【作者】 王辉；

【导师】 黄田；

【作者基本信息】 天津大学 ， 机械制造及其自动化， 2009， 博士

【摘要】 本文密切结合并联构型装备实用化和产业化发展的实际需求，系统研究了并联装备开放式数控系统建造中的若干关键技术，包括开放式数控系统的设计理论及开发方法、插补算法、速度控制、运动学标定技术等内容。论文取得了如下创造性成果：采用二次插补策略，分别构造了操作空间和关节空间的实时插补算法。分析了插补原理性轮廓误差在工作空间全域内的变化规律，指出在PVT插补模式下由二次插补算法引起的全域轮廓误差上界远小于数控系统本身的分辨率，能够有效满足并联构型装备实现高速高精度轨迹控制的要求。将速度过渡算法与二次插补策略综合考虑，导出了基于直线加减速的精确实时插补算法，保证了运动轨迹的精度和速度平稳性。在不影响轮廓精度的前提下，实现了多程序段间的速度平滑转接，提高了数控系统的加工运行效率。以“PC+可编程多轴运动控制器”的开放式结构为核心，构建了数控系统硬件平台。采用双端口RAM与中断通讯相结合的方式建立了主从CPU间的协调运行机制。通过构造系统内部的环形缓存实时数据流，实现了主机的多任务重叠流水处理。在此基础上，采用模块化设计思想，开发出与ISO标准兼容的数控代码解释、友好的人机交互界面和系统管理功能，以及自动、点动、手轮、回零等数控功能。以3-HSS并联机床为对象，提出一种可将影响末端可控和非可控误差的几何误差源有效分离的误差建模方法，在此基础上构造了具有分层递阶格式的几何误差参数辨识模型。提出一种采用二次激光测量有效分离末端姿态和位置误差信息的检测手段，并采用修正控制模型输入的策略实现了末端位置精度的软件补偿。计算机仿真和试验结果表明，本文提出的一整套运动学标定方法是行之有效的。样件切削试验和几何精度检测结果表明，3-HSS并联机床的精度水平已达到普通型加工中心的检验标准，数控系统运行稳定、功能完备，可满足实际加工需求，进而为并联构型装备的实用化发展奠定了良好基础。更多还原

【Abstract】 This dissertation deals with some key issues in the development of open architecture CNC system of parallel kinematic machines (PKMs), including interpolation, velocity transition, kinematic calibration and the design methodology of open architecture CNC. The following contributions have been made.Considering the kinematic characteristics of PKMs, a two-step interpolation strategy is proposed. The theoretical trajectory error due to the two-step interpolation strategy and the nonlinear mapping is estimated in the entire workspace. The simulation results show that the upper error bound of the PVT algorithm is far less than the resolution of CNC system for the moderate feed rate.On the basis of the two-step interpolation strategy and linear acceleration rule, a real-time interpolation algorithm is presented. Moreover, the velocity transition technique for the different segments is adopted to enable the machine to achieve sufficient tracking accuracy.The“PC+PMAC”architecture is employed in the development of the hardware of the open CNC system. Meanwhile, the CNC software is designed on the basis of a coordinating mechanism to enhance the communication speed between the master-slave CPUs using the techniques such as interrupt, dual-loop buffer, and real-time dataflow for multiple task handling, etc. A number of embedded modules are also developed such as human-machine interface (HMI), NC code interpreter compatible to ISO standard, Handwheel, Home, Jog, Auto, etc.Taking the 3-HSS parallel kinematic machine as an example, the error mapping function is formulated in such a way that the geometric errors affecting the compensatable and uncompensatable pose errors can be separated. Based upon the previous investigation, a hierarchical approach is proposed to implement the geometric error identification using leaser interferometer. This allows the error compensation to be carried out by modifying the trajectory commands resided in the CNC system. The simulation and experiment results verify the validity and effectiveness of the proposed approach.A real cutting experiment has been carried out on the 3-HSS parallel machine tool. The metrological results show that the accuracy in terms of both dimensions and geometry is fairly good in comparison with the conventional milling machines.更多还原