The MARK III flexible automatic assembly cell

MARK III is a new concept in flexible automatic assembly (FAA) cells and has technically evolved out of the MARK II concept. The MARK III FAA cell is stepwise upgradeable and enables a major reduction in the cost of feeders and programming. It is a hybrid cell, combining automatic and manual assembly. The cell consists of a railtrack-mounted robot and adopts the sub-batch principle. Developed in order to account for the assembly of a vast range of products and variants, the MARK III allows for near-zero changeover times. By incorporating free-coupled manual assembly stations, the stepwise automation of manual operations is supported. These factors permit the automatic assembly of products with an annual volume normally too low to justify automation. Likewise, MARK III offers excellent opportunities for gradual capacity increase. Furthermore, it can account for unpredictable order schemes. The MARK III FAA cell also adopts a new programming and control system (FACE) which enables a drastic reduction in programming costs. This paper describes the evolution of this FAA cell from research to industrial launch.     

基于机器视觉的机械手装配系统设计

为了解决工业生产过程中料板的自动装配问题,提出了一种基于机器视觉的机械手定位装配检测系统,建立了实验平台。系统通过工业相机对料盘进行图像采集,将所采集的信息传送给工控机,借助图像处理程序,采用图像预处理实现了对图像的降噪,结合BLOB分析对图像特征进行了提取,获得了料盘上装配孔的位置信息,通过控制机械手动作,移动到装配位置,旋转相应角度,实现料板的自动定位装配。实验结果表明,该系统装配准确度高,误差小,满足了工业上的要求。     

Robotics developments and industrial applications

comau, a Fiat Group Company, designs and builds machining systems and integrated, automatic metalworking assembly, welding, storage and handling installations.In this paper we describe the robots manufactured by comau: smart and mast families.The smart is a six axis, all-electric industrial robot.The smart applications are in spotwelding (the largest) and automatic unloading and loading.The mast is a family robot whose oustanding characteristic is modularity: the number and type of arms in the system can be tailored to the application.smart and mast family robots have the same Control System and the same high level language.As a special application a smart Laser has been developed by comau, which includes inside the mechanical parts the beam delivery system.     

Calibration of an smt robot assembly cell

A new calibration method for an assembly robot cell is described. The proposed method is a combination of a model-free, numerical, relative robot calibration procedure and a procedure for the robot periphery calibration. Two important simplifications based on the study of an assembly process are introduced into the calibration strategy. A robot is calibrated in a task (Cartesian) space. The robot workspace and the number of calibrated degrees of freedom (dof) in the task space are reduced in accordance with the difficulty measure of the task. An automatic measurement system for measuring the relative robot accuracy was developed. An original principle of transforming the robot endpoint approach distance into the one-dimensional position displacement error is introduced. The accuracy errors of each particular calibrated dof in the task space is measured separately. The error tables are used in a direct robot calibration procedure that is based on the linear interpolation of the discrete position-error functions. An iterative inverse calibration algorithm used in a particular robot cell is described. An efficient sensor-based system for an additional simultaneous robot periphery calibration is presented. The implementation of the proposed calibration methodology in the pick-and-place robot cell for Surface Mount Technology (SMT) is presented. © 1994 John Wiley & Sons, Inc.     

A model for output evaluation of an intelligent robotic assembly station

The evolution of intelligent robots has brought widespread changes in the concept of automatic assembly. An intelligent robot can successfully accomplish assembly in a multiple end product processing and unstructured component part(s) handling environment. This advanced capability of the robot dictates a major change in their basic output characteristics. For example, task service time of an intelligent assembly robot is no longer completely deterministic like that of an ordinary pick-and-place type robot. In this paper, a typical component insertion type assembly task is analyzed to show that the task service time is a random variable consisting of two (2) parts, a deterministic component and a stochastic component. Thus, with the assumption of exponential part input an assembly station served by a single intelligent robot is modeled as an M/G/1 queueing model. A robot availability factor is also introduced into the service time random variable. Closed form expressions for important system performance parameters are obtained under the assumption of three (3) different probability distributions for the stochastic part of the service time random variable.     

