Patent ID: 8504307

Claim:
A machine diagnosing method for diagnosing a machine damage in a full closed loop position control machine, wherein the full closed loop position control machine comprises a first position detector for detecting a rotation position of a motor, and a second position detector for directly detecting a position of a drive object driven by the motor, and wherein the full closed loop position control machine controls the position of the drive object based on an inputted position command value, a rotation position of the motor acquired with the first position detector, and a position of the drive object acquired with the second position detector, the machine diagnosing method comprising: a drive object driving force estimating step for estimating a drive force that drives a drive object, based on at least a torque command value to the motor acquired using the position command value, being multiplied by a torque thrust conversion coefficient; an elastic deformation error estimating step for estimating an elastic deformation error of the drive object with the drive object driving force and a spring constant of the drive object; a positional deviation calculating step for calculating a positional deviation between a rotation position of the motor detected by the first position detector and a position of the drive object detected by the second position detector; and a machine damage diagnosing step for diagnosing a machine damage state of the drive object by calculating a machine damage coefficient using a difference between the elastic deformation error of the drive object and the positional deviation, comparing the acquired machine damage coefficient with a previously set threshold value, and diagnosing the machine damage state of the drive object based on a result of the comparison.