Method and apparatus for driving a servo system while suppressing residual vibration generated during position control

A method for driving a servo system comprising the steps of:

• calculating and storing, in response to a move command, a target trajectory for suppressing vibration of a controlled object having a movable unit at a time point immediately after a stop of displacement of the movable unit by using a model of the controlled object, a constraint of an actuator for driving the movable unit and a boundary condition for the displacement;
• generating target positions during the displacement of the movable unit based on the target trajectory;
• calculating a drive signal to eliminate a difference between a target position and a position of the movable unit detected by a displacement detection device;
• driving the actuator by the drive signal to displace the movable unit to a predetermined final position determined by the move command;
• detecting vibration of the controlled object at a time point immediately after the stop of the displacement, modifying the target trajectory based on the detected vibration such that a vibration immediately after the stop of displacement is minimized, and storing the modified target trajectory;
• and
• controlling the position of the movable unit in response to a subsequent move command based on the modified and stored target trajectory.

An apparatus for driving a servo system comprising:

• a movable unit moving on or with a structure;
• an actuator for imparting a drive force to said movable unit;
• a control unit for producing a drive signal for said actuator to eliminate a difference between a target position and an actual position of said movable unit;
• a movement detection device for detecting the actual position of said movable unit;
• and
• an operation unit including first means for calculating and storing, in response to a move command, a target trajectory for suppressing a vibration of said movable unit at or after stop of movement of aid movable unit based on a stored model of said movable unit and the structure, a constraint for said actuator and a boundary condition determined by the move command, and second means for generating target positions of said movable unit during movement of said movable unit based on the stored target trajectory and supplying the target positioned at various times to said control unit.