Contour error real-time estimation method based on spatial arc approximation

Abstract

The invention belongs to the technical field of precision high-efficiency numerical control machining, and relates to a contour error real-time estimation method based on spatial arc approximation in a spline curve interpolation process. According to the method, a parameter initial value for Newton iteration on a parameter curve is calculated based on a first-order Taylor series expansion method before a perpendicular foot is calculated in each Newton iteration, and then a single iteration parameter final value is calculated according to the parameter initial value by using a Newton iteration method. In order to avoid greatly increasing the calculation time of the algorithm, circulation is ended under double constraints of an iteration terminating precision condition and a maximum iteration number condition to obtain a parameter estimation value of the perpendicular foot, and a contour error vector estimation value is calculated. The method still can effectively guarantee the estimation precision of a contour error when the follow-up error is relatively large, and has great significance for improving the spline curve interpolation machining contour precision of a high-grade numerically-controlled machine tool.

Description

technical field [0001] The invention belongs to the technical field of precision and high-efficiency numerical control processing, and relates to a method for real-time estimation of contour errors based on space arc approximation during spline curve interpolation processing. Background technique [0002] With the rapid development of the high-end equipment field, the high-speed CNC machining technology for complex curved surface parts is becoming more and more widely used. In view of the fact that the machining tool paths of complex curved surface parts are mostly curves with complex geometric characteristics, when using traditional straight line and arc interpolation CNC machining, due to the existence of the first-order discontinuity point when the straight line and arc segments approach the ideal curve, it will lead to The frequent acceleration and deceleration of the feed axis during processing affects the processing quality and processing efficiency. Parametric spline...

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Problems solved by technology

[0003] Document "A Novel Contour Error Estimation for Position Loop-Based Cross-Coupled Control", Yang et al., IEEE / ASME Transactions on Mechatronics, 2011, 16(4): 643-655, this document proposes a method based on close arc approximation Contouring error estimation method, however, this method is only applicable to two-dimensional plane contours, and the estimation accuracy is low when the following error is large; the literature "A Real-time contouring errorestimation for multi-axis motion systems using the second-orderapproximation" , Zhu et al., International Journal of Machine Tools and Manufacture, 2013, 68: 75-80, this document proposes a real-time estimation method for the second-order approximate space contour error based on the point-to-curve distance formula. When the value is large, the estimation accuracy is also low, and the estimation algorithm obtains the distance value from the actual point to the ideal curve, not the contour error vector value

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