Abstract
The problem of high-speed traversal of sharp toolpath corners, within a prescribed geometrical tolerance 𝜖, is addressed. Each sharp corner is replaced by a quintic Pythagorean–hodograph (PH) curve that meets the incoming/outgoing path segments with G 2 continuity, and deviates from the exact corner by no more than the prescribed tolerance 𝜖. The deviation and extremum curvature admit closed-form expressions in terms of the corner angle 𝜃 and side-length L, allowing precise control over these quantities. The PH curves also permit a smooth modulation of feedrate around the corner by analytic reduction of the interpolation integral. To demonstrate this, real-time interpolator algorithms are developed for three model feedrate functions. Specifying the feedrate as a quintic polynomial in the curve parameter accommodates precise acceleration continuity, but has no obvious geometrical interpretation. An inverse linear dependence on curvature offers a purely geometrical specification, but incurs slight initial and final tangential acceleration discontinuities. As an alternative, a hybrid form that incorporates the main advantages of these two approaches is proposed. In each case, the ratio \(f=V_{\min }/V_{0}\) of the minimum and nominal feedrates is a free parameter, and the improved cornering time is analyzed. This paper develops the basic cornering algorithms—their implementation and performance analysis are described in detail in a companion paper.
Similar content being viewed by others
References
Bronshtein IN, Semendyayev KA, Musiol G, Muehlig H (2004) Handbook of mathematics, 4th edition. Springer, Berlin
Ernesto CA, Farouki RT (2012) High-speed cornering by CNC machines under prescribed bounds on axis accelerations and toolpath contour error. Int J Adv Manuf Tech 58:327–338
Farouki RT (1994) The conformal map \(z \rightarrow z^{2}\) of the hodograph plane. Comput Aided Geom Design 11:363–390
Farouki RT (2008) Pythagorean-hodograph curves: algebra and geometry inseparable. Springer, Berlin
Farouki RT, Manjunathaiah J, Jee S (1998) Design of rational cam profiles with Pythagorean-hodograph curves. Mech Mach Theory 33:669–682
Farouki RT, Manjunathaiah J, Nicholas D, Yuan G-F, Jee S (1998) Variable feedrate CNC interpolators for constant material removal rates along Pythagorean–hodograph curves. Comput Aided Design 30:631–640
Farouki RT, Manjunathaiah J, Yuan G-F (1999) G codes for the specification of Pythagorean–hodograph tool paths and associated feedrate functions on open–architecture CNC machines. Int J Mach Tools Manuf 39:123–142
Farouki RT, Rajan VT (1988) Algorithms for polynomials in Bernstein form. Comput Aided Geom Design 5:1–26
Farouki RT, Sakkalis T (1990) Pythagorean hodographs. IBM J Res Develop 34:736–752
Farouki RT, Shah S (1996) Real-time CNC interpolators for Pythagorean–hodograph curves. Comput Aided Geom Design 13:583–600
Nittler KM, Farouki RT (2015) Efficient high-speed cornering motions based on continuously–variable feedrates. II. Implementation and performance analysis, preprint
Sencer B, Ishikazi K, Shamoto E (2015) A curvature optimal sharp corner smoothing algorithm for high–speed feed motion generation of NC systems along linear tool paths. Int J Adv Manuf Tech 76:1977–1992
Shi J, Bi QZ, Wang YH, Liu G (2014) Development of real-time look-ahead methodology based on quintic PH curve with G 2 continuity for high–speed machining. Appl Mech Mater 464:258– 264
Shi J, Bi Q, Zhu L, Wang Y (2015) Corner rounding of linear fixed-axis tool path by dual PH curves blending. Int J Mach Tools Manuf 88:223–236
Šír Z, Jüttler B (2005) Constructing acceleration continuous tool paths using Pythagorean hodograph curves. Mech Mach Theory 40:1258–1272
Šír Z, Wings E, Jüttler B (2007) Rounding spatial G code tool paths using Pythagorean hodograph curves. Trans ASME J Comput Inf Sci Eng 7:186–191
Tsai Y-F, Farouki RT (2001) Algorithm 812: BPOLY: an object-oriented library of numerical algorithms for polynomials in Bernstein form. ACM Trans Math Software 27:267– 296
Tsai Y-F, Farouki RT, Feldman B (2001) Performance analysis of CNC interpolators for time-dependent feedrates along PH curves. Comput Aided Geom Design 18:245–265
Walton DJ, Meek DS (2009) G 2 blends of linear segments with cubics and Pythagorean–hodograph quintics. Int J Comput Math 86:1498–1511
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Farouki, R.T., Nittler, K.M. Efficient high-speed cornering motions based on continuously-variable feedrates. I. Real-time interpolator algorithms. Int J Adv Manuf Technol 87, 3557–3568 (2016). https://doi.org/10.1007/s00170-016-8740-z
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00170-016-8740-z