汽车变速箱零部件装配自动测量系统

汽车变速箱装配过程中部分零部件分装涉及到选择调整垫片的过程,垫片尺寸是否合适将直接影响变速箱整体的装配质量,为了满足新型号变速箱的数字化生产需求以及提高生产系统的工作准确性,需要将人工经验为主导的传统制造模式向轻量化、智能化的新型制造模式转化.本文结合某企业MQ250变速箱装配线的具体需求,为了提高生产现场的数字化程度以及对测量任务的管理能力,设计并实现了一套新型的变速箱零部件装配的测量系统.首先根据相对测量的原理,设计了测量模块,并分析了测量模块最优化的问题,最终通过最小二乘法实现了测量模块的优化.经过实际生产情况表明,本测量系统适应了MQ250变速箱零部件的装配需求,保证装配效率的情况下提升了整体装配质量,提高了装配生产线的数字化水平.     

An intelligent assembly robotic system based on Relative Pose measurements

One of the major problems in realizing intelligent assembly robotic systems has been the difficulty of compensating for uncertain and erroneous situations. In particular, pose (position and orientation) uncertainties lead to a challenging problem. In this paper, we outline a Relative Pose-based Strategy for effective dynamic end-pont control of manipulators in uncertain environments. The introduced strategy imposes new requirements on the higher levels of the control. Besides appropriate planning, control and sensing strategies, an advanced supervision system architecture needs to be provided. In this paper, the fundamental issues relating to intelligent assembly robotic system design are briefly discussed and an overall control architecture is introduced. The lower portions of the proposed architecture, viz. the Execution and the Supervisory Levels are described in detail.     

基于装配自由度分析解决欠约束问题

装配是机械制造过程中的一个重要环节,在装配过程中,经常会遇到欠 约束问题。在复杂装配环境下,某个装配零件的欠约束会对其他零件的装配产生意想不到的 结果。装配时,约束条件和零件自由度之间存在一种内在联系,通过建立基体和目标零件的 自由度空间坐标系,对约束条件和自由度关系分析,得到约束条件和自由度关系的逻辑值, 通过逻辑值判断剩余自由度的个数和类型,从而为快速解决欠约束问题提供了一种途径。     

Off-line error prediction, diagnosis and recovery using virtual assembly systems

Automated assembly systems often stop their operation due to the unexpected failures occurred during their assembly process. Since these large-scale systems are composed of many parameters, it is difficult to anticipate all possible types of errors with their likelihood of occurrence. Several systems were developed in the literature, focussing on on-line diagnosing and recovery of the assembly process in an intelligent manner based on the predicted error scenarios. However, these systems do not cover all of the possible errors and they are deficient in dealing with the unexpected error situations. The proposed approach uses Monte Carlo simulation of the assembly process with the 3-D model of the assembly line to predict the possible errors in an off-line manner. After that, these predicted errors are diagnosed and recovered using Bayesian reasoning and genetic algorithms. Several case studies are performed on single-station and multi-station assembly systems and the results are discussed. It is expected that with this new approach, errors can be diagnosed and recovered accurately and costly downtimes of robotic assembly systems will be reduced.     

Smart control of the assembly process with a fuzzy control system in the context of Industry 4.0

Assembly line balancing is important for the efficiency of the assembly process, however, a wide range of disruptions can break the current workload balance. Some researchers explored the task assignment plan for the assembly line balancing problem with the assumption that the assembly process is smooth with no disruption. Other researchers considered the impacts of disruptions, but they only explored the task re-assignment solutions for the assembly line re-balancing problem with the assumption that the re-balancing decision has been made already. There is limited literature exploring on-line adjustment solutions (layout adjustment and production rate adjustment) for an assembly line in a dynamic environment. This is because real-time monitoring of an assembly process was impossible in the past, and it is difficult to incorporate uncertainty factors into the balancing process because of the randomness and non-linearity of these factors. However, Industry 4.0 breaks the information barriers between different parts of an assembly line, since smart, connected products, which are enabled by advanced information and communication technology, can intelligently interact and communicate with each other and collect, process and produce information. Smart control of an assembly line becomes possible with the large amounts of real-time production data in the era of Industry 4.0, but there is little literature considering this new context. In this study, a fuzzy control system is developed to analyze the real-time information of an assembly line, with two types of fuzzy controllers in the fuzzy system. Type 1 fuzzy controller is used to determine whether the assembly line should be re-balanced to satisfy the demand, and type 2 fuzzy controller is used to adjust the production rate of each workstation in time to eliminate blockage and starvation, and increase the utilization of machines. Compared with three assembly lines without the proposed fuzzy control system, the assembly line with the fuzzy control system performs better, in terms of blockage ratio, starvation ratio and buffer level. Additionally, with the improvement of information transparency, the performance of an assembly line will be better. The research findings shed light on the smart control of the assembly process, and provide insights into the impacts of Industry 4.0 on assembly line balancing.     

