High precision measurement of free formed parts using industrial robots

Abstract

We present an optical 3D-measurement system for highest possible flexibility for employment in an industrial environment, conceived for various industrial applications. The system is based on a 3D-measurement head attached to an industrial robot for positioning. The 3D sensor uses the structured light approach with multiple wavelength phase shifting and consists of two CCD cameras and a grid projector. To achieve high accuracy even at objects, which lack of geometric diversity, we combine the reconstruction process with indirect photogrammetry, in which structured objects of known shape are placed in fixed locations in the background. The paper presents the components of the system, describes the processing steps-generation of rawdata, sensor calibration, hand to sensor calibration, alignment of pointclouds, and compares results for different set-ups.