外文翻譯--逆向工程中自由曲面測(cè)量的最優(yōu)參數(shù)確定和數(shù)據(jù)處理（英文）

1、Int J Adv Manuf Technol (2003) 21:678–690 Ownership and Copyright ? 2003 Springer-Verlag London LimitedDetermination of the Optimal Parameters for Freeform Surface Measurement and Data Processing in Reverse EngineeringF.

2、-J. Shiou, Y.-F. Lin and K.-H. ChangDepartment of Mechanical Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Road, 106 Taipei, TaiwanOne objective of this work is to determine t

3、he optimal combi- nation of the probe diameter and grid distance for freeform surface measurement, and another is to determine the optimal parameters for the local Shepard interpolation. The optimal combination of the pr

4、obe diameter and grid distance for freeform surface measurement was determined through a Tagu- chi matrix experiment. The smaller the probe diameter and grid distance, the better the accuracy of the surface normal based

5、on the configured matrix experimental result. The optimal parameters, namely the exponent µ and the radius R, for the local Shepard interpolation were determined by using the minimisation method of the root-mean-squ

6、are normalised error (RMSNE) between the measured data points and the theoretical data points on a standard steel ball surface. The optimal parameters determined were actually applied to the measure- ment of a freeform s

7、urface (mouse surface) on a coordinate measuring machine (CMM). The local Shepard interpolation method was used to interpolate 16 control points from 1054 measured data points. Bi-cubic Bezier- and B-spline surface CAD m

8、odels were constructed through these interpolated control points.Keywords: Bezier surface; Bi-cubic B-spline surface; Root- mean-square normalised error (RMSNE); Shepard interpolation method; Taguchi’s matrix experiment1

9、. IntroductionThe need for rapid product design is increasing. Reverse engineering has played an important role in rapid product design in recent years. The 3D data of a physical model or aCorrespondence and offprint req

10、uests to: Dr Fang-Jung Shiou, Department of Mechanical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Rd. 106 Taipei, Taiwan. E-mail: shiou@mail.ntust.edu.tw Received 17 Jan

11、uary 2002 Accepted 16 April 2002sample part can be digitised through a 3D laser scanner system (non-contact type) or a coordinate measuring machine (CMM, contact type) (Fig. 1). The main advantages of a contact probe are

12、 high accuracy, good repeatability, and easy operation. However, low measuring speed, wear of probe tip and the problem of probe radius compensation are the main disadvan- tages of a contact probe. A non-contact probe, b

13、ecause of its high measuring speed, lack of contact force, and absence of probe radius compensation, etc., has been applied to CMM and CNC machining centres for the measurement of freeform surfaces in recent years [1,2].

14、 For further editing, modification or smoothing of massive digitised point data, 3D scanned data processing software is usually necessary [3,4]. Through the use of computer-aided design, and manufacturing and engineering

15、 techniques, an analytical model can then be constructed from the processed data and studied. The measuring accuracy of the 3D data of a physical model measured with a CMM is reliable and better than that with a 3D laser

16、 scanner system. However, the measuring speed with a CMM is slower than for a 3D laser scanner system. From the information of the normal vector at each control point, the probe radius compensation must be calculated, in

17、 order to obtain the data points on the workpiece surface for measure- ment with a CMM (Fig. 2) [5]. The optimal combination of the probe radius and the grid distance for freeform surface measurement on a CMM has not bee

18、n studied in the litera- ture review. The projections of data points on the x,y-plane, which are originally equidistant, become scattered after the compensation for probe radius (Fig. 3). Data points with a rectangular g

19、rid on the x,y-plane are convenient and helpful for the purpose of performing measuring path planning and for building the CAD model. Data points located on the rectangular grid can be estimated from the scattered data p

20、oints using the Shepard interpolation method. This method has been proven to be suitable for the graphic representation of surfaces [6]. The parameters of the local Shepard interpolation method for the nodes with a large

21、r node distance are not clearly defined in [6]. One objective of this work is to determine the optimal combination of the probe diameter and grid distance for free- form surface measurement, and the other is to determine

22、 the680 F.-J. Shiou et al.Fig. 2. General process to construct an unknown freeform surface from the measured data points by Coons procedure.from the measured data points plays an important role in the measuring accuracy.

23、 Different combinations of probe diameter and grid distance result in different surface normals. The angle between the theoretical surface normal and the calculatedsurface normal should be as small as possible. These two