【作者】 王海涛；

【导师】 赵东标；

【作者基本信息】 南京航空航天大学 ， 机械工程， 2011， 博士

【摘要】 数控技术作为支持现代装备制造业的关键性技术，对航空航天、汽车、轮船等制造业的发展起着重要作用，对制造装备的功能和性能起决定性作用。数控加工中加工路径的尖锐拐角及高曲率容易引起过切、机床震动和数据饥饿等现象，严重影响加工质量和加工速度。本课题提出的数控加工速度前瞻控制算法能够自动分析加工路径，发现并处理路径危险点，对速度轨迹提前规划，实现速度的平滑过渡，防止过切等现象，能有效保证较高的加工效率及加工精度。本文在江苏省自然科学基金（招标）项目（No.BK2003005）、国家自然科学基金(No.51005122)和航空基金(No.2008ZE52049)的资助下，系统研究了前瞻控制中的加减速算法、连续微小线段的自适应前瞻控制策略、以及参数曲线的前瞻控制方法并且探讨了NURBS曲线的S型加减速前瞻控制策略。论文的主要工作如下：在前瞻控制算法的组成构架中，加减速算法作为研究的基础，本文首先建立了数控前瞻控制中的加减速算法的通用模型，系统分析了前瞻中加减速算法中位移、速度、加速度等变化量，并且充分考虑了前瞻时速度轨迹和实际加工速度轨迹之间的误差，提出了一种实际加工中的速度误差修正方法，使实际加工速度严格按照前瞻时的轨迹进行，为以后研究各种曲线的前瞻控制奠定了基础。针对目前数控加工常用的将曲线离散成微小线段的加工方法，提出了一种针对连续微小线段的自适应前瞻控制方法。首先通过分析微小线段衔接处的速度约束条件，确定其衔接处的最优速度，并且根据实际加工路径曲率自适应的确定前瞻距离。通过优化控制策略，最大程度减少了迭代计算。针对参数曲线的加工特点，提出了一种参数曲线的前瞻控制算法。此算法根据参数曲线的曲率自适应地调整插补速度，并且根据相邻插补点的速度差值分析加工路径上的速度敏感点，通过比较分析速度敏感点，在前瞻路径上对速度进行统一加减速规划，在满足机床加减速性能的同时，提高了加工表面质量和加工效率。在分析参数曲线前瞻控制的基础上，针对目前复杂曲面中常用的NURBS曲线，探讨了一种NURBS曲线的S型加减速前瞻控制策略。通过分析曲率上升和下降区域近似找出速度敏感点，并且针对NURBS曲线和S型加减速计算的复杂性，在频繁加减速的区域用更为简便的三角函数方法统一规划加减速，减少速度的频繁变化和系统的计算量，保证加工的实时性。实验结果表明，所提出的数前瞻控制策略能够有效规划加减速路径，在满足机床性能的基础上，提高加工质量和加工效率。更多还原

【Abstract】 Numerical control technology is the critical technology of modern equipment manufacturingindustry, which plays an important role in aviation, marine, automobile and other projects. Itdetermines the function and performance of manufacture equipment. Overshooting, mechanicalharmful vibrations and data starvation directly impact on the maching quality. This paper proposed alook-ahead algorthm that can analyze tool path, find dangerous points and deal with sensitivesituations in machining automatically. This method can guarantee speed change smoothly andimprove machining efficiency and machining quality.Supported by natural science fundation of Jiangsu province (No.BK2003005), National NaturalScience Foundation of China (No.51005122)and Aeronautical Science Foundation of China (No.2008ZE52049), this dissertation places emphases on acceleration and deceleration algorithm,consecutive line blocks look-ahead algorithm, and an adaptive parametric look-ahead interpolationalgorithm. And an S shape acceleration and deceleartion for the NURBS look-ahead algorithm alsohas been reaseached in the dissertation.In terms of configuration of look-ahead algorithm, the basic is acceleration and declelerationalgorithm. By analyzing the acceleration and decleration mathematical model in the look-aheadalgorithm, the ralationship between the speed, acceleration and decleration distance can be determined,that laies a foundation for the look-ahead algorithm.At present, in most CNC system the tool path is discreted consecutive line blocks. So theconsective look-ahead algorithm is proposed in the paper. By presenting the mathematical modeladjust the velocity automatically to achieve maximum in machining of consecutive line blocks withhigh speed, and the high curvature points are found according the speed. Then the optimal look-aheadblocks and velocity characteristic are estimated. Then the algorithm can make velocity changingsmoothly.Then a look-ahead interpolation algorithm for parametric curves is studied. This method improvedthe machining accuracy and detected the sensitive points by confining the chord error in a limitedrange. Through dividing look-ahead distance into two parts, sensitive points were analyzed, acontinuous velocity and accelerating profile were found out which reduced the jerk relate problem.This satisfied not only machining accuracy but also acceleration and deceleration performace ofmachine tools.Based on the parametric curves look-ahead algorithm, the NURBS look-ahead algorithm based on S shape is researched. By dividing the curve into curvature increased segment and curvaturedecreased segment according to he different curvature movement and re-planning the velocity curvesin the velocity changing frequently tool path to reduce computation. This algorithm can meet the realtime requirements to look ahead in CNC system.The experimental results are provided to verify the feasibility and precision of the proposedinterpolation algorithm. The machining qualitiy and efficiently are greatly improved.更多还原