Computer-aided analysis of reconfigurable fixtures and sheet metal parts for robotic drilling

This paper presents an automated manufacturing system for drilling sheet metal parts. All stand-alone systems such as the robot, a set of reconfigurable fixtures and the CAD/CAM workstation have been integrated into a flexible manufacturing system. This system analyzes and evaluates a given fixturing layout and assembles the reconfigurable fixtures automatically using a robot manipulator. An optimum fixturing layout and assembly are achieved by examining the workpart from a stress-strain point of view. In addition, issues such as geometric constraints, yielding and buckling, database design, collision detection, fixturing sequential control and the automatic assembly of fixture elements are considered. The computational and analytical concepts for the reconfigurable fixturing and drilling system are also presented in this paper.     

Toward an object-oriented and automated approach for achieving robotic assembly

This paper elaborates an object-oriented and automated approach for generating assembly sequences and achieving robotic assembly. This system, built with database and artificial intelligence (AI) techniques, provides the robot with the assembly sequence layout for the automatic handling rule. The critical set of problems is derived from various schemes such as model-based object recognition, features information, geometric and physical constraints between components, knowledge interpretation and robot task sequencing. Pattern recognition regarding shapes and features, along with a knowledge-based assembly, are the key issues of the authors' work. The methodology is shown through two illustrative examples involving different designs of parts in an assembly environment.     

柔性装配系统的集成与设计

自行开发的柔性装配系统FAS ,将PC机、机器人、PLC和产品识别装置各单元集成于一个协调工作的自动装配系统。通过网络互连通信、信息集成 ,完成系统各单元的硬件构成和软件模块设计 ,为中小批量产品的装配提供了一个柔性化的解决方案。     

Information system structure for a task level robot assembly language for on-line program generation

The increasing industrial need for production automation in one of a kind production and increasing demand for one of a kind or small batch production requires that automation is carried out by programmable automatic equipment in order to ensure that this equipment can be rapidly and easily adjusted and configured to the ever changing production tasks. In order that the adjustment and reconfiguration of the production equipment can be carried out quickly, reliably and in compatibility with the state of the production plant at the time of task execution it is necessary that the equipment tasks can be specified by a specification language, which is much more abstract than the task specification languages that are today commercially available for machine tool and robot programming, and that the corresponding compiler can be controlled by the system controlling the sequence of operations of the assembly plant. To comply with this need a task level robot programming language for assembly operations has been developed with a level of abstraction corresponding to the level of abstraction for the command: Mount part A. The compiler of the language retrieves information about placement and orientation of the parts to be assembled from a database. The information is supplied to the database by proper sensors mounted on the assembly plant, implying that the program which is generated corresponds to the state of the physical plant at program execution time. Additionally, making available information of permitted production assembly sequences has enabled the compiler to be controlled by a system that optimizes the sequence in which a particular assembly should be carried out respecting present availability of resources needed for the assembling tasks.In this paper the designed robot language, the corresponding compiler and the necessary information structures are presented.     

Robot programming system for assembly: Conceptual graph-based approach

This work develops a method for robot program synthesis. Currently, the programming task is one of the major hurdles of robotic application. Progress towards automatic synthesis of robot programs will ease industrial robot application. The proposed system provides a means towards automated (guided by knowledge) conversion of a user's request, expressed in natural language, to the appropriate conceptual model of the required task. This model incorporates the information necessary for understanding, planning, and sensory-guided performance of the required robotic task.First, we state the problem of robotic assembly and recognize its hierarchic structure as the structure of a system that builds a predesigned assembly. Next, we present and analyze the requirements of the robotic assembly domain. This analysis enables us to draw conclusions concerning the most suitable methodology for the development of a support system for assembly program synthesis and interpretation. It is the conceptual graph-based approach. Then we present the algorithm of the proposed conceptual graph-based system and show how the system synthesizes robotic assembly operations, such as valid assembly sequences and sequences of special treatments for the assembled components (including the determination of the required resources). Finally, a case study illustrates the approach developed here on a large family of multi-axisymmetric components. We also present illustrative examples of working sessions with the current implementation of the system.     

