Automated Assembly Systems Research Articles

Adaptive automation assembly: Identifying system requirements for technical efficiency and worker satisfaction

Manual assembly work systems bring high flexibility but low productivity in comparison to fully automated systems. To increase productivity but maintain flexibility, future systems need to incorporate greater levels of automation which complement or augment the capabilities of the human operators who provide the manual work. Future systems should be designed for social and economic sustainability within fluctuating conditions and for adaptive utilisation of operators’ individual capabilities to maintain levels of productivity and personal satisfaction. To successfully create such systems with greater adaptivity and interactivity between people and technology a comprehensive understanding of design requirements is needed; the current problem is that there is no standard valid framework. The work described in this paper employed a three-component investigation to identify the various key requirements that are needed to form such a design framework for future human-automation assembly systems. This involves separate activities with different methodologies involving literature reviews, surveys and business case analysis to define use case scenarios and requirements for creating adaptive automation assembly system demonstrators. The different methodological approaches and results for all of the three component studies are described, along with conclusions and implications for further research work and for industry in general.

Collaborative and traditional robotic assembly: a comparison model

In the last decade, robot manufacturers have started to produce collaborative industrial robots, that can work while safely sharing the workspace with a human operator. In this way, robot repeatability, combined with human dexterity, can move automated assembly to a new level of flexibility. The aim of this paper is to investigate the conditions at which such systems, called collaborative assembly systems (CAS), can be better performing than the traditional manual or automated assembly systems. Throughput and unit direct production cost are considered for the comparison. The estimation of such performance figures, which is straightforward in traditional automated assembly systems, becomes more complex in the case of collaborative systems. In fact, both task allocation between the human and the robot, and the way they collaborate/interfere with each other during assembly, affect the throughput of CAS. With the aim of taking into account such parameters, we introduce a set of system variables and a mathematical model which allow to estimate the real convenience of the implementation of CAS in the industrial scenario. In the paper, the model is applied to compare CAS to manual assembly and to noncollaborative automated assembly, both with parameters derived from the literature and in a case study. Finally, a set of implementation conditions is derived, related to the task allocation that maximises CAS performance.

Integration of Multi-Camera Vision System for Automatic Robotic Assembly

An automated assembly cell does not come with the luxury of intelligence. A non-adaptive robot manipulator must have more accurate parts and assembly fixtures to a greater accuracy than their assembly tolerances. Accurate parts presentation and the fixturing of assemblies can be a complex and costly portion of an automated cell. Machine vision can be integrated with the assembly process to effectively and efficiently guide the assembly process. This paper presents a framework for an automatic assembly system that consists of an industrial robot and a three-camera vision system, where the tasks involve object detection, pose estimation during pick and place operations, and assembly verification. Given a pocket calculator as an application, the proposed framework can successfully perform autonomous assembly of a pocket calculator. The experiment results verified the efficacy of the proposed method.

Change management in modular assembly systems to correspond to product geometry change

Modular assembly systems are a category of changeable manufacturing systems, which can handle the rapid change in customer demands, product design change and market fluctuations. On the operational level, jigs and fixtures are fundamental elements of assembly systems. They are used to hold parts and subassemblies in place, and directly affect assembly cost, quality and time. Therefore, modular fixtures that can adapt to different geometries are becoming a very important enabler for changeable manufacturing. In this paper, two mathematical models are presented to optimise the use of a passive modular assembly fixture plan in an automated assembly system by considering different production scenarios and constraints. These models optimise the changeability plan of the modular fixture by minimising the number of dowel replacements between different part geometries assuming that the candidate dowels locations for each part have been determined using existing methods in the literature by considering different assembly requirements. The first model, LRTE, considers all possible part rotations and translations on the fixture to minimise setup time. In addition, the second model, SLRTE, enables the system to simultaneously optimise job sequence. This paper presents various examples in different sizes, and the results show that the model can effectively reduce the fixture setup time up to %50.

