为了提高复杂自由曲线数控加工的效率和精度,采用NURBS曲线拟合加工曲线,建立其曲率半径计算数学模型,针对自由曲线曲率半径变化范围大的特点,提出一种冗余误差控制NURBS曲线插补算法与模糊推理运算相结合的进给速度确定新方法.经MATLAB环境下进给速度插补过程仿真,并与冗余误差控制进给速度插补算法、弓高误差控制自动调节速度插补算法比较,结果表明:该方法可根据自由曲线的曲率半径及其变化率值经模糊推理方法确定出合适的进给速度以提高加工效率,并能使弓高误差不超出最大允许值以保证加工插补精度.
In order to improve the efficiency and accuracy of numeric control machining of free curve,NURBS curve was employed to fit the processed curve,and a mathematical model for calculating the curve radius was established.Considering the huge variation of free curve radius,a new method which combined fuzzy inference operation and NURBS interpolation operation of the auto-controlled feeding speed was proposed.The results of the experiment in the Matlab environment,show that comparing with the adaptive feeting speed interpolation algorithms based on redundancy error or arch height error,the method improves the processing efficiency by using fuzzy inference to determine the proper feeding speed according to the radius of free curve and its change rate,and ensures that the error of arch height will not exceed the maximum permissible value so that the interpolation accuracy can be ensured.