An evaluation and comparison of PLC programming techniques : innovation report

Few significant changes in Programmable Logic Controller (PLC) software design techniques have taken place since PLC's were first introduced in the 1960's. Programs written in the traditional language used in PLC's, ladder logic, are generally thought to be difficult to maintain and modify, and thus ill suited to the support of modem flexible manufacturing processes. This work demonstrates that the choice of PLC software structure used in a project has an impact on process flexibility with an appropriate choice providing significant cost savings in development time. An overview of work on formalised programming tools conducted in academia is provided together with a report on the PLC software structures used in industry. The factors influencing the choice of PLC and software structure are identified. Familiarity was found to be a major factor influencing selection. A method for comparing code structures, which allows the results to be expressed as a time saving (and consequently a cost) has been created. Implementation of this approach was used to show that the formalised programming tool under test provides a 33% increase in "right first time" rate together with an 80% time saving over traditional contact based ladder logic. Among experienced practitioners, performance with step-based ladder logic was found to be a close match to the formalised tool, demonstrating that the commonly perceived limitations are the result of the structure in which the language is used rather than a function of the programming tool itself. Further investigation of participant preferences among skilled PLC users showed a mismatch between their performance with a tool and their preference, with at least 25% selecting a tool based on their prior knowledge rather than performance. This highlights the need for the use of objective measures when conducting evaluations between products and technologies. With the information provided in this work, automation end users are provided with a mechanism for ensuring the selection of automation tools best suited to their business needs, whilst at the same time providing automation vendors with the ability to best demonstrate the strengths of the products

Web service control of component-based agile manufacturing systems

Current global business competition has resulted in significant challenges for manufacturing and production sectors focused on shorter product lifecyc1es, more diverse and customized products as well as cost pressures from competitors and customers. To remain competitive, manufacturers, particularly in automotive industry, require the next generation of manufacturing paradigms supporting flexible and reconfigurable production systems that allow quick system changeovers for various types of products. In addition, closer integration of shop floor and business systems is required as indicated by the research efforts in investigating "Agile and Collaborative Manufacturing Systems" in supporting the production unit throughout the manufacturing lifecycles. The integration of a business enterprise with its shop-floor and lifecycle supply partners is currently only achieved through complex proprietary solutions due to differences in technology, particularly between automation and business systems. The situation is further complicated by the diverse types of automation control devices employed. Recently, the emerging technology of Service Oriented Architecture's (SOA's) and Web Services (WS) has been demonstrated and proved successful in linking business applications. The adoption of this Web Services approach at the automation level, that would enable a seamless integration of business enterprise and a shop-floor system, is an active research topic within the automotive domain. If successful, reconfigurable automation systems formed by a network of collaborative autonomous and open control platform in distributed, loosely coupled manufacturing environment can be realized through a unifying platform of WS interfaces for devices communication. The adoption of SOA- Web Services on embedded automation devices can be achieved employing Device Profile for Web Services (DPWS) protocols which encapsulate device control functionality as provided services (e.g. device I/O operation, device state notification, device discovery) and business application interfaces into physical control components of machining automation. This novel approach supports the possibility of integrating pervasive enterprise applications through unifying Web Services interfaces and neutral Simple Object Access Protocol (SOAP) message communication between control systems and business applications over standard Ethernet-Local Area Networks (LAN's). In addition, the re-configurability of the automation system is enhanced via the utilisation of Web Services throughout an automated control, build, installation, test, maintenance and reuse system lifecycle via device self-discovery provided by the DPWS protocol...cont'd

Co-Creating Open Hardware - Technological Feasibility Of Measures For A Distributed And Agile Planning Preparation

The open and co-operative way of shaping product development in co-creation communities is increasingly experiencing an upswing in its relevance for future product generations. The knowledge of many is pooled across company boundaries and offers space for interdisciplinary and specialised innovations. Platforms (e.g., Github, Instructables etc.) have become established and enable participants to make their own artefacts public, share them, and develop them further with others. In the currently prevailing company-driven linear value creation, there is an early exchange between the knowledge carriers in production and the developers as part of integrated product development. In the new setup, the way in which the exchange previously occurred is no longer applicable. The new digital platforms missing of production sovereignty makes the established system of company-internal experience and knowledge sharing impossible. There is need for a new approach to overcome the decoupling of product development and production. A sub-division of Operations Planning and Scheduling (OPS) is Planning Preparation, whose primary responsibility is to provide early advice aimed at enhancing the producibility. For this new environment, the concept of distributed and agile Planning Preparation (daPP) is proposed. In this approach, strategies and measures previously utilised in the field of distributed and agile planning preparation are discussed and evaluated through an expert survey, focusing on the objectives of active operational execution and technological feasibility. Based on the evaluation, a technological feasibility map is presented, and four areas are defined. This map enables the identification of measures whose technological implementation yields the most substantial positive outcomes on improving producibility of Open Hardware in digital platform-based product development processes

