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This paper presents the design analysis fabrication and testing of a high-bandwidth piezo-driven parallel kinematic nanopositioning XY stage. The monolithic stage design has two axes and each axis is composed of a doubly clamped beam and a parallelogram hybrid flexure with compliant beams and circular flexure hinges. The doubly clamped beam that is actuated by a piezoelectric actuator acts as a linear prismatic axis. The parallelogram hybrid flexures are used to decouple the actuation effect from the other axis. The mechanism design decouples the motion in the X- and Y-directions and restricts parasitic rotations in the XY plane while allowing for an increased bandwidth with linear kinematics in the operating region. Kinematic and dynamic analysis shows that the mechanical structure of the stage has decoupled motion in XY-direction while achieving high bandwidth and good linearity. The stage is actuated by piezoelectric stack actuators, and two capacitive gauges were added to the system to build a closed-loop positioning system. The results from frequency tests show that the resonant frequencies of the two vibrational modes are over 8 kHz. The stage is capable of about 15 μm of motion along each axis with a resolution of about 1 nm. Due to parallel kinematic mechanism design, a uniform performance is achieved across the workspace. A PI controller is implemented for the stage and a closed-loop bandwidth of 2 kHz is obtained.
Date of Publication: Aug. 2011