NURBS curve interpolation fast pre-reading processing method based on advance-retreat method

Abstract

The invention provides a NURBS curve interpolation fast pre-reading processing method based on an advance-retreat method. The method is characterized in that fast dispersion is carried out on a curvature smooth area of a curve through the advance-retreat method to enable parameter step increment to change quickly, and the number of curve points needing to be processed in the pretreatment process is reduced, and meanwhile, a velocity sensitive region is detected; and a curvature radius calculating function serves as an objective function, and a curvature radius minimum point of the velocity sensitive region is found through a step-length acceleration method, thereby enhancing identification and analysis processing speed of the velocity sensitive region in the forward-looking processing process and realizing fast forward. The method comprises the following specific steps: carrying out fast recognition of the velocity sensitive region through the advance-retreat method; obtaining a curvature extremum value approximation point of the velocity sensitive region; and correcting the curvature extremum value point of the velocity sensitive region, processing being finished. The method greatly reduces the number of points needing to be processed in the pretreatment process, and greatly improves real-time performance of the forward pretreatment process.

Description

technical field [0001] The invention relates to a fast pre-reading processing method for NURBS curve interpolation based on an advance and retreat method. Background technique [0002] High-speed and high-precision machining not only requires the CNC system to have a real-time interpolation algorithm, but also the control accuracy must reach the sub-micron level. The real-time performance of the interpolation algorithm even determines the possibility of high-speed machining. Non-uniform rational B-spline Rationa1B-spline, NURBS) curve has good shape expression ability, and it is more and more widely used in the modeling design and manufacturing of automobile, aircraft, shipbuilding and other surface parts, and has become the only form of expressing free curve and surface in STEP-NC. The processing file code expressed in NURBS form is concise, and there is no loss of precision. Its code volume is only 1 / 10 to 1 / 100 of the traditional NC code, which has incomparable advantages...

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Problems solved by technology

[0007] 2) Comparative document 2: NURBS interpolation method based on machine tool dynamics and curve characteristics, application number: 201010546987.9, the method in comparative document 2 consists of three links: pre-interpolation, forward-looking information processing and real-time interpolation: pre-interpolation The link adopts the speed adaptive adjustment algorithm; the forward-looking information processing link first divides the acceleration and deceleration areas according to t...

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