A service-oriented approach to embedded component-based manufacturing automation

This thesis is focused on the application of Component-Based (CB) technology to shop oor devices using a Service Oriented Architecture (SOA) and Web Services (WS) for the purpose of realising future generation agile manufacturing systems. The environment of manufacturing enterprises is now characterised by frequently changing market demands, time-to-market pressure, continuously emerging new technologies and global competition. Under these circumstances, manufacturing systems need to be agile and automation systems need to support this agility. More speci cally, an open, exible automation environment with plug and play connectivity is needed. Technically, this requires the easy connectivity of hardware devices and software components from di erent vendors. Functionally, there is a need of interoperability and integration of control functions on di erent hierarchical levels ranging from eld level to various higher level applications such as process control and operations management services. [Continues.

A next generation manufacturing control system for a lean production environment

This thesis focuses on addressing the need for a new approach to the design and implementation of manufacturing control systems for the automotive industry and in particular for high volume engine manufacture. Whilst the operational domain in the automotive industry has moved to lean production techniques, the design of presentday manufacturing control systems is still based on systems intended for use in a mass production environment. The design and implementation of current manufacturing control systems is therefore inappropriate when viewed from a business context. The author proposes that it is possible to create a more appropriate manufacturing control systems based on an optimised use of advanced manufacturing technology within the complete business context. Literature is reviewed to provide a detailed understanding of the relationship between modem operating practices and the application of contemporary control systems. The primary tasks of manufacturing control systems, within the context of a structured systems approach to manufacturing technology, production management and industrial economics are identified. A study of modem manufacturing control system technology is carried out, highlighting the fundamental principles that influence application engineering in this area. The thesis develops a conceptual design framework that aids the identification of attributes required of a next generation manufacturing control system (NGCS), in order to enhance the business performance of lean automotive manufacturing. The architecture for a next generation control system is specified and a Proof of concept system implemented. Potential advances over contemporary practice are identified with the aid of a practical implementation at a major automotive manufacturer

Ageneric predictive information system for resource planning and optimisation

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel UniversityThe purpose of this research work is to demonstrate the feasibility of creating a quick response decision platform for middle management in industry. It utilises the strengths of current, but more importantly creates a leap forward in the theory and practice of Supervisory and Data Acquisition (SCADA) systems and Discrete Event Simulation and Modelling (DESM). The proposed research platform uses real-time data and creates an automatic platform for real-time and predictive system analysis, giving current and ahead of time information on the performance of the system in an efficient manner. Data acquisition as the backend connection of data integration system to the shop floor faces both hardware and software challenges for coping with large scale real-time data collection. Limited scope of SCADA systems does not make them suitable candidates for this. Cost effectiveness, complexity, and efficiency-orientation of proprietary solutions leave space for more challenge. A Flexible Data Input Layer Architecture (FDILA) is proposed to address generic data integration platform so a multitude of data sources can be connected to the data processing unit. The efficiency of the proposed integration architecture lies in decentralising and distributing services between different layers. A novel Sensitivity Analysis (SA) method called EvenTracker is proposed as an effective tool to measure the importance and priority of inputs to the system. The EvenTracker method is introduced to deal with the complexity systems in real-time. The approach takes advantage of event-based definition of data involved in process flow. The underpinning logic behind EvenTracker SA method is capturing the cause-effect relationships between triggers (input variables) and events (output variables) at a specified period of time determined by an expert. The approach does not require estimating data distribution of any kind. Neither the performance model requires execution beyond the real-time. The proposed EvenTracker sensitivity analysis method has the lowest computational complexity compared with other popular sensitivity analysis methods. For proof of concept, a three tier data integration system was designed and developed by using National Instruments’ LabVIEW programming language, Rockwell Automation’s Arena simulation and modelling software, and OPC data communication software. A laboratory-based conveyor system with 29 sensors was installed to simulate a typical shop floor production line. In addition, EvenTracker SA method has been implemented on the data extracted from 28 sensors of one manufacturing line in a real factory. The experiment has resulted 14% of the input variables to be unimportant for evaluation of model outputs. The method proved a time efficiency gain of 52% on the analysis of filtered system when unimportant input variables were not sampled anymore. The EvenTracker SA method compared to Entropy-based SA technique, as the only other method that can be used for real-time purposes, is quicker, more accurate and less computationally burdensome. Additionally, theoretic estimation of computational complexity of SA methods based on both structural complexity and energy-time analysis resulted in favour of the efficiency of the proposed EvenTracker SA method. Both laboratory and factory-based experiments demonstrated flexibility and efficiency of the proposed solution.The Engineering and Physical Sciences Research Council

