Modeling and Calibration of Active Thermal-Infrared Visual System for Industrial HMI

Abstract

In the industrial application of the human-machine interface (HMI), thermal-infrared cameras can detect objects that are limited by visible-spectrum cameras. It can receive the energy radiated by a target through an infrared detector and obtain the thermal image corresponding to the heat distribution field on the target surface. Because of its special imaging principle, a thermal-infrared camera is not affected by the light source when imaging. Compared to visible-spectrum cameras, thermal imaging cameras can better detect defects with poor contrast but temperature differences or internal defects in products. Therefore, it can be used in many specific industrial inspection applications. However, thermal-infrared imaging has the phenomenon of thermal diffusion, which leads to noisy thermal infrared images and limits its applications in high precision industrial environments. In this paper, we proposed a high precision measurement system for industrial HMI based on thermal-infrared vision. The accurate measurement model of the system was established to deal with the problems caused by imaging noise. The experiments conducted suggest that the proposed model and calibration method is valid for the active thermal-infrared visual system and achieves high precision measurements.