Design Of Cross-scale Stickslip Nanopositioner And Its Control System

With the development of nanotechnology,nanomanipulation,which is the key technology,faces higher and higher requirements.Nanomanipulation refers to the manipulation of objects in nanoscale,which is the basis of nanoscience research.The core technology of nanomanipulation is positioning and drive technology in nanoscale,which has obtained more attention from scientific researchers and has made great progress.Increasing requirements of nanomanipulation technology promote the research and development of cross-scale positioning technology.Cross-scale devices has small size so that they can realize millimeter-level movement,nanoscale resolution,nanoscale repeat positioning accuracy in a limited space.The devices play an important role in precision machining,biological engineering,semiconductor manufacturing,medical robots,optical manufacturing,aerospace and other scientific fields.For some devices which require demanding high-speed,high-precision,the current representative of cross-scale precision drive technology are:macro micro hybrid drive,ultrasonic drive,direct drive,inchworm-type drive,inertial drive.The inertial stickslip drive technology is widely used in various fields because of its advantages such as large stroke,high resolution,simple structure,small size,high integration and high speed.Under the background of research and application,this paper proposes a cross-scale precision drive technology with piezoelectric ceramics as the driving source,which is called inertial stickslip drive technology.Sponsored by the Jiangsu province outstanding youth fund(project number BK2012005),based on research and analysis of domestic and international cross-scale drive technology,this paper conducts the research in four aspects:design of nanopositioner based on stickslip principle,integration dynamics modeling,simulation and analysis of nanopositioner,design of drive and closed loop control system,experimental study of nanopositioner and control system.First of all,the nanopositioner based on stickslip principle is designed.In order to meet the requirements of nanomanipulation in a limited environment,the nanopositioner should have small size,large stroke,high precision and high speed.Piezoelectric ceramic actuator is selected as the driving source.The transmission mechanism is flexible hinge.In order to ensure accuracy of positioning in condition of high speed and large stroke,the nanopositioner is integrated with a grating as a feedback component.The drive unit of the nanopositioner is designed as a separate module,which can adjust the friction to greatly improve the load.Secondly,the integration dynamics model of the nanopositioner is established to simulate,analyze and optimize the nanopositioner.The electrical model and mechanical model of piezoelectric ceramic actuator are established respectively.A dynamic model is established for the drive unit which is composed of piezoelectric ceramics,flexible hinges,and mass blocks.According to the stickslip principle,the integrated dynamic model of the nanopositioner is established combined with the LuGre friction model.The dynamic simulation is carried out to analyze the influence of design parameters,load and friction on the motion performance of the nanopositioner.According to the simulation results,the structural design of the nanopositioner is optimized.Then,drive and closed-loop control system is designed.Power device of piezoelectric ceramic actuator is designed and manufactured.In order to ensure that the power device meets the needs of experiment,necessary tests are carried out.On the basis of power supply parameters and integrated model,simulation is conducted to analyze the influence of amplitude,frequency and step time of the voltage signal on the motion performance of the nanopositioner.The closed-loop control method which can identify and filter error signals is designed to collect the pulse signal of the grating.According to effective pulse,the control method can get the direction and counts to achieve the feedback control of displacement.PC program is written to achieve closed-loop control so that the nanoscale precision of the nanopositioner can be guaranteed in condition of high speed and large stroke.Finally,experiments are conducted after prototype manufactured.A test system is built to measure the open-loop performance and closed-loop performance of nanopositioner.Open-loop performance mainly includes resolution,minimum stepsize,maximum speed,stepsize repeatability,load capacity and effect of friction reduction.In the closed-loop performance test,positioning precision is measured with highest resolution of measuring equipment.In condition of high speed and large stroke,both positioning precision and motion curve are measured with large range to verify accuracy and correctness of the closed-loop control algorithm.