Patent ID: 6668202
Filing Date: 2003-12-23
Classification: G05B

Abstract:
A position control system of a stage driving mechanism which drives a stage at least in one-axial direction, the position control system comprising:a position detector for detecting a position of the stage; a feedback control system for controlling a motor, which is a driving source of the stage, on the basis of a detected positional value obtained from the position detector and a positional command value; a Proportional Integral Derivative (PID) controller for generating a current target value for the motor from the difference between the detected positional value and the positional command value; and a disturbance observer comprising a signal processing unit for carrying out high-speed calculation according to a predetermined program, wherein the signal processing unit has a filtering function to filter a torque command value for the motor, an input torque estimating and filtering function carrying out estimation for obtaining an estimated input load torque from the detected positional value, and a function to calculate an estimated disturbance load torque from the difference between the filtered torque command value and the estimated input load torque and to calculate a correction value for the current target value so as to cancel a disturbance torque by multiplying the estimated disturbance load torque by an inverse number of a motor torque constant.