【作者】 陈闯；

【导师】 黄田； 王辉；

【作者基本信息】 天津大学 ， 机械制造及其自动化， 2013， 博士

【摘要】 本文密切结合一种用于大型铝合金结构件高速加工的新型三坐标动力头——A3头的高速高精度控制问题，系统研究了该动力头的运动学建模、轨迹插补算法、数控系统开发、动力学参数辨识与力矩控制等关键技术，论文取得如下创造性成果：(1)采用矢量链法建立了A3头的位置、速度和加速度模型，并构造出刀具欧拉角与A/B轴转角、角速度和角加速度间的映射关系，为后续的轨迹规划及动力学辨识与力矩控制提供了必要的模型。(2)针对所选用开放式数控系统的特点，研究了基于二次插补策略的轨迹插补方法。基于线性加速度运动规律和坐标轴分解原理，系统研究了点矢同步插补算法。针对刀具绕参考点作定点转动的情况，提出通过设置第二进给速率实现刀具矢量插补的算法，有效提高了插补过程中的计算效率。(3)提出基于工控机+可编程多轴运动控制器的开放式数控系统总体架构，并结合A3头外围设备的逻辑控制要求，搭建系统硬件平台。利用层次化设计思想，提出适合五轴联动数控加工的数控系统软件体系架构，并在LabVIEW环境中开发出控制系统软件平台的主要功能模块，有效地提高了软件工作效率与系统可靠性。(4)在运用虚功原理建立A3头刚体动力学模型的基础上，构造出系统动力学参数辨识模型。考虑A3头本身的结构特点及待辨识参数对其动力学特性的影响差异，提出一种分层递阶的辨识策略，通过适当的轨迹规划，有效消除或抵消库仑摩擦对辨识结果的影响，进而提高了动力学参数的辨识精度。通过在不同工况下的试验，验证了所提出辨识方法的正确性和有效性。(5)以动力学参数辨识结果建立力矩补偿模型，在单轴PD伺服控制算法的基础上，提出一种基于粗插补信息的动力学前馈控制方法。实验结果表明，相较单轴运动学控制，这种控制策略可有效降低关节伺服轴的跟随误差。上述工作为基于A3头的新型五轴高速加工装备的研发和实用化发展奠定了坚实的技术基础。更多还原

【Abstract】 This dissertation deals with the key issues of high-speed and high-precisioncontrol of a novel3-DOF PKM (parallel kinematics machine) module named the A3head which is employed for large aluminum structural components high-speedmachining, covering a complete spectrum in terms of kinematic modeling, trajectoryinterpolation, development of CNC system, dynamic identification and torque controlmethod. The following contributions have been made.(1) By means of vector chain method, the kinematic models of the A3head areformulated for position, velocity and acceleration analyses. The mapping relationsbetween Euler angles and A/B angles are established in terms of angular position,angular velocity and angular acceleration. The above work provides necessarymathematical models for trajectory planning and torque control.(2) According to the characteristics of the open CNC system, the trajectoryinterpolation is studied on the basis of two-step interpolation strategy. Based on thelinear acceleration profile and the coordinate axis decomposition principle, thepoint-vector synchronous interpolation algorithm is studied systematically. Aiming atthe situation of tool rotating around the reference point, the vector interpolationalgorithms is accomplished by setting of the second feedrate, which improve theeffectiveness of interpolation computation.(3) Based on “IPC+Turbo PMAC” architecture, an open CNC systemframework of the A3head is proposed. Integrated with various peripheral equipments,the hardware platform is constructed. Adopting the modularization and hierarchydesign idea, the software architecture for five-axis machining is proposed andessential functions are developed in the circumstance of LabVIEW.(4) With the aid of the virtual work principle, the inverse dynamic model isformulated, allowing the model suitable for dynamic parameter identification to beestablished. Considering the characteristics of the load torques under differentworking conditions, a hierarchical strategy is proposed for dynamic parameteridentification. The merit of this strategy lies in that it enables the influences due to theCoulomb frictions to be counteracted or eliminated via proper path planning, therebythe identification accuracy to be significantly improved. The experiments under different working conditions are carried out to verify the validity and effectiveness ofthe proposed approach.(5) The dynamic torque compensation model is formulated by using the result ofdynamic parameter identification. On the basis of single-axis PD control, an approachfor feed-forward control is proposed at the coarse interpolation stage. Experimentalresults show that the proposed approach can effectively reduce the servo trackingerrors in the joint space in comparison with the single-axis kinematic control method.The outcomes lay a solid foundation for the development for the novelhigh-speed five-axis machine based on the A3head.更多还原