Abstract: To realize smooth transition from feed rate to acceleration which could reduce mechanical shock to the machine tools, and to guarantee the machining accuracy, an adaptive Non-Uniform Rational B-Spline (NURBS) curve interpolation algorithm based on S-shape acceleration/deceleration with look ahead function was proposed. According to demand of chord error, the feed rate and location parameters for each interpolation point were defined, and the changed point and constant region of speed were found. To avoid the interaction of acceleration/deceleration process between consecutive speed changed points, the changed points of each speed were analyzed based on permitted algorithm such as maximum acceleration, jerk and S-shape acceleration/deceleration, thus the key point which decided the process of acceleration/deceleration was selected. On this basis, the key point was controlled with S-shape acceleration/deceleration, and the smooth transition from feed rate to acceleration was realized. Thus the machine tools' demand was satisfied. The simulation result showed that the proposed algorithm could satisfied the requirement of high speed and high precision, and its feasibility was also verified.

Key words: non-uniform rational B-spline, feed　rate changed points, look-ahead algorithm, S-shape acceleration/deceleration algorithm

摘要： 为实现加工过程中进给速度和加速度的平滑过渡，减小其突变时对机床的冲击，更好地保证加工精度，提出一种基于S型加减速的前瞻自适应非均匀有理B样条曲线插补算法。该算法根据弓高误差的要求，确定出各插补点的自适应进给速度及位置参数，然后找出速度改变点及其等速区间。为避免相邻速度改变点间加减速过程的互相影响，分别在插补前瞻距离和预前瞻距离内，根据设备允许的最大加速度、加加速度以及S型加减速算法对各速度改变点参数进行分析，筛选出决定加减速过程的关键点，再进行S型加减速控制，使进给速度和加速度得以平滑过渡，从而满足机床加减速能力的要求。仿真结果表明，该算法能够满足高速高精度的要求，验证了其可行性。

关键词: 非均匀有理B样条, 进给速度改变点, 前瞻算法, S型加减速算法