# US 12,157,227 B2 · Robot control method 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 12,157,227 B2 - Document ID: US12157227B2 - Status: Granted - Kind: B2 - Application number: 17/585,602 - Filed: 2022-01-27 - Published: 2022-08-04 - Granted: 2024-12-03 - Earliest claimed: 2021-01-29 - Assignees: Seiko Epson Corporation - Applicants: Seiko Epson Corporation - Inventors: Koji Yoshii - Web page: https://patentgrep.com/patent/US12157227B2 ## CPC - B25J 9/1633: {compliant, force, torque control, e.g. combined with position control} - B25J 9/0093: {co-operating with conveyor means} - B25J 9/1612: {characterised by the hand, wrist, grip control} - B25J 13/085: {Force or torque sensors (B25J13/082, B25J13/084 take precedence)} - B25J 15/0616: {with vacuum} - B25J 19/02: Sensing devices - G05B 2219/39514: Stability of grasped objects - G05B 2219/40599: Force, torque sensor integrated in joint - 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}) - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) ## Abstract A robot control method for controlling a robot is provided. The robot has a robot arm and a force detection unit detecting a force applied to the robot arm and grips a target object conveyed on a belt with an end effector provided at the robot arm. The method includes: a gripping step of executing an operation of gripping the target object with the end effector; and a determination step of determining whether the gripping of the target object is normally performed or not, based on a result of detection by the force detection unit in the gripping step. ## Claims ### Claim 1 A robot control method for controlling a robot that has a robot arm and a force detection unit detecting a force applied to the robot arm and that grips a target object conveyed on a belt with an end effector provided at the robot arm, the method comprising: a gripping step of executing an operation of gripping the target object with the end effector; and a determination step of determining whether the gripping of the target object is normally performed or not, based on a result of detection by the force detection unit in the gripping step, wherein when the gripping of the target object is normally performed, the end effector grips a surface of the target object rather than edge of the surface of the target object or the belt, wherein the end effector is configured to grip the target object by suction, and in the gripping step, a pressing operation of lowering the end effector and pressing the end effector against the target object while performing the suction, and a lifting operation of lifting the end effector while performing the suction after the pressing operation, are sequentially executed, in the determination step, when a maximum value of a force detected by the force detection unit in the pressing operation is less than a first threshold, it is determined that the gripping of the target object is not normally performed, in the determination step, when a magnitude of a force detected by the force detection unit in the lifting operation is less than a second threshold, it is determined that the gripping of the target object is not normally performed. ### Claim 2 (depends on 1) The robot control method according to claim 1, further comprising: a release step of executing an operation of releasing the gripped target object when it is determined in the determination step that the gripping of the target object is not normally performed, wherein in the release step, a timing of releasing the gripped target object is made different between when it is determined that the gripping of the target object is not normally performed in the pressing operation and when it is determined that the gripping of the target object is not normally performed in the lifting operation. ### Claim 3 (depends on 1) The robot control method according to claim 1, further comprising: a reporting step of reporting that the gripping of the target object is not normally performed when it is determined in the determination step that the gripping of the target object is not normally performed. ### Claim 4 (depends on 1) The robot control method according to claim 1, wherein in the determination step, the determination is performed based on information about a force detected over time by the force detection unit. ### Claim 5 (depends on 1) The robot control method according to claim 1, wherein the force detection unit has a quartz crystal force sensor. ### Claim 6 A robot system comprising: a robot having a robot arm and a force detection unit that detects a force applied to the robot arm; and a control unit controlling driving of the robot arm so as to grip a target object conveyed on a belt with an end effector provided at the robot arm, wherein the control unit executes an operation of gripping the target object with the end effector, and determines whether the gripping of the target object is normally performed or not, based on a result of detection by the force detection unit, wherein when the gripping of the target object is normally performed, the end effector grips a surface of the target object rather than edge of the surface of the target object or the belt, wherein the end effector is configured to grip the target object by suction, and in the gripping, a pressing operation of lowering the end effector and pressing the end effector against the target object while performing the suction, and a lifting operation of lifting the end effector while performing the suction after the pressing operation, are sequentially executed, in the determining, when a maximum value of a force detected by the force detection unit in the pressing operation is less than a first threshold, it is determined that the gripping of the target object is not normally performed, in the determining, when a magnitude of a force detected by the force detection unit in the lifting operation is less than a second threshold, it is determined that the gripping of the target object is not normally performed.