A Novel Spatial Filter System Compensates the Measurement Error Caused by Object's Pattern.

Abstract

Spatial Filters detect the components of a specific spatial frequency contained in optical pattern on object's surface, and the movement or velocity of it are estimated by measuring the frequency of the filter's output. However, the error of the conventional method increase in cases of low speed measurement, small amount of composition of a spatial filter frequency, or large change of patterns.We developed a novel spatial filter in which a CCD line sensor was used to detect object's pattern and DSP (TMS 32025) performed calculation of spatial filters. We also analyzed about the phenomena that measurement error increase in several conditions of the patterns on object's surface, and developed a method which compensates this error. This paper presents the system configuration, the analysis of measurement error, the compensation method, and experimental results show that this method drastically reduce the measurement error caused by object's pattern.