Design of a Large Range XY Nanopositioning System

Abstract

Achieving large motion range (>1 mm) along with nanometric motion quality (<10 nm) simultaneously has been a key challenge in nanopositioning systems. Practical limitations associated with the individual physical components (bearing, actuators, and sensors) and their integration, particularly in the case of multiaxis systems, have restricted the range of currently available nanopositioning systems to approximately 100 خ¼m per axis. This paper presents a novel physical system layout, comprising a bearing, actuators, and sensors, that enables large range XY nanopositioning. The bearing is based on a parallelkinematic XY flexure mechanism that provides a high degree of geometric decoupling between the two motion axes by avoiding geometric overconstraint, provides actuator isolation that allows the use of largestroke singleaxis actuators, and enables a complementary endpoint sensing scheme using commonly available sensors. These attributes help achieve 10 mm أ— 10 mm motion range in the proposed nanopositioning system. Having overcome the physical system design challenges, a dynamic model of the proposed nanopositioning system is created and verified via system identification. In particular, dynamic nonlinearities associated with the large displacements of the flexure mechanism and resulting controls challenges are identified. The physical system is fabricated, assembled, and tested to validate its simultaneous large range and nanometric motion capabilities. Preliminary closedloop test results, which highlight the potential as well as pending challenges associated with this new design configuration, are presented.