产品表面检测的变步长采样机制研究

Research on variable-step sampling mechanism in inspection of product surface

针对产品表面缺陷检测系统中,由于定步长数据采集造成数据冗余量大、工作效率低的现象,提出变步长自适应的数据采集方式,以信号变化为采样依据实现调频。首先,基于采样步长的影响因素(乃奎斯特采样定理、识别尺寸、弧度畸变及空间畸变),推导出采样步长的函数关系表达式。其次,采用Matlab仿真平台,利用最小二乘法拟合,具体分析并验证被检产品各待检区域通过公式计算得到的采样步长均在95%的置信区间内。实验表明:推导出的采样步长公式为产品各待检区域旋转步长的合理选取提供理论依据;该模式可以根据不同信号实现频率自适应调节,可提高获取信息的利用率并减少数据冗余。

For product surface defect detection,a method of data acquisition based on variable-step self-adaption was proposed to achieve frequency modulation on sampling basis of signal changes due to large data redundancy and low efficiency caused by fixed-step data collection. Firstly,the function relationship expression for sampling step was deduced according to the influence factors(Nyquist sampling theory,identifiable size,radian distortion and space distortion)of sampling step.Secondly,it is specifically analyzed and verified that the sampling step (obtained by using the formula)of each area of verified product is within 95% of confidence interval based on the Matlab simulation platform and the method of least squares fitting. The test results show that the deduced sampling step formula provides a theoretical basis for reasonable selection of rotation step in each area to be inspected. The mode can implement adaptive adjustment of frequency according to different signals,which can improve efficiency of data acquisition and reduce data redundancy.