«Handling Uncertainties in Industrial Production Bearbeitet von Sven Rogalski 1. Auflage 2011. Buch. xi, 186 S. Hardcover ISBN 978 3 642 18116 0 ...»
Flexibility Measurement in Production Systems
Handling Uncertainties in Industrial Production
1. Auflage 2011. Buch. xi, 186 S. Hardcover
ISBN 978 3 642 18116 0
Format (B x L): 15,5 x 23,5 cm
Gewicht: 467 g
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Chapter 4 Practical Experience in the New Methodology With the goal of veriﬁcation of the evaluation methodology, a software tool called ecoFLEX was developed, which makes use of the mechanisms for the assessment of ﬂexibility of production systems described in the previous chapter. The detailed description of this software tool in terms of its architecture, its implementation and its operating principle will be the ﬁrst topic discussed in this chapter. Since a software-based realization of the methodology alone is not sufﬁcient to prove its viability in real conditions, the software tool was practically tested subsequent to its development through an industrial case study. The second focal point in this chapter is therefore the detailed explanation of the resulting experience from the analysis of Quantity, Mix and Expansion ﬂexibility. From this the evaluation methodology can be veriﬁed a by considering a detailed review of all requirements and the fulﬁlment of these.
4.1 Implementation of the Evaluation Methodology A fundamental task in the realization of the ecoFLEX tool was the implementation of a suitable software (in accordance with Sect. 2.5.4), the details of this which follow here. The software was developed based on modern technologies to achieve various technical advantages, such as simple advancement opportunities or higher versatility e.g. in distributed environments. This in turn results in ergonomic beneﬁts for both the user and for the developers of the ecoFLEX software.
4.1.1 Software Architecture of ecoFLEX The development of ecoFLEX focused on providing the necessary functionality required for the automation of the procedure for the ﬂexible evaluation of production systems, as described in Sect. 3.2. With this in mind, a software concept was developed, intended to support three successive base iterations (see Fig. 4.1).
Base Iteration 1:
Construction of a production system model as an
representation of the production infrastructure which is under investigation
Base Iteration 2:
Collection and structuring of relevant data for flexibility calculation, based on the chosen evaluation objects/abstraction
Base Iteration 3:
Flexibility calculation through the application of the flexibility metrics to the evaluation objects of the production system model
Fig. 4.1 Base iterations for ﬂexibility evaluation, automated through ecoFLEX
An aspect which until now was not supported by software was the automatic detection of ﬂexibility deﬁcits and a concurrent generation of the proposed solution for their closure. This Base Iteration 4 (ﬂexibility interpretation/evaluation) is, at the present stage of eocFLEX development, reserved only for the user. The Fig. 4.2 shows the concept of the modular software architecture of ecoFLEX, which ensures the highest possible degree of user support in the ﬂexibility assessment.
The basic elements of the architecture form the interfaces; the conﬁguration module PSM; the module for data processing; the module for the ﬂexibility assessment; the graphical user interface (GUI) and the database. These terms are explained
Interfaces: Since the vast majority of data needed to conduct the ﬂexibility l assessment is already available in the different operational planning and control systems, the appropriate interfaces to these systems are necessary. As seen in Fig. 4.2, there are two basic types of interfaces. One type being the interfaces for collecting ﬂexibility relevant data from the operational systems in a manufacturing environment. These can be used to implement planning and controlling related functions of short-and medium-term production and commercial operations. Prime examples are ERP systems, which cover products which possess such functionality. PPC- BDE-, SCM- systems or other systems for controlling and scheduling also partially contribute to the support of the overall functionality and therefore provide necessary ﬂexibility information. The other type is made up of the ecoFLEX interfaces to digital tools usually used for long-term factory planning. These are used to transfer object relevant information on the production infrastructure to ecoFLEX in order to build the PSM. This information is obtained from the digital models for the layout plan and the lineand workplace conﬁgurations.
Conﬁguration module PSM: This module directly supports the ﬁrst of the l
Fig. 4.2 System concept of software architecture of ecoFLEX and their integration into the IT landscape of the user companies system objects like workplaces, lines and segments as well as their mutual dependencies can be identiﬁed due to the semantics contained within the standards.
The semantics refer to the CAD Plant Design symbols from each block name, label, layer, line type etc. As a result, the corresponding information based objects can be compiled. Provided that an appropriate demand for manual rework exists and that automated model building is not possible, the PSM conﬁguration module provides the relevant features which are also suited to the building of scenario alternatives.
Module for Data Processing: This module forms the basis for the second of the l three base iterations, the collection and structuring of relevant data for the ﬂexibility analysis. A prerequisite for this is the PSM derived from the conﬁguration module, since this can clearly deﬁne the system objects and their mutual dependencies. This results in a purposeful, object related data mapping. We distinguish between two types of data structure, which is why each has a separate sub-module available. The ﬁrst is the object-oriented data processing according to the cost-related calculation parameter as shown in Table 3.3. The extracted cost information under the cost accounting reference frame presented 112 4 Practical Experience in the New Methodology in Sect. 3.3 is hereby separated into variable and ﬁxed cost components, which in turn are broken down for each object parameter. The second sub-module which deﬁnes the non-cost-related calculation parameters (see Table 3.2), deals with the assignment of the object data which fall into this category, taking into account the relationships modeled in the PSM. Fundamentally, the collection and structuring of both categories of ﬂexibility relevant data on the respective sub-modules is automatically, as well as manually possible. This offers the advantage of a thorough data survey even in the absence of some system interfaces and allows user-speciﬁc value assignment for alternative scenarios, as well.
