Reverse engineering of engine intake ports by digitization and surface approximation

This paper describes a research development for the design of engine intake ports using reverse engineering techniques. The background is typical of many automotive applications where digitization and reverse engineering become necessary when the design is subject to changes during production or testing. After careful analysis of the problem, CMM contact measurement was selected to digitize the complex intake ports. Part segmentation and semi-automatic scanning were applied to the digitization process. For the purpose of data reduction and surface approximation, a new approach to the fitting of rational B-splines was developed. This is because rational B-splines have more flexibility and can approximate complex geometry more accurately than traditional Bezier or B-splines. Furthermore, skinning—a cross-sectional design technique—was utilized to construct the surface to reduce the computation cost. Surface merging was also implemented to maintain the surface boundary continuity. Finally, the enclosed surface volume is produced and can be transferred to commercial CAD/CAM systems through IGES translation. Examples with complex intake ports were described to validate the approach.