Real-Time Seam Tracking Technology of Welding Robot with Visual Sensing

A seam tracking system with visual sensing free from calibration was developed for the robot applied in gas tungsten arc welding. A visual sensor with double-layer filter system was researched for the different levels of the welding current. An image processing in C+?+ language was developed to extract the seam trajectory and the offset of the torch to the seam in the welding images of aluminum alloys plates with grooves. The rectifying rule of the robot used in this paper was found based on the experimental data, and the seam tracking controller was also analyzed and constructed. The experimental results on straight line seam and curve seam demonstrated the efficiency of the proposal seam tracking system.     

Acquisition of Weld Seam Dimensional Position Information for Arc Welding Robot Based on Vision Computing

Recognition and identification of weld environment and seam dimensional position by computer vision is a key technology for developing advanced autonomous welding robot. Aiming at requirements for recognition of weld seam image characteristics, this paper first presents an improved algorithm of subpixel edge detection based on Zernike moments. Comparing with the Ghosal’s original algorithm, the improved algorithm deals with mask effect and first derivative model on edge gradient direction so that it has the strong robust to noise, self-thinning ability and higher locating precision. An algorithm based on ZMs to extract line is also proposed, the comparative results with SHT and RHT show the method has the highest calculation speed and accuracy. The stereovision technology is developed to identify dimensional position of weld seam by computing dimensional coordinates of the weld seam. According to characteristics of weld seam, view field scope model and stereovision model based on baseline are studied and a stereo matching method is presented. In order to evaluate the algorithms and models presented in this paper, a welding robot systems with single camera fixed on the weld torch end-effector has been established for the robot to identify the dimensional position of typical weld seam by one-item and two-position method. The experiment results on S-shape and saddle-shape weld seams show that the vision computing method developed in this paper can be used for acquiring weld seam dimensional position information in welding robot system. Thus the welding path is mapped before the welding operation is executed.     

焊接机器人曲线焊缝的自动跟踪控制

为实现焊接机器人对曲线焊缝的自动跟踪,提出一种简便的位姿实时调整策略和协调视觉跟踪与机器人运动的视觉伺服控制方法。建立了曲线焊缝视觉跟踪过程中焊接机器人期望位姿的数学模型;设计了一种上下层结构的模糊视觉伺服控制器,通过建立焊缝特征点像素坐标偏差与末端轴旋转角度之间的关系模型,动态确定模糊论域的大小,在机器人期望位姿的基础上仅仅通过调整末端轴的旋转量来保证图像特征点始终存在于相机视场内。通过模拟焊接机器人自动跟踪曲线焊缝的实验,验证了所提策略与方法的有效性。     

Research on the Real-time Tracking Information of Three-dimension Welding Seam in Robotic GTAW Process Based on Composite Sensor Technology

Aiming at the shortcomings of teaching-playback robot that can??t track the three-dimensional welding seam in real time during GTAW process, this paper designed a set of composite sensor system for tracking the three-dimensional welding seam based on visual sensor and arc sensor technology, which can effectively acquire three-dimensional welding seam information, such as clear images of seam and pool and stable arc voltage signals. The characteristic values of weld image and arc voltage signals were accurately extracted by using proper processing algorithm, and the experiments have been done to verify the precision of processing algorithms. The results demonstrate that the error is very small, which is accurate enough to meet the requirements of the subsequent real-time tracking and controlling during the welding robot GTAW process.     

激光拼焊焊缝跟踪系统视觉检测方法的研究

激光焊接作为一种新的焊接技术,其对焊缝跟踪提出很高的精度要求。本文针对焊缝跟踪系统中视觉检测单元的精度进行了深入分析,分别对跟踪系统视觉单元精度的定义,视觉检测精度控制的原理,图像的采集以及图像处理的方法做了研究,并提出了一种精确的直线焊缝跟踪视觉检测方法。     

基于双模控制的焊接机器人焊缝自动跟踪系统

该文提出了一种基于双模控制的焊接机器人焊缝自动跟踪系统.系统中应用新一代激光焊缝传感器测量焊缝的位置,并采用Fuzzy-P双模分段控制进行焊缝的纠偏.系统中采用DSP作为核心控制器产生控制信号,驱动焊枪横向步进电机和纵向步进电机动作,实现焊接机器人焊枪对焊缝的实时自动跟踪.实验证明,基于双模控制的焊缝自动跟踪系统可以实现焊接机器人焊枪对焊缝的实时自动跟踪.该系统完全满足实际焊接工程的需要.     

