Development of an Autonomous Robot for Gas Storage Spheres Inspection

Inspection for corrosion of gas storage spheres at the welding seam lines must be done periodically. Until now this inspection is being done manually and has a high cost associated to it and a high risk of inspection personel injuries. The Brazilian Petroleum Company, Petrobras, is seeking cost reduction and personel safety by the use of autonomous robot technology. This paper presents the development of a robot capable of autonomously follow a welding line and transporting corrosion measurement sensors. The robot uses a pair of sensors each composed of a laser source and a video camera that allows the estimation of the center of the welding line. The mechanical robot uses four magnetic wheels to adhere to the sphere’s surface and was constructed in a way that always three wheels are in contact with the sphere’s metallic surface which guarantees enough magnetic atraction to hold the robot in the sphere’s surface all the time. Additionally, an independently actuated table for attaching the corrosion inspection sensors was included for small position corrections. Tests were conducted at the laboratory and in a real sphere showing the validity of the proposed approach and implementation.     

基于专家系统的焊枪姿态智能控制系统

针对管道焊接机器人焊枪姿态控制问题,提出了一种基于专家系统的焊枪姿态智能控制系统。在基于专家系统的智能控制基础上加入神经网络模糊控制,二者采取并行控制与知识共享的策略,实现管道焊接机器人焊枪姿态的综合集成智能控制。系统中采用ADXRS300微机械陀螺作为焊枪位置传感器,获取焊枪的空间位置后,通过专家系统的经验推理,得到合适的俯仰角,并采用ARM7作为控制器驱动焊枪俯仰角步进电机动作,实现对焊枪俯仰角的实时调节。     

Assisting manual welding with robot

This paper presents a first attempt to assist manual welding with a physically interactive robot. An interactive control scheme is developed to suppress the vibrations of torch during the welding of novice welders. The torch is attached to the end-effector of a haptic-robot. Human and robot act together on the welding torch: the human controls the direction and speed; the robot suppresses the sudden and abrupt motions. The control scheme is developed by experimenting with an air-paint-brush. The painting process emulates the actual welding. Such an emulating environment is useful to surmount the difficulties of experimentation with actual welding. The impedance parameters of the control scheme are investigated. A damping value is determined for an effective vibration suppression and minimum human effort. A variable impedance control scheme is applied to ease the manipulation of the torch while not welding. The results of real welding of novice welders with and without robot assistance are presented. There is a considerable improvement in the performance of the welders when they are assisted with the robot.     

基于PLC技术的焊接机器人主从协调运动控制系统研究

焊接机器人运动控制系统的控制功能直接决定了焊接工作质量,利用PLC技术优化设计焊接机器人主从协调运动控制系统。在系统硬件设计方面,装设位置、速度、旋转电弧等传感器设备,利用传感数据检测焊接机器人实时位姿。在考虑焊接机器人组成结构、工作原理以及动力驱动方式的情况下,构建焊接机器人的数学模型。结合当前位姿和控制目标之间的位置关系,规划焊接机器人主从协调运动轨迹,在约束条件的作用下,利用PLC控制器生成控制指令,作用在改装的焊接机器人驱动器上,实现系统的焊接机器人主从协调运动控制功能。通过系统测试实验得出结论：与传统控制系统相比,优化设计系统的速度控制误差、姿态角控制误差分别降低了0.075mm/s和0.38°,在优化系统控制下,主从焊接机器人的运动轨迹与规划轨迹之间无明显差异。     

Quasi-Omnidirectional Fuzzy Control of a Climbing Robot for Inspection Tasks

This work presents a novel method to quasi-omnidirectional control of an intelligent inspection robot designed to work inside and outside spherical storage tanks. The main objective is to promote a stable and smooth navigation during inspection tasks, ensuring the safety motion under adhesion and kinematic constraints. The robot is designed with four independent steerable magnetic wheels and a mechanical topology that allows the correct adjustment of adhesion system. A scheduled Fuzzy control is developed to achieve an optimal behavior and maximize the robot’s maneuverability, considering the magnetic restrictions of adhesion system and kinematic constraints of the inspection robot. The high adaptability of its mechanical topology (i.e., wheel misalignment, magnetic adhesion system, wheel camber and flexibilities in mechanical structure) and gravitational disturbance introduce many nonlinear characteristics in dynamic behavior that cannot be neglected, making the determination of its dynamic model a complex task. The Fuzzy approach allows to project a control system without a depth knowledge of its dynamic properties, to minimize the dynamic disturbances found in robot structure. Thus, the proposed motion control works according to the robot specific characteristics to ensure the quasi-omnidirectional motion over a reliable adhesion to tank surface and to minimize the effects of wheels kinematic constraints.     

