A Complementary Sensor Approach to Reverse Engineering

2000 ◽  
Vol 123 (1) ◽  
pp. 74-82 ◽  
Author(s):  
C. Bradley ◽  
V. Chan
Keyword(s):  
Reverse Engineering ◽  
Boundary Data ◽  
Surface Patch ◽  
Free Form ◽  
Data Set ◽  
B Spline ◽  
Cloud Data ◽  
Surface Patches ◽  
Free Form Surface ◽  
Touch Probe

A complementary sensor technique for reverse engineering objects that are represented by a three-dimensional (3D) cloud data set is reported. The research focuses on objects whose surface form is manifest as a set of distinct free-form surface patches, each of which is enclosed by a boundary. The method incorporates three stages: (1) laser scanner-based digitization of all the free-form surface patches, (2) touch probe-based digitization of the surface patch boundaries, and (3) modeling of both data sets to create a complete B-spline curve and surface representation of the object. The patch boundary data, defined by the touch probe, is employed to segment the free-form surface data into the constituent patches. Furthermore, the boundary data is incorporated within a B-spline surface fitting process to constrain the boundaries. The two sensors functionally complement each other; the range sensor provides the required dense resolution of 3D points on the free-form surfaces whereas the touch probe accurately defines the patch boundaries. The method is ideal for objects comprised of both functional engineering features, e.g. bearing holes or precise mounting locators, and aesthetic features, such as hand grips or part covers. The touch probe is also ideal for digitizing boundaries where occlusion prevents the use of an optical digitizer. The laser-based sensor has an accuracy specification of 50 microns (over a 40-mm depth of field) whereas the touch probe is accurate to 4 microns over a 25-mm measurement length. An example part is modeled that has multiple free-form patches (defining the part’s outer cover) that require a large cloud data set for complete coverage. The corresponding patch boundaries accurately define the location of critical part mounting locations that require the touch probe’s precision.

scholarly journals A GC2 Joining Procedure for B-Spline Patches in Reverse Engineering

1997 ◽  
Author(s):  
Tachung Yang ◽  
Cheng-Chung Wang
Keyword(s):  
Reverse Engineering ◽  
Coordinate Measuring Machine ◽  
Surface Patch ◽  
Geometric Continuity ◽  
Huge Amount ◽  
B Spline ◽  
Surface Patches ◽  
Spline Surface ◽  
Surface Models ◽  
Measuring Machine

Reconstruction of surface models is a vital part in reverse engineering. Because of the huge amount of data from Coordinate Measuring Machine (CMM), processes for division of data into groups, surface patch reconstruction, and patch joining are inevitable in the CAD systems tailored for reverse engineering applications. Existing techniques of surface patch joining have the disadvantages, such as computational complication or lack of desired geometric continuity. A GC2 joining technique for B-spline surface patches by utilising a Bezier patch joining technique was proposed in this paper. This method possesses the merits in which only the control vertices near the joining boundaries of patches are modified and no additional blending surfaces at the joints of patches are created.

Generation of Regularly Aligned Curved Surface Patches on Free-Form Surface for Patch Division Milling

2012 ◽  
Vol 523-524 ◽  
pp. 54-57
Author(s):  
Kai Xu ◽  
Hiroyuki Sasahara
Keyword(s):  
Tool Path ◽  
End Milling ◽  
Added Value ◽  
Curved Surface ◽  
Surface Patch ◽  
Free Form ◽  
Feed Speed ◽  
Machined Surface ◽  
Surface Patches ◽  
Free Form Surface

This study describes a new machining strategy to make regularly aligned cutter marks on free-form surface efficiently for increasing the added value of industrial product. While the free-form surface is divided into many small patch segments employing curved surface patch division milling technique which can substitute for the conventional method, thus avoiding the influence of the change in the curvature. And the patch segments will be machined by a spiral tool path respectively, so that regularly aligned cutter marks can be successfully formed on the curved surface patches by controlling cross-feed, feed speed per tooth, number of teeth and the length of the tool path. Comparing the machined surface and the simulation result, the cutter marks agree with it. If the surface is machined only by the ball end milling with a machining center, this method will be a very effective tool for the machinery industry.

