Study Of Slip-Stick Precision Positioner For Nanomanipulation In SEM

The nanomanipulation robot in SEM is a precision system for manipulating nanoscale objects in SEM. Because of characteristics such as the large chamber and real-time visual feedback, the nanomanipulation robot in SEM is studied extensively in recent years, and becoming an important tool for people to explore the micro world. The performance of the precision positioner, which serves as the arm of the nanomanipulation robot, will determine the manipulation quality of the robot. Consequently, to improve the manipulation efficiency and quality of nanomanipulation robot, this paper devises a 3-DOF precision positioning system for nanomanipulation in SEM.According to the special environment in SEM and performance needed to perform the nanomanipulation, this paper devises a set of slip-stick 3-DOF precision positioner. This positioner is composed of two horizontal positioners and a vertical positioner according to the modular thought, which are all actuated by the piezoelectric stack. To improve the reliability of the positioners and minimize them, the structure of flexible fringe is adopted. This 3-DOF precision positioner has the characteristics of small dimensions, light weight and high reliability, and can moves over a displacement of several millimeters with the resolution of nanometer.To better analyze the impact of different parameters on performance and optimize the structure of the slip-stick positioners, this paper chooses reasonable models of piezoelectric actuator and friction to build the dynamic models of the precision positioners. The model of piezoelectric stack is composed of an ideal piezoelectric ceramic, a spring and a damper. And the LuGre dynamic friction model is used to describe the friction. Simulation by MATLAB/Simulink demonstrates the accuracy and efficiency of the dynamic models.According to the demand to drive the piezoelectric stack, the driver system is studied. This paper designs a piezoelectric driver, and compute the power loss and heat dissipation of the driver to make sure its stability and reliability.Finally, to acquire the performance of the precision positioning system, this paper builds the experiment system to test piezoelectric ceramic driver and the 3-DOF precision positioner. The results show the system has a nice performance and satisfies the technical demand of manipulating nanoscale objects in SEM.