Planning of circlelocus for multi-path/multi-layer welding robot with automatical error-correction

In this paper, a planning algorithm for multi path/multi layer circular locus is poposed. The algorithm is applied to weld the nipples on the header of boiler. Multi path/multi layer circular locus is planned according to three teaching points, which is lapped head on end to satisfy the requirement of technology. For the nipples wherever they are arranged radially or axially, even if there are errors caused by positioning and thermal deformations, providing that nipple's position and orientation relative to the teaching one can be measured, the multi path/multi layer circular locus can be planned without teaching any more. The algorithm has been applied in welding robot for manufacturing power station' boiler.

Path Planning of Planar Kinked Line Seam by Visual Servoing for Robotic Welding

Welding path planning can substitute for the manual teaching process of the robot and can promote the autonomous level of the robotic welding. A path planning method by visual servoing was presented, in which the optimal angle of charge-coupled device (CCD) camera was also planned. Aiming at planning two forms of kinked line seams, obtuse angle seam and right angle seam, a practicable solution was put forward. In this solution, the intersection of two adjacent straight segments is detected in each local seam image, and if intersection is found, the seam errors are calculated using the next straight segment. The experimental results show that kinked line seam can be well planned using this solution.

Study on path planning and compensation of off-line programming for thick walled curve welding

Thick walled curve welding are usually joined by multi-layer and multi-pass welding, which quality and efficiency could be improved by off-line programming of robot welding. However, the precision of off-line programming welding path was decreased due to the deviation between the off-line planned welding path and the actual welding path. A path planning algorithm and a path compensation algorithm of multi-layer and multi-pass curve welding seam for off-line programming of robot welding are developed in this paper. Experimental results show that the robot off-line programming improves the welding efftcieney and precision for thick walled curve welding seam.

Digital Twin Implementation of Autonomous Planning Arc Welding Robot System

Industrial robots are currently applied for ship sub-assembly welding to replace welding workers because of the intelligent production and cost savings.In order to improve the efficiency of the robot system,a digital twin system of welding path planning for the arc welding robot in ship sub-assembly welding is proposed in this manuscript to achieve autonomous planning and generation of the welding path.First,a five-dimensional digital twin model of the dual arc welding robot system is constructed.Then,the system kinematics analysis and calibration are studied for communication realization between the virtual and the actual system.Besides,a topology consisting of three bounding volume hierarchies(BVH)trees is proposed to construct digital twin virtual entities in this system.Based on this topology,algorithms for welding seam extraction and collision detection are presented.Finally,the genetic algorithm and the RRT-Connect algorithm combined with region partitioning(RRT-Connect-RP)are applied for the welding sequence global planning and local jump path planning,respectively.The digital twin system and its path planning application are tested in the actual application scenario.The results show that the system can not only simulate the actual welding operation of the arc welding robot but also realize path planning and real-time control of the robot.

Path planning for MIG surfacing of robot-based remanufacturing system

Robot-based remanufacturing system can scan the worn parts and develop the corresponding models, compare them with the standard model, calculate the weld deposit, implement welding path planning, and repair the worn parts with MIG surfacing automatically. This paper investigates the welding path planning after calibrating, scanning and model rebuilding. The following aspects are contained： introducing the planning principle, selecting the suitable welding process based on welding parameters （current and speed）, calculating welding overlap quantity by the superposition method. Also, it has been verified that good weld profile can be obtained with the optimized parameters.

