CN1601563A - Direct and fast prototype mfg, method based on discrete data points - Google Patents
Direct and fast prototype mfg, method based on discrete data points Download PDFInfo
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- CN1601563A CN1601563A CN 200410067323 CN200410067323A CN1601563A CN 1601563 A CN1601563 A CN 1601563A CN 200410067323 CN200410067323 CN 200410067323 CN 200410067323 A CN200410067323 A CN 200410067323A CN 1601563 A CN1601563 A CN 1601563A
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Abstract
The method includes two steps: (1) in the step of pretreatment of discrete data, based on characters of B-spline curve and curved face, procedure of solving constructed curve and face is carried out by using selected discrete data points as control vertexes through steps of data smoothing, data compaction, segmentation of data area, extraction of feature point and sorting; (2) based on discrete data points, slice documents are generated directly. According to complexity of shape of surface, cumulation shaping is carried out by using thinner layers in implementing quick prototype fabrication for that area, where varied surface curvature is larger. On the contrary, thicker layers are adopted for that area, where varied surface curvature is smaller. The invention raises manufacturing efficiency, shortens cycle of developing products.
Description
Technical field
The present invention relates to a kind of prototype making process, specifically is a kind of based on the direct fast prototype making process of discrete data point.Be used for the imitated and improvement field of industrial products.
Background knowledge
At reverse engineering and rapid prototyping technique integration problem, proposed respectively both at home and abroad in recent years many with based on the relevant algorithm of the rapid prototyping manufacturing of discrete data point, comprise discrete data Preprocessing Algorithm, three-dimensional modeling algorithm and triangulation etc.
Find by prior art documents, people such as Lee Kwan H are at " computer and industrialengineering " 2000,38 (1), " the Direct integration of reverseengineering and rapid prototyping " that delivers on the P21-38 (" it is directly integrated that reverse engineering and rapid prototyping are made ", " computing machine and Industrial Engineering "), this article directly generates fast prototype making process at reverse engineering and rapid prototyping technique integration problem to discrete data point and has carried out comparatively detailed introduction, and has developed a kind of based on the direct synusia document generating method of discrete data point.Although the feasibility of this method and effectively being verified, yet because discrete data point Surface Method resultant curvature complexity of calculation, the method that makes document introduce can't be used the Processing Strategies of " regionality ", makes efficient thereby reduced moulding." regionality " Processing Strategies is based in the fast prototype making process of cad model comparatively proven technique, and its validity has been proved and experimental verification widely.
Summary of the invention
The objective of the invention is to overcome deficiency of the prior art, the Processing Strategies of " regionality " is incorporated into based on the direct rapid prototyping technique of discrete data point, provide a kind of based on the direct fast prototype making process of discrete data point, make its Processing Strategies of taking " self-adaptation " property carry out reverse engineering and rapid prototyping technique directly integrated, make efficient thereby improve rapid shaping, to shorten product development cycle, to improve the market competitiveness.
The present invention is achieved by the following technical solutions, the present invention is based on the character of B batten (B-spline) curved surface, characteristics in conjunction with the rapid shaping manufacturing technology, the geological information of full use discrete data measurement point specifically comprises the discrete data pre-service and generates two basic steps based on the direct synusia file of discrete data point:
1, measurement data pre-service
Utilize the characteristic of B-spline surface that discrete data is carried out pre-service.In the acquisition process of moulding measurement of curved surface data,, make measurement result comprise " noise point " and have a large amount of redundant datas because actual measurement is subjected to the influence of various human factors.In order to make the product that satisfies accuracy requirement, measured 3 d-dem data point is carried out pre-service be based on a key link in the direct rapid prototyping technique of discrete data point.Pre-service to discrete data generally comprises: data smoothing, data compaction, data area are cut apart, feature point extraction and ordering.