Development of assembly system with quick and low-cost installation

ABSTRACT

Cell production systems for assembly operations generally require tool changes using several hands and a customized work table. The initial setting and resetting of the assembly system are costly. We implemented a system comprising the use of only two hands and without the requirement of tool changers. In addition, multiple sensors are used to perform tasks robustly to avoid errors. The peg-in-hole task is performed robustly against errors without the precise positioning of objects. The objective is to develop a system that is lean and agile and can be set up quickly. We evaluate this system based on the task-board and assembly tasks during the assembly challenge in the industrial robotics category of the World Robot Summit 2018.     

Intelligent workload balance control of the assembly process considering condition-based maintenance

Balancing the workloads of workstations is key to the efficiency of an assembly line. However, the initial balance can be broken by the changing processing abilities of machines because of machine degradation, and at some point, re-balancing of the line is inevitable. Nevertheless, the impacts of unexpected events on assembly line re-balancing are always ignored. With the advanced sensor technologies and Internet of Things, the machine degradation process can be monitored continuously, and condition-based maintenance can be implemented to improve the health state of each machine. With the technology of robotic process automation, workflows of the assembly process can be smoothed and workstations can work autonomously together. A higher level of process automation can be achieved. Real-time information of the processing abilities of machines will bring new opportunities for automated workload balance via adaptive decision-making. In this study, a fuzzy control system is developed to make real-time decisions to balance the workloads based on the processing abilities of workstations, given the policy of condition-based maintenance. Fuzzy controllers are used to decide whether to re-balance the assembly line and how to adjust the production rate of each workstation. The numerical experiments show that the buffer level of the assembly line with the proposed fuzzy control system is lower than that of the assembly line without any control system and the buffer level of the assembly line with another control system is the lowest. The demand can always be satisfied by assembly lines except the one with another control system since there is too much production loss sacrificed for the low buffer level. The sensitivity analysis of the control performance to the parameter settings is also conducted. Thus, the effectiveness of the proposed fuzzy control system is demonstrated, and intelligent automation can improve the performance of the assembly process by the fuzzy control system since real-time information of the assembly line can be used for adaptive decision-making.     

非串行CIMS生产线可靠性建模、分析与综合

采用等效工作站方法,对非串行CIMS生产线可靠性进行了研究,得到了一条缓冲库可 用度的定理,并推导出在稳态情况下,非串行CIMS系统(如装配线和拆卸线)可以转变成串 行系统求解.同时分析出加工过程不丢失工件的充要条件和若干必要条件,绘出一幅PK-K 曲线,可以给出可行解的大致范围,有助于具体问题的求解.     

Automatically generating assembly tolerance types with an ontology-based approach

In most cases, designers have to manually specify both assembly tolerance types and values when they design a mechanical product. Different designers will possibly specify different assembly tolerance types and values for the same nominal geometry. Furthermore, assembly tolerance specification design of a complex product is a highly collaborative process, in which semantic interoperability issues significantly arise. These situations will cause the uncertainty in assembly tolerance specification design and finally affect the quality of the product. In order to reduce the uncertainty and to support the semantic interoperability in assembly tolerance specification design, an ontology-based approach for automatically generating assembly tolerance types is proposed. First of all, an extended assembly tolerance representation model is constructed by introducing a spatial relation layer. The constructed model is hierarchically organized and consists of part layer, assembly feature surface layer, and spatial relation layer. All these layers are defined with Web Ontology Language (OWL) assertions. Next, a meta-ontology for assembly tolerance representations is constructed. With this meta-ontology, the domain-specific assembly tolerance representation knowledge can be derived by reusing or inheriting the classes or properties. Based on this, assembly tolerance representation knowledge is formalized using OWL. As a result, assembly tolerance representation knowledge has well-defined semantics due to the logic-based semantics of OWL, making it possible to automatically detect inconsistencies of assembly tolerance representation knowledge bases. The mapping relations between spatial relations and assembly tolerance types are represented in Semantic Web Rule Language (SWRL). Furthermore, actual generation processes of assembly tolerance types are carried out using Java Expert System Shell (JESS) by mapping OWL-based structure knowledge and SWRL-based constraint knowledge into JESS facts and JESS rules, respectively. Based on this, an approach for automatically generating assembly tolerance types is proposed. Finally, the effectiveness of the proposed approach is demonstrated by a practical example.     

