Design And Research Of Piezoelectric Ceramic Micro-drive Positioning System Based On FPGA

Nanotechnology is widely used in bio-detection,robotics,precision manufacturing,aerospace and other fields,and its goal is to operate microscopic objects on the nanometer scale.As the most widely used observation and manipulation instrument for nanotechnology,Atomic Force Microscope(AFM)plays an increasingly important role in biomedical fields such as bio-real-time detection and operation.High-speed,high-precision AFM is a complex system,which mainly includes atomic force detection mechanism,micro-cantilever deflection signal detection mechanism,three-dimensional drive positioning platform and signal real-time processing mechanism.Piezoelectric(PZT),as a key factor in the scanning drive positioning of AFM system,its positioning accuracy,response speed and other properties play a decisive role in the further development of AFM in the field of micro-nano.In this paper,the micro-drive positioning system of piezoelectric ceramics is studied in terms of positioning accuracy and response speed,and a set of high-precision and fast-responding piezoelectric ceramic micro-drive positioning system including software and hardware is designed.This paper will deeply analyze the key issues involved,such as the performance of the control circuit,the output performance of the drive power supply,the performance of the displacement signal processing circuit and the effectiveness of the control algorithm,and give a solution.The main research contents include the following aspects:Firstly,the structural composition and working principle of the piezoelectric ceramic micro-drive positioning system are analyzed.The system is divided into three parts:control module,drive power module and displacement signal processing module.In the control module,the programmable logic device FPGA is used as the main controller to realize the communication with the host computer and the processing of the instruction,the processing of the AD and DA data,the execution of the control algorithm,and the data storage.In the drive power module,by analyzing the characteristics of the two-stage operational amplifier and the influencing factors of the operational amplifier stability,the design of the linear DC-amplified driving power supply with the high-precision,low-offset voltage OP177B and the high-voltage integrated operational amplifier PA85A cascade is proposed.Combined with phase compensation and isolation resistors,the output voltage resolution and power supply stability of the drive power supply are fully guaranteed.In the displacement signal processing module,the micro-displacement signal is amplified to the volt-level size by the high-precision operational amplifier INA129U for controller processing,and processed by Butterworth low-pass filter to achieve 2nm output resolution.Secondly,the software system of piezoelectric ceramic micro-drive positioning system is designed,including upper computer interface and lower computer main control program,which realizes software control and signal processing of positioning platform.The upper computer interface mainly includes the setting of the serial port;the setting of the waveform,the amplitude and the frequency,etc.;the setting of the parameters such as the fuzzy PID input voltage and the output displacement.The design of the lower computer mainly includes:DDS waveform signal generator,DA and AD drive function,algorithm control and so on.Thirdly,according to the inconsistent pressure curve and buck curve caused by the nonlinear characteristics such as hysteresis,creep and temperature drift inherent in piezoelectric ceramics,the traditional PID algorithm and fuzzy PID algorithm are used to design K_p,K_i,K_d parameters,through the experimental results analysis,the fuzzy PID algorithm is more effective than the traditional PID algorithm to improve the response speed and control accuracy of piezoelectric ceramics.Four,the design of the piezoelectric ceramic micro-drive positioning system including hardware and software structure of the experimental test,including:amplitude and frequency test of DDS output waveform signal;drive voltage linearity,ripple,stability,static performance and dynamics Performance testing;output noise and output resolution testing of displacement signal processing circuits;open loop hysteresis curve testing,incremental PID and fuzzy PID positioning performance testing.