Existing discrete data is level and smooth, cut apart and the common ground of feature point extraction algorithm is based on discrete data point curvature and the curvature differential calculates, i.e. the calculating of discrete data point curvature and differential thereof is the marrow of above-mentioned algorithm.Yet, the calculating of discrete data point curvature and differential thereof is difficult point and the emphasis in the Computer-aided Geometric Design, although the algorithm that calculates at discrete data curvature is a lot, obtaining of discrete data curvature remains the technological difficulties that computational accuracy is low, calculated amount is big.In order to overcome discrete data curvature and differential calculation problem, thus more effectively carry out discrete data level and smooth, cut apart the extraction with unique point, the present invention is based on the character of B-spline surface:
A) locality: the B-spline basis function as can be known, and is only influential to one section curve wherein when moving a control vertex, whole piece B-spline curve (curved surface) do not exerted an influence.
B) bag convexity: B-spline curve (curved surface) must be in the formed convex closure of control polygon.Convex closure is the critical nature of B-spline curve (curved surface), and this interesting property can be to having important directive function based on the discrete data point disposal route.
C) similarity: be the B-spline surface of control vertex structure with the discrete data point of choosing and there is strong similarity in fitting surface based on all discrete points.
Level and smooth to traditional discrete data, cut apart with Feature Points Extraction and improve, make it under the situation that calculated amount reduces, obtain discrete data pretreating effect preferably.
To carry out the B-spline curve interpolation intrinsic because the pretreated defective of existing discrete data is based on discrete data point, therefore, in order to overcome the defective of this inherence, the viewpoint that the present invention discards tradition up hill and dale, and open up new approaches audaciously: given series of discrete data point, the present invention utilizes measured discrete data point to construct the B-spline curve for control vertex, thus utilize the curve constructed to discrete data point carry out data smoothing, data compaction, the data area is cut apart and feature point extraction.Because interpolation B-spline curve is " counter an asking " process, need carry out finding the solution of huge matrix in conjunction with boundary condition, therefore, calculated amount is bigger; Is " just an asking " process and utilize discrete data point for the structure that control vertex carries out the B-spline curve, need not carry out finding the solution of equation, and therefore, required calculated amount is less, and this is one of advantage of this invention.
2, generate based on the direct synusia file of discrete data point
The present invention implements the moulding measure according to the complexity (curvature of curved surface) of processed solid object surface shape: at the bigger zone of solid object surface curved transition, implementing to adopt the thinner layer sheet to accumulate moulding when rapid prototyping is made; On the contrary,, adopt thicker synusia to accumulate, to improve shaping efficiency at the less zone of solid object surface curved transition.
Strategy is made in the moulding of " self-adaptation " property, in the rapid shaping manufacture process based on cad model, has improved shaping efficiency greatly.Given this, the present invention makes application of policies in the direct rapid prototyping technique based on discrete data point with the moulding of " self-adaptation " property, to improve shaping efficiency.Because " regionality " moulding strategy is to be prerequisite to calculate by the curvature of moulding curved surface, therefore, " regionality " forming method is applied to the matter of utmost importance that direct rapid prototyping manufacturing is faced based on discrete data point is how to calculate the curvature of curved surface.In order to address the above problem, the present invention has developed a kind of direct manufacture method of " self-adaptation " property based on discrete data point.
The present invention is a kind of emerging rapid prototyping technique data processing method, utilize the direct integrated thought of reverse engineering and rapid prototyping manufacturing, helping shortening the Products Development cycle, also is one of the following reverse engineering that generally adopts and rapid prototyping integrated approach.The present invention improves traditional discrete data → rapid prototyping manufacturing section file algorithm, utilize the character of B-spline surface, with the discrete data point of choosing is that control vertex structure B-spline surface is to calculate the discrete point geological information, make people can obtain information such as curvature, method direction and geometric configuration, and then discrete data carried out pre-service, and implement " self-adaptation " property moulding manufacturing strategy and improve the rapid shaping working (machining) efficiency.By the moulding entity, the more existing technology of the present invention improves shaping efficiency 5-10%, can be used for various manufacturing industry based on clay or bubbles model, mold manufacturing industry and medically is being used for artificial organs customization etc. at different.
