A Method of Reverse Control Point Estimation for Nurbs

A technology of control points and tool position points, which is applied in the field of numerical control technology spline tool position trajectory fitting, can solve the problems of low calculation efficiency and large number of calculations, and achieve the effect of reducing calculations

Active Publication Date: 2021-04-13
XIANGTAN UNIV
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

[0007] For this reason, the embodiment of the present invention provides a method for NURBS reverse control point estimation to solve the problems of many calculation times and low calculation efficiency in the prior art

Method used

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  • A Method of Reverse Control Point Estimation for Nurbs
  • A Method of Reverse Control Point Estimation for Nurbs
  • A Method of Reverse Control Point Estimation for Nurbs

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Embodiment

[0038] Step 1: According to the known tool position points and the contour error fitted into the NURBS curve, the tool position points are simplified, and the tool position points representing the typical contour are selected;

[0039] Such as figure 2 As shown, input the tool position point P 0 ,...,P n , given the contour error d r as a control factor. Let P k point as the starting point, P j As an endpoint, where 0≤k≤j-2, k+2≤j≤n. Pick the middle point P i , ki to line P k P j The error d. Compare d with threshold d r size, if d is greater than d r , continue to search down, otherwise save P j point to P k =P j As a new starting point, P j =P j+2 As a new destination, continue the search.

[0040] Such as image 3 As shown, taking a mouse tool point as an example, different contour errors are used as thresholds to obtain different simplified tool points.

[0041] Step 2: Take the simplified relief point as the initial value, usually the simplified relief p...

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Abstract

The embodiment of the present invention discloses a method for NURBS reverse control point estimation, which is characterized in that it includes the following steps: Step 100, through the known tool position point and setting the error threshold value fitted to the NURBS curve profile, the tool calibration Simplify the position points, and select the tool position point representing the typical contour; step 200, determine the initial value of the control point by adding 2 to the simplified tool position point; step 300, use the initial value of the control point as the fitting initial value, and use Perform fitting, and calculate the fitted contour error; step 400 , compare each calculated contour error with an error threshold, and increase or decrease control points according to the comparison result until the error threshold is met with the least number of control points. The present invention breaks through the shortcomings of the traditional method, estimates more accurate control points according to the known contour threshold, and calculates the required control points after several iterations based on this, which can greatly improve the efficiency of reverse NURBS calculation.

Description

technical field [0001] The embodiment of the present invention relates to the technical field of numerical control technology spline tool position trajectory fitting, and specifically relates to a method for NURBS inverse control point estimation. Background technique [0002] CNC machine tool is a kind of efficient automatic processing equipment, which can automatically process the processing parts in strict accordance with the processing program. Usually, the machine tool has the function of small line segment and circular arc interpolation. With the continuous development of CNC technology, the interpolation function of CNC system is becoming more and more The richer, NURBS spline interpolation function is an important embodiment of high-end CNC machine tools. [0003] NURBS curves are widely used in part CAD modeling, but due to the need to offset the modeling curves, generally the NURBS curves are not directly used as the tool position trajectory of NC machining. A more...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G05B19/4099G05B19/4103
CPCG05B19/4099G05B19/4103G05B2219/33003G05B2219/34135
Inventor 吴继春阳广兴方海国尹硕辉周会成
Owner XIANGTAN UNIV
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