综合业务信息查询系统设计与实现

综合业务信息查询系统是依托Oracle数据库开发的大规模、多功能信息支持系统,可以提供法律法规、单位情况、装备性能、战场环境、战备工程等数据查询服务。系统使用ADO数据访问技术,通过UDP协议实现进程间通信,编写了支持多媒体信息查阅的实用查询程序集。     

Price-based buffer sizing in assembly systems

Internal transfer pricing mechanism will be applied to the problem of buffer allocation in the context of interfacing an assembly line with multiple parallel production lines. Economic effect of buffer sizing iin assembly will be analyzed by means of internal transfer pricing. New internal transfer pricing scheme will be designed to increase the efficiency of assembly system globally not sub-optimally. This new approach will enhance the economic benefit of production channel between an assembly line and multiple production lines. This study will give the basic idea for the application of internal transfer pricing mechanism in various kinds of manufacturing system to increase economic efficiency globally.     

C51在单片机嵌入式系统中的应用

介绍了用 C语言开发单片机时所遇到的问题 ,以 Franklin为例 ,介绍了 C5 1在 80 5 1系列单片机嵌入式系统中的使用技巧。提出了用 ASM5 1与 C5 1结合起来混合编程的新方法 ,在 C5 1语言不便处理或效率较低时调用汇编函数 ,另一种是用汇编识别 C5 1函数 ,开发出的系统更易维护 ,可靠性高 ,移植性强。     

Analysis of assembly operations difficulty: a fuzzy expert system approach

Typical mechanical products can be assembled in various sequences of assembly operations. These sequences have high impact on the assembly time, machine utilization and even on the product quality. In order to select the best sequence of assembly operations, proper evaluation of the various sequences of assembly operations is required. This, in turn, requires the consistent evaluation of each assembly operation in the sequence. The assembly operations can be evaluated for various criteria, of which the operation difficulty is the most meaningful. This paper describes a methodology to analyse the assembly operations and calculates an operation's degree of difficulty using an expert system. This analysis consists of two steps: the first one identifies the main parameters that affect the assembly difficulty and assigns fuzzy triangular values to these parameters. The second step assigns weights to the parameters in order to maximize the agreement with a domain expert. The expert system analyses the difficulty of the assembly operation performed in two orientations: horizontal and vertical. The expert system then assigns a triangular fuzzy number as the aggregate measure of the operation's difficulty.     

The development of an autonomous assembly robot

This paper presents various projects which are being developed at the Institute for Informatics at the Robotics Research Group. Several of these projects will be integrated to support the development of an autonomous assembly robot. With its two arms under sensor guidance, the robot will be capable of assembling a standard benchmark (workpieces). To achieve mobility, the robot will be equipped with a self-propelled platform. Several vision systems are employed in order to support the navigation of the robot and the assembly task. An AI-based system is being developed for assembly planning, implicit programming, route planning (obstacle avoidance), assembly monitoring, and error recovery.     

Knowledge-based approach and system for assembly-oriented design,Part II: the system implementation

Assembly is one of the most important stages for product development. Assembly-oriented design (AOD) is a new approach to designing assemblies, which uses a number of design and analysis tools to help the designer plan out and analyze candidate assembly schemes prior to having detailed knowledge of the geometry of the parts. Using this approach, many assembly schemes can be inexpensively evaluated for their ability to deliver the important characteristics of the final product. This research proposes a knowledge-based approach and develops an expert design system to support top-down design for assembled products. The presentation of research report is divided into two parts: the knowledge-based approach (Part I) and the knowledge-based expert design system (Part II). This paper is the second part of the report (Part II). It will focus on the development of knowledge-based expert design system for assembly oriented design. The knowledge-based assembly oriented design system, i.e., the assembly oriented design expert system (AODES) is constructed to integrate assembly modeling and design, assembly planning, assemblability analysis and evaluation within a concurrent engineering environment. This intelligent system is implemented by integrating object-oriented representation, constraint-based modeling, rule-based reasoning, truth maintenance, and interfacing to database management system and CAD module, in which fuzzy logic based knowledge representation and inference technique are also applied to deal with uncertain data and knowledge in the design process. The developed system differs from the existing systems adopting part-first bottom-up modeling technique, in which a comprehensive intelligent framework is used for assembly modeling and design in a top-down manner from the conceptual level to the detailed level. It is able to help obtain better design ideas, provide users with suggestions so as to create and improve a design, and therefore give users the possibility to assess and reduce the total production cost at an early stage during the design process. Through the use of the system, the concurrent engineering knowledge can be effectively incorporated into the assembly design process in an integrated manner. A case assembly design shows that the intelligent modeling and design system is feasible.     

