Interaction Effects of Environment and Defect Features on Human Cognitions and Skills in Visual Inspections

Abstract

This paper discussed the external environmental conditions and humans’ internal cognition relating to the visual inspection process of actual mass productions. In visual inspection, human perception and recognition are indispensable to the detection and pass-fail discrimination of the defects, because only those form the discipline of the inspection. First, the effects of the external environment on the defect detection rate were evaluated based on the experimental results. Both defects’ features and environmental factors such as the display luminance and defects’ contrast and size are significant for the peripheral visual inspection. Some of the main effects reported in previous studies were verified again, and new interaction effects and whole factors became clear by quantitative analysis. The second was experiments and analyses of human perception and cognition of actual visual inspection targets. A wearable eye-tracker was used to observe experts and a beginner. The visual inspections by the experts were highly efficient because of their skilled perception at first glance and discrimination based on various industrial knowledge in addition to the defect’s appearance. The experts could stably detect a tiny and low-contrast defect on product images including much disturbing stimulus, and it is thought that their sensitivity and resolution were improved based on “attention” because they answered with high confidence. On the other hand, under the same situation, the number of the beginner’s focal points much increases, and processing speed deteriorates remarkably. Finally, some suggestions were summarized based on the results of the first and second topics about the environment of the visual inspection to raise the efficiency of defect detection and pass-fail judgement.