Measurement and control of rolling of a precision moving table

This paper presents a new system to measure and control the rolling of a precision moving table. In this system, the roll error of the table is monitored by a new measuring method, and is controlled to be zero by a feedback control system. The new method utilizes two angle probes to scan the roll angular profile of the surface of a mirror mounted on the table. The output data of the two probes consist of the same roll error and the roll angular profile data with an interval of the probe distance. The roll error and the roll angular profile can then be separated from each other by using the probe output data. Experimental results show that the roll error can be measured and controlled to a level that is determined by the stability of the angle probes