基于DSP的机器人视觉伺服系统研究

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,其研究成果可以直接用于机器人自动避障、轨迹线跟踪和运动目标跟踪等问题中。本文针对机器人视觉伺服系统要求快速准确的特点,设计了基于TMS320C6201的机器人视觉图像处理系统,并分析了基于图像雅可比矩阵的机器人视觉伺服方法的基本原理。     

基于CPLD的彩色视觉移动机器人路径跟踪系统

路径跟踪是机器人视觉导航控制基本技术之一,为使机器人沿地面彩色引导线自主运动,并能在适时离线执行任务后自动返航,提出了一种用可编程逻辑器件(CPLD)实现的视觉伺服PID控制方法.该方法利用图像特征反馈对其所跟踪的路经进行实时识别跟踪.仿真结果表明,该方法改善了控制算法的实时性,提高了移动机器人的路径跟踪精度与速度.     

移动机器人视觉伺服系统上位机软件的设计与实现

针对移动机器人视觉伺服系统,采用C++语言设计了一款基于Qt的跨平台实时数据可视化上位机软件。该软件执行图像处理算法和数据分析,实现绘制移动机器人实时轨迹和实时参数曲线等功能。首先介绍了移动机器人的硬件组成和功能。其次阐述了上位机软件的开发环境和设计步骤,并详细叙述图像算法的运行流程和实时在线绘制波形图等功能。最后通过视觉伺服跟踪控制实验采集数据,并实时显示来验证所设计上位机软件功能的有效性。     

基于结构光的机器人弧焊混合视觉伺服控制

A novel hybrid visual servoing control method based on structured light vision is proposed for robotic arc welding with a general six degrees of freedom robot. It consists of a position control inner-loop in Cartesian space and two outer-loops. One is position-based visual control in Cartesian space for moving in the direction of weld seam, i.e., weld seam tracking, another is image-based visual control in image space for adjustment to eliminate the errors in the process of tracking. A new Jacobian matrix from image space of the feature point on structured light stripe to Cartesian space is provided for differential movement of the end-effector. The control system model is simplified and its stability is discussed. An experiment of arc welding protected by gas CO_2 for verifying is well conducted.     

基于宏微机器人的焊缝跟踪研究

提出了一种基于宏微运动机器人的焊缝跟踪方法．首先,通过若干点的简单示教获得焊缝位置信息,并通过拟合建立焊缝模型．在该模型的基础上,对机器人的宏动进行运动规划．采用激光结构光视觉测量焊缝坐标,并根据焊缝图像偏差控制机器人的微动．结合机器人的宏动规划运动和微动自动调整,实现大范围、高精度的焊缝跟踪．利用宏微运动平台进行了焊缝跟踪实验,实验结果验证了所提出方法的有效性．     

焊接机器人焊缝自动跟踪系统

本文提出了一种焊接机器人焊缝自动跟踪系统用以实现焊枪对焊缝的实时自动跟踪。系统中应用激光焊缝传感器测量焊缝的位置,并采用Fuzzy-P双模分段控制进行焊缝的纠偏。DSP作为系统的核心控制器产生控制信号,驱动焊枪横向步进电机和纵向步进电机动作,调整焊枪实时跟踪焊缝。实验证明,基于双模控制的焊缝自动跟踪系统可以实现焊接机器人焊枪对焊缝的实时自动跟踪。该系统完全满足实际焊接工程的需要。     

仿人视觉过程的机器人视觉伺服系统研究

提出了一种模仿人类视觉过程的动态图像目标跟踪方法,其采用基于模板匹配的识别技术,通过模仿人类视觉目标定位过程运用遗传算法实现了对运动物体的视觉跟踪。利用此方法实现了一套视觉伺服机器人的运动目标跟踪系统,通过实验说明该方法能够满足系统的实时性要求,同时具有一定的抗噪能力。     

基于示教与视觉纠偏的机器人自动焊接方法研究

给出了一种示教与纠偏相结合的焊缝跟踪方法，用于实现机器人的自动焊接．针对传统的示教再现机器人，由激光视觉传感器测量实际路径与示教路径之间的偏差．机器人控制器根据示教路径和偏差，对焊枪的运动方向和位置进行调整，实现焊缝跟踪．利用六自由度机器人和激光结构光视觉传感器设计了实验系统，对所提方法进行了实验．实验结果验证了该方法的有效性．     

