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.

A real-time predictor-modification-evaluation–corrector-modification-evaluation parametric interpolator for numerical control transition curves

“…The approximation error ε is 1 mm, and the number of line segments k in each window is 5. The maximum feedrate, the maximum acceleration, and the maximum jerk are 0.05, 0.001, 2 and 0.001 mm/ms, 3 respectively. First, with the smoothing module, a smooth tool path, composed of the solid blue lines and the dotted red lines in Figure 7(b), is generated.…”

“…2 With this method, a smooth tool path with curvature continuity is achieved. Then, an acceleration/deceleration (ACC/ DEC) scheduling 3 and a look ahead scheme 4 are implemented simultaneously to generate the corresponding feedrate profile in real time. Based on the tool path and feedrate profile, a series of reference points are generated by the interpolator, 5 and the reference points guide the NC machining along with the path.…”

Linear programming feedrate optimization

“…A method of bi-directional scan was presented in [14,15], and applied in multiple subsequent works [16][17][18]. As the name suggests, the main idea of the method lies in combination of a forward and backward pass (or scan) of the toolpath.…”

Look-ahead-window-based interval adaptive feedrate scheduling for long five-axis spline toolpaths under axial drive constraints

“…Scheduling of the appropriate feedrate is acknowledged as one of the most important tasks in computer numerical control (CNC) machining to achieve favorable machining quality and efficiency. 1–3 This is because of the fact that too low feedrate results in inefficiency feed motion, while too high feedrate may lead to the axial drive limitations being exceeded, which not only goes against the machining quality but also makes damage to the machine tools possibly. 4 One can schedule constant feedrate with initial launching and final braking for routine linear or circular toolpaths, while for free-form spline toolpaths, it is no longer suitable because the variable geometry within one spline toolpath requires different axial drive capabilities.…”