The velocity smooth control method based on NURBS curve interpolation

According to the properties of non-uniform rational B-spline(NURBS) interpolation and space vector theory, a method of vector transfer based on the five phased S-curve acceleration and deceleration was developed, which aimed at the complex algorithm of the seven phased S-curve and the shortages of current velocity smooth control method. The proposed approach was designed to satisfy the requirements of NC machining with high-speed and high-accuracy. The NURBS curve theory and the principle of interpolation based on the speed control was taken firstly, and velocity and step length on account of the chord error were analysed. Then the principle of vector transfer based on the five phased S-curve acceleration and deceleration was analysed in detail, and also the relationships between machine contour error and the maximum speed allowed at path switching was discussed. Simulation result of a practical example demonstrated that on the premise of satisfying the accuracy and simplifying algorithm, the method can not only ensure the continuous acceleration and avoid flexible impact, but also can realize smooth transfers along a continuous segment trajectory.