Description of drawings
Fig. 1 the inventive method process flow diagram
The moulding of Fig. 2 embodiment of the invention camera model is figure as a result
Embodiment
The rapid prototyping manufacturing system combines mechanical engineering, CAD, Numeric Control Technology, laser technology and material science and technology, can automatically, directly, quickly and accurately design philosophy be turned materially prototype or direct finished parts with certain function, thereby can estimate fast product design, modification and function test, shorten the Products Development cycle effectively.
Related for a better understanding of the present invention based on the direct rapid prototyping technique scheme of discrete data point, be further described below in conjunction with accompanying drawing and concrete implementation method.
The flow process of the inventive method and the present invention see Fig. 1 to existing based on the improvement of discrete data point fast prototype making process.As can be seen from the figure, technical scheme of the present invention has been avoided the curve reestablishing process based on discrete data point, because this process is exactly based on the difficult point of discrete data rapid prototyping manufacture process with consume the place computing time, therefore the present invention is the direct integrated thought of a kind of reverse engineering and rapid prototyping manufacturing, it helps shortening the Products Development cycle, is a kind of emerging rapid prototyping technique data processing method.
Embodiment
1, measurement data pre-service
Technical scheme of the present invention is B-spline curves, the curved surface of control vertex structure with the discrete data point of choosing, and directly utilizes the curve of these structures, curved surface to carry out data smoothing and feature extraction.
According to the digital information of profile in kind and the difference of measuring planing method, measure the gained discrete data point and be divided into: put in order and unordered point.If these discrete data points utilize some particular devices measured, promptly these discrete data points have inherent continuity and certain arrangement sequence P
I, jAt this class discrete data point, the discrete data point of each row or column (for example second the row P
I, 2) can directly be utilized as control vertex, its processing procedure is simpler.Yet in most cases, what face is the discrete data point that has no inherent order, and at this class data point, the treatment step that the present invention takes is as follows:
A) discrete data point is cut into slices: seek a slice direction according to measured solid object surface shape, for example along z or x direction of principal axis; A given slice distance δ (on the δ be according to concrete testee shape the distance between given two-layer section), along slice direction all discrete data points are carried out synusia and divide, form slice of data (these type of data are similar to CT data type medically commonly used).
B) discrete data point ordering: whenever all discrete datas between two-layer (for example j and j+1) section sort and are P according to a certain coordinate (for example slice direction is the z direction of principal axis, ordering can according to x axial coordinate direction) " dictionary " mode of carrying out
i
After control vertex is chosen and finished, then utilize them to carry out B-spline curves, curved surface structure.Utilize structure B-spline curves, curved surface that control vertex (discrete data point of choosing) is carried out parametrization then and be positioned at the corresponding point of structure B-spline curves, curved surface in the hope of it, and calculate the geological information of these corresponding point, finally discrete data is carried out pre-service and direct rapid prototyping manufacturing provides foundation how much based on discrete data point " self application " property for follow-up.Camera model shown in Figure 2 is of a size of 135mm * 55mm * 80mm., and the discrete data point that measures is divided into 8 son four edge regions, adopts two 3 B-spline surfaces to construct at every subregion.
2, generate based on the direct synusia file of discrete data point
The rapid shaping technique scheme that the present invention takes adopts mixed-forming error strategy.In order to ensure formed precision, when section was calculated, the present invention carried out the moulding scheme determination according to following manner:
When curvature κ＞0 of curved surface at a P ', and put P ' when the first half of the circle of curvature, the present invention adopts the slicing mode of " from bottom to top ".
When curvature κ＜0 of curved surface at a P ', and put P ' when the Lower Half of the circle of curvature, the present invention adopts the slicing mode of " from top to bottom ".
Determine after the slicing mode, then can be according to different curve forms, calculate accumulation slice of cylinder thickness d ', and therefrom determine smallest cylinder sheet thickness as this regional slice of cylinder thickness d '
Min:
Minimized′(u，v)
Boundary condition is:
(u.v) ∈ structure B-spline surface, and z (u, v)=c is a constant.
