Visual sensing technology

Recently the spread of arc welding robots is conspicuous, and as the sensors for the robots, wire touch sensor and arc sensor have been put to practical use. However, when the welding of high quality is required, the objects which are welded complately automatically in unmanned state are limited. Mitsubishi Heavy Industries, Ltd. has advanced the research on unmanned welding, and in particular, on the visual sensor which can detect plural objects during welding. In this report, the outline of visual sensors, the example of their development in Mitsubishi, and the limit of visual sensing are mentioned. As the light sensors for arc welding, there are point sensor, linear sensor and area sensor, and the linear and area sensors are called visual sensor. The visual sensors have been utilized for the profile control of welding lines, the adaptive control of welding conditions, the profile control and adaptive control of welding lines and the monitoring of welding. As the examples of applying visual sensors, the applications to GMA multi-layer welding, GMA narrow groove welding and orbital TIG welding are reported. As nthe limit of visual sensors, in the linear sensor, the grasp of melting phenomena, the effect of surface roughness and color, and the problem of sensing position, and in the area sensor, the problem of the blooming and smear phenomena of cameras are discussed. (K.I.)