小型断路器柔性装配中视觉识别系统的设计与应用

现代制造业对小型断路器（MCB）生产过程的效率和精度要求都在不断提高,传统的人工装配效率低且装配质量参差不齐,而传统基于振动盘上料的自动装配技术限制了制造的柔性化水平。针对上述问题以及未来的市场需求,提出了一种基于机器视觉的小型断路器柔性装配系统,该系统搭建专用的视觉识别模块,通过VGG-16架构的深度学习分类器和特征模板匹配方法,对小型断路器零件的种类、位置坐标、当前姿态进行识别,并将识别结果发送给工业机器人控制器,指导工业机器人对不同型号产品的不同零件类型通过机器人夹爪的灵活切换来完成不同的装配任务。实验表明,该系统对零件种类识别准确率为99.8%,坐标偏差在±0.3mm以内,旋转角度偏差在±0.8°以内,达到了MCB装配的精度要求,符合柔性化制造的需求。     

Artificial intelligence and robotic assembly

Traditionally, most industrial robots are programmed by teaching. The emergence of robot-level programming languages has improved the programmer's ability to describe and modify the robot moves. However, commercially available robot-level programming languages still fall short of the robot user's need to program complex tasks, and consequently, are not widely used in industry. There is an increasing need for integrating sensors feedback into the robot system to provide better perception and for improving the capacity of the robot to reason and make decisions intelligently in real time.The role of artificial intelligence in programming and controlling robots is discussed. Available robot programming systems including robot-level, object-level, and task-level languages are reviewed. The importance of developing intelligent robots in broadening the scope of flexible automation and opening the door to new robotic applications in space, under water and in harsh environments is outlined. The current development and implementation of programming and control systems for intelligent robots, at McMaster University, are explained. A number of research issues are discussed such as (1) automatic task planning, (2) knowledge representation and use, (3) world modeling, (4) reasoning in automatic assembly planning, and (5) vision monitoring of actions. Examples of geometric, functional, and handling reasoning, as they apply to assembly, are provided. The systems described in this paper are being implemented in the center for flexible manufacturing research and development. Several pieces of hardware are used, including a six-axis articulated robot, a grey-level vision system with a multi-camera, Micro VAX II, and a variety of graphics monitors. The languages available for software development include Common LISP, C, OPS5, VAL II, PASCAL, and FORTRAN 77. The domain of application is currently focused on mechanical assembly.     

Performance analysis of robotic kitting systems

Robotic kitting and presenting parts in the from of a kit to an assembly robot can provide significant flexibility, control, expandability, and productivity in both the part stores and final assembly operations. The problem of selecting the proper design of a robotic kitting configuration based on desired performance criteria is discussed. Several models of recommended robotic kitting configurations were developed and then analyzed using a robot cell simulator, SINDECS-R, and a robot motion time program, RTM. Each of these models was evaluated for a variety of typical operating conditions and compared based on performance in order to provide guidance for designers. The most favorable robotic kitting design as found in this analysis is the miniload on-board robot/automated storage-retrieval kitting system.     

Programming and control of a two-hand assembly system

This paper presents the implementation of an original cooperating system for precise assembly operations. The whole mechanical architecture consists of a conventional manipulator robot and a micro-manipulator setting in parallel. The micro-manipulator used is a manipulator-gripper in a left hand configuration. The mechanism of the manipulator-gripper was designed to achieve active or passive fine compliant motions. Some details of its technology are given. A real-time distributed computer system has been developed for coordinated-motion control. Programming assignments are explained. For complex assembly tasks, automatic fine motion strategies are obtained by a rule-based expert system.     

