焊缝跟踪应用的线激光视觉伺服控制系统

设计了一套由三轴直角坐标机器人、线激光传感器和工业计算机组成的焊缝跟踪系统。研究了该系统所涉及的测量原理、特征点测量方法和基于模糊自适应的控制方法。通过高斯核相关算法(KCF)在焊接过程中实时检测焊缝特征点,并根据测量原理计算获得特征点相对于相机坐标系的三维坐标值。设计了一种自适应模糊控制器,通过自适应模糊控制器计算坐标的偏差值和偏差变化率得到焊枪末端运动轨迹的控制量,同时对模糊控制器的输入输出论域、模糊规则和隶属函数进行实时动态更新。实施了焊缝跟踪实验。结果显示:采用最大焊接电流为350 A的惰性气体保护焊(MIG),在强烈弧光和飞溅的干扰下,该系统能实时跟踪焊接工件,跟踪精度为0.325 3mm,传感器测量频率为20Hz。焊接过程中焊枪末端运行平稳,焊缝轨迹跟踪准确,且抗干扰能力,能满足焊接应用要求。     

A visual seam tracking system for robotic arc welding

A novel circular laser three-dimensional (3D) scanner is developed instead of a one-dimensional laser spot scanner (1D) and two-dimensional (2D) striped laser light. Using the proposed circular laser scanner, a seam tracking system is constructed, and architecture based on the Visual C++ and RAPID languages which determines the cooperation among image processing modules is carried out. Finally, real seam tracking experiments are investigated and the error analysis is carried out. The results show that: (1) the proposed system can realize seam tracking; (2) the precision of this system is affected by the light scanning system, calibration results, image processing, and the welding seam 3D algorithm—the tracking accuracy is satisfied for robotic arc welding; (3) this system can be used in a welding robot system as a weld seam finder, flatness detector, and weld seam tracker.     

机器人视觉伺服系统控制结构的研究

对机器人视觉伺服系统的研究是机器人领域中的重要内容之一，其研究成果可直接用于机器人手-眼系统，移动机器人的自动避障及对周围环境的自适应，轨线跟踪等问题，该文介绍了三种主要的机器人视觉伺服系统；基于位置的控制系统，基于图像的控制系统，2-1/2D视觉伺服，并详细论述了它们的控制结构及由此产生的优缺点，最后分析了今后的发展趋势。     

基于视觉定位的机器人焊接系统

本文基于三维扫描视觉系统开发了具有对汽车零部件在线整体定位功能的机器人焊接系统.详细介绍了系统的组成、工作流程及被焊接工件机器人视觉定位过程,为汽车焊接过程提出了一套自动化、柔性化应用方案,可以有效克服工件的装卡误差,大大提高焊接质量.     

基于虚拟仪器技术的分布式机器人视觉伺服系统

研究一种构造分布式机器人视觉伺服系统的方法。在分布式机器人视觉伺服系统的基础上,运用NI公司(美国国家仪器公司)的LabVIEW,将四自由度机器人系统和实时图像采集系统连接起来,构成了基于LabVIEW的分布式机器人视觉伺服系统。推导了视觉伺服机器人系统的图像雅克比矩阵,用LabVIEW语言编写了基于逆模型的控制算法,给出了实验结果。     

视觉伺服机器人系统的无标定目标运动估计

机器人视觉伺服系统是机器人领域一重要的研究方向。该文建立了三自由度平面机器人视觉伺服系统,着重研究在摄像机与机器人坐标系无标定的情况下对目标的运动估计,提出了一种无标定算法,采用Kalman滤波完成目标的运动估计,并验证了它的有效性。     

The decoupling visual feature extraction of dynamic three-dimensional V-type seam for gantry welding robot

The International Journal of Advanced Manufacturing Technology - During the welding manufacturing of a circular pressure vessel, the V-type seam’s position relative to welding torch varies...     