Module for Flexibility Analysis: The third base iteration, the application of l ﬂexibility metrics to the evaluation objects of the production model, will be performed within this module which is divided into two sub-modules. The ﬁrst deals with the implementation of the assessment methods described in Sect. 3.2 to determine the Volume-, Mix- and Expansion ﬂexibility of production systems. The actual application of these methods, however, comes into play in the second sub-module in which the calculation parameters are transferred from the module to the data processing. The resulting calculation delivers the individual ﬂexibility coefﬁcients for the system objects identiﬁed by the PSM.
Graphical User Interface (GUI): The graphical user interface, GUI for short, l has two fundamental tasks. One being the visualization of the production system model created in the PSM conﬁguration module, as well as the object based calculation results of the ﬂexibility analysis. Secondly, the GUI gives the user the possibility to exercise a simple inﬂuence on the structure of the PSM to be evaluated and its accompanying data allocation, because it allows the interactive access to the PSM conﬁguration module and the module for data preparation (see the preceding description of the two modules).
Database: The database provides the foundation for the persistent, modell related ﬁling of all the information on a production system needed for the ﬂexibility analysis. All of the collected data and structures can be permanently stored in the database, enabling, for example, comparisons between different production systems or different developmental statuses of a system. Data from the internal information management of ecoFLEX are also stored here, such as semantic information to CAD Factory Design symbols which are used in the PSM conﬁguration module standards.
4.1.2 Implementation of ecoFLEX
The basis for the implementation of the evaluation methodology was the open development platform Eclipse. The result represents the ﬂexibility evaluation tool ecoFLEX, the development of which involved the following software development
4.1 Implementation of the Evaluation Methodology 113 The implementations were performed in version 3.4.0 of the Eclipse Developl ment Environment, using the Java programming language based on the Java Development Toolkit (JDK) version 1.6_10.
The Rich Client Platform (RCP) of Eclipse (Eclipse RCP) version 3.4.0 was used l for the construction of the Graphical User Interface.
The relational database MySQL version 5.1 was utilised for persistent data l storage and data management. This allows the storage of ecoFLEX objects and their associations using the Java-compatible Open-Source-PersistenceFramework Hibernate version 3.3.1.
Figure 4.3 shows a screenshot of the window of the Eclipse development environment.
The Project Navigator can be seen on its left side (1), which contains the project folder ecoFLEX. This includes, inspired by the modular structure of the developed software architecture (see Fig. 4.2), various subfolders in which the project ﬁles generated for the prototype compilation are stored. They in turn describe the speciﬁc ecoFLEX functionality in the form of source code stored there, as shown in the right side (2) of the Eclipse window. Shown there is the Eclipse Fig. 4.3 Project structure of ecoFLEX in the Eclipse development environment 114 4 Practical Experience in the New Methodology workspace with an excerpt from the source code of the ﬁle MengenFlex.java from the subfolder Evaluation method. The structure of the source code in the project ﬁles can be extracted from the Outlines in the Project Navigator in the Eclipse window (3).
As mentioned above, the Java programming language forms the basis of the implementations which were undertaken. A decisive reason for this is, for one, its object orientation which accommodates various mechanisms in the evaluation methodology (see Sect. 3.2). For another, the architecture neutrality is preserved, which is beneﬁcial for the ease of integration of ecoFLEX into its intended IT infrastructure. Multiple project types can be distinguished for the Eclipse Development Environment which was implemented in this context and in the interest of a progressive, supportive implementation approach.
They are characterized by different development goals (such as Database applications, Internet applications, Eclipse Plug-ins or Rich Client applications) and therefore by different source ﬁle types, as well as their applicable tools and Plug-ins.
For the development of ecoFLEX, the project type Plug-in Project (RCP) was selected, for which the RCP- Framework of Eclipse was used to ensure a modular, simple and clear conﬁguration of the graphical interface. Another framework that ecoFLEX uses is Hibernate. It creates an object-relational bridge to the database, and can thereby store the status of an ecoFLEX object in the MySQL database and can also recreate it.
4.1.3 Functionality of ecoFLEX
In order for the ecoFLEX software to be employed in its basic conﬁguration, a suitable computer system is required. The minimal requirements of such a system are the existence of 32-bit computer architecture with a processor capacity of 1 GB and a working memory capacity of 512 MB, as well as having Windows, Linux or Solaris as operating systems to support the required Java console. After installation of the ecoFLEX software, it may be started via a specially provided program icon in the program folder. The subsequent approach to the targeted ﬂexibility analysis is described in the following sub-chapter.
18.104.22.168 Structure of the Program Window
As ecoFLEX starts, a special programme window will open which is divided from a functionality perspective, into an analysis area and parameter area (horizontal view).
Regarding the ﬂexibility analysis, these two areas are divided into an original- and an alternative representation (vertical view), as can been seen in Fig. 4.4.
The analysis area itself consists of three so-called functional ﬁelds. On the left in the original view associated ﬁeld (1), the model of the considered production system is statically presented in its initial/original conﬁguration with the associated
4.1 Implementation of the Evaluation Methodology 115
Fig. 4.4 Graphical user interface of ecoFLEX
system objects. On the other hand, conﬁgurations which differ from the original model can be compiled in the alternative view associated ﬁeld (3). Here, in contrast to the ﬁeld (1), a unique toolbar with the appropriate functionality for model changes is integrated. The middle ﬁeld (2), which includes both an original and an alternative view, consists of three tabs. The ﬁrst, called Results, allows the display of object-oriented indices to the original as well as to the alternative models.