Kinematic corner smoothing for high speed machine tools

Abstract This paper presents a novel kinematic corner smoothing technique for high-speed CNC machine tools. Typically, reference tool-paths compromised of short G01 moves are geometrically smoothed by means of arcs and splines within the NC system. In this study, a continuous feed motion is generated by directly planning jerk limited velocity transitions for the drives in the vicinity of sharp corners of the tool-path. This approach completely eliminates the need for geometry based path smoothing and feed planning. Contouring errors at sharp corners are controlled analytically by accurately calculating cornering speed and duration. Since proposed approach bases on kinematically planning axis motion profiles, it exploits acceleration and jerk limits of the drives and delivers a near-time optimal motion. Experimental validation and comparisons are presented to show significant improvement in the cycle time and accuracy of contouring Cartesian tool-paths.

[1]  Michele Heng,et al.  Design of a NURBS interpolator with minimal feed fluctuation and continuous feed modulation capability , 2010 .

[2]  C. Okwudire,et al.  Minimum-time cornering for CNC machines using an optimal control method with NURBS parameterization , 2016 .

[3]  Manfred Weck,et al.  Sharp Corner Tracking Using the IKF Control Strategy , 1990 .

[4]  Pascal Ray,et al.  Bspline approximation of circle arc and straight line for pocket machining , 2010, Comput. Aided Des..

[5]  Eiji Shamoto,et al.  A curvature optimal sharp corner smoothing algorithm for high-speed feed motion generation of NC systems along linear tool paths , 2014, The International Journal of Advanced Manufacturing Technology.

[6]  Rida T. Farouki,et al.  High-speed cornering by CNC machines under prescribed bounds on axis accelerations and toolpath contour error , 2012 .

[7]  Meng-Shiun Tsai,et al.  A novel integrated dynamic acceleration/deceleration interpolation algorithm for a CNC controller , 2016 .

[8]  Yusuf Altintas,et al.  Feedrate Optimization for Spline Interpolation In High Speed Machine Tools , 2003 .

[9]  Yusuf Altintas,et al.  Local toolpath smoothing for five-axis machine tools , 2015 .

[10]  Rida T. Farouki,et al.  Algorithms for time-optimal control of CNC machines along curved tool paths , 2005 .

[11]  Masayoshi Tomizuka,et al.  Trajectory planning for coordinated motion of a robot and a positioning table. II. Optimal trajectory specification , 1990, IEEE Trans. Robotics Autom..

[12]  Pierre Bourdet,et al.  A new format for 5-axis tool path computation, using Bspline curves , 2004, Comput. Aided Des..

[13]  Li Bing Zhang,et al.  The transition algorithm based on parametric spline curve for high-speed machining of continuous short line segments , 2011 .

[14]  Brian A. Barsky,et al.  Approximately Arc-Length Parametrized C3 Quintic Interpolatory Splines , 1999 .

[15]  Yusuf Altintas,et al.  High speed CNC system design. Part I: jerk limited trajectory generation and quintic spline interpolation , 2001 .

[16]  Eiji Shamoto,et al.  High speed cornering strategy with confined contour error and vibration suppression for CNC machine tools , 2015 .

[17]  Xavier Beudaert,et al.  5-axis local corner rounding of linear tool path discontinuities , 2013 .

[18]  R. Bryan Greenway,et al.  Development and implementation of a NURBS curve motion interpolator , 1998 .

[19]  M. Tsai,et al.  Development of a dynamics-based NURBS interpolator with real-time look-ahead algorithm , 2007 .

[20]  Les A. Piegl,et al.  The NURBS Book , 1995, Monographs in Visual Communication.

[21]  Yoram Koren,et al.  Five-axis surface interpolators , 1995 .

[22]  Pau-Lo Hsu,et al.  Perfectly Matched Feedback Control and Its Integrated Design for Multiaxis Motion Systems , 2004 .

[23]  Pierre-Jean Barre,et al.  Influence of a Jerk Controlled Movement Law on the Vibratory Behaviour of High-Dynamics Systems , 2005, J. Intell. Robotic Syst..

[24]  H. Ding,et al.  A real-time look-ahead interpolation methodology with curvature-continuous B-spline transition scheme for CNC machining of short line segments , 2013 .

[25]  Zhixiao Wang,et al.  Trajectory planning for coordinated motion of a robot and a positioning table. I. Path specification , 1990, IEEE Trans. Robotics Autom..

[26]  Han Ding,et al.  A Practical Continuous-Curvature Bézier Transition Algorithm for High-Speed Machining of Linear Tool Path , 2011, ICIRA.

[27]  Yusuf Altintas,et al.  Virtual CNC system. Part II. High speed contouring application , 2006 .

[28]  Y. Altintas,et al.  Quintic Spline Interpolation With Minimal Feed Fluctuation , 2005 .