机器人实时视觉伺服系统控制方案的研究

本文针对机器人实时视觉伺服系统,考虑了机器人关节伺服反馈与视觉伺服反馈之间的相互联系,提出了实时控制方案,设计了合理的关节饲服控制器与视觉伺服控制器,以达到改善系统性能的目的。试验结果表明,当采用上述两个控制器时,系统的动静态性能得到了明显的改善。     

双队列控制的激光视觉焊缝跟踪系统研究

设计与实现了一套激光视觉引导的焊缝自动跟踪系统,包括系统的整体硬件构成和关键算法。在工业机器人末端安装激光视觉传感器构成焊缝跟踪系统的硬件部分。采用小波变换滤除焊缝图像噪声,采用改进的Steger算法和Hough变换方法提取激光条纹中心直线,进一步提取出焊缝位置。提出一种双队列控制策略,在采集的焊缝特征点的基础上进一步插值,从而实现激光视觉引导的焊缝自动与平滑跟踪。实验结果表明,该系统具有较好的跟踪精度,能满足工业实际需求。     

轮式移动焊接机器人弯曲焊缝跟踪控制

分析了轮式移动焊接机器人弯曲焊缝轨迹跟踪问题，建立了机器人的数学模型，采用基于积分backstepping时变状态反馈方法设计了控制器，利用Laypunov方法证明系统是镇定的。针对旋转电弧传感器仅能检测单方向偏差的情况，根据焊枪前端上一时刻和当前时刻的位置对跟踪轨迹的方位角进行估计。控制器在对机器人速度和角速度控制的同时，还对十字滑块进行了控制，使跟踪更加快速、平滑。最后通过数值仿真和机器人实际运动仿真证明了该方法的有效性。     

Seam tracking and visual control for robotic arc welding based on structured light stereovision

A real-time arc welding robot visual control system based on a local network with a multi-level hierarchy is developed in this paper. It consists of an intelligence and human-machine interface level, a motion planning level, a motion control level and a servo control level. The last three levels form a local real-time open robot controller, which realizes motion planning and motion control of a robot. A camera calibration method based on the relative movement of the end-effector connected to a robot is proposed and a method for tracking weld seam based on the structured light stereovision is provided. Combining the parameters of the cameras and laser plane, three groups of position values in Cartesian space are obtained for each feature point in a stripe projected on the weld seam. The accurate three-dimensional position of the edge points in the weld seam can be calculated from the obtained parameters with an information fusion algorithm. By calculating the weld seam parameter from position and image data, the movement parameters of the robot used for tracking can be determined. A swing welding experiment of type Ⅴgroove weld is successfully conducted, the results of which show that the system has high resolution seam tracking in real-time, and works stably and efficiently.     

Real-time seam tracking for robotic laser welding using trajectory-based control

In this paper a real-time seam tracking algorithm is proposed that can cope with the accuracy demands of robotic laser welding. A trajectory-based control architecture is presented, which had to be developed for this seam tracking algorithm. Cartesian locations (position and orientation) are added to the robot trajectory during the robot motion. In this way, sensor information obtained during the robot motion is used to generate the robot trajectory while moving. Experiments have been performed to prove the tracking capabilities of the seam tracking algorithm.     

基于虚拟现实技术的移动机器人视觉伺服控制系统设计

为了有效确保移动机器人视觉伺服控制效果,提高移动机器人视觉伺服控制精度,设计了基于虚拟现实技术的移动机器人视觉伺服控制系统。通过三维视觉传感器和立体显示器等虚拟环境的I/O设备、位姿传感器、视觉图像处理器以及伺服控制器元件,完成系统硬件设计。从运动学和动力学两个方面,搭建移动机器人数学模型,利用标定的视觉相机,生成移动机器人实时视觉图像,通过图像滤波、畸变校正等步骤,完成图像的预处理。利用视觉图像,构建移动机器人虚拟移动环境。在虚拟现实技术下,通过目标定位、路线生成、碰撞检测、路线调整等步骤,规划移动机器人行动路线,通过控制量的计算,实现视觉伺服控制功能。系统测试结果表明,所设计控制系统的位置控制误差较小,姿态角和移动速度控制误差仅为0.05°和0.12m/s,移动机器人碰撞次数较少,具有较好的移动机器人视觉伺服控制效果,能够有效提高移动机器人视觉伺服控制精度。