MOTOR DRIVE DEVICE

A motor drive device of the invention is used to drive a motor while performing feedback control so that actual operation follows a command. This motor drive device includes a feedback controller for performing feedback control by outputting a torque command, and a viscous friction calculator for calculating a viscous friction torque compensation value by multiplying a speed command by a viscous friction coefficient. The motor drive device drives the motor based on a driving signal generated by adding the viscous friction torque compensation value to the torque command. The motor drive device further includes an evaluation index measurement section for measuring an amount of overshooting and positioning settling time by inputting the position command and a motor position or a load position, and a servo adjustment section for repeating positioning operation a plurality of times while changing the viscous friction coefficient, and determining a value of the viscous friction coefficient that brings the amount of overshooting to a specified value or the positioning settling time to a minimum.