Design Concept of an Integrated Vision System for Cost-effective Part-Presentation

Abstract

The cost of feeding parts to a robot for either machine loading or for assembly has been recognized as excessively expensive. The lack of a cost-effective generic part-presenter has prevented the flexibility of the overall manufacturing automation to be fully exploited. For this reason, the design concept of an integrated microprocessor-controlled vision system based on retroreflective vision sensing has been developed at the Material Handling Research Center in Atlanta. Where the orientation of a part can be characterized by its silhouette, outline, or structured “engineering landmarks,” the concept of using retroreflective materials in vision-guided part-presentation system has been proven to have significant potential for improving reliability, reducing computation, and lowering implementation cost. This paper presents optic design concepts for collocated illumination for cost effective part-presentation. The design concepts are illustrated with practical applications and experimental results. The uniformity of the image irradiance across the sensor surface, in general, depends on several factors such as the intensity distribution of the light source, the reflectance characteristics of the object and background, and the geometrical relationship between the imaging sensor, the illumination source, and the target. The trust of this paper focuses on the analytical model which characterizes the influences of these factors for optic design of retro-reflection. This engineering basis is not only necessary for developing practical yet potentially cost-effective optic design concepts, but also provides a useful tool for performance prediction to drive the design for vision-guided part-presentation.