基于ADAMS的弧焊机器人运动仿真

机器人三维运动仿真是当前机器人研究领域中重要的研究方向之一。采用CAD软件Pro/E和机械系统动力学仿真软件ADAMS,对德国CLOOS公司生产的76AW型弧焊机器人建立了三维运动仿真模型。采用Denavit-Hartenberg方法建立了连杆坐标系下的机器人运动学模型,并采用Matlab编写了运动学正、逆解的程序。详细阐述了模型的建立方法及具体过程,实现了在ADAMS环境下的机器人焊缝路径的运动仿真。为机器人动力学及离线编程技术的研究提供了基础。     

机器人点焊工作站在汽车制造中的应用

机器人焊接系统属于多智能体系统（Multi—Agent systems,MAS）,机器人点焊系统集成的关键是如何处理好MAS的通信和工作协调。本文介绍汽车车身机器人点焊的工作流程,重点介绍了机器人点焊工作站的控制原理及工作站集成技术。     

Interpolation of orientation for precise path generation in industrial robots

Industrial robots are versatile mechanical systems that require accurate tracking of continuous end-effector trajectories. However, a variety of control problems are encountered due to the deviation between the desired and actual paths.In this study, a new continuous path planning method based on an interpolation of orientation scheme is applied for precise path generation in robot welding. This method guarantees minimum deviation of positioning and orientation errors. Also, a new trajectory error evaluation strategy is developed to describe the trajectory errors at the effect points, which are very important in some robot jobs such as arc-welding operations.The simulation study of circular motions in arc-welding operations shows the effectiveness of the proposed approach.     

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.     

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。     

An auto-programming system of MAG welding parameters for vision-based robot

The on-line auto-programming of MAG welding parameters for a vision-based robot mainly aims at improving the adaptability of a welding robot in a complex welding environment, and it is a new kind of intelligent control method of weld quality. The authors developed an experimental system of an MAG welding robot with 3-D vision according to the requirements of real-time auto-programming of welding parameters. In the system, the scam geometry parameters, i.e., root gap and root face in a single V-groove, are used as input variables, while the welding process parameters, i.e., welding current and speed, are used as output variables. The relation between input and output variables is described by a fuzzy model. Experimental results show that the system can result in increased weld quality.     

高性能机器人控制系统的研究

本文介绍了高性能机器人控制器的研制情况．该系统具有较高的控制精度，可 完成对机器人和多个外部轴的协调控制．为便于国内用户使用，实现了中文界面功能键驱动 的汉字编程示教盒．为适应机器人生产线的需要，提供了丰富的联网功能和生产线监控诊断 功能．目前该系统已用于新松公司的6kg工业机器人产品中．     

Stabilizing manipulator motion along a given surface

We consider mechanical systems like a manipulating robot, an excavator, and other similar devices. Known solutions for the general problem of manipulator motion stability have been obtained under rather strong assumptions. A special but important case of the stability problem under natural assumptions is solved in this work. We have constructed a control law that stabilizes the motions of a system lying inside a given surface. One example of such surface might be the surface along which a welding seam goes in the problem of automated welding with a manipulator.     

An approach to the path planning of tube–sphere intersection welds with the robot dedicated to J-groove joints

In actual manufacturing process, many weldments have large dimensions and complex shapes, and they are usually assembled through a multi-pass welding process. The joints of the tube–sphere intersection (J-groove joints) are complex. This paper presents a complete solution in determining the welding paths based on a developed J-groove joint robot. Generating complex welding paths in terms of cubic B-spline curves is made easy using path control modules such as interpolation module and local modification module. The point inversion module using particle swarm optimization is introduced to address the partition of path, which is required of the welding process. Experimental results show that higher efficiency as well as better weld quality can be achieved, indicating a promising and practical use of the robot for welding applications, which is rarely available at present.     

