A measurement system based on visual servoing and error correction method using multiple CCD camera module and structured target for three dimensional measurement - art. no. 671907

In the shipyard, the precision requirement of the error margin is less then +/- 2mm for producing 20000 mm by 20000 mm sized panels. This paper proposes a measurement system and an error correction method using several cameras and consecutive image data for a large scale panels to satisfy requested precision bounds. The purpose of this paper is the error correction of a measurement data using the matching of four consecutive camera image data that is built up using four CCD camera modules. This module consists of a CCD Camera, rotary stage and rotary stage controller. The error correction method is established using the mid point of direction vectors from each camera and a relation between the origin camera and others. The relation is estimated using corresponding points between each image plane. A direction vector from each CCD camera is measured using the change in the angle of rotary stage. Especially, to measure the dimension of the shape efficiently, a structured target must be at a center on an image plane. By the visual servoing, a target is moved to the center of the image plane. This means the motion of the measurement system, the change of the angle according to orientation of the rotary stage, is controlled by an image based feedback system. An advantage in using this method is to be able to get the measurement accuracy. With this advantage, we propose the error correction algorithm using four consecutive image data for the correction of the measurement data error. In order to evaluate the proposed algorithm, experiments are performed in real environment, shipbuilding process.