Data Processing And Analysis Based On The High Accuracy Micro-displacement Platform

High-precision micro-displacement control technology is the comprehensive technology to achieve high-precision motion control. In terms of the control system of micro-displacement platform, the control accuracy of the control system is affected directly because of the noises led by signal acquisition and quantification, the mechanical noise of the system and the nonlinearity of micro-displacement sensor. In order to improve the control accuracy of the platform, the design and implementation of the digital filtering algorithm and the nonlinear correction algorithm was studied in this article.According to the advantages and disadvantages of IIR and FIR filter, FIR digital filters were as the research subjects. The phase of FIR digital filter is linear and this filter is applicable for the system of micro-displacement platform. The real time data exchange technology between LabVIEW program and DSP chip program was used for testing, analyzing and designing FIR filter. The tap number of low pass filter with hamming window should be 100 and its cutoff frequency was 700Hz. Tap number of notch filter with hamming window should be 121, the center frequency was 300Hz and its bandwidth was 100Hz. The results of experiment showed that the noises of the system were weakened effectively and that the SNR(signal-to-noise radio) of output signal in the system could be increased from 21dB to 47dB.In order to achieve nonlinear correction of capacitive sensor, the inverse function theory was adopted in this article. In the experiment, the position signal was input by PC. The actual displacement of micro-displacement platform corresponding to input signal was measured by Laser Interferometer. Meanwhile, the voltage values collected by capacitive sensor was stored in the DSP chip. According to the data measured, the polynomial fitting function of Origin software was used for fitting function expression of nonlinearity curve of capacitive sensor. The third order inverse function expression could be able to be gotten and meet requirements of the system. The program of nonlinear correction was written in the DSP chip based on inverse function and achieved nonlinear correction for capacitive sensor. The result of nonlinear correction for capacitive sensor was tested in verification experiment of nonlinear correction for capacitive sensor. After the nonlinear correction was finished, the relationship between voltage and displacement was linear. The micro-displacement platform generated 5?m displacement corresponding to the change of voltage ?.In this article, FIR filter and the part of nonlinear correction designed improved the control accuracy of the control system of micro-displacement platform effectively.