基于机器视觉和力反馈的自动装配技术研究

针对工业生产中自动装配技术装配精度不高的问题,提出了一种基于机器视觉和六维力传感器的自动装配控制方法。使用两个单目摄像头对目标进行两次定位,通过改进的NCC匹配算法进行一次定位,通过基于边缘特征的模板匹配进行二次定位,利用六维力传感器获取装配过程中的力与力矩变化情况,并基于反馈的力与力矩提出了直线运动与螺旋线运动两种装配轨迹规划策略。在搭建的机器人平台上对两种策略进行了对比实验,实验结果表明,在轴孔间隙较大时直线运动装配效率较高,但当轴孔间隙小于0. 1 mm时,直线运动的装配效率和成功率均大幅下降,而螺旋线运动的装配时间主要与装配孔直径有关,对于不同轴孔间隙装配表现稳定,并能以较高成功率实现精度0. 05 mm的轴孔装配。     

机器人插件作业的视觉导引方法研究

插件作业（parts mating）是装配机器人的一项基本作业环节．本文介绍了以双目立体视觉 实现该作业的视觉导引方法．该方法通过采用人机交互方式,借助于人的智慧,提高了图像 特征提取和匹配的准确性和可靠性、可直观准确地给出插件作业的动作参数,克服了自动视 觉计算复杂、鲁棒性差的缺点,适用于机器人遥操作作业．实验表明,基于人机交互的机器 人插件作业在立体视觉导引下是完全可行的．     

A novel vision-based method for 3D profile extraction of wire harness in robotized assembly process

Automating stages for deformable objects in the production line, in which assembling a wire harness into a predefined position is a complex task owing to the specialized characteristics of the objects. Besides a few automatized systems proposed in the other studies to implement this task under simplified setup conditions, a significant portion of this process remains to be completed manually in industrial environments. To construct an automatic wire harness assembly system, the development of a method that can automatically detect the wire harness profile in a 3D environment and, consequently, guide robot arms to implement assembly tasks is indispensable. Therefore, this study presents an approach that satisfies this requirement, which not only proposes a deep learning-based system to detect the wire profile, but also improves the accuracy of the detected results through a correction method according to the depth values of contiguous areas. The verification of the approach in a robot system that highlights its usefulness and practicality demonstrates the potential of the proposed method to replace people and consequently, reduce labour costs in factory environments.     

用Visual C++开发装配机器人微机屏幕示教盒

文章用VC＋＋6．0开发了一个精密装配机器人微机屏幕示教盒。该示教盒是基于PC机的精密装配机器人语言编程系统平台的组成部分。用户可通过鼠标操作该屏幕示教盒实现装配机器人的在线示教编程,从而可以替代传统的用单片机制作的示教盒。     

Towards robot cell matrices for agile production – SDU Robotics' assembly cell at the WRC 2018

ABSTRACT

To support shifting to high mix/low volume production, manufacturers in high wage countries aim for robotizing their production operations – with a special focus on the late production phases, where robotic assembly cells are then confronted with any complexities resulting from part and product varieties. The ‘World Robot Challenge 2018’ (WRC 2018) emulated such high mix/low volume production scenarios in a competition taking place in Tokyo, Japan. As part of our activities in SDU's newly founded I4.0 Lab, we integrated and advanced our experiences and developments from our various R & D projects in a novel robotic assembly cell design to compete in the WRC 2018. This article describes the system architecture as well as main aspects of its implementation regarding robot control, robot programming and computer vision and how they contributed to winning the challenge. Due to the application of collaborative robots, the cell design allows for operation without fences. Hence, multiple copies of the cell can be arranged in a highly reconfigurable, highly adaptable matrix structure in which several production flows can be handled concurrently. This concept was demonstrated by the installation of a duplicate cell that allowed for parallel developments on two cells and prolonged development also after shipping the first cell to Japan.