大型空间焊缝车载柔性机械臂跟踪精度研究

发布时间：2018-06-10 16:15

本文选题：移动焊接机器人 + 柔性机械臂　；参考：《东北石油大学》2017年硕士论文

【摘要】：随着现代工业规模逐渐扩大,对大型焊接结构件的需求越来越高,如大型舰船甲板和舱体、海洋平台钢结构组块等,由于移动焊接机器人不受固定工位的限制,柔性机械臂更是可以灵活地调整姿态适应不同形式的空间焊缝,因此成为智能化焊接领域的研究热点之一。而柔性机械臂末端对焊缝的跟踪精度是保证焊接质量的重要条件,因此探究影响车载柔性机械臂轨迹跟踪精度的因素以及提高跟踪精度的方法具有非常重要的意义。首先,将复杂的车载柔性机械臂系统简化为平面柔性连杆机构,将空间折线焊缝简化为平面锯齿波的形式。建立车载柔性两杆机械臂的运动学模型,基于运动弹性动力学分析方法,详细介绍了车载柔性机械臂数学模型和系统模型的建立过程。为计算分析柔性机械臂弹性振动和轨迹跟踪误差提供理论基础。然后,在小车匀速运动条件下进行焊缝轨迹跟踪仿真,分析焊缝跟踪过程中引起柔性机械臂剧烈的弹性振动主要原因。为降低小车运动对机械臂的影响,规划了一种小车变速运动的方案。基于广义惯性椭球原理确定机械臂良好工作空间,进而确定使得机械臂动力学性能最好的小车最佳位置,基于小车最佳位置规划了另一种变速运动方案。最后针对不同尺寸的焊缝,对比分析了三种小车运动方案的跟踪误差。最后,利用质量-弹簧-阻尼模型模拟具有宏微结构的柔性机械臂,分析此类柔性机械臂基本的振动特性。基于宏、微弹性振动对系统影响的不同,针对不同相对大小的焊缝轨迹,提出两种宏机械臂末端轨迹规划,通过对比轨迹跟踪误差,验证柔性宏微机械臂能否有效地提高轨迹跟踪精度。然后对影响车载柔性机械臂跟踪精度的因素,诸如结构参量,材质搭配,集中质量,宏末端轨迹规划进行了仿真分析,获得了许多对此类移动焊接机械臂设计和控制有价值的信息。
[Abstract]:With the expansion of modern industrial scale, the demand for large welded structural parts becomes more and more high, such as large ship decks and bulkheads, steel structure blocks of offshore platforms, etc., because mobile welding robots are not restricted by fixed working places. Flexible manipulators can adjust their posture flexibly to suit different types of space weld, so it becomes one of the research hotspots in intelligent welding field. The tracking accuracy of the welding seam at the end of the flexible manipulator is an important condition to ensure the welding quality. Therefore, it is of great significance to explore the factors that affect the tracking accuracy of the flexible manipulator and the methods to improve the tracking accuracy. Firstly, the complex vehicle flexible manipulator system is simplified as a planar flexible linkage mechanism, and the space broken line weld is simplified as a plane sawtooth wave. The kinematics model of the vehicle flexible two-bar manipulator is established. Based on the kinematic elastic dynamics analysis method, the mathematical model and the system model of the vehicle flexible manipulator are introduced in detail. It provides a theoretical basis for the calculation and analysis of elastic vibration and trajectory tracking error of flexible manipulator. Then, the weld track tracking simulation is carried out under the condition of uniform motion of the trolley, and the main causes of the violent elastic vibration of the flexible manipulator during the weld tracking process are analyzed. In order to reduce the influence of the vehicle motion on the manipulator, a scheme of variable speed motion of the trolley is proposed. Based on the generalized inertial ellipsoid principle, the good workspace of the manipulator is determined, and the optimal position of the vehicle which makes the dynamic performance of the manipulator is determined. Based on the optimal position of the vehicle, another scheme of variable speed motion is proposed. Finally, the tracking errors of three kinds of vehicle motion schemes are compared and analyzed for weld seam with different sizes. Finally, the mass-spring-damping model is used to simulate the flexible manipulator with macro and micro structure, and the basic vibration characteristics of this kind of flexible manipulator are analyzed. Based on the different effects of macro and micro elastic vibration on the system, two kinds of trajectory planning of the end of the macro manipulator are proposed for the different relative size of weld trajectory, and the trajectory tracking error is compared. It is verified that the flexible macromanipulator can effectively improve the tracking accuracy. Then the factors that affect the tracking accuracy of the flexible manipulator are simulated and analyzed, such as structure parameters, material collocation, concentrated mass, and macro end trajectory planning. A lot of valuable information has been obtained for the design and control of this kind of mobile welding manipulator.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP241

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