汽车白车身点焊作业多机器人路径规划研究

针对白车身焊装生产线多机器人焊接工作量大、焊接工作复杂的问题,提出了一种自适应精英蚁群算法的多机器人焊接路径规划方法。在蚁群算法的基础上,对算法核心参数进行调整,再将自适应更新策略和精英蚂蚁系统加入到蚁群算法中,增强算法全局搜索能力,提高算法收敛速度,并通过TSP模型检验了算法的性能;最后,以白车身焊装生产线某车型主拼工位的焊接作业为例,对方法的有效性进行了验证。结果表明,改进后的蚁群算法具有较好的搜索效率和搜索能力,多机器人焊接路径间不相交,符合焊接的工艺要求,为多机器人焊接路径规划问题提供了一种新的方法。

基于人工免疫-改进粒子群优化算法的机械臂轨迹规划研究

焊接机器人运动轨迹复杂、控制精度要求高。提出了一种满足多目标约束的轨迹规划方法。针对机器人轨迹平滑性要求,以5次非均匀有理B样条(Non-Uniform Rational B-Splines,NURBS)曲线为基础,对笛卡儿空间路径点进行参数化表达;根据工业机器人路径约束及工况需求,选取时间、能耗、跃度3个运动学指标作为目标优化函数,采用人工免疫双态粒子群进行轨迹优化;为了平衡粒子“探索”与“利用”,增加双模态模型,引入人工免疫系统,提升了粒子多样性与后期收敛能力;根据Pareto解集得到满足约束的焊接机器人各关节最优轨迹,通过Matlab仿真证明了方法的有效性;最后,针对空间相贯曲线焊缝进行了焊接试验。结果显示,规划的轨迹符合实际工程需求。

Adaptive pass planning and optimization for robotic welding of complex joints

Current industrial robotic welding systems can- not achieve automated solutions for multi-layer multi-pass welding of complex joints due to the presence of non- uniform and irregular welding groove geometries. This paper presents an adaptive pass planning approach for robotic welding of such complex joints. The welding groove is first segmented considering both the variation in groove dimension and the reachability of the robot welding torch. For each welding segment, the welding passes are planned to be in accordance with welding practices, viz., keeping the same number of welding passes in each layer while maintaining consistent welding parameters. An adaptive pass adjustment scheme is developed to address the discrepancies between the simulated results and the actual welding deposition after finishing a few layers of welding. Corresponding robot paths are generated and optimized to ensure minimum joint movement subject to three constraints, viz., reachability, collision-free and singularity avoidance. The proposed approach has been sim- ulated with the arc welding of a Y-type joint found typically in offshore structures.

基于改进蚁群算法的焊接机器人路径优化

针对传统蚁群算法(ACO)在焊接机器人路径规划的过程中收敛速度慢、易陷入局部最优解等问题,提出一种改进蚁群算法(DWAG)。DWAG在ACO基础上提出了基于动态权重策略以及排序因子策略的信息素更新方式,加快了算法在求解过程中的收敛速度;通过引入遗传算法中的交叉与变异操作,扩大了算法在求解过程中的搜索空间;最后以白车身后地板总成某工位对DWAG进行20次的仿真验证。仿真结果表明相比于ACO,DWAG的焊接路径更短、收敛速度更快同时求解问题时寻优性能的稳定性更佳。

大型阀门环形焊缝变姿态焊接路径规划

针对大型阀门环形焊缝,采用等高圆弧填充路径规划策略,建立了基于坡口尺寸和焊接道次、焊枪碰撞验证、焊枪角度修正的多层多道路径规划方法。通过将焊缝拟合成扇形焊缝、等腰圆弧梯形焊缝与扇环焊缝,计算出每一道焊缝的焊枪位置、焊枪角度、摆动幅度,对焊缝干涉判断,确定焊枪偏转角,实现机器人阀门变姿态焊接的离线编程,避免了焊接过程中的机器人干涉碰撞。最终实现了大型蝶阀的焊接,焊接接头表面平面,无裂纹、未熔合的缺陷,经过超声探伤,无内部缺陷,焊缝合格率为100%。焊接接头组织由珠光体和铁素体组成,晶粒细小均匀,其抗拉强度为536 MPa,屈服强度为468 MPa,断后伸长率为14%,0℃冲击吸收能量为54 J。

