# US 2019/0039244 A1 · Robot arm, method of estimating amount of iron powder contained in lubricant of connecting part of robot arm, and abnormality sign determination system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0039244 A1 - Document ID: US20190039244A1 - Status: Published application - Kind: A1 - Application number: 16/019,699 - Filed: 2018-06-27 - Published: 2019-02-07 - Earliest claimed: 2017-08-01 - Assignees: Toyota Jidosha Kabushiki Kaisha - Applicants: Toyota Jidosha Kabushiki Kaisha - Inventors: Shun SATO - Web page: https://patentgrep.com/patent/US20190039244A1 ## CPC - B25J 9/1674: {characterised by safety, monitoring, diagnostic} - B25J 9/126: {Rotary actuators} - B25J 13/087: {for sensing other physical parameters, e.g. electrical or chemical properties} - B25J 19/0062: {Lubrication means} - G01N 33/2888: {Lubricating oil characteristics, e.g. deterioration (lubricating properties G01N33/30)} - G05B 19/4062: Monitoring servoloop, e.g. overload of servomotor, loss of feedback or reference - G05B 2219/42271: Monitor parameters, conditions servo for maintenance, lubrication, repair purposes - G05B 2219/42306: Excess in error, compare reference with feedback - 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}) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - 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 average value of differences between command current values acquired at a plurality of timings when the motor is controlled at a rotation speed within a preset fixed range in a preset period and an average value of the command current values in the period is acquired, and the average value of the differences is accumulated in an order of the acquisition. When a difference between an accumulated value of the average values of the differences up to an N−1th time and an accumulated value of the average values of the differences up to an Nth time becomes greater than or equal to a preset value, and then become less than the preset value, and then again becomes greater than or equal to the preset value, a notification of an abnormality sign in the robot arm is transmitted. ## Claims ### Claim 1 A robot arm comprising: a motor; a control unit configured to control the motor based on data indicating a command current value; an arm configured to operate based on a driving force of the motor; and a connecting part connecting the motor to the arm and including a lubricant, wherein an average value of differences between the command current values acquired at a plurality of timings when the motor is controlled at a rotation speed within a preset fixed range in a preset period and an average value of the command current values in the period is acquired, and the average value of the differences is accumulated in an order of the acquisition, and when a difference between an accumulated value of the average values of the differences up to an N−1th time (N is a natural number of two or greater) and an accumulated value of the average values of the differences up to an Nth time becomes greater than or equal to a preset value, and then become less than the preset value, and then again becomes greater than or equal to the preset value, a notification of an abnormality sign in the robot arm is transmitted. ### Claim 2 A method of estimating an amount of iron powder contained in a lubricant of a connecting part of a robot arm comprising a motor configured to operate based on data indicating a command current value and an arm configured to operate based on a driving force of the motor, which are connected with the connecting part interposed therebetween, the method comprising: acquiring an average value of differences between the command current values acquired at a plurality of timings when the motor is controlled at a rotation speed within a preset fixed range in a preset first period and an average value of the command current values in the first period, and accumulating the average values of the differences in an order of the acquisition; and estimating the amount of the iron powder based on a product of an accumulated value of the average values of the differences and a preset coefficient. ### Claim 3 (depends on 2) The method according to claim 2, wherein the preset coefficient is a value obtained by dividing a measured amount of the iron powder contained in the lubricant when the robot arm is operated for the second period by the accumulated value of the average values of the differences in a preset second period. ### Claim 4 (depends on 3) The method according to claim 3, wherein the second period is a period, when a difference between the accumulated value of the average values of the differences up to an N−1th time (N is a natural number of two or greater) and the accumulated value of the average values of the differences at an Nth time becomes less than a preset value, from when the average value of the differences is acquired for the first time until when the average value of the differences at the Nth time is acquired. ### Claim 5 An abnormality sign determination system of a robot arm comprising: a motor; a control unit configured to control the motor based on data indicating a command current value; an arm configured to operate based on a driving force of the motor, a connecting part connecting the motor to the arm and including a lubricant; and a server communicably connected to the robot arm, wherein the control unit acquires an average value of differences between the command current values acquired at a plurality of timings when the motor is controlled at a rotation speed within a preset fixed range in a preset period and an average value of the command current values in the period, and transmits data indicating the average value of the differences to the server, and the server accumulates the average values of the differences in an order in which the control unit acquires the average value of the differences, and when a difference between an accumulated value of the average values of the differences up to an N−1th time (N is a natural number of two or greater) and an accumulated value of the average values of the differences up to an Nth time becomes greater than or equal to a preset value, and then become less than the preset value, and then again becomes greater than or equal to the preset value, the server determines that there is an abnormality sign in the robot arm. ### Claim 6 An abnormality sign determination system of a robot arm comprising: a motor; a control unit configured to control the motor based on data indicating a command current value; an arm configured to operate based on a driving force of the motor, a connecting part connecting the motor to the arm and including a lubricant; and a first server communicably connected to the robot arm, wherein the control unit acquires, every time the lubricant is replaced, an average value of differences between the command current values acquired at a plurality of timings when the motor is controlled at a rotation speed within a preset fixed range in a preset period and an average value of the command current values in the period, and transmits data indicating the average value of the differences to the first server, and the first server accumulates the average values of the differences in an order in which the robot arm acquires the average value of the differences, and when a difference between an accumulated value of the average values of the differences for a first lubricant and an accumulated value of the average values of the differences for a replaced lubricant becomes greater than or equal to a preset value at a point when periods since the first lubricant and the replaced lubricant are started to be used become equal, the first server determines that there is an abnormality sign in the robot arm. ### Claim 7 (depends on 6) The abnormality sign determination system of a robot arm according to claim 6, wherein the first server transmits data indicating the accumulated value of the average values of the differences for the replaced lubricant excluding the accumulated values of the average values of the differences for the first lubricant and for a lubricant in use to a second server and deletes the data from the first server.