3D打印机G代码预处理优化算法

为了突破现有3D打印机控制系统原有的文件处理模式的限制，提出将G代码程序在PC端先行预处理的方法。在程序预处理过程中，同时对多段微小线段进行前瞻控制和速度规划；预处理结束后，再将处理结果输入3D打印机执行打印操作。该方法减少了3D打印机处理器负担，且通过PC端预处理可以得到更优化的计算结果。实验测量数据证明：G代码预处理方法与传统G代码处理方法相比，节省了打印机处理器处理时间，同时提高了打印品质。     

Smooth feedrate planning for continuous short line tool path with contour error constraint

In the machining program for free form surfaces, the tool path is usually represented as continuous short lines. For the computer numerical control, the feedrate profile for short line tool path should be smooth and optimized in order to achieve high machining quality and high speed. In high speed machining, the feedrate profile also has a strong influence on contour accuracy. This paper presents a new real-time smooth feedrate planning algorithm for short line tool path, in which the contour error constraint is included. To realize contour error control, the feedrate is adaptively adjusted based on the curvature radius of the tool path, which is directly estimated from the short lines. The 7-phase jerk-limited look-ahead planning is employed to generate a smooth feedrate profile. The target feedrate filter (TFF) and planning units merging techniques are developed to improve the smoothness of the feedrate profile and reduce the overhead on look-ahead. The advantage of the proposed algorithm is that it is not only convenient to achieve the balance among accuracy, smoothness and productivity by adjusting parameters, but also efficient in design, which makes it possible to be implemented on low cost hardware platforms. Experiment results demonstrate the feasibility of the proposed algorithm on smooth feedrate planning and contour error control for continuous short line tool path.     

基于干涉预处理的NURBS曲线前瞻插补算法

鉴于直接自适应插补容易在加工过程中引起较大的速度波动,而按曲率极值点对NURBS曲线进行分段插补造成加减速过程中加速度和加加速度超限,提出一种基于干涉预处理的非均匀有理B样条曲线前瞻控制插补算法。首先对曲线进行自适应处理,得到各自适应插补点的运动参数;然后找出其中加速度或加加速度超限的点(即危险点),并对这些点的速度进行前瞻控制,根据前瞻控制信息对相邻危险点进行干涉处理,最终得到用来对曲线分段的危险点信息和相应的控制策略;最后根据各危险点之间的干涉类型对曲线进行实时插补。仿真实验表明,该算法能够在保证加工精度的前提下,实现进给速度的平滑过渡,并且能够保证加速度和加加速度不超限。     

A Look-Ahead Routing Procedure for Machine Selection in a Highly Informative Manufacturing System

Many dispatching rules have been developed for the on-line control of product flow in a job shop. The introduction of a highly informative manufacturing system (HIMS) has added a new requirement to a classical job-shop control problem: the selection of machines by parts of different types. An HIMS can keep a great deal of information on the status of the system, such as information on what is scheduled in the near future with great accuracy, which can be used for shop floor control. For example, the knowledge of the time when the next parts arrive at the machines can be used for better routing. This article tests the effect of the use of this knowledge for part routing on the part's flow time and tardiness under a look-ahead routing procedure (LARP). LARP assigns a new part to a machine so that the assignment minimizes the flow time or tardiness of the current part and the next N parts arriving after the current part. A test shows that the reduction of part flow time is up to 11% and the reduction of tardiness is up to 21% for the cases with this procedure.     

高速高精度CORDIC处理器的ASIC实现

针对数字信号处理领域复数运算的要求,实现了一种16位高速高精度复数运算的通用CORDIC处理器。电路采用半定制设计流程,在200M时钟频率下通过Nanosim后仿真表明,电路达到了高速高精度的设计要求。可广泛应用于雷达、信号处理、通信等涉及到复数运算的领域。     

有功调度超前控制和在线水火电协调控制策略

根据有功调度不同的调度时间段，探讨了利用超短期负荷预测结果实现超前控制的可能性，并对应每个调度时间段建立数学模型;具体实施上，针对不同区域电网间调节资源的差异，以及同一区域内机组构成方式经常变更的特点，提出水火电机组协调控制理想的解决构架，作为现有控制性能标准（CPS）控制策略实际运用的补充。其有效性已在多个实际电网工程实践中得到检验。     

一种优化的NURBS曲线插补算法

为弥补目前非均匀有理B样条插补算法的不足,提出一种优化的非均匀有理B样条曲线插补算法。算法采用插补前S曲线加减速方法,不仅优化了前瞻过程,而且在回溯过程中考虑了短样条的情况。算法对长样条和短样条非均匀有理B样条曲线能用统一的方法进行插补,通过引入环形缓冲区和预插补(非离线),提高了加工效率,同时合理地安排插补任务增强了系统的实时性。通过MATLAB仿真,验证了算法的有效性。     

字符二维码的编码模式选择算法

字符二维码的编码通过针对特定字符集划分模式来编码, 各个模式之间需要转换以达到最高的编码效率. 首先研究DataMatrix国际标准“向前检验”算法, 发现“向前检验”算法具有局限性, 并不能直接应用与字符二维码的模式选择. 因此, 本文在“向前检验”的基础上, 结合了多阶段决策方法的原理, 引入混合模式计数的方法, 提出了一种字符二维码的“向前检验”算法, 并应用于字符二维码的模式选择. 实验表明, 该算法有效的进行了字符二维码的模式选择, 很好的解决字符二维码的模式选择问题.     

高速加工中速度前瞻控制新算法研究

为了避免在高速加工中高曲率轮廓导致的工件过切和机床的异常振动，提出了一种实时的速度前瞻软件控制新算法.该算法基于S型加减速方案，通过采用三次样条曲线拟合对离散加工路径的分析发现高曲率点，根据加减速特性预估高曲率点处的最优速度，最后对加工路径施加相应的运动学曲线规划，实现了加工速度自适应于加工路径的变化.应用该算法使得加工速度变化平稳，较之传统控制方法大大提高了加工效率.