Application of the structured illumination method for automated visual inspection of the loudspeaker cones

The purpose of this study is to develop an automated visual inspection of the loudspeaker cones, for determining the shape and concentricity of the cone. The study integrates a visual module, a control module, and a mechanism module into one non-contact 3D automatic measurement system for solving the problems concerning the automated inspection of the cone. The measurement techniques include (1) measuring local feature of the cone using the multi-image to improve repeatability accuracy instead of measuring the whole cone by using only one image for implementation, (2) applying triangulation-based to obtain 3D range data of the cone can be converted into the shape of the cone for obtaining height measurement. The experimental results show that the inspecting system has excellent repeatable accuracy and reliability. The machine vision system is thus able to keep up with the loudspeakers cones production process, can inspect every cone, and reject the defective ones.