GA-based time-optimal feedrate scheduling on NURBS tool path with geometric and drive constraints

The feedrate scheduling with consideration of the geometric and drive constraints is of great importance to minimize the machining time in high-speed and high-precision machining. In this study, a time-optimal feedrate scheduling method is proposed for the parametric interpolation of a non-uniform rational B-splines (NURBS) tool path to improve the machining efficiency. First, the feedrate profile is represented by a smooth B-spline curve. Afterward, the feedrate optimization model on the basis of the genetic algorithm (GA) is developed considering the chord error, tangential kinematic, and drive constraints. The unknown variables, i.e., the knot vector and control points of the B-spline feedrate profile, are determined alternately during a progressive knot insertion process. To improve the computational efficiency, a splitting method is put forward to break down the feedrate optimization problem into a set of small and independent parts for parallel computing. Finally, the split feedrate segments are combined and further optimized to generate a global time-optimal B-spline feedrate profile. The GA-based feedrate scheduling method is conveniently reconfigurable and extendable, i.e., the constraints can be relaxed or tighten easily according to the machining requirements. The effectiveness and superiority of the proposed method are validated by several practical implementations.