmission error for the reducer according to claim 1, wherein the index is a time when the angular transmission error of the reducer is measured. ### Claim 5 (depends on 1) The method of correcting the angular transmission error for the reducer according to claim 1, wherein the inertial sensor is a gyro sensor. ### Claim 6 A robot system comprising: an arm; a reducer having an input shaft and an output shaft coupled to the arm; a motor coupled to the input shaft and generating power for rotating the arm via the reducer; an encoder detecting a rotation angular position of the input shaft; an inertial sensor provided in the arm and detecting a rotation angular velocity of the arm; and a control apparatus creating correction data for correction of the angular transmission error of the reducer, wherein the control apparatus rotates the arm in an input rotation angular range smaller than a necessary input rotation angular range of the input shaft necessary for creation of the correction data, when the arm rotates in the input rotation angular range, measures and records the angular transmission error of the reducer based on an output value from the encoder and an output value from the inertial sensor, using a time when the angular transmission error of the reducer is measured or an angle at which the angular transmission error of the reducer is measured as an index, determines whether or not an accumulated value of the indexes is equal to or larger than a predetermined value, when the accumulated value of the indexes is smaller than the predetermined value, measures the angular transmission error of the reducer and updates a record, and, when the accumulated value of the indexes is equal to or larger than the predetermined value, creates the correction data based on the recorded angular transmission error of the reducer.