Content-based assembly search: A step towards assembly reuse

The increased use of CAD systems by product development organizations has resulted in the creation of large databases of assemblies. This explosion of assembly data is likely to continue in the future. In many situations, a text-based search alone may not be sufficient to search for assemblies and it may be desirable to search for assemblies based on the content of the assembly models. The ability to perform content-based searches on these databases is expected to help the designers in the following two ways. First, it can facilitate the reuse of existing assembly designs, thereby reducing the design time. Second, a lot of useful designs for manufacturing, and assembly knowledge are implicitly embedded in existing assemblies. Therefore a capability to locate existing assemblies and examine them can be used as a learning tool by designers to learn from the existing assembly designs. This paper describes a system for performing content-based searches on assembly databases. We identify templates for comprehensive search definitions and describe algorithms to perform content-based searches for mechanical assemblies. We also illustrate the capabilities of our system through several examples.     

Implementing a hybrid simulation model for a Kanban-based material handling system

Plant floor material handling is a loose loop in most assembly plants. Simulation offers a quick, controllable and tunable approach for prototyping complex material handling processes in manufacturing environments. This paper proposes a hybrid simulation approach, using both discrete event and agent-based technologies, to model complex material handling processes in an assembly line. A prototype system is implemented using a commercial multi-paradigm modeling tool. In this prototype, JIT principles are applied to both the production and the material handling processes. The system performance is evaluated and system optimization directions are suggested. The proposed hybrid modeling approach facilitates the implementation of a responsive and adaptive environment in that various “what-if” scenarios can be simulated under different simulation configurations and real-time situations.     

Safe Collaborative Assembly on a Continuously Moving Line with Large Industrial Robots

Robot safety standards defines Collaborative Operation as a state in which purposely designed robots work in direct cooperation with a human within a defined workspace. That is, an operator and an industrial robot complete assembly tasks at the collaborative workspace. A prerequisite to ensuring safety during all phases of operation is an understanding of the nature of hazards pertinent to collaborative systems. An automotive assembly station, where plastic panels are assembled on a continuously moving line, formed the basis for research operations meant to understand safety issues when a large industrial robot aids an operator in assembly tasks. This led to the development of a laboratory demonstrator whose design and functioning will be presented in this article. Additionally, the hazards identified during risk assessment along with measures to mitigate the associated risks will be presented in order to highlight the nature of hazards pertinent to collaborative systems.     

基于机器视觉的航天器密封舱内结构装配精度检测系统设计

目前航天器机械加工装配作业依赖人工操作,影响航天器密封舱内结构装配精度。为此,设计了航天器密封舱内结构装配精度检测系统,为高精度装配航天器密封舱内结构提供基础。由于航天器密封舱舱内结构较为复杂,为了保证使用电池供电时,检测系统能够保持稳定可靠工作模式,应保证电池电量充足前提下,系统发出预警信息,以便工作人员及时采取相应解决措施。在电池供电电路中,设计欠电压电路监测形式,该电路主要是由电压比较器LM393和555和谐振电路构成。当电池供电量不足时,谐振电路中的微电流高效率650nm谐振腔发光二极管会出现闪烁报警信号。以STC89C52RC-40I-PDIP40单片机中央控制单元为核心芯片,检测航天器密封舱密封性能。依据机器视觉检测原理,使用非线性滤波算法增强图像,避免外界噪声对图像采集结果造成影响,滤除图像上若干白点。设计检测流程可得到仪器板安装精度和设备安装支架装调检测结果。由实验结果可知,该系统检测精度最高与实测值一致,为航天器密封舱内结构优化提供设备支持。     

Control system for motion control of a piezoelectric micromanipulation robot

Abstraet-Micromanipulation by microrobots has become an issue of primary importance in industry and biomedicine, since human manual capabilities are restricted to certain tolerances. The manipulation of biological cells or the assembly of a microsystem composed of several microcomponents are good examples. An automated microrobot-based micromanipulation desktop station has been developed at the University of Karlsruhe. The process of assembly takes place in the field of view of a light optical microscope. This paper focuses on motion control problems of the piezo-driven microrobots employed by the station. The ability to adapt itself to the process requirements is of great importance for micromanipulation robots. They must be able to operate in a partially defined environment and to ensure reasonable behavior in unpredicted situations. A neural control concept based on a reference model is proposed as a solution. It is shown that the neural controller is able to learn the desired behavior. It considerably outperforms an analytically designed linear controller in the real environment.