Method for calibrating a force constant of a motorized stage used for supporting and moving a workpiece

摘要

Methods are disclosed for calibrating a force constant of a movable stage. In an exemplary method, in first and second preliminary pre-stepping motions of the stage, a baseline force and a calibration force, respectively, as exerted by the stage are measured. From a force-variation ratio of the baseline force and calibration force an inverse closed loop factor is estimated. In at least one subsequent pre-stepping motion of the stage before a respective use of the stage for holding an object, a residual force-variation ratio is estimated, a force-compensation factor is updated from the residual force-variation ratio, and a respective force-variation coefficient is determined from the force-compensation factor.

主权项

1. A method for calibrating a movable stage coupled to an actuator that receives force commands from a controller, the method comprising:
obtaining baseline information by generating a first motion of the moveable stage with the actuator; obtaining calibration information by generating a second motion of the moveable stage with the actuator at different time from a time of the first motion of the movable stage; estimating a first force-variation ratio from the baseline information and the calibration information in at least one of the first motion and the second motion; updating a force-compensation factor of the controller using the estimated first force-variation ratio; and determining a force-variation coefficient of the movable stage from the force compensation factor.