Positioning control method

A positioning control method wherein driving means for driving a table holding a workpiece and movable in a predetermined direction and measuring means for measuring the displacement of said driving means and the position of the table are provided on a base and wherein the workpiece held on the table is positioned to a target position using a displacement signal measured by said measuring means, the method being characterized in that a compensator is provided based on a definition of a base vibration model having:

• a motor transfer function for generating motor displacement from an input that is the sum of input torque and a table propelling force multiplied with a reducer and Cartesian-to-polar coordinate transformation constant;
• a table transfer function for multiplying a deviation between an output that is said motor displacement multiplied with a reducer and polar-to-Cartesian coordinate transformation constant and table displacement with a table-displacement-to-force conversion spring constant to generate said table propelling force and to output table displacement from said table propelling force;
• and
• a base driving transfer function for generating base displacement by multiplying the base displacement with a base-displacement-to-force conversion spring coefficient and inputting the same with said table propelling force, table displacement being generated from a difference between said table displacement and said base displacement.