Abstract：To improve the registration efficiency of free-form surface work piece, according to RANSAC preliminary registration algorithm, a new two-step registration method of free-form surface was proposed based on coplanar 4-point sets algorithm and improved iterative closest point(ICP) exact registration algorithm. The coplanar 4-point sets were searched through the distance and proportional relationship among points based on RANSAC. The invariants of coplanar 4-point sets were used to constraint the sample extracted by RANSAC algorithm, and the point cloud was marked to get a good initial position after preliminary registration. The method was improved based on original ICP algorithm to optimize the result of preliminary registration. The registration error was minimized to realize the exact registration. The registration simulation of CAD surface cloud models of two simple work pieces was completed. The results show that compared to traditional ICP algorithm, the running time of the proposed algorithm was reduced by 48% with increased accuracy by 56%.
2015, Vol. 36 
