Research Of Nano-micro Displacement Sensor's Signal Acquisition And Processing For The AFM

The 21st century is the era of nanotechnology, every country over the world has been arranged the nano research as a national development strategy, which will bring enormous social and economic developments. Nanotechnology research needs a variety of observations and operational tools, such as atomic force microscopy widely used in nano-observation (AFM), but the nano-operation has many problems, such as: the piezoelectric which drivers the probe nano displacement output has hysteresis, creep and nonlinear defects, that affecte nano-driven static and dynamic performance. Although many study and improvement of piezoelectric nonlinearity and hysteresis problems have been proposed, such as voltage-based control model, but this method will result in the positioning system as a complex nonlinear system, it seriously reduces the operation of high-precision control, which limits the further application of the piezoelectric ceramic in the nano-environment. This article is based on the driving characteristics of PZT, we designed a real-time nano-displacement measurement sensors, and then extracted weak signals, at last, based on the negative feedback loop control method to improve the nonlinear piezoelectric and hysteresis, the system can provide a simple way to achieve the AFM nanometer-level manipulation in real time.This paper is supported by the National Nature Science Foundation key projects "the robotic operating system theory and implementation in the nano-environment". It is also based on the research foundation of force sensor in robot sensor laboratory over years in Hefei Institute Intelligent Machines of Chinese Academy of Sciences and based on nano/micro meter displacement test platform in nano manipulation lab of CAS. The high resolution sensor, which can measure real-time PZT driving nano meter has been designed.The main studies of the paper are expressed as follows:1. Optimization of the mechanical structure of the sensor, and improves the amplification effect of ratio, design a rapid prototyping method of online authentication combining the real-time measurements under no accumulation situation in the laboratory.2. Construction of nano meter displacement information acquisition system: First analyze the weak signals and research the effect of kinds of algorithm, second design two data collection system, which are based on acquisition card and labview soft and based on DSP2812 embedded system, which utilizes SPI interface to get the 24bits AD conversion information. The first one can analyze the characters of signals fast, the other one is portable to provide displacement information for control.3. Weak signal processing research: Design the weak signal amplification circuit, which integrated analog filter and digital filter combined the advantages of five order butterworth low-pass filter algorithm, wavelet transform and FIR filter, all can reduce the noise.4. Detailed illustrated of the structure of two sets of sensor test system platform based on PI and force platform: The system not only calibrate the sensor, but also can analyze the sensor static and dynamic performance characteristics. At last, we can get the sensor's function and discuss the results.