Impact-Free, Time-Saving, Non-Overshooting Position Control
Original Publication Date: 1984-Jan-01
Included in the Prior Art Database: 2005-Feb-02
Fast and accurate positioning of wafers is particularly important in wafer-exposure machines. For an impact-free position control of the tables, operated by DC motors, the speed profile must be continuous. The predetermined speed profile for position control is corrected by a travel-deviation detector. For this purpose, the table system to be controlled must be capable of continuously following the motor-dependent forces, so that the voltage profile to be predetermined for motor energization must be based on the time behavior of the table system. For a cosine-shaped speed curve for obtaining a maximum speed, there is a constant sinusoidal acceleration function.