Design and Stiffness Modeling of a Compact 3-DOF Compliant Parallel Nanopositioner for the Tool Servo of the Ultra Precision Machining

Nanopositioners are widely applied in micro/nano manipulation, atomic force microscope (AFM), nanoimprint lithography, and precision machining. With a rapid increasing demand of the manufacture of the complex non-rotationally symmetric (NRS) optical freeform surface, different tool servo mechanisms for the ultra-precision machining have been developed in recent years. Multi-DOF nanopositioners based on the compliant parallel mechanisms (CPMs) provide an efficient solution. A compact spatial 3-Degree of Freedom (DOF) compliant parallel nanopositioner is proposed in this paper. The nanopositioner possesses three translational DOFs of the orthogonal coordinates. Three two-level tiny displacement amplifiers are arranged to obtain large magnification. Sufficient output stiffness is a prior design consideration. Combined with three single-DOF nanopositioning stages (NPSs) and one shared end-effector, a 3-DOF stiffness modeling approach is presented to obtain the whole input/output stiffness and coupling ratio. Simulation results validate the precision, accuracy, and high-efficiency of the presented stiffness modeling method using a simple design example. The design and stiffness modeling approaches provide the foundation of the performance indexes optimization, and are helpful to fulfill the rapid increasing demand of the multi-axis tool servo for the ultra-precision machining.