Automatic Test and Sorting System for the Slide Valve Body of Oil Control Valve Based on Cartesian Coordinate Robot

Current industrial robotics technology is often not well integrated with the enterprise’s on-site environment and actual working conditions and small and medium-sized enterprises are unable to achieve product automation due to production cost constraints. In order to meet the medium and small scale production of the slide valve body of OCV (Oil Control Valve) of a certain enterprise and its special process requirements, the automatic test system and sorting system based on the production environment of the enterprise are studied and designed. Firstly, according to the production conditions and process requirements of the enterprise, the overall design scheme of the automatic production line is put forward based on the existing automatic assembly system. Secondly, the test description is further improved by analysing and interpreting the test requirements of the products in detail and the automatic test system and test process are designed. Finally, according to the sorting process requirements, a Cartesian coordinate robot sorting system with two-terminal manipulators parallel operation is designed and its sorting motion scheme is optimized. The automatic test system and sorting system are seamlessly connected with the automatic assembly system, which can efficiently complete the automatic test and sorting of products and meet the production cycle time.

Balancing mixed-model assembly systems in the footwear industry with a variable neighbourhood descent method

This paper addresses new Mixed-model Assembly Line Balancing Problems (MALBP) in a real industrial context, the stitching systems of a footwear company. The work is part of large ongoing projects with this industry, and the main purposes are minimising the number of required workstations and smoothing the operators’ workload. The company has invested in new flexible automated assembly systems, which accommodate dozens of workstations and many moving boxes. Footwear components are inside boxes (with various quantities) which can move from the warehouses to a convenient workstation or between any workstations (in any order). This is a significant and distinct feature of the MALBP, together with the fact that the assignment of different skilled operators and machines is achieved simultaneously. An optimisation model is developed, in part to facilitate the understanding of the situation and to solve small-size instances. Due to the complexity of the problems, we had to devise an approximate method, based on the Variable Neighbourhood Descent (VND) metaheuristic and integrating an adaptation of the Ranked Positional Weighted (RPW) method. The adapted RPW method is used to create initial feasible solutions, while preassigning special operators and machines. After choosing good initial solutions, VND is applied to improve their quality. The new contributed method, named as RPW-VNDbal, is tested with medium and large instances, in two distinct stitching systems. A Lower Bound of the objective function and Simulation contribute to evaluate the solutions and their practicability. The results implemented by the project team, show that the RPW-VNDbal method is fast enough and offers better solutions than those implemented by the experienced operation managers of the company.

The development of an automated assembly system for a speaker coil and assemble fixture

This study develops an automated prototype machine for a speaker coil and the positioning of plastic fixtures. Users need only to place the positioning fixtures and coils into the trays. The machine will then automatically set the coils into the plastic fixtures.The PLC (Programmable Logic Controller), the center of the system, and motors will drive the mechanism. According to the demand requested of the production line, the system is divided into three sections (upper, middle, and lower). The upper section is the plastic locating fixture and feeding system which is composed of motors and cylinders. A user needs only to place a plastic locating fixture into the top tank. The plastic locating fixture can be arranged, ordered, and automatically assembled by the automated transport mechanism. The middle section and lower section of the machine are positioned sleeve assembly systems and voice coil alignment systems. A rotating assembly system is composed of several cylinders. Its main function is to move the fixtures and initiate a smooth assembly with the voice coil (located at a lower position). An automatic alignment system is used along with two electric slides and a linear slide to form an X-Y moving platform. A 10 * 10 removable coil tray is placed on the X-Y platform. With this, the top of the mechanism can be successfully assembled and positioned.This study introduces an automatically system that is used to assemble a speaker coil and its fixture. The system can complete 100 assembly operations in seven minutes. This satisfies the original system's requirements. When 100 speaker coils fill the tray, the system will automatically send out a warning signal and the tray will be moved out of the system.

Research on Multi Station Automatic Assembly System

A multi station automatic assembly system was designed for MEMS products. The system includes three assembly stations and the loading and unloading station. It can finish the automatic assembly totally form part to product. This paper introduces the structure and the work principle. Experimental results show that the automatic assembly system plays an important role in the application of the automatic assembly of MEMS with better accuracy and efficiency.

