Control of a long-stroke precision scanning stage

This study presents the control of a long-stroke precision scanning stage. The stage considered is combined by a linear motor-driven long-stroke stage (X, Y) and a piezoelectric-driven two degrees of freedom (2-DOF) nano-stage (Y, θ_Z). Therefore, it can provide long-stroke and high-precision positioning. The feedback signal for this stage is obtained using a 3-DOF laser interferometer measurement system. Integral sliding-mode controllers are used to control the linear motor-driven stage and PID controllers are used to control the piezo-stage for precision positioning. This paper presents the design of the controllers and the control results. Experimental results show that when X-axis scanned at speed 100mm/s, the averaged error and root mean square (RMS) error for y positioning are 10.6 nm and 13.1 nm and the averaged error and RMS error of θ_Z are 0.17 and 0.22 respectively.