船体分段测量点数据与CAD模型自动匹配方法研究

Methods of automatically matching measurment points data with CAD model for hull blocks

为了能准确分析船体分段的建造误差,给出合理的建造精度评价,船体分段测量点数据与CAD模型的精准匹配是关键.针对目前船厂通常采用全站仪进行测量,提出一种以全站仪测得的船体分段测量点集为处理对象,自动进行测量点数据与CAD模型匹配的算法.该算法分粗匹配与精匹配两部分,粗匹配采用主元分析(PCA)法来缩小测量点集与CAD模型点集间的错位,通过搜索最近点法来确定对应点对;精匹配以粗匹配的结果作为初始位置,采用欧拉旋转理论对测量点集进行旋转和平移调整使匹配结果最优.实例表明,该算法不需要明确测量点与CAD模型点的对应关系,能自动匹配二者,准确地评价船体分段建造精度,为后续装配提供依据.

Precise matching of measurement data with a CAD model for hull blocks is the key to accurately analyze construction errors and rationally evaluate construction precision.An algorithm to automatically match measurement data with a CAD model was proposed.The measurement data was measured by a total station which is currently used in shipyards.The algorithm was divided into two steps.One was rough matching and the other was precise matching.Rough matching that adopts a PCA algorithm can narrow the dislocation between measurement data and the CAD model.The pair-wise points were matched by searching the minimum distance.Initialized by the former result and based on rough matching,precise matching that adopts Euler rotation theory led to perfect matching by translating and rotating the measured points.Experimental results show that the proposed algorithm can automatically match measurement data with a CAD model without prior information on transformation,and it can evaluate the construction precision of hull blocks accurately,providing an instructive basis for subsequent assembly.