High-precision Positioning System using a Low-stiffness Dual Stage Actuator

In this paper, a dual stage actuator (DSA) system that is able to achieve both large stroke and high precision positioning is proposed. The DSA system is composed of an industrial linear motor and a commercial CD/DVD laser pickup head used as coarse and fine actuators, respectively. Since the pickup head is constructed as a low-stiffness fine actuator, by implementing a high control bandwidth for the fine actuation, the system is able to reject disturbances stemming from the low mechanical coupling of the DSA design. By estimating the relative distance of the two actuators without a position sensor, a phase lag compensator and a feedforward controller are implemented for the coarse actuation. Experimental results demonstrate that the DSA system is able to position over a long range of 500 mm at ϕ 15 nanometer static precision with a settling time of only 1.72 seconds.