Arc welding robot system with seam tracking and weld pool control based on passive vision

The automatic control in square-wave alternating current (AC) gas tungsten arc welding (GTAW) is significant for a “teach and playback” robot to overcome the variation of the seam trajectory and the seam gap in the welding process. This paper presents a welding robot system based on the real-time visual measurement in the different levels of the welding current. The primary objective is to measure the offset of the torch to the seam center and the size of seam gap by passive vision, track the seam and control the weld pool in real time. A novel visual image analysis algorithm was developed for seam tracking and seam gap measuring, free from robot calibration. The control algorithm based on the knowledge base was established to control the weld formation by regulating the welding current and wire feed rate. The welding practice for the rocket storage tank demonstrates the efficiency of the proposed system.     

Predictive IP controller for robust position control of linear servo system

Position control is a typical application of linear servo system. In this paper, to reduce the system overshoot, an integral plus proportional (IP) controller is used in the position control implementation. To further improve the control performance, a gain-tuning IP controller based on a generalized predictive control (GPC) law is proposed. Firstly, to represent the dynamics of the position loop, a second-order linear model is used and its model parameters are estimated on-line by using a recursive least squares method. Secondly, based on the GPC law, an optimal control sequence is obtained by using receding horizon, then directly supplies the IP controller with the corresponding control parameters in the real operations. Finally, simulation and experimental results are presented to show the efficiency of proposed scheme.     

Compact visual control system for aligning and tracking narrow butt seams with CO2 gas-shielded arc welding

In this paper, a visual control system is proposed to locate the start welding position and track the narrow butt welding seam in container manufacturing. It estimates the error between the welding torch and the welding seam with a camera and a panel computer. It adjusts the torch’s position via a stepper motor to eliminate the error. A decision controller with three gates is designed to decide the working procedure. Feature extraction algorithms are designed according to the seams and pre-weld spots. The seam line and the position of the pre-weld spot are detected to locate the start welding position in initial aligning. Then the torch is aligned to the seam. In the welding stage, the reference feature is determined with many frames of images based on their statistical property. The current estimated feature is checked to ensure only normal features to be used for welding seam tracking. Experiments are well conducted to verify the effectiveness of the proposed system and methods.     

Automatic seam tracking in pipeline welding with narrow groove

Grain structure is an important and readily observable feature in aluminum alloy castings. Depending on the constitutional and heat-flow conditions in a solidified aluminum alloy, various morphologies are possible. Grain refining is one of the predominant techniques in controlling the quality of castings. It plays a vital role in improving metallurgical characteristics and mechanical properties of aluminum alloys. Fine equiaxed grains ensure remarkable benefits. There are a number of techniques to achieve fine equiaxed grain structure, but grain refinement by the addition of grain refiners referred to as inoculation is the most popular due to its simplicity. Grain refinement has been studied extensively by researchers for several decades, not only for developing efficient grain refiners but also for achieving an understanding of the mechanism of grain refinement. In spite of its commercial importance, benefits and numerous scientific studies in this area, the grain refinement of aluminum and its alloys is still a controversial subject. Solute elements like titanium segregate to the inoculants/melt interface affecting the dendrites and also affect the constitutional undercooling at the solid–liquid interface. This segregating power of an element is quantified by the growth restricting factor (GRF). In the present investigation, the effect of GRF on grain refinement of aluminum-silicon alloys was studied by the addition of Al-5Ti-1B master alloy. It is evident from this investigation that the growth rate of grains is inversely proportional to the GRF.     

基于无标定视觉伺服机器人的运动物体跟踪

介绍机器人视觉伺服的一般原理,然后选取图像的全局特征描述子-图像矩来描述图像的特征信息,推导出基于图像矩特征的图像雅可比矩阵,并按李雅普诺夫稳定性方法推导出模型无关的无定标视觉伺服控制律.最后通过运动物体轨迹跟踪的仿真试验,验证了摄像机固定和eye-in-hand两种结构下算法的正确性和有效性.     

