Digital twin-enabled advance execution for human-robot collaborative assembly

A reliable human-robot workcell relies on accurate and nearly real-time updated models, especially in a constrained yet dynamic environment. This paper investigates digital twin-driven human-robot collaborative assembly enabled by function blocks. Leveraging sensor data, digital models are developed to precisely mimic physical human-robot collaborative settings supported by a digital-twin architecture. An advance-execution twin system based on the current status through real-time condition monitoring performs assembly planning and adaptive robot control using a network of function blocks. An augmented reality-based interaction method using HoloLens further facilitates human-centric assembly. An engine-assembly case study is performed to validate the effectiveness of the system.     

Brainwaves driven human-robot collaborative assembly

This paper introduces an approach to controlling an industrial robot using human brainwaves as a means of communication. The developed approach starts by establishing a set of training sessions where an operator is enquired to think about a set of defined commands for the robot and record the brain activities accordingly. The results of the training sessions are then used on the shop floor to translate the brain activities to a set of robot control commands. An industrial case study is carried out to assist the operator in coordinating a collaborative assembly task of a car engine manifold.     

基于注意力时空特征网络的装配动作识别

为实现工人装配动作过程的识别,防止由于工人装配动作不规范而造成装配产品质量问题,研究基于深度学习方法的装配动作识别,提出一种基于通道注意力的融合时间和空间信息特征网络模型来识别装配动作的方法.利用MYO臂环传感器采集表面肌电信号,建立一个包含多种装配动作的数据集;搭建一个用于装配动作识别的神经网络,对网络模型进行评估....     

网络环境下组合夹具虚拟装配平台的构建

基于网络的虚拟装配是实现产品网络化设计制造的一项重要技术.为了在网络环境下实现组合夹具的交互式虚拟装配,运用VRML与Java相结合的技术,构建了组合夹具交互式、网络化虚拟装配平台.研究了组合夹具网络化虚拟装配中的相关关键技术,包括夹具元件及装配模型的创建与优化处理、Java实现对夹具VRML场景的实时、交互控制等.给出了创建组合夹具虚拟装配平台的具体实现方法,通过实例验证了装配平台的可行性.研究工作为基于网络的虚拟装配技术走向实用化作了有益的探索.     

SolidWorks在液压集成块设计中的应用

以小型液压机液压系统为例,利用三维设计软件Solid Works辅助液压集成块阀体设计;利用Simulation Xpress应力分析工具对阀体进行了有限元分析,生成了二维工程图;建立了三维液压元件库,完成了液压集成块的装配,生成了装配体的爆炸图,制作了集成块备件手册,具有实际的工程应用价值。     

Intelligent control planning strategies with neural network/fuzzy coordinator and sensor fusion for robotic part macro/micro-assembly tasks in a partially unknown environment

This paper addresses the problems of the robotic part assembly in a partially unknown environment. The process can be broken down into two phases. First, a macro-assembly, locating various shaped assembly holes or receptacles (targets) in the workspace corresponding to the shapes of the parts and then bringing the part to the corresponding target, despite existing obstacles. This is accomplished by combining a neural network control strategy coordinating with a mobile multiple optical sensor as well as fuzzy optimal controls. Depending on topological relationships among the part’s present position, the position of obstacles, and the target position in the workspace, a specific rulebase from a family of distinct fuzzy rulebases for avoiding obstacles is activated. An entropy function, which is a useful measure of the variability and the information in terms of uncertainty, is introduced to measure its overall performance of a task execution related to the part assembly task. Second, a micro-assembly, placing the part at a position that is ready to mate successfully with the target without jamming. Depending on a mating type, namely, a rightside, a leftside, or a straight approach toward a target, which is determined by fusing sensor information obtained by optical sensors, a specific rulebase is activated. Fuzzy set theory is used to address the uncertainty associated with the macro and the micro-assembly procedures. Using the control of a robotic part assembly task as an example, a systematic method, not a heuristic one, that can determine an optimal rulebase among feasible fuzzy rulebases which can execute the part assembly task successfully, based on a fuzzy entropy is introduced. The degree of uncertainty associated with the part assembly tasks is used as an optimality criterion, e.g. minimum fuzzy entropy, for a specific task execution. The results show the effectiveness of the above methodologies. The proposed technique is applicable to a wide range of robotic tasks including part mating with various shaped parts, pick and place operations, and motion planning.     