A Generic Approach to Free Form Surface Generation

2002 ◽  
Vol 2 (4) ◽  
pp. 294-301 ◽  
Author(s):  
J. Cotrina-Navau ◽  
N. Pla-Garcia ◽  
M. Vigo-Anglada
Keyword(s):  
Theoretical Approach ◽  
Differentiable Manifold ◽  
Surface Generation ◽  
Free Form ◽  
B Spline ◽  
Free Form Surface ◽  
Manifold Theory ◽  
Free Form Surfaces

A theoretical approach to construct free form surfaces is presented. We develop the concepts that arise when a free form surface is generated by tracing a mesh, using differentiable manifold theory, and generalizing the B-spline scheme. This approach allows us to define a family of practical schemes. Four different applications of the generic approach are also presented in this paper.

Free form surface fitting onto cloud data

2003 ◽  
Vol 2003.43 (0) ◽  
pp. 210-211
Author(s):  
Motoaki NISHIO ◽  
Takayuki GOTOH
Keyword(s):  
Surface Fitting ◽  
Free Form ◽  
Cloud Data ◽  
Free Form Surface

Computation and Simulation of 5-Axis Cutter Based on Scattered Point Cloud Data

2012 ◽  
Vol 602-604 ◽  
pp. 1740-1743
Author(s):  
Wen Hui Zhao ◽  
She Liu
Keyword(s):  
Reverse Engineering ◽  
Distance Function ◽  
Point Cloud ◽  
Complex Surface ◽  
Conjugate Problem ◽  
Local Feature ◽  
Conjugate Points ◽  
B Spline ◽  
Cloud Data ◽  
Cad Cam

The complex surface is modeled by triangular surface, B-spline or non-uniform rational B-spline first and then the planing of the cutter is followed in reverse engineering. But this require CAD/CAM software and operator’s experiene. Because of this，the research on direct NC cutter generation from point cloud have become the focus of research in reverse engineering. The normal，curvature，surface vary et al parameters are calculated by principle component analysis method and so on, which define the local feature of the surface hidden in the point cloud. Then，based on local feature，point cloud is simplified. It is proved that two points with minimal orientation-distance on a pair of smooth surfaces are conjugate points. Thus the conjugate problem between the tool surface and the part surface is converted into optimization process of orientation-distance function. The cutter trace and the cutter interference are achieved by local and global optization of the orientation-distance function.

Statistical evaluation of the influence of the uncertainty budget on B-spline curve approximation

2017 ◽  
Vol 11 (4) ◽  
Author(s):  
Xin Zhao ◽  
Hamza Alkhatib ◽  
Boris Kargoll ◽  
Ingo Neumann
Keyword(s):  
Laser Scanning ◽  
Statistical Significance ◽  
Model Misspecification ◽  
Uncertainty Budget ◽  
Free Form ◽  
Data Set ◽  
Nested Model ◽  
B Spline ◽  
Uncertainty In Measurement ◽  
Spline Curves

AbstractIn the field of engineering geodesy, terrestrial laser scanning (TLS) has become a popular method for detecting deformations. This paper analyzes the influence of the uncertainty budget on free-form curves modeled by B-splines. Usually, free-form estimation is based on scanning points assumed to have equal accuracies, which is not realistic. Previous findings demonstrate that the residuals still contain random and systematic uncertainties caused by instrumental, object-related and atmospheric influences. In order to guarantee the quality of derived estimates, it is essential to be aware of all uncertainties and their impact on the estimation.In this paper, a more detailed uncertainty budget is considered, in the context of the “Guide to the Expression of Uncertainty in Measurement” (GUM), which leads to a refined, heteroskedastic variance covariance matrix (VCM) of TLS measurements. Furthermore, the control points of B-spline curves approximating a measured bridge are estimated. Comparisons are made between the estimated B-spline curves using on the one hand a homoskedastic VCM and on the other hand the refined VCM. To assess the statistical significance of the differences displayed by the estimates for the two stochastic models, a nested model misspecification test and a non-nested model selection test are described and applied. The test decisions indicate that the homoskedastic VCM should be replaced by a heteroskedastic VCM in the direction of the suggested VCM. However, the tests also indicate that the considered VCM is still inadequate in light of the given data set and should therefore be improved.

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