基于改进多目标平衡优化器算法的点焊机器人路径规划

点焊机器人在工业领域内被广泛应用,合理的焊接顺序可以提高生产效率。为了实现点焊机器人的路径最优规划,针对点焊路径和工作时间建立多目标问题模型,提出一种融合改进快速非支配排序的多目标平衡优化器算法(DMONEO)。加入快速非支配排序,并采用生存评分策略替代拥挤度因子,可以更好地保持种群的多样性,防止DMONEO过早收敛。TSPLIB基准实验结果表明,DMONEO算法相比于其他算法性能表现更好。最后在实际点焊机器人的路径规划应用中进行仿真实验并与其他算法对比,结果表明提出的算法得到的优化效果更好,耗时更短。

焊接机器人在焊接技术应用中的关键技术分析

随着工业自动化的不断发展,焊接机器人在焊接技术应用中扮演着越来越重要的角色。焊接机器人能够在其既定程序的操纵下制作高质量元件,减少技术工人的工作量,相较于人力焊接有一定优势,本文旨在探析焊接机器人在焊接技术应用中的关键技术。要实现高效、稳定和精确的焊接过程,关键技术的研究和应用至关重要。因此,探析焊接机器人的焊接关键技术很有价值。

机器人电阻点焊电极压力均压平衡控制研究及应用

针对车门翼板高强度双相钢机器人点焊中因为电极压力控制不当而出现的压痕、变形和扭曲等缺陷,分析电极压力对点焊质量的影响。采用ANSYS数值模拟软件比较分析不同电极压力下板材等效压力变化情况,分析结果显示,相较于电极压力为4 000 N,电极压力为3 000 N时,焊点等效压力波动较小,塑性变形也相对较小。针对车门翼板点焊,确定了合理的点焊电极压力为3 300 N,并设计了分阶段控制曲线,通过FANUC点焊控制系统对电极压力进行实时监测和补偿,有效控制了电极压力的波动。此外,利用均压平衡宏程序,可以根据板材形状变化和电极磨损等因素实时调整电极压力。试验结果表明,采用均压平衡控制后,电极压力波动控制在±5%以内,焊点表面压痕深度减少约20%,焊点质量明显提升。

激光螺旋点焊的断裂行为与断口研究

为研究激光螺旋点焊的断裂行为和断口特征,以期为高性能激光点焊的应用提供理论支持。采用振镜搭载机器人的激光螺旋焊接系统对1 mm厚汽车用高强钢进行焊接,设计了一种类阿基米德螺旋线扫描路径以使焊点热输入均匀分布,并对焊接接头的断裂行为进行分析。研究发现,在拉剪力的作用下,激光螺旋点焊主要发生的断裂失效形式为单面焊点撕出断裂和双面焊点撕出断裂,裂纹的萌生及扩展均是沿着熔合区和热影响区交界处。粗晶热影响的大角度晶界比例相对较少,为18.69%,KAM均值最大为0.65,存在的应力应变相对较大,使得裂纹更倾向于在粗晶热影响区萌生和扩展。

基于DELMIA/Robotics的白车身焊接机器人路径仿真研究

针对汽车焊接机器人工位缺乏精确可靠的焊接过程分析,本文应用DELMIA/Robotics软件实现汽车侧围的机器人焊接工位运动仿真。结果表明,运用DELMIA/Robotics可以有效降低运行成本和机器人编程时间。

工业机器人点焊工艺系统探析

点焊机器人主要由工业机器人本体、点焊钳、点焊机和点焊工艺控制系统组成,点焊工艺控制系统作为点焊机器人的核心总控单元控制点焊机器人、点焊钳,点焊机协同动作进行点焊自动作业。系统软件主要由运动控制单元、参数配置单元、指令集和点焊工艺功能单元等多个部分组成,承担着机器人/电焊钳运动控制、点焊机逻辑控制和其他配套设备逻辑控制等重要任务,系统的工艺参数也是通过控制系统的人机交互界面进行设置。控制系统把参数、运动节拍、IO信号通过执行程序有机地执行和调度起来后,点焊机器人就带着电焊钳执行各种指定的动作完成对工件的点焊加工。