摄像头微机控制伺服系统

本文提出并研制了一种采用工业控制计算机精确控制摄像头位置与旋转速度的伺服系统。文章给出了伺服系统原理及硬软件结构。     

焊接机器人非奇异Terminal滑模控制系统研究

针对焊接机器人不确定性系统的特点,进行了非奇异Terminal滑模控制系统研究。建立了焊接机器人动态模型;确定了控制系统的硬件结构,并在此基础上探讨了系统非奇异Terminal滑模控制的基本原理。最后,结合实例对焊接机器人非奇异Terminal滑模控制系统进行了数值仿真。结果表明,该控制系统的自适应性强,精度高,误差可以快速收敛到0。     

移动机器人视觉控制系统的目标提取

在移动机器人视觉控制系统中,目标标志物的提取是关键技术之一。本文提出了利用基于标记的分水岭算法分割移动机器人目标标志物图像,首先将获取的目标标志物图像进行预处理,包括转换为灰度图像、进行空间滤波和二值化操作,接着对预处理后的图像进行数学形态学处理,最后利用基于标记的分水岭算法分割目标标志物图像。实验结果表明,该算法不但正确的分割了目标标志物图像,并很好的保护原图像的边缘信息,验证了该算法的有效性。     

基于开放式控制器的机器人视觉伺服系统研究

针对Motoman-sv3x型工业机器人系统的专用封闭式机构的局限性,提出了一种开放式机器人视觉伺服控制系统。该伺服系统控制基板主要由4片数字信号处理器和1片可编程逻辑器件组成,其中3个单元控制6个逆变器,另一个单元实现整流和电机制动功能。通信单元采用通用串行总线,实现数字信号处理器与上位机间的快速通信,视觉系统采用基于图像的双目视觉伺服控制。该系统实时性好,运算速度快,能够实现复杂的机械臂动作控制。     

焊接机器人视觉焊缝跟踪系统分析

分析了一套焊接机器人视觉焊缝跟踪系统的总体构成.首先简述了焊接机器人及跟踪系统的总体构成,分析了机器人视觉系统寻找焊缝位置的视觉处理的动作流程,并对其中重要的步骤进行了详细的描述,重点介绍了机器人依照输入偏差与示教轨迹叠加跟踪真实焊缝的控制过程.最后使用Matlab软件仿真3关节平面机器人的跟踪焊缝的运动.     

开放式点焊机器人控制系统设计

为解决封闭式控制系统带来的弊端,结合现场焊接机器人技术要求,设计了开放式点焊机器人控制系统,提供了分层式体系与结构化功能模块.多轴运动控制器(PMAC)用于实现机器人运动学算法,伺服放大器采取速度模式控制方式,位置环算法由PMAC完成,速度环算法在伺服放大器中完成,并实现了离线编程与三维仿真.研究结果表明:分层式系统结...     

基于DSP的焊接进给工作台伺服控制系统的研究

提出一种用于点焊机的焊接进给工作台伺服控制系统.系统基于高性能数字信号处理器(以下简称DSP)芯片TMS320F2812,对三轴直流伺服电机进行实时控制.反馈电路采用模块化设计,实现了对电机编码器的输出信号的采集.完成了DSP辛片软件编程,包括多区间变参数的数字PID控制器,数字测速M/T法等.最后通过实验在双轴工作平台上进行定位分析和稳定性仿真,系统达到较高的位置控制.     

不确定机器人鲁棒自适应控制

针对不确定、时变和非线性机器人系统的实时性要求,提出了采用滑模变结构和RBF神经网络相结合来构造控制器.用带有符号函数的滑模变结构控制器来产生一个控制输入信号,同时利用具有快速学习能力的RBF神经网络来学习外界的不确定性,增强系统的自适应能力,使之达到更佳的控制效果,并在文中证明了系统的稳定性.最后给出了对两连杆机器人的仿真,验证了控制效果.