Global Toolpath Smoothing and Interpolation Based on Time-Parametrized B-Spline Optimization

Toolpath smoothing is essential for CNC machining to achieve high machining efficiency and quality. To generate smooth trajectories with high efficiency, a global toolpath smoothing and interpolation method is proposed in this paper. Time-parametrized B-spline curve is adopted, so that the convex hull property can be used to make trajectories satisfy the geometric and kinematic constraints. B-spline trajectories with C2 continuity are initially constructed based on the reference points extracted through kinematic corner smoothing. Then, the B-splines are optimized and stitched into an entire trajectory to improve the smoothness. The knot spans of the B-spline trajectory are finally adjusted to achieve high motion efficiency and eliminate constraint violation. Simulations have been conducted to validate the effectiveness of the proposed method. The proposed method shows significant advantage in controlling jerk maximum and improving trajectory smoothness over a local smoothing method based on finite impulse response (FIR) filter. In addition, the proposed method reduces the total duration time by 16.14%, which greatly improves the efficiency.