一种点焊机器人在C空间中的智能轨迹规划算法

针对点焊机器人在C空间中的轨迹规划问题,提出一种基于蚁群算法的智能轨迹规划参数自适应蚁群算法(parameter adaptive ant colony algorithm,PAACA),以期改进蚁群算法易早熟、收敛速度慢的问题,在PAACA中构建一种复合线性适应度函数,此函数可以智能控制算法中信息素的作用强度,从而提高寻优能力。通过MATLAB进行仿真测试证明了PAACA的优越性,并将智能轨迹规划应用在工业机器人实体中,用KEBA控制器进行3D建模仿真示教和机器人本体运行,验证了C空间中的智能轨迹规划PAACA具有很强的实际应用价值。

移动焊接机器人结构设计与路径规划

针对大型焊接件生产中存在的大范围复杂焊缝以及狭窄空间内部焊接条件恶劣的情况,设计一种新型移动焊接机器人。采用3个独立驱动的OMNI全向轮作为机器人的移动机构,同时在移动机构底盘安装支撑轮及可调节磁吸附装置,并设计五自由度机械臂作为焊接执行机构;对机器人移动平台与机械臂分别进行运动学分析以及整体运动学分析,推导出机器人末端执行器与驱动轮、机械臂关节角位移之间的函数关系;针对曲率变化较大的焊缝难以焊接的问题,提出基于改进粒子群优化算法的多段直线逼近曲线的移动平台路径规划算法,并用MATLAB仿真验证了该路径规划算法可以完成任意曲率曲线的焊缝离散化,在满足焊接精度的前提下,能够减少焊缝离散点数目,提高了移动平台路径规划的效率。

融合改进RRT和TEB算法的移动焊接机器人路径规划

针对移动焊接机器人路径规划中快速遍历随机树(RRT)算法搜索时间较长、易生成曲折且避障性能差的路径,以及时间弹性带(TEB)算法存在速度输出跳变等不足,提出1种改进RRT和TEB的移动焊接机器人路径规划融合算法。引入目的性扩展和关键点提取策略改进RRT算法,提高算法的搜索效率和规划路径的平滑性;引入最小安全距离对速度的约束改进TEB算法,使移动焊接机器人能够有效避开障碍物,同时增加目标点对速度的约束,减少对移动焊接机器人的冲击;融合改进RRT和TEB算法,使移动焊接机器人能够动态规划路径,避免动态障碍物的干扰,且对其进行仿真和实物验证。结果表明:改进RRT算法的路径搜索时间减少了58.84%,路径拐点数减少了73.33%;融合改进的RRT与TEB算法用于移动焊接机器人的路径规划,机器人与障碍物之间的安全距离增加了50%,在到达目标点前可提供足够的速度缓冲时间,极大提高了机器人运行的稳定性和避障能力。

机器人点焊板材厚度检测的数值模拟与变量程序应用研究

针对轿车车门内板点焊过程中,机器人伺服焊枪经过多个焊点操作后工件间隙扩大,以及钣金厚度变化造成的焊接质量下降问题。基于ANSYS有限元技术对高强度双相钢机器人点焊过程进行热传导数值模拟分析,研究板材厚度变化对焊接热传导效率及熔核直径大小的影响。试验结果表明,当板材厚度为1.9~2.0 mm时,熔核直径达到最大值,随着板材厚度的增加,熔核直径减小,焊接质量下降。为解决这一问题,运用KUKA机器人伺服焊枪的板材厚度动态检测功能和变量程序跳转指令,在板材厚度超出公差值(1.8~2.5 mm)时中断机器人焊接程序并及时报警,减少了板材间隙增大带来的飞溅、虚焊等缺陷,提高形核质量和焊接精度,保证车门内板高强度双相钢点焊的前后焊点质量稳定。