NURBS曲线S形加减速寻回实时插补算法

发布时间：2018-05-02 03:13

本文选题：NURBS运动控制 + 实时插补　；参考：《机械工程学报》2017年03期

【摘要】：针对高速高精加工中传统的NURBS算法沿曲线方向进行单一插补时,曲线的弧长与参数之间无精确的解析关系、进给速度又总是受到非线性变化的曲线曲率约束,导致基于S型加减速进行NURBS插补时,曲线长度的实时计算以及对减速点的预测十分困难,无法获得曲线余下部分的速度约束信息,而且在进行实时插补的过程中可能出现计算负荷过大、导致数据饥饿的现象,影响整个系统的实时性。针对以上问题,提出了一种寻回插补实时算法。该算法不依赖于曲线弧长的精确计算,采用正向与反向同步插补的方法。在前瞻插补模块中先对曲线进行逆向插补,确定正反向插补的校验点,以及正向插补所需的相关信息;在实时插补模块中,通过对比校验点的速度,判断是调用逆向插补的数据还是继续进行正向插补,从而实现满足速度约束条件的最优插补。该算法无须求解高次方程并可以保证以确定的速度通过曲率极值点和曲线终点,很好地保证了插补过程中的实时性。通过插补实例证明了算法简单高效、适应性以及实时性好,能够满足高速高精度数控加工的要求。
[Abstract]:When the traditional NURBS algorithm is interpolated along the curve direction in high speed and high precision machining, there is no exact analytical relation between the arc length and the parameters of the curve, and the feed speed is always constrained by the nonlinear curve curvature. As a result of NURBS interpolation based on S-type acceleration and deceleration, the real-time calculation of curve length and the prediction of deceleration point are very difficult to obtain the velocity constraint information of the rest of the curve. Moreover, in the process of real-time interpolation, the calculation load may be too large, resulting in the phenomenon of data starvation, which affects the real-time performance of the whole system. In order to solve the above problems, a real-time algorithm of retrieval interpolation is proposed. This algorithm does not depend on the accurate calculation of curve arc length, and adopts the method of forward and reverse synchronous interpolation. In the forward interpolation module, the curve is first inversely interpolated to determine the calibration points of forward and backward interpolation, and the relevant information needed for forward interpolation. In the real-time interpolation module, the speed of calibration points is compared. It is judged whether to call the data of reverse interpolation or to continue the forward interpolation so as to realize the optimal interpolation that satisfies the speed constraint condition. The algorithm does not need to solve the higher order equation and can guarantee the real time of interpolation process through the curvature extremum and the end point of the curve at a certain speed. The interpolation example shows that the algorithm is simple, efficient, adaptive and real-time, and can meet the requirements of high-speed and high-precision NC machining.
【作者单位】：哈尔滨理工大学机械动力工程学院;
【基金】：国家自然科学基金重点资助项目(51235003)
【分类号】：TG659

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