Kosmas Alexopoulos

DESYMA: assessing flexibility for the lifecycle of manufacturing systems

The objective of this work is to describe a method of assessing the flexibility of a manufacturing system, in an uncertain market environment, under lifecycle considerations. The flexibility of a manufacturing system is determined by statistical analysis of the discounted cash flow (DCF) estimates of the manufacturing systems lifecycle cost, over a time horizon and for a large variety of market scenarios. The systems lifecycle cost is calculated at a minimum level with the help of a specially developed algorithm. The method is used in a test case for investing in a production system, using real-life data derived from the automotive industry.

The role of simulation in digital manufacturing: applications and outlook

Digital manufacturing technologies have been considered an essential part of the continuous effort towards the reduction in a product’s development time and cost, as well as towards the expansion in customisation options. The simulation-based technologies constitute a focal point of digital manufacturing solutions, since they allow for the experimentation and validation of different product, process and manufacturing system configurations. This article investigates simulation-based applications in a series of different technological and manufacturing domains. First, this article discusses the current industrial practice, focusing on the use of information technology. Next, a series of simulation-based solutions are explored in the domains of product and production process design, as well as in the area of enterprise resource planning. The current technologies and research trends are discussed in the context of the new landscape of computing hardware technologies and the emerging computing services, including the initiatives comprising both the Internet cloud and the Internet of things.

Quantifying the flexibility of a manufacturing system by applying the transfer function

This paper discusses a method of estimating the flexibility of a manufacturing system. The proposed approach is motivated by the dynamic behaviour analogy between a mechanical and a manufacturing system. The main hypothesis is that the flexibility of a manufacturing system can be calculated in the same manner as the damping factor of a mechanical system. In order for the validity of the proposed method to be tested and discussed, a set of experiments has been designed and executed, initially for a simple production system. An industrial production system has also been studied using the same approach. The results prove that this method can be used for the estimation of a manufacturing systems flexibility.

Volume and product flexibility: a case study for a refrigerators producing facility

This paper presents a study of flexibility for the punching department in a commercial refrigerators manufacturing system. Three different technology solutions for the punching department are studied under different sets of production requirements: conventional press machines, CNC machines and laser machines solution. Analysis of changing the required production volume, as well as the introduction of new products takes place and thereafter volume and product flexibility provided by the punching department has been studied. The flexibility of the system is investigated with the use of the Penalty of Change (POC) method. The application of the method gives a good picture of the flexibility characteristics for the alternative solutions for the punching department

Oscillator analogy for modelling the manufacturing systems dynamics

The purpose of this paper is to present an approach of modelling and analysis of the dynamic behaviour of manufacturing systems. The manufacturing system is considered to be responding to an excitation, namely a demand that varies over time, by producing a number of parts over time. This resembles a mechanical system that displaces its mass responding to a varying input force. Based on this analogy, this paper establishes a manufacturing systems modelling method. A system identification technique is used for deriving inertia, damping and stiffness from the manufacturing systems response to different excitations. Based on these attributes, the response of a manufacturing system to any given input can be estimated. Furthermore, a definition for assessing manufacturing flexibility, based on this approach, is being discussed.

A web-based platform for collaborative product design and evaluation

This paper presents a web-based integrated platform for supporting the collaborative product design activities. An overview of the overall Digital Factory framework, in which the Collaborative Prototype Designer (CPD) resides, has been given first. Next, the CPDs functional architecture is presented including the way it addresses the needs for collaboration during the product design process. The CPD is based on the integration of a spectrum of technologies, including Content Management, Computer-Aided Design (CAD), Virtual & Augmented Reality (VR/AR) and Decision Support, through a Web-based user friendly interface. The major contribution of the proposed approach is the CPDs flexible architecture, which takes into consideration the design needs of both mechanical and nonmechanical products and it is therefore, considered being applicable to a wide range of products. It integrates design activities, processes, methods and tools in a modular feature, easy to be used and be enhanced even further. The CPD mainly aims at SMEs that usually cannot afford an expensive commercial solution, for supporting of the collaborative product design.

A concept for context-aware computing in manufacturing: the white goods case

A key characteristic for industrial production in the Industry 4.0 paradigm is the connection of physical items like sensors, devices and enterprise assets, connected both to each other and to the Internet. In this Internet of Things environment, things will sense more data, become context-aware and provide added-value information to assist people take more relevant and valuable decisions. Context-aware information distribution may offer substantial value to manufacturing. It provides task-relevant information or services to users in a manufacturing shop-floor improving decision making through context-driven recommendations. This paper presents a context-aware information distribution system to support users in an industrial environment. The system aims at utilising data collected from sensors located at a shop-floor in order to increase the visibility of shop-floor processes by providing the right information, to the right people, at the right time. The system’s architecture and key elements have been developed for a pilot implementation in the white goods industry and are presented in this study.

A method for comparing flexibility performance for the lifecycle of manufacturing systems under capacity planning constraints

The objective of this work is to describe a method for comparing the flexibility performance of manufacturing systems, in an uncertain environment, under lifecycle considerations and capacity planning constraints. The manufacturing systems costs are estimated over a time horizon and for a large variety of possible market scenarios. In order for the lifecycle cost values to be comparable among different systems, their values are calculated with the use of a special purpose algorithm. Statistical analysis of the estimated cost values is then employed for assessing the flexibility of each manufacturing system. The method is applied in an industrial case for checking, also from a flexibility point of view, the investment on a production system, using real life industrial data.

A Hybrid Approach to the Verification and Analysis of Assembly and Maintenance Processes Using Virtual Reality and Digital Mannequin Technologies

This chapter discusses the concept and the first pilot implementation of a hybrid approach to the realistic representation of human performance in virtual manufacturing environments. The approach employs simulation principles of both virtual reality (VR) and digital mannequin (DM) technologies. The software tool developed, called VRSP, enables the immersive virtual performance of an industrial task, in an adequately realistic and user-friendly way, and the control of a mannequin within the virtual environment, based upon the spatially tracked user interactions of the immersed human. Design and implementation aspects of VRSP are described. An industrial test case is presented to demonstrate the capability of VRSP to deal with real process tasks. There follows a discussion, focused on the results and the future perspectives of this research work.

ErgoToolkit: an ergonomic analysis tool in a virtual manufacturing environment

The virtual manufacturing tools are usually equipped with digital human models for the simulation of manufacturing tasks. This enables designers to analyse alternative design solutions and to obtain ergonomic performance measures. An ergonomic assessment requires the availability of ergonomic analysis tools integrated into the virtual manufacturing process. This article presents ErgoToolkit, which implements ergonomic analysis methods, already available in literature or company practice, into digital tools for ergonomics, integrated into state-of-the-art virtual manufacturing software. These ergonomic tools are: the Posture Definition and Recognition and the Stress Screening. The former provides the functionality of defining and automatically recognising digital human postures, while the latter objectively evaluates ergonomically any unfavourable situations in a manual work process. It is shown that they are viable tools in detecting ergonomic problems, early in a development process, prior to physical installation. The benefits of the tools with the existing industrial practice are discussed. This article also describes technical implementation issues along with the application of the tools in an automotive case study.