Structural and Dynamic Characteristic Analysis for Automatic Magazine Feeder in Automation Assembly System for LED Convergency Lighting

Structural and Dynamic Characteristic Analysis for Automatic Magazine Feeder in Automation Assembly System for LED Convergency Lighting

Design and Implementation of a Fully Automatic Assembling System for Automobile Fuel Tank Overturn Valve

At present, at least one or two overturn valves are required in each automobile production process. However, the production and assembly of overturn valve is still in the stage of manual assembly, which leads to low production efficiency. This paper mainly designs a fully automatic assembly system based on the structure of the overturn valve. The automatic assembly system includes loading, assembly, transportation of blanks and other work stations, and automatic assembly based on the PLC control system. At the same time, the human interaction page touch screen is used for data monitoring and parameter setting. The experimental results show that the assembly system can complete the automatic assembly of the overturning valve of the fuel tank stably and reliably

Robust active vision industrial CAD parts recognition system

In automated assembly systems the machine parts identification is entirely different from simple object recognition; moreover the ability of humans to differentiate between correct and not correct machine parts is better but it is a difficult task for a machine. In general, with fast moving machine parts on the conveyor manual defect detection by human inspectors is impractical. Also it is expensive, inaccurate, subjective, eye straining and causes other health issues to quality control inspectors. A computer vision-based non-contact inspection technique is developed with image processing methods by considering these problems, for defect detection in industrial machine parts. The present work will help the industrial robot used in assembly process and industrial inspection systems. In this paper features-based industrial object detection techniques are implemented in MATLAB to recognise the presence of the industrial CAD parts in the query image. In the end the actual industrial tool images are also used to show the accuracy and robustness of the proposed machine vision system for industrial manufacturing automation.

An Efficient Insertion Control Method for Precision Assembly of Cylindrical Components

In this paper, an efficient insertion control strategy is presented for precision assembly of cylindrical components with interference fit. It has two inherent advantages compared with existing insertion methods in the domain of precision assembly. First, it does not need preparatory actions dedicated for horizontal forces before insertion actions, which is realized by integrating the preparations into the insertion step. Second, instead of inserting with fixed incremental depth, it estimates the insertion depth for every action to be as large as possible with a probabilistic approach. Specifically, the insertion of components is modeled as a stochastic state transition process with the uncertainty described by Gaussian distribution. The state transition function is well defined based on analysis of the historical assembly data and the universal mechanical properties of the components. An assessment function is also elaborately designed to evaluate the performance of the state transition function in order to stimulate the control strategy to behave progressively or conservatively. Finally, the action to be taken for the current state is decided by iterative calculations in N steps estimation manner. An automatic assembly system is developed to verify the effectiveness of the proposed control method. Experimental results show that the assembly process with the proposed insertion control strategy can finish within 30 steps, which is at least four times more efficient than the process with the traditional method.

Product family formation based on complexity for assembly systems

System complexity in development of products for the automated assembly systems causes significant issues, if left unaddressed. Products with similar level of complexity tend to cause similar issues in production. Development of product families based on complexity is an important tool to avoid such issues. This paper presents a novel approach to classify the products based on complexity level for assembly systems. Assembly aspects are then used, which define the complexity levels of individual parts. The individual part complexity level is further merged with the assembly sequence in the form of binary rooted trees. Hierarchical clustering is also employed to find the similarity coefficients of different products. These products are finally segregated based on the generated coefficients. Four products are used as a part of thorough case study to show the working principle of the proposed approach along with the results and associated discussion.

Robotic assembly of smartphone back shells with eye-in-hand visual servoing

Abstract Research concerning smartphone assembly has attracted increasing attention from the manufacturing industry. This paper presents an automatic back shell assembly system using real-time visual servoing in an eye-in-hand configuration. Look-then-move and look-and-move control approaches are sequentially proposed to handle distal and proximal assembly tasks, respectively. During distal assembly, binocular vision is employed to assist a robotic manipulator to locate and reconstruct the positions and orientations of a cellular phone and its back shell in the work space. After lifting the back shell up and then reaching the top of the cellular phone, there is no binocular field of view. A seemingly novel way of 3-D reconstruction by two uniocular fields of view of the two cameras is proposed. With the pair of monocular vision sensors, two monocular visual servo control laws are employed sequentially to perform the proximal assembly task autonomously. Based on the experimental results, the robotic manipulator can be driven to hold the back shell by a vacuum absorption device and position it precisely onto the smartphone to accomplish the automatic assembly task even if the vision system is only roughly calibrated. The proposed control approach for distal and proximal assembly appears to be efficient, flexible, and reliable for potential applications in industrial manufacturing.

