Application of perfect 2 DOF PDD2 control with flow disturbance observer for pneumatic stage

In the field of positioning control, magnetic actuators such as linear motors have been widely used. However it cannot be used for electron beam exposure apparatus due to the magnetic leak and heat generation. Therefore, positioning control with air pressure actuators is proposed instead of magnetic actuators. The problem of using air pressure actuators is an inactive response with air's compressibility. Therefore, this paper presents the positioning control methods of PDD2 control, on the condition that servo valve including air system is imperfect integrator, and the speeding of positioning control with perfect 2 d.o.f. control. However, repeatability cannot be conformed due to flow and mechanical disturbances. Therefore, this paper also presents a compensation method of flow disturbance named flow disturbance observer and perfect 2 d.o.f. PDD2 control with flow disturbance to improve the response of target value. Finally, the repeatability of perfect 2 d.o.f. PDD2 control with flow disturbance is presented.