When actual slice is calculated, if same section and a plurality of patch intersect, must compare the minimum slice thickness that each patch is determined, therefrom choose the slice thickness of minimum, as final slice thickness to accumulate moulding.Carry out the validity that rapid shaping is made algorithm in order to verify as " basic curved surface " based on constructing curve, this example with this algorithm with carry out rapid shaping based on discrete data point cad model (discrete data point being carried out the cad model of match gained with two 3 B-spline surfaces) and make algorithm and compare its result such as table 1.
Table 1 (camera)
| Parameter | Based on constructing curve (the present invention) | Based on fitting surface (cad model) |
| Cut layer thickness d | ????0.12mm-0.65mm | ?????0.1mm-0.6mm |
| Surplus δ | ????????0.1mm | ?????????0.1mm |
| Synusia quantity | ?????????382 | ??????????394 |
| The accumulation total area | ????18.87×10 5mm | ??????19.90×10 5mm |
Claims (4)
1, a kind of based on the direct fast prototype making process of discrete data point, it is characterized in that, character based on B-spline surface, characteristics in conjunction with the rapid shaping manufacturing technology, the geological information of full use discrete data measurement point specifically comprises the discrete data pre-service and generates two steps based on the direct synusia file of discrete data point:
1) discrete data pre-service: given series of discrete data point, character based on B-spline curve, curved surface, to discrete data point carry out that data smoothing, data compaction, data area are cut apart, feature point extraction and ordering, the discrete data point that utilization is chosen carries out the structure of B-spline curve, curved surface for control vertex, be " just an asking " process, omit finding the solution of equation;
2) generate based on the direct synusia file of discrete data point: implement the moulding measure according to the complexity of processed solid object surface shape: at the bigger zone of solid object surface curved transition, implementing to adopt the thinner layer sheet to accumulate moulding when rapid prototyping is made, on the contrary, at the less zone of solid object surface curved transition, adopt thicker synusia to accumulate.
2, according to claim 1ly it is characterized in that based on the direct fast prototype making process of discrete data point the characteristic based on B-spline surface is meant:
A) locality:, when moving a control vertex, only influential to one section curve wherein according to the B-spline basis function;
B) bag convexity: B-spline curve, curved surface must be in the formed convex closure of control polygon;
C) similarity: be the B-spline surface of control vertex structure with the discrete data point of choosing and there is strong similarity in fitting surface based on all discrete points.
3, according to claim 1ly it is characterized in that when discrete data point had no inherent order, treatment step was as follows based on the direct fast prototype making process of discrete data point:
A) discrete data point is cut into slices: seek a slice direction according to measured solid object surface shape, a given slice distance δ, on the δ be according to concrete testee shape the distance between given two-layer section, along slice direction all discrete data points are carried out synusia and divide, form slice of data;
B) discrete data point sorts: all discrete datas between every two-layer section are sorted according to a certain coordinate " dictionary " mode of carrying out is P
i
4, according to claim 3ly it is characterized in that when section was calculated, when curvature κ＞0 of curved surface at a P ', and some P ' adopted the slicing mode of " from bottom to top " when the first half of the circle of curvature based on the direct fast prototype making process of discrete data point; When curvature κ＜0 of curved surface at a P ', and some P ' adopts the slicing mode of " from top to bottom " when the Lower Half of the circle of curvature.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103229176A (en) * | 2010-10-15 | 2013-07-31 | 菲迪亚斯技术公司 | Rapid prototyping method and device |
| CN103295240A (en) * | 2013-06-26 | 2013-09-11 | 山东农业大学 | Method for evaluating similarity of free-form surfaces |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US6079831A (en) * | 1997-04-24 | 2000-06-27 | Orbtek, Inc. | Device and method for mapping the topography of an eye using elevation measurements in combination with slope measurements |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103229176A (en) * | 2010-10-15 | 2013-07-31 | 菲迪亚斯技术公司 | Rapid prototyping method and device |
| CN103229176B (en) * | 2010-10-15 | 2016-08-24 | 普维斯公司 | Fast prototype method and equipment |
| CN103295240A (en) * | 2013-06-26 | 2013-09-11 | 山东农业大学 | Method for evaluating similarity of free-form surfaces |
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