An Ultra Precision Straight Motion System (2nd Report)

Five Degrees of Freedom Control of Motion

Abstract

In order to realize straight motion at the highest level of accuracy, the system is introduced in which five degrees of freedom of a moving table vertical and horizontal positions, and pitch, roll and yaw angles are controlled precisely. The table is supported by active air bearings composed of piezo-actuators and air pads. Motion accuracies of the table to the straight edge masters are measured by several capacitance micrometers. Control system with PID-PD controller is designed and motion-positioning resolutions of 0.02 μm and 0.02 arc sec are achieved. Straight motion accuracies were 0.05 μm in vertical and horizontal positions, 0.06 arc sec in pitch, 0.07 arc sec in roll and 0.03 arc sec in yaw angles over 1 000 mm travel at table speed of 10 mm/s.