机器人逆运动学分析与仿真

研究机器人动态优化问题。根据机器人所持焊枪的运动轨迹,针对机器人可沿空间任意直线轨迹焊接,是焊接机器人关节控制策略中的难点,运用ADAMS软件对焊接机器人进行逆运动学求解,采用拉格朗日方法建立了系统的微分方程,运用pro/E建立了焊接机器人的三维模型,导入ADAMS中添加约束关系和设置仿真参数后建立焊接机器人的虚拟样机模型,对机械手沿空间任意直线轨迹运动的工况进行了逆运动学仿真,得到了各关节的角速度和角加速度曲线,并根据仿真结果提出了使焊接更加平稳的改进方案,结果表明方法不仅为焊接机器人的路径规划提供了参考数据,而且保证了焊接机器人在焊接过程中优良精确的动态特性和静态特性,具有重要的工程实际意义。     

Magnetic mechanical capsule robot for multiple locomotion mechanisms

This paper proposes a magnetic mechanical capsule robot which crawls in a fluid-filled tube. The developed capsule robot employs two locomotion mechanisms simultaneously. It has spiral ribs at both ends, which are rotated by a small on-board motor. Such rotating spiral structures generate a driving force of the capsule robot. We invented a magnetic mechanical mechanism to transfer the rotational motion of the frontal part into the linear motion of the middle part. Using this original mechanism, the linearly moving part at the middle of the capsule robot generates a supportive driving force. The improved mobility is evaluated in experiments. The developed capsule robot employing multiple locomotion mechanisms moves 44% faster than the spiral motion-based capsule robot. The developed magnetic mechanical mechanism and the mobile robotic platform could be used for pipe inspection robots or medical robots.     

基于梯度下降和二分法的移动机器人轨迹规划方法

轨迹规划是移动焊接机器人轨迹控制的基础,是该系统中重要的组成部分。为了提高多关节移动焊接机器人轨迹规划的效率和精确性,同时考虑到多关节焊接机器人的运动特性提出了一种梯度下降法和二分法结合的轨迹规划方法。移动焊接机器人由机械杆和机器人移动平台组成,由于移动平台提供移动性使得移动焊接机器人相对固定的机械臂有更大的工作空间。近年来,此类系统的研究已在经学术界和工业界迅猛发展。论文首先建立移动焊接机器人的运动学模型,并且阐述梯度下降法和二分法结合算法的设计步骤。然后,采用典型的正弦波形作为焊缝轨迹,通过仿真验证该方法的应用前景和可行性。     

球罐焊接机器人控制器及程序设计分析

介绍了焊接机器人的工作原理及采用的S7-200可编程控制器，就其控制系统构成、 硬件接口、软件程序设计等要点进行了详细分析．工艺实验与实践证明，该系统工作稳定可 靠，跟踪精度高，满足球罐自动焊要求．     

热膨胀电极位移法用于机器人点焊过程的研究

本文首次将热膨胀电极位移法用于机器人点焊．采用 高精度、高分辨率的光栅位移传感系统，对机器人点焊电极位移变化规律进行了研究．试验 结果表明，测量数据准确，重复性高，为电极位移法用于机器人点焊质量监控提供了新的途 径．     

弧焊机器人视觉测量控制系统

提出了一种基于结构光的弧焊机器人双目立体视觉测量控制系统。该系统硬件主要由结构光发射器、CCD摄像机、机器人、焊机以及通过局域网连接的两台控制计算机组成。从结构光照射形成的两幅图像中提取对应特征点,结合摄像机和激光器之间的几何位置关系,分别求取三组对应的特征点空间坐标,经过信息融合后得到特征点对应的空间位置。利用递推最小二乘法拟合焊缝的空间位置,根据一定的步长选取对应直线上的点传送到运动控制计算机以进行运动轨迹规划,并通过运动控制卡驱动机器人运动完成焊接任务。实验表明该系统性能较好。