T-Spline Based Unifying Registration Procedure for Free-Form Surface Workpieces in Intelligent CMM

Han, Zhenhua; Wang, Yingmo; Ma, Xinhui; Liu, Shugui; Zhang, Xiaodong; Zhang, Guoxiong

doi:10.3390/app7101092

Cited by 5 publications

(5 citation statements)

References 35 publications

(23 reference statements)

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“…To find the spline coefficients for the n + 1th observation cycle, one can use the coefficients already found for the n-th cycle. Indeed let fn (x) = anx 3 + bnx 2 + cnx + dn , fn+1 (x) = an+1x 3 wherein O(Δx 2,3 ; Δp 2,3 ) -limited function of the second and third degree increments of the coefficients p (i.e., a, b or c) and the argument x. Due to the small increments, it is small value of a higher order than Δx, Δa, Δb, Δc and can be neglected.…”

Section: Methodsmentioning

confidence: 99%

“…To approximate the deformations of objects of significant area (for example, objects on the ground), quite satisfactory accuracy can be obtained by the finite element method with an appropriate choice of network shape and element sizes (see, for example, [1], [2]). The construction of surfaces, their approximation by splines based on the results of automatic measurement in various fields of engineering using modern software and computer equipment is a solved problem [3].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Possibility of using local spline functions for estimating displacement values when observing deformations of buildings

Labuznov

2020

E3S Web Conf.

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This paper discusses the issue of determining the values of displacement points on the walls of buildings and structures during deformations using geodetic measurements of the values of displacements of adjacent points. It is proposed to use spline functions of one or two variables to calculate the offsets of points where no measurements were made, or where observations stopped starting from a certain stage. It is proposed to determine the spline coefficients either by interpolating the results from one observation cycle to arbitrary points, or by interpolating the observation results in previous cycles to points that were not observed in the new observation cycle. A specific example is used to evaluate the accuracy of the interpolation results and provide practical recommendations for using the methods in practical calculations. When considering the two-dimensional case, it is concluded that the approximation of the linear spline of two variables is not accurate enough, and it is proposed to use splines of a higher degree.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Possibility of using local spline functions for estimating displacement values when observing deformations of buildings

Labuznov

2020

E3S Web Conf.

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“…Chen et al [22] proposed a split-connection T-spline fitting algorithm based on the conjugate gradient method by dividing the point cloud into a set of B-spline patches adaptively. Han et al [23] constructed a unified free-form surface model based on T-spline and proposed its discretization and high-precision evaluation method through registering the measured point clouds. Lu et al [24] introduced a segmentation technique to identify the inactive and active regions of the T grid, and proposed a fast T-spline fitting method based on T grid segmentation.…”

Section: Introductionmentioning

confidence: 99%

Research on on-machine measurement of machining error based on T-spline surface reconstruction

Fu¹,

Sheng²,

Luo³

et al. 2021

Meas. Sci. Technol.

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The machining quality of the parts can be directly inspected and analyzed through contact on-machine measurement. However, during the measurement of free-form surfaces, aiming at the problem that the spline surface fitting method requires too many measuring points and the original design information is not borrowed during reconstruction, a T-spline surface reconstruction method based on the centroidal Voronoi tessellation (CVT) sampling strategy is proposed. In the uv parameter region of the original designed NUBRS surface, the Gaussian curvature of the surface is taken as the regional density function, and the CVT is generated by the Lloyd algorithm. Based on the T-grid constructed by an adaptive quadtree method, three kinds of surface feature points are defined as measuring points. By using constrained optimization theory and hierarchical T-mesh knowledge, the generation and local optimization of T-spline surface based on the reconstruction of the original NUBRS surface control points is realized. At last, the example of the surface machined by Makino V77 machine tool and measured with BLUM TC60 probe shows that, the method in this paper can effectively fit a surface which is more suitable for actual processing by adjusting a relatively small number of control vertices with a limited number of measurement points.

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“…Future intelligent three-coordinate measuring machines has attracted the attention of Han et al 10 who proposed a T-spline based unifying registration technique for free-form surface artifact in intelligent CMM. While artificial intelligence approach to freeform shapes registration has been investigated by several others scholars.…”

Section: Introductionmentioning

confidence: 99%

Study of geometrical defects of free-form surface machined using neural network

Bloul

Chanal

Aour

et al. 2021

Advances in Mechanical Engineering

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The manufacture of total hip arthroplasty (THA) requires the control of the quality of free form surfaces. In fact, the polyethylene insert is deformed to fit the overall geometry of the femoral part, which has an impact on the quality of the contact. In this paper, we propose a method for evaluating the defects of complex forms. The originality of the approach is the use of artificial intelligence to position the cloud of measured points, obtained with a three-dimensional measuring machine equipped with a contactless sensor, with regard to the 3D CAD model of the THA. The artificial intelligence algorithm used is based on neural networks that are trained using a virtual positioning realized with 3D CAD software. Finally, the difference between the positioned point cloud and the CAD model allows us to evaluate the shape defect of the measured THA surface. We found that the error of the proposed method is at the vicinity of micron scale.

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T-Spline Based Unifying Registration Procedure for Free-Form Surface Workpieces in Intelligent CMM

Cited by 5 publications

References 35 publications

Possibility of using local spline functions for estimating displacement values when observing deformations of buildings

Possibility of using local spline functions for estimating displacement values when observing deformations of buildings

Research on on-machine measurement of machining error based on T-spline surface reconstruction

Study of geometrical defects of free-form surface machined using neural network

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