A universal velocity profile generation approach for high-speed machining of small line segments with look-ahead

摘要

Usually a complex contour-machining program generated by CAD/CAM systems composes a lot of small line segments. The intelligence of look-ahead is key to meeting the demand of high speed and high accuracy in the machining of these line segments. By now most researchers just utilize the simplest trapezoidal velocity profiles to deal with the look-ahead problem. Also the number of look-ahead line segments in most commercially available CNC systems is fixed, which cannot make full use of CNC processors. Therefore, a universal velocity profiles generation approach and corresponding optimal look-ahead algorithm based on dynamic back tracking along a doubly linked list are proposed in this paper. Two novel strategies, one for reducing feed rates fluctuation and the other for reducing move errors that come from digital integration and accumulated computation, are also presented. By using the proposed look-ahead techniques, arbitrary velocity profiles having the desired acceleration and deceleration characteristics for the movement of a lot of small line segments can be generated efficiently. Thus, the machining productivity can be dramatically increased without sacrifice of accuracy. The results of simulations and experiments showed the proposed approach was feasible and effective.