Robot diagnosing method

A robot diagnosing method of detecting a deviation amount caused by a lost motion,

• the robot diagnosing method comprising:
• a first step of preparing a robot and a line sensor,
• the robot including
• a robot arm including one or a plurality of joint portions including a first joint portion,
• an end effector attached to the robot arm, and
• a robot control portion configured to control the robot arm and the end effector, the line sensor including
• a light emitter configured to emit a light ray,
• a light receiver configured to receive the light ray emitted from the light emitter, and
• a detecting portion configured to detect a position of a detected portion based on a light receiving state of the light receiver, the detected portion being inserted between the light emitter and the light receiver;
• a second step of inserting the detected portion of the end effector between the light emitter and the light receiver;
• a third step of, after the second step is performed, detecting the position of the detected portion by the line sensor;
• a fourth step of, after the third step is performed, rotating the first joint portion in a first direction by a predetermined angle based on a command value from the robot control portion while maintaining a state where the detected portion is being inserted between the light emitter and the light receiver;
• a fifth step of, after the fourth step is performed, detecting the position of the detected portion again by the line sensor;
• and
• a sixth step of detecting the deviation amount caused by the lost motion at the first joint portion based on (i) the position of the detected portion based on the position of the detected portion detected in the third step and the command value from the robot control portion in the fourth step and (ii) the position of the detected portion detected in the fifth step.