Parallel acceleration/deceleration feedrate scheduling for computer numerical control machine tools based on bi-directional scanning technique

Abstract

The acceleration/deceleration feedrate scheduling is one of the most important techniques in computer numerical control systems. Along with this technique, the bi-directional scanning technique is always employed. The bi-directional scanning technique consists of a backward scanning process followed by a forward scanning process. The two scanning processes in the conventional methods are executed in a serial manner by scanning through all the scheduling blocks one by one. Consequently, the feedrate scheduling will suffer from a heavy computational burden when there are massive blocks to be scanned, which deteriorates its real-time performance for computer numerical control machining. To alleviate the computational burden, a parallel acceleration/deceleration feedrate scheduling approach is proposed in this article. With this method, the scheduling blocks are splitted into several scheduling units and the feedrate for each of them is scheduled simultaneously. The feasibility of the proposed approach is validated through the feedrate scheduling for two widely used butterfly and helix paths. For a constructed example of feedrate scheduling, a significant acceleration ratio about 3.7 on a personal computer with a quad-core central processing unit is achieved.