Transplanting Assembly of Carbon Nanotubes

The manufacture of nanotechnology products requires assembly of nano scale components to macro/micro-scale systems, which is a major challenge in attempting to industrialize nanotechnologies. A new approach to assemble nanostructures is developed with a control of individual nanostructure's location and alignment in a long-range order. A concept of transplanting assembly has been developed to embed carbon nanotubes into micro-scale polymer blocks, which then serve as carriers for the embedded carbon nanotubes, facilitating the handling and assembly of them. This technique includes vertical growth of carbon nanotubes, nanopellet casting, planarization, nanopellet separation, transplantation and bonding. This assembly technology can be broadly applied to manufacture many nano scale products including carbon nanotube tipped atomic force microscope probes.     

Recurrent neural network for motion trajectory prediction in human-robot collaborative assembly

Effective and safe human-robot collaboration in assembly requires accurate prediction of human motion trajectory, given a sequence of past observations such that a robot can proactively provide assistance to improve operation efficiency while avoiding collision. This paper presents a deep learning-based method to parse visual observations of human actions in an assembly setting, and forecast the human operator's future motion trajectory for online robot action planning and execution. The method is built upon a recurrent neural network (RNN) that can learn the time-dependent mechanisms underlying the human motions. The effectiveness of the developed method is demonstrated for an engine assembly.     

淋浴喷头大身注射模设计

分析了淋浴喷头大身的工艺特点,介绍了淋浴喷头大身注射模结构设计和工作过程。模具采用斜导柱抽芯机构、齿轮齿条弧形抽芯机构解决了塑件成型问题,用锁扣机构实现了顺序开模,用摆杆先复位机构解决了工作过程中的干涉问题。模具结构紧凑,设计合理。     

Employing fractals and FEM for detailed variation analysis of non-rigid assemblies

Many studies on non-rigid assemblies, or assemblies of non-rigid components, suggest that the component variation affects the assembly dimensional quality. However, little is known about how the variation of surface micro-geometry of assembly components influences the assembly dimensional quality. In this paper, a new method based on the fractal geometry and finite element method (FEM) is proposed to study such an influence. In the new method, a special fractal function, named the Weierstrass–Mandelbrot (W–M) function, is used to extract and represent the characteristics of surface micro-geometry of assembly components. FEM is applied to analyze the deformation of non-rigid assemblies by integrating the variation of component micro-geometry. The sensitivity matrix between the component variation and assembly variation is obtained by using the existing influence coefficients method. It is found that contributions of the surface micro-geometry of assembly components to the final variation of non-rigid assemblies could be substantial under certain conditions. The proposed method is illustrated through a case study on an assembly of two flat sheet metal components under different fixture-releasing conditions.     

空调翅片模具切口模块的设计制造

介绍了切口模块的设计特点及制造工艺。为保证齿形与销孔的位置精度 ,切口模块在加工过程中采取了一系列的工艺措施 ,特别对切口模块的关键工序进行了严格控制 ,加工出的切口模块每对试切及装配后冲切0.115mm厚铝片毛刺全部控制在0 .02mm以内 ,各模块一致性好 ,每对模块均可互换。     

三维钢网装配机械的模块化设计与应用

以产品装配工艺和装配机械的功能分析为基础,将模块化原理应用于三维钢网系列装配机械的设计上。对三维钢网装配机械进行了功能模块的划分与创建,并对主要功能模块的结构进行了阐述。最后给出了一种装配机械模块的典型配置方案。     

基于视觉的工业机器人装配演示示教研究

针对工业机器人编程效率低下、智能化程度不高和人机交互性能弱等问题，提出一种基于视觉的工业机器人装配演示示教系统，该系统包括目标检测与中心点定位模块、装配动作分类识别模块和机器人动作执行模块。在目标检测与中心点定位模块中,提出一种目标物体中心点定位和机器人抓取方法，使用实例分割算法识别物体类别，通过掩码均值化处理和坐标转换计算物体3D姿态信息；在装配动作分类识别模块中，建立基于深度学习网络的动作分类识别模型，该模型的输入为装配动作视频帧，输出为动作分类标签；最后，机器人动作执行模块根据物体类别、物体3D姿态和动作分类标签等信息规划机器人装配动作，控制机器人执行装配任务。以轴孔装配为例，验证了上述方法的有效性，实现了基于视觉演示的机器人装配模仿编程，对机器人演示示教研究具有一定的参考价值。     

Assembly and Disassembly Processes in Product Life Cycle Perspectives

Industrial companies change the paradigms of business operations from optimisation of manufacturing processes to optimisation of products life cycles in order to activate the value of products, taking into account the potentials of product services in all phases of each product's life. From design to the end of their life capital intensive products, like manufacturing or assembly systems, are linked to a manufacturer network by global communication systems. This network allows special services even in the phases of usage and recycling. For this new paradigm it is necessary to develop strategies, methods and technologies to manage the business processes and the information and knowledge required in all phases of a product's life and to industrialise the processes of design, assembly, usage, service and remanufacturing by disassembly and recycling. It is the objective of this paper to define the processes for management of life cycle with a focus on assembly, service and disassembly of capital intensive products.     

