基于位置敏感探测器的激光位移传感器小波优化方法  

Wavelet Optimization Method of Laser Displacement Sensor Based on Position Sensitive Detector

作　　者：邾继贵[1] 陈浩[1] 薛彬[1] 

机构地区：[1]天津大学精密测试技术及仪器国家重点实验室,天津300072

出　　处：《中国激光》2013年第3期185-191,共7页Chinese Journal of Lasers

基　　金：国家科技重大专项(2009ZX04014-092)资助课题

摘　　要：在激光位移传感器中引入位置敏感探测器(PSD)可在狭小空间内实现测量,但易受外界因素影响使得输出信号中包含大量噪声,严重影响PSD位置检测精度。为在此测量环境下有效提取PSD位置信号,提出一种利用小波阈值去噪技术提高基于PSD的激光位移传感器检测精度的方法。该方法在离散小波变换的基础上,将PSD的原始测量信号进行多尺度小波分解,通过软阈值量化处理含噪声的小波系数后重构测量信号。实验中通过选择不同的基小波、变化分解尺度以及控制信号采样数量等过程评价小波去噪的效果,最终证实:选取合适的小波去噪组合算法可使去噪后信号不仅保持原始测量平均值,且标准差减小至2μm以下,能显著提高传感器位置检测精度,缩短测量时间。The laser displacement sensor which uses position sensitive detector （PSD） as position detector can realize the displacement measurement in small space, but the PSD is vulnerable to external environment. Therefore, there are lots of noises in the output signal which severely affect the accuracy of PSD position detection. For the purpose of effectively extracting the useful PSD position signal, this paper presents a wavelet threshold denoising technology to improve the accuracy of position detection of laser displacement sensor based on PSD. Based on the discrete wavelet transform, the original signal of the PSD can be decomposed into multiple scales and then be reconstructed with quantified wavelet coefficients which contain the noise by soft thresholding function. The result of wavelet denoising is evaluated by the experiments such as using different kinds of base wavelet, changing the decomposition scale and considering different amounts of signal samples. The experimental results indicate that, by selecting the appropriate combination algorithm of wavelet denoising, the denoised signal can maintain the mean value of the original signal and the standard deviation can be minimized to 2 μm or below, which significantly improves the position detection accuracy of the sensor and shorten the measurement period.

关 键 词：测量 位置敏感探测器 小波去噪 激光位移传感器 软阈值 

分 类 号：TH74[机械工程—光学工程]