Servo control device with coarse and fine movement

A servo control device including a coarse-movement shaft motor that drives a coarse movement shaft that performs a linear movement in a determined axial direction, and a fine-movement shaft motor that drives a fine movement shaft that is attached to a movable part of the coarse movement shaft and performs a linear movement on the movable part of the coarse movement shaft, and controlling a position of an integrated shaft determined on a basis of a position of the coarse movement shaft and a position of the fine movement shaft, the device comprising:

• processing circuitry configured to implement
• a coarse-movement reference model unit that calculates a coarse-movement model position by performing a predetermined filter computation on a basis of a position command;
• a coarse-movement follow-up control unit that controls the coarse-movement shaft motor such that a coarse-movement-shaft motor position follows the coarse-movement model position on a basis of the coarse-movement-shaft motor position provided from the coarse-movement shaft motor and the coarse-movement model position;
• an integrated reference model unit that calculates an integrated model position by performing a predetermined filter computation on a basis of the position command;
• and
• a fine-movement follow-up control unit that controls the fine-movement shaft motor such that a fine-movement-shaft motor position follows a fine-movement model position on a basis of the fine-movement-shaft motor position provided from the fine-movement shaft motor and the fine-movement model position obtained from the integrated model position and the coarse-movement model position, wherein
• the integrated reference model unit sets a response time constant of the integrated model position with respect to the position command, in a range in which the fine-movement model position does not exceed a movable range of the fine movement shaft, on a basis of a change ratio of the position command and a response time constant of the coarse-movement model position with respect to the position command.