Local order scheduling for mixed-model assembly lines in the aircraft manufacturing industry

Multi-variant products to be assembled on mixed-model assembly lines at locations within a production network need to be scheduled locally. Scheduling is a highly complex task especially if it simultaneously covers the assignment of orders, which are product variants to be assembled within a production period, to assembly lines as well as their sequencing on the lines. However, this is required if workers can flexibly fulfill tasks across stations of several lines and, thus, capacity of workers is shared among the lines. As this is the case for final assembly of the Airbus A320 Family, this paper introduces an optimization model for local order scheduling for mixed-model assembly lines covering both assignment to lines as well as sequencing. The model integrates the planning approaches mixed-model sequencing and level scheduling in order to minimize work overload in final assembly and to level material demand with regard to suppliers. The presented model is validated in the industrial application of the final assembly of the Airbus A320 Family. The results demonstrate significant improvement in terms of less work overload and a more even material demand compared to current planning.     

基于机器视觉和深度神经网络的零件装配检测

针对工业生产中存在着大量的零件识别定位以及装配检测等,传统人工检测效率低、劳动强度大、识别不准确。文章提出了一种基于深度神经网络的零件装配检测方法。首先该方法对零件图像和装配图像进行采集,选择Mask-RCNN网络进行训练,对装配零件进行分类以及定位,通过已识别的零件类型判定装配件是否存在漏装;然后将分割后的零件图像进行二值化处理,利用Canny算子提取零件图像轮廓;最后利用图像的Hu矩特征与正确的零件图像轮廓进行对比,判断装配是否正确。通过实验验证可得,该方法在零件装配中的漏装和换装检测中效果较好,并表现出较高的鲁棒性。     

The Investigation of the Movements and Temperatures in the Cathode of an Aluminum Reduction Furnace

Temperature and movements occurring in the cathode of a reduction furnace were explored by constructing and operating for short periods a number of 10 KA cells or “one-bar furnaces”. Each furnace consisted essentially of a slice across a high amperage industrial furnace and thus contained one cathode bar together with its carbon block (or blocks) and its attendant rammed-carbon side-lining, brickwork, etc. The steel box was specially designed to permit the conditions obtained in a large furnace to be simulated, and also to enable the restraints on expansion to be varied experimentally. Temperatures and outward movements of cathode block and box sections, and arching of the cathode bar, were measured during preheating, starting, and operation.During preheating some cracks opened in the blocks due to the greater thermal expansion of the steel bar. After starting sodium penetrated into the upper layers of the block causing expansion tending to close cracks at the top and produce an arching of the cathode block assembly, but cracking from the bottom, which could permit the arch to collapse. Increased restraint at the ends of the block assembly reduced the sodium expansion but could increase the arching. Different methods of mounting the blocks on the bars were investigated.     

Integration of Product Design and Assembly Planning in the Digital Factory

As assembly process planning fulfils the main function of connecting product design to production simulation and thus, the production system itself, a feasible software solution is needed to support this process. Thus, a novel concept is presented that aims at improving the integration of digital product design and assembly planning by introducing a consistent data structuring. This approach helps to reduce redundant tasks and supports the continuous data exchange. It is based on the use of assembly features, i.e. pre-defined geometry elements that contain additional technological information.The prototypical implementation of the concept focuses on the use of commercially available software tools, expanding them with additional functionality for the application of assembly features. The feature-based concept has been tested with a scenario from the automotive supplier industry. For the considered assembly, a comparison between the conventional and the feature-based planning approach is presented in the paper. It points out that the major advantages of the developed concept can be seen in an improved data consistency as well as a higher level of efficiency within the planning activities.     

新型汽车变速箱压装机控制系统的设计

文章介绍了一种新型汽车变速箱压装机控制系统的设计,对系统的硬件组态及控制功能作了主要描述.汽车变速箱压装机是汽车变速箱装配流水线上的一台机电一体化专用自动装配设备,该机除具有自动压装功能、自动检测报警功能外,还能与装配管理系统联网,实现网络化管理与控制功能.整个系统采用了SLC500可编程控制器、触摸屏、安全光幕控制器等控制部件,为机床提供了安全可靠的装配质量保证.     

牙镜模具的计算机辅助造型设计

三维装配图和分离场景图为对零件间的运动分析、干涉分析以及对部件的工作原理分析提供了便捷有效的方法和途径。本文阐述了利用MDT的三维功能进行牙镜模具零部件的造型设计和装配图的组装及分离场景图的创建过程。