A New Approach for Accuracy Control of Outfitting Structure Using 3D Laser Scanning

Abstract

Shipbuilding industry is a field which includes labor and technology intensive. Shipyard always lay stress on the quality of their products (Block, Unit, Structure etc.). Accuracy control is one of the important working items among the quality control work of products. The meaning of accuracy control in the shipbuilding industry can normally be interpreted as “Dimensional Accuracy Control”. The dimensional accuracy control includes all of the activities to control actual products to keep the same condition as their original design. There are two ways to achieve dimensional accuracy control in a broad sense. The first is to use all of the activities to prevent the deformation of blocks. The other one is to repair the deformed blocks using hardware to measure, and software to analyze the deformation value. Until now, most shipyards use the second method to do accuracy control work. In yards, the measurement work for the hull structure can be done by tape rule, line hammer, Level, Theodolite and Total Station. After 2005, 3D-designing of ships is beginning, and most of blocks are measured by Total Station. Presently, there are also some difficulties to check the whole dimensions of outfitting structures by Total Station: 1. The shape of the outfitting unit is more complex than the hull structure. 2. The setting position of pipe is depends on the hull structure, while it is not significant to measure the single pipe by Total Station. 3. Total Station can measure the object one by one only. It is not suitable for such structures which have so many pipes and equipment. To obtain dimensional vaults of outfitting structures accurately and quickly, 3D-laser scanning was performed. At present, a laser scanner has been used for inspection and reverse engineering in industry, especially in the construction field. In this paper, for shipbuilding engineering, a new approach on using 3D-laser scanning data to do outfitting structure accuracy control work has been proposed. The main aspects of this paper are as follows: 1. Explication of the characteristics, working principle, and applications of 3D-laser scanning. 2. The present accuracy control method of the ship outfitting structure has been explained. Also, the current problems and how to improve those problems with 3D-laser scanning data have been described. 3. Field test ---- a data process of using point cloud to accuracy control of engine block