# US 2015/0177084 A1 · External force judgment method and external force judgment device of human-collaborative industrial robot > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2015/0177084 A1 - Document ID: US20150177084A1 - Status: Published application - Kind: A1 - Application number: 14/582,615 - Filed: 2014-12-24 - Published: 2015-06-25 - Earliest claimed: 2013-12-25 - Assignees: Fanuc Corporation - Applicants: Fanuc Corporation - Inventors: Youichi INOUE - Web page: https://patentgrep.com/patent/US20150177084A1 ## CPC - G01L 5/0028: {Force sensors associated with force applying means (G01L5/0052, G01L5/0057, G01L5/0061 take precedence)} - B25J 9/1676: {Avoiding collision or forbidden zones} - G01L 5/0076: {Force sensors associated with manufacturing machines (G01L5/0066, G01L5/0071 and B23Q17/09 take precedence; for the specific machine or operation involved see relevant class, e.g. B21 - B42)} - G01L 5/18: for measuring ratios of force - G05B 2219/40201: Detect contact, collision with human - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) - 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 An external force judgment method including a reference value acquisition step of acquiring a reference value of a relative position or angle of a second member with respect to a first member when a robot on which no external force is acting or on which a known external force is acting is assumed to be operated by a predetermined command in advance; a measured value acquisition step of acquiring a measured value of a relative position or angle of the second member with respect to the first member when the robot is operated by the predetermined command; and a judgment step of judging the presence or absence of an external force acting on the robot based on a difference between the reference value and the measured value and a predetermined threshold value. ## Claims ### Claim 1 An external force judgment method for judging a presence or absence of an external force acting on a robot including a first member and a second member movably connected to the first member through a deceleration mechanism, the method comprising: a reference value acquisition step of acquiring a reference value of a relative position or angle of the second member with respect to the first member when the robot on which no external force is acting or on which a known external force is acting is assumed to be operated or is operated by a predetermined command in advance; a measured value acquisition step of acquiring a measured value of a relative position or angle of the second member with respect to the first member when the robot is operated by the predetermined command, wherein, one of a detection unit and a detected unit paired with the detection unit is arranged on the first member or a part not relatively moving with respect to the first member, whereas another of the detection unit and the detected unit is arranged on the second member or a part not relatively moving with respect to the second member, and a value detected by the detection unit is the measured value; and a judgment step of judging the presence or absence of an external force acting on the robot based on a difference between the reference value acquired by the reference value acquisition step and the measured value acquired by the measured value acquisition step and a predetermined threshold value. ### Claim 2 (depends on 1) The external force judgment method according to claim 1, wherein the reference value acquisition step includes acquiring the reference value based on the value detected by the detection unit when one of the detection unit and the detected unit paired with the detection unit is arranged on the first member or the part not relatively moving with respect to the first member, whereas the other of the detection unit and the detected unit is arranged on the second member or the part not relatively moving with respect to the second member. ### Claim 3 (depends on 1) The external force judgment method according to claim 1, wherein the reference value acquisition step includes calculating the reference value using a robot model corresponding to the robot on which no external force is acting or on which a known external force is acting. ### Claim 4 (depends on 1) The external force judgment method according to claim 1, wherein the reference value acquisition step includes detecting the reference value detected by operating the robot on which no external force is acting or on which a known external force is acting by the predetermined command. ### Claim 5 (depends on 1) The external force judgment method according to claim 1, wherein the second member is rotatably connected to the first member, and the reference value acquisition step and the measured value acquisition step include acquiring the relative angle of the second member with respect to the first member. ### Claim 6 (depends on 1) The external force judgment method according to claim 1, wherein the second member is linear-movably connected to the first member, and the reference value acquisition step and the measured value acquisition step includes acquiring the relative position of the second member with respect to the first member. ### Claim 7 (depends on 1) The external force judgment method according to claim 1, wherein the predetermined command is a stop command for the robot. ### Claim 8 An external force judgment device for judging a presence or absence of an external force acting on a robot including a first member and a second member movably connected to the first member through a deceleration mechanism, the device comprising: a reference value acquisition unit for acquiring a reference value of a relative position or angle of the second member with respect to the first member when the robot on which no external force is acting or on which a known external force is acting is assumed to be operated or is operated by a predetermined command in advance; a measured value acquisition unit for acquiring a measured value of the relative position or angle of the second member with respect to the first member when the robot is operated by the predetermined command, the measured value acquisition unit including a detection unit and a detected unit paired with the detection unit, wherein, one of the detection unit and the detected unit is arranged on the first member or a part not relatively moving with respect to the first member, whereas another of the detection unit and the detected unit is arranged on the second member or a part not relatively moving with respect to the second member, and a value detected by the detection unit is the measured value; and a judgment unit for judging the presence or absence of an external force acting on the robot based on a difference between the reference value acquired by the reference value acquisition unit and the measured value acquired by the measured value acquisition unit and a predetermined threshold value.