Real-time variable feed rate NURBS curve interpolator for CNC machining

Authors: Cheng, C.-W.¹; Tsai, M.-C.²

Source: The International Journal of Advanced Manufacturing Technology, Volume 23, Numbers 11-12, June 2004 , pp. 865-873(9)

Publisher: Springer

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Abstract:

This paper presents a real-time control algorithm based on Taylor's expansion for implementing variable feed rate non-uniform rational B-spline (NURBS) curve interpolators using a digital signal processor for precision CNC machining. To efficiently compute the NURBS curve and its derivatives in real-time, an effective method is proposed. The variable feed rate NURBS curve interpolator can be used to realise the ACC/DEC before feed rate interpolation in which the ACC/DEC (acceleration/deceleration) planning on the feed rate command executes before the interpolation takes place, so that the path command errors caused by conventional ACC/DEC planning using the post feed rate interpolation can be effectively eliminated. To demonstrate the performance of the proposed algorithm, an X-Y table driven by two servomotors is controlled to track command paths represented by multiple blocks of NURBS curves. Experimental results verify the effectiveness of the proposed method.

Keywords: Variable feed rate; NURBS curve; Interpolator; CNC; DSP

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s00170-003-1732-9

Affiliations: 1: Department of Mechanical Engineering, National Cheng Kung University, Tainan 701, Taiwan ROC, 2: Department of Mechanical Engineering, National Cheng Kung University, Tainan 701, Taiwan ROC, Email: mctsai@mail.ncku.edu.tw

Publication date: 2004-06-01