Structural and Dynamic Characteristic Analysis of a Feeder for an Automatic Assembly System of an LED Convergent Lighting Module

Structural and Dynamic Characteristic Analysis of a Feeder for an Automatic Assembly System of an LED Convergent Lighting Module

Convertibility Evaluation of Automated Assembly System Designs for High Variety Production

The recent advancements in technology and the high volatility in automotive market compel industries to design their production systems to offer the required product variety. Although, paradigms such as reconfigurable modular designs, changeable manufacturing, holonic and agent based systems are widely discussed to satisfy the need for product variety management, it is essential to practically assess the initial design at a finer level of granularity, so that those designs deemed to lack necessary features can be flagged and optimised. In this research, convertibility expresses the ability of a system to change to accommodate product variety. The objective of this research is to evaluate the system design and quantify its responsiveness to change for product variety. To achieve this, automated assembly systems are decomposed into their constituent components followed by an evaluation of their contribution to the system's ability to change. In a similar manner, the system layout is analysed and the measures are expressed as a function of the layout and equipment convertibility. The results emphasize the issues with the considered layout configuration and system equipment. The proposed approach is demonstrated through the conceptual design of battery module assembly system, and the benefits of the model are elucidated.

Novel processes and related technologies for micro metal forming

Processes with high energy assistance, such as ultrasonic vibration or local heating, and automatic assembly system in a progressive die were developed for micro metal forming in order to improve process accuracy of micro product due to some size effects in this study. Furthermore, application of textured diamond like carbon (DLC) coating on die surface was attempted to improve the tribological performance for dry micro forming operations.

Integrated Fuzzy PROMETHEE and Fuzzy Linear Program for Functions Evaluation in Convergent Products: Case for Digital Products

Background/objectives: Recently, convergent products are introduced in digital products. Fast assembly and new product development and dynamic product configuration are all considered in convergent product concept. The fast technology development and dynamic customer demands require a more efficient and flexible system for new product development. This paper proposes an integrated decision making model for convergent product evaluation under fuzzy environment.Methods/statistical analysis: First the fuzzy decision matrix is formed and using fuzzy PROMETHEE the pairwise comparison is performed. Then, by fuzzy linear programming (FLP) the weights of the functions with respect to attributes pairwise matrices are obtained. Finally, the fuzzy output is transformed to crisp one employing fuzzy analytic hierarchy process (FAHP). The contribution are in developing a new fuzzy linear program, integrate it with PROMETHEE and using them in convergent product function evaluation.Findings: The results are helpful in business plan and road map of businesses for obtaining competitive advantage and profit maximization. Some of the products are considered and customers’ views are collected to form a new product converging the requirements asked by customer’s altogether. The dynamic customer views make the system responsive to different convergent products.Application/improvements: The applicability and the validity of the proposed method are evaluated in a case study. The case study is conducted in a pioneering digital online shopping company. The model is a decision aid for managers of the company to promote to a fast automation assembly system being able to provide product functions integrated to deliver customers’ desired products.

Machine parts recognition and defect detection in automated assembly systems using computer vision techniques

Machine parts recognition and defect detection in automated assembly systems using computer vision techniques

Automated experience-based learning for plug and produce assembly systems

This paper presents a self-learning technique for adapting modular automated assembly systems. The technique consists of automatically analysing sensor data and acquiring experience on the changes made on an assembly system to cope with new production requirements or to recover from disruptions. Experience is generalised into operational knowledge that is used to aid engineers in future adaptations by guiding them throughout the process. At each step, applicable changes are presented and ranked based on: (1) similarity between the current context and those in the experience base; (2) estimate of the impact on system performance. The experience model and the self-learning technique reflect the modular structure of the assembly machine and are particularly suitable for plug and produce systems, which are designed to offer high levels of self-organisation and adaptability. Adaptations can be performed and evaluated at different levels: from the smallest pluggable unit to the whole assembly system. Knowledge on individual modules can be reused when modules are plugged into other systems. An experimental evaluation has been conducted on an industrial case study and the results show that, with experience-based learning, adaptations of plug and produce systems can be performed in a shorter time.