【作者】 解顺强；

【导师】 龙运佳；

【作者基本信息】 中国农业大学 ， 车辆工程， 2003， 博士

【摘要】 本文结合国家重点基础研究基金资助项目(973项目)：数学机械化与自动推理平台项目—机构学及数控技术中的数学机械化方法，和清华大学机械工程学院基金资助项目：并联机构非线性动力学特性及其关键技术，主要以清华大学和齐齐哈尔第二机床厂联合开发的一种新型混联虚拟轴机床为背景，对其进行了动力学分析；同时对虚拟轴机床中的6-SPS型Stewart平台进行了动力学建模的研究。主要内容如下： 1．将递推牛顿-欧拉动力学算法推广到更一般情况。给出了运动底座串联机器人的递推牛顿-欧拉动力学算法的两种形式。一种是不考虑连杆重力的，一种是考虑连杆重力的。得到并应用数学方法证明了这两种算法之间的关系：后一种算法可以由前一种算法通过改动初始值得到。将这种通过改动初始值的算法运用到新型混联机床的动力学分析上，结果表明该算法具有较好的计算效率。 2．从两个不同角度，建立了端铣刀动态铣削力／力矩的两个模型。并对其中一个不需重新标定的模型，取不同的铣削参数给出了动态铣削力和力矩的仿真。 3．对混联机床进行了正、反运动学分析，得到其位置、速度、加速度的解析解。 4．将混联机床看作是由串联结构和并联结构构成的。运用牛顿-欧拉方法，分别建立了并联结构各个分离体的牛顿-欧拉动力学方程；运用推广的递推牛顿-欧拉动力学算法，给出了串联结构的动力学方程。通过使用消元技巧，得到了整个机构的封闭形式的动力学逆问题公式。通过仿真得到如下结论：动平台运动所需的滑块驱动力，与动平台相对机床的对称面做其对称运动所需的另一滑块的驱动力对应相等。考虑铣削过程，对动力学逆问题公式进行了仿真。研究了铣削参数的变化对驱动力的影响。 5．从逆动力学公式出发，建立了动力学正问题模型。针对两种情况进行了正动力学仿真研究：一种是不考虑铣削过程，一种是考虑铣削过程。 6．建立了混联机床的振动模型，仿真研究了不同的铣削参数对振动特性的影响。相轨图表明振动呈现混沌特性。 7．运用图论方法，建立了6-SPS型Stewart平台的动力学方程。首先构成树形结构，并画出了系统的有向图。其次给出了关联矩阵、通路矩阵、转轴矩阵、滑移轴矩阵等量，通过运算得到了树形结构的动力学方程。结合约束方程，最后得到6-SPS型Stewart平台的动力学方程。更多还原

【Abstract】 In this dissertation, supported by the National 973 Program of China (Mathematic Mechanization and Automatic Deduction Platform-Mathematic Mechanization Method in Mechanics and Digital Control Technique) and the Mechanical Engineering School Foundation of Tsinghua University (Nonlinear Dynamic Characteristics of Parallel Mechanism and its Key Technique), dynamic analyses for a novel hybrid machine tool developed by Tsinghua University and the second machine tool factory in Qiqihaer are investigated and the dynamic modeling of 6-SPS Stewart platform is presented, the major contents are as follows:1. An iterative Newton-Euler dynamics algorithm is extended to general case. Two iterative Newton-Euler dynamics algorithms with movable base are given. The weight of each link is neglected in first case and considered in second case. The relationship between two algorithms, that is the latter can be derived by varying the initial value of the former, is derived and verified using a mathematical method. The algorithm varying the initial value of the former is applied to the dynamic analyses for the hybrid machine tool .The results show that the calculating efficiency is higher.2. Two kinds of milling force /moment models for end-milling cutter are derived respectively from two views. One of them does not need to be calibrated again. Choosing different milling parameters, milling force and moment are simulated.3. The inverse and forward kinematic analyses of the hybrid machine tool are given. The analytic solutions of displacement, velocity and acceleration for the machine tool are obtained.4. The hybrid machine tool is regarded as being composed of series and parallel structures. Using Newton-Euler approach, Newton-Euler dynamic equations for each isolated body of the parallel structure are established. The dynamic equations for the series structure are given using the extended iterative Newton-Euler dynamics algorithm. Then, a closed-form inverse dynamic formulation is derived through some elimination techniques. The simulation results show that the actuating forces required in one slider while the moving platform conducts one movement is equal to the actuating forces required in another slider while the moving platform conducts the symmetric movement about the symmetric plane of the machine tool. The inverse dynamic simulation considering milling process is carried out. The influence of milling parameters on the actuating forces is investigated.5. Based on the inverse dynamic formulation of the hybrid machine tool, the forward dynamic equations are developed. In two cases, one neglecting the milling process and the other considering it, simulations of the forward dynamics are investigated.6. The vibration model of the hybrid machine tool is established. The influence of milling parameters on vibration characteristics is investigated by simulation. Phase trajectory plots show that the vibration is chaotic.7. The dynamic equations for 6-SPS Stewart platform are established through graph theory. First,tree structure is constructed, and the oriented graph of the system is drawn. Second, the incidence matrix, entry matrix, rotation axis matrix, sliding axis matrix and so on are given. The dynamic equations of tree structure are obtained by calculating. Finally, the dynamic equations of 6-SPS Stewart platform are obtained by constraint equation.更多还原