# US 11,077,553 B2 · Robot and offset correction device for force sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,077,553 B2 - Document ID: US11077553B2 - Status: Granted - Kind: B2 - Application number: 16/126,024 - Filed: 2018-09-10 - Published: 2019-03-14 - Granted: 2021-08-03 - Earliest claimed: 2017-09-11 - Assignees: Seiko Epson Corporation - Applicants: Seiko Epson Corporation - Inventors: Yasuhiro Shimodaira - Web page: https://patentgrep.com/patent/US11077553B2 ## CPC - B25J 9/1633: {compliant, force, torque control, e.g. combined with position control} - B25J 9/1692: {Calibration of manipulator} - 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}) ## Abstract A robot includes a robot arm, a force sensor that is provided on the robot arm, and a processor that is configured to execute computer-executable instructions so as to control the robot and process a sensor output of the force sensor. The processor is configured to: set an offset calculation period after resetting the force sensor; and perform an offset calculation operation for calculating a value based on the sensor output during the offset calculation period as an offset and a correction operation for subtracting the offset from the sensor output at the time of force detection after the elapse of the offset calculation period. ## Claims ### Claim 1 A robot comprising: a robot arm; a force sensor that is provided on the robot arm; and a processor that is configured to execute computer-executable instructions so as to control the robot and process a sensor output of the force sensor, wherein the processor is configured to: set an offset calculation period after resetting the force sensor; and perform an offset calculation operation for calculating a value based on the sensor output during the offset calculation period as an offset and a correction operation for subtracting the offset from the sensor output at the time of force detection after the elapse of the offset calculation period. ### Claim 2 (depends on 1) The robot according to claim 1, wherein a value based on the sensor output is an average value of the sensor output during the offset calculation period. ### Claim 3 (depends on 2) The robot according to claim 2, wherein the force sensor includes a plurality of a force detection element and a plurality of an amplification circuit amplifying an output signal of the force detection element, and the processor is configured to execute the offset calculation operation and the correction operation using the output signal of the amplification circuit as the sensor output. ### Claim 4 (depends on 3) The robot according to claim 3, wherein the processor is configured to convert an offset-corrected signal obtained by performing the correction operation on an output signal of the amplification circuit into a force signal representing a force relating to each of a plurality of detection axes. ### Claim 5 (depends on 2) The robot according to claim 2, wherein the force sensor outputs a force signal representing a force relating to each of a plurality of detection axes, and the processor is configured to execute the offset calculation operation and the correction operation by using the force signal relating to each of the plurality of detection axes as the sensor output. ### Claim 6 (depends on 2) The robot according to claim 2, wherein the processor is configured to set the offset calculation period to a period corresponding to N cycles (N is an integer of 1 or more) of natural vibration of an arm end included in the robot arm provided with the force sensor. ### Claim 7 (depends on 2) The robot according to claim 2, wherein the processor is configured to set a standby period to wait until the sensor output is stabilized, before the offset calculation period. ### Claim 8 (depends on 1) The robot according to claim 1, wherein the force sensor includes a plurality of a force detection element and a plurality of an amplification circuit amplifying an output signal of the force detection element, and the processor is configured to execute the offset calculation operation and the correction operation using the output signal of the amplification circuit as the sensor output. ### Claim 9 (depends on 8) The robot according to claim 8, wherein the processor is configured to convert an offset-corrected signal obtained by performing the correction operation on an output signal of the amplification circuit into a force signal representing a force relating to each of a plurality of detection axes. ### Claim 10 (depends on 1) The robot according to claim 1, wherein the force sensor outputs a force signal representing a force relating to each of a plurality of detection axes, and the processor is configured to execute the offset calculation operation and the correction operation by using the force signal relating to each of the plurality of detection axes as the sensor output. ### Claim 11 (depends on 1) The robot according to claim 1, wherein the processor is configured to set the offset calculation period to a period corresponding to N cycles (N is an integer of 1 or more) of natural vibration of an arm end included in the robot arm provided with the force sensor. ### Claim 12 (depends on 1) The robot according to claim 1, wherein the processor is configured to set a standby period to wait until the sensor output is stabilized, before the offset calculation period. ### Claim 13 An offset correction device for correcting an offset of a force sensor, comprising: a processor that is configured to process a sensor output of the force sensor, wherein the processor is configured to: set an offset calculation period after resetting the force sensor; calculate a value based on an output of the force sensor during the offset calculation period as an offset; and subtract the offset from the output of the force sensor at the time of force detection after the elapse of the offset calculation period. ### Claim 14 (depends on 13) The offset correction device according to claim 13, wherein a value based on the sensor output is an average value of the sensor output during the offset calculation period. ### Claim 15 (depends on 14) The offset correction device according to claim 14, wherein the processor is configured to set a standby period to wait until the sensor output is stabilized, before the offset calculation period. ### Claim 16 (depends on 13) The offset correction device according to claim 13, wherein the processor is configured to set a standby period to wait until the sensor output is stabilized, before the offset calculation period.