| CNC interpolation algorithm is one of the most important part in CNC controller, which influences the machining accuracy and efficiency. The traditional tool-path smoothing algorithm can not guarantee the tool-path have G~2 continuity and meet real-time processing requirements at the same time. Under consideration of ensuring the G~2 continuity, this paper research a sectional fitting algorithm, improving the machining efficiency and quality.The paper proposes a interpolation scheme for short line segments based on B-spline blending strategy, it is a sectional fitting algorithm, dividing the tool-path into many look-ahead blocks by look-ahead break point, and then fitting each look-ahead block until generate the whole tool-path. Without considering chord error and shape-preservation, we generate the initial C~2 continuity Bezier path and then detect the defective segments in the initial path.Based on various constraint conditions of CNC machining, the paper propose a blending algorithm based on B-spline to adjust the defective segments. After this blending algorithm adjust the defective segments, the whole tool-path have G~2 continuity, is rigidly shape-preserving and under confined chord error.Considering the demand of real-time processing, the blending algorithm, inverse matrix operations and matrix multiplication of this algorithm is optimized, improving the algorithm efficiency, shortening the running time and implementing the paper’s sectional fitting scheme in real time.Based on the study above, simulation experiment and actual verification have been done to analyze the generated tool-path whether meet various constraints, testing time performance and get the synthetic velocity, acceleration and jerk. Experiment results show that the tool-path generated by this algorithmis more smooth, speed curve is more smooth, and reduces the amplitude of synthetic acceleration and jerk, improve the surface quality of the parts. |
