Robot arm, method of estimating amount of iron powder contained in lubricant of connecting part of robot arm, and abnormality sign determination system

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.

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.