Low-stiffness dual stage actuator for long rage positioning with nanometer resolution

This paper presents a dual stage actuator (DSA) capable of long-stroke positioning with nanometer resolution without an additional vibration isolation. The DSA system is composed of a linear motor and a compact Lorentz actuator used as the coarse and fine actuators, respectively. Since the fine actuator is constructed for a low-stiffness, the disturbances from the base are mechanically reduced and rejected by means of a feedback control. In addition, this system only requires one sensor measuring the fine actuator position, because the coarse actuator velocity and position can be estimated from the transmissibility of the fine actuator. Experimental results demonstrate that the DSA moves 100 mm and reaches the ±30 nm error band (peak-to-peak) in 0.41 s. At static positioning, the DSA achieves a precision of ±2.5 nm (peak-to-peak).