Application of ICP Algorithm for Optimized Registration of Object Surface and Unfolding Surface in Ship-Hull Plate Forming

초록

Generally, external pieces of ship hull are deformed by using flame bending (line heating), multi-press forming, and die-less forming method. The forming methods generate the required in-plane/bending strain or displacement on the flat plate to make the curved shape. Multi-press forming imposes the forced displacements on the flat plate by controlling the position of each pressing points based upon the shape difference between the flat plate and the curved-object shape. The flat plate has been obtained from the unfolding system that is independent of the ship CAD. Apparently, the curved surface and the unfolded-flat surface are expressed by different coordinate systems. Therefore, one of the main issues is to find a registration of the unfolded surface and the curved shape for the purpose of estimating minimum amount of forming works by comparing the two surfaces. This paper presents development of an efficient algorithm to get an optimized registration of two different surfaces in the multi-press forming of curved shell plates. The algorithm is based on the ICP (Iterative Closest Point) algorithm. It consists of three iterative procedures, namely, finding a transformation matrix, finding the closest points to minimize the distance between the unfolded surface and curved surfaces, and determining similarity of two surfaces. Thereby that allows the minimized forming works in ship-hull forming.