基于工业机器人的飞机交点孔精镗加工关键技术研究

发布时间：2018-04-20 08:43

本文选题：飞机装配 + 机器人　；参考：《浙江大学》2016年博士论文

【摘要】：交点孔作为飞机大部件装配连接的关键部位,其位姿精度直接影响飞机部件之间的互换协调性和飞机整机的装配质量。为了消除装配过程中由于定位和装配变形等原因形成的累积误差,保证交点孔位姿精度要求,在飞机装配现场需要对其进行精加工。传统的数控机床占地面积大、灵活性差,无法应用于工装设备密集、工作空间狭小的飞机装配现场。为此,本文提出了一种基于工业机器人的交点孔精镗加工方法,并针对机器人存在的机械刚度较低、定位精度较差、易产生变形和振动等问题,深入研究了机器人位姿优化、误差补偿和振动抑制等关键技术,以保证交点孔的位姿精度和加工质量。论文主要研究内容和创新点如下:阐述了飞机交点孔的重要作用及其加工技术的发展现状。介绍了基于工业机器人的交点孔精镗加工系统的结构组成和加工工艺流程。为了实现机器人的准确定位,构建了加工系统完整的坐标系体系,给出了工具坐标系和工件坐标系的具体标定方法,并采用Denavit-Hartenberg方法建立了系统所用KUKA KR360-2机器人的运动学方程。在深入研究机器人刚度模型及刚度特性的基础上,揭示了机器人在单方向上的平移变形与所受外力之间的严格线性关系,提出了一种可以定量地评价机器人处于某一位姿时刚度大小的性能指标。该指标具有坐标系不变性,参考坐标系的不同不会影响其对机器人刚度性能的评价结果。以该指标最大化为目标,对于普通孔加工(无干涉、无第7轴)和飞机交点孔加工(有干涉、有第7轴)等不同情况,分别建立了不同的机器人位姿优化模型,并采用基于雅克比矩阵的迭代IKP法对模型进行了求解。通过机器人受力变形试验验证了刚度性能指标的正确性,而机器人在壁板钻孔和交点孔镗孔中的具体应用实例也证明了位姿优化方法的有效性。研究了基于激光跟踪仪的机器人位姿误差补偿技术。对于机器人末端物体结构复杂、形状不规则而导致其位姿难以直接测量的情况,提出了一种基于点集匹配运算的位姿误差补偿方法,借助于辅助定位点,实现了机器人位姿误差的计算和补偿;对于机器人镗孔加工这一特殊情况,提出了一种面向对象的位姿误差补偿方法,直接测量计算镗孔刀具的位置误差和方向偏差,并对其进行补偿。在飞机交点孔精加工中,通过上述方法,机器人末端镗孔刀具的位置精度可以调整到0.05mm,方向精度可以调整到0.05°,满足了某大型飞机交点孔的位姿精度要求。在综合考虑机器人镗孔加工特点及其刚度特性的基础上,研究揭示了镗孔加工的振动机理:振动的主体为机器人自身,振动的类型为具有位移反馈的强迫振动,振动时的刀具运动轨迹为椭圆,而且该椭圆的形态与主轴旋转频率密切相关。根据以上结果,提出了一种基于压脚机构的振动抑制方法,通过压脚与工件之间的摩擦力抵消切削力对机器人的作用,从而抑制机器人振动的发生。通过机器人镗孔加工试验,验证了上述机器人振动机理分析的正确性。在飞机交点孔精镗加工过程中,通过压脚抑制机器人的振动,交点孔孔壁表面粗糙度达到Ra0.8,孔径公差达到H7级,满足了某大型飞机交点孔的加工质量要求。最后,对全文工作进行了概括总结,并对有待进一步研究的内容进行了分析展望。
[Abstract]:As the key part of the assembly connection of the aircraft components, the position accuracy of the intersection directly affects the interchangeability and coordination between the aircraft components and the assembly quality of the aircraft. In order to eliminate the cumulative error caused by the location and assembly deformation in the assembly process, and to ensure the accuracy requirements of the position and posture of the intersection, it is needed in the aircraft assembly site. The traditional CNC machine tools have large area and poor flexibility, and can not be applied to the assembly site of aircraft with dense working equipment and small working space. Therefore, this paper puts forward a method of precision boring processing based on industrial robots, which is low in mechanical stiffness, poor in positioning accuracy and easy to produce. The key technologies of robot pose optimization, error compensation and vibration suppression are deeply studied to ensure the position and pose accuracy and processing quality of the intersection holes. The main research contents and innovation points of this paper are as follows: the important role of the plane intersection and the development status of the processing technology are expounded. The industrial machine based on industrial machine is introduced. In order to realize the accurate positioning of the robot, the complete coordinate system of the machining system is constructed, the specific calibration method of the tool coordinate system and the workpiece coordinate system is given, and the KUKA KR360-2 robot used by the system is established by the Denavit-Hartenberg method. On the basis of the study of the stiffness model and stiffness characteristics of the robot, the strict linear relationship between the translational deformation and the external force in the single direction is revealed, and a performance index which can quantitatively evaluate the stiffness of a robot in a certain position is presented. The index has the invariance of the coordinate system. The difference of the reference coordinate system will not affect the evaluation results of the stiffness performance of the robot. With the objective of maximizing the index, the optimization model of the robot position and posture is established for the different conditions of the ordinary hole machining (no interference, no seventh axis) and the machining of the intersection of the plane (there are seventh axes), and the Jacobian matrix is adopted. The iterative IKP method is used to solve the model. The correctness of the stiffness performance index is verified by the force deformation test of the robot, and the practical application of the robot in the drilling of the wall plate and the boring hole of the intersection point also proves the effectiveness of the position and posture optimization method. In the case of complex structure and irregular shape of the robot end, the position and posture of the robot can not be measured directly. A position and attitude error compensation method based on the point set matching is proposed. With the aid of the auxiliary positioning point, the calculation and compensation of the position and posture error of the robot are realized. The position error compensation method of the object orientation is used to directly measure the position error and direction deviation of the boring tool and compensate it. In the precision machining of the plane intersection hole, the position precision of the boring cutter can be adjusted to 0.05mm through the above method, and the direction precision can be adjusted to 0.05 degrees to meet a large aircraft. On the basis of comprehensive consideration of the machining characteristics and stiffness characteristics of the boring hole of the robot, the vibration mechanism of the boring machining is revealed. The main body of the vibration is the robot itself, the type of the vibration is the forced vibration with displacement feedback, the tool path of the tool is ellipse in the vibration and the shape of the ellipse. The rotation frequency of the spindle is closely related. Based on the above results, a method of vibration suppression based on the press foot mechanism is proposed. The vibration of the robot is suppressed by the friction force between the press and the workpiece. The vibration of the robot is suppressed. The vibration mechanism of the robot is verified by the robot boring machining test. Correctness. During the machining process of the aircraft intersection hole, the surface roughness of the intersection hole wall is Ra0.8 and the aperture tolerance reaches H7 by pressing the foot to suppress the vibration of the robot, and the processing quality requirements of a large aircraft intersection hole are met. Finally, the full text work is summarized, and the further research content has been carried out. Analysis of the prospects.

【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：V262.4;TP242.2

【参考文献】