Abstract:

A non-uniform rational B-spline (NURBS) parametric curve interpolation and S-shape acceleration／deceleration (ACC／DEC) algorithm for the CNC machine tool were studied. In the proposed algorithm, the commanded velocity was maintained at most of the time and adaptively reduced in large curvature areas to meet the demand ofthe machining accuracy requirement. In addition, an S-shape look ahead algorithm was proposed to limit the acceleration and jerk values within the machine’s capabilities during the whole interpolation process, which could  reducemechanical shock to the machine tools. The real time performance of this interpolator wasalso measured to demonstrate its practical application. A NURBS curve interpolation result was provided to verify the feasibility and advantages of the proposed algorithm.

Key words: non-uniform rational B-spline; S-shape acceleration／deceleration algorithm; look-ahead algorithm; CNC interpolate