Operator interfaces for the lifecycle support of component based automation systems

Current manufacturing automation systems (specifically the powertrain sector) have been facing challenges with constant pressures of globalisation, environmental concerns and ICT (Information and Communication Technology) innovations. These challenges instigate new demands for shorter product lifecycles and require customised products to be manufactured as efficiently as possible. Manufacturing systems must therefore be agile to remain competitive by supporting frequent reconfigurations involving distributed engineering activities. [Continues.

EFFICIENCY OF FLEXIBLE FIXTURES: DESIGN AND CONTROL

The manufacturing industries have been using flexible production technologies to meet the demand for customisation. As a part of production, fixtures have remained limited to dedicated technologies, even though numerous flexible fixtures have been studied and proposed by both academia and industry. The integration of flexible fixtures has shown that such efforts did not yield the anticipated performance and resulted in inefficiencies of cost and time. The fundamental formulation of this thesis addresses this issue and aims to increase the efficiency of flexible fixtures.To realise this aim, the research in this thesis poses three research questions. The first research question investigates the efficiency description of flexible fixtures in terms of the criteria. Relative to this, the second research question investigates the use of efficiency metrics to integrate efficiency criteria into a design procedure. Once the efficiency and design aspects have been established, the third research question investigates the active control of flexible fixtures to increase their efficiency. The results of this thesis derive from the outcome of seven studies investigating the automotive and aerospace industries. The results that answer the first research question use five criteria to establish the efficiency of flexible fixtures. These are: fundamental, flexibility, cost, time and quality. By incorporating design characteristics in respect of production system paradigms, each criterion is elaborated upon using relevant sub-criteria and metrics. Moreover, a comparative design procedure is presented for the second research question and comprising four stages (including mechanical, control and software aspects). Initially, the design procedure proposes conceptual design and verification stages to determine the most promising flexible fixture for a target production system. By executing detailed design and verification, the design procedure enables a fixture designer to finalise the flexible fixture and determine its efficiency. Furthermore, a novel parallel kinematics machine is presented to demonstrate the applicability of the design procedure’s analytical steps and illustrate how appropriate kinematic structures can facilitate the efficiency-orientated design of flexible fixtures.Based on the correlation established by the controller software’s design procedure, the active control of flexible fixtures directly affects the quality criterion of flexible fixture efficiency. This provides the answer to the third research question, on general control strategies for active control of flexible fixtures. The introduction of a system model and manipulator dynamics proposes force and position control strategies. It is shown that any flexible fixture using a kinematic class can be controlled, to regulate the force and position of a workpiece and ensure that process nominals are preserved. Moreover, using both direct and indirect force control strategies, a flexible fixture’s role in active control can be expanded into a system of actively controlled fixtures that are useful in various processes. Finally, a position controller is presented which has the capacity to regulate both periodic and non-periodic signals. This controller uses an additional feedforward scheme (based on the Hilbert transform) in parallel with a feedback mechanism. Thus, the position controller enables flexible fixtures to regulate the position of a workpiece in respect of any kind of disturbance

Modelling flexible manufacturing systems through discrete event simulation

As customisation and product diversification are becoming standard, industry is looking for strategies to become more adaptable in responding to customer’s needs. Flexible manufacturing systems (FMS) provide a unique capability where there is a need to provide efficiency through production flexibility. Full potential of FMS development is difficult to achieve due to the variability of components within this complex manufacturing system. It has been recognised that there is a requirement for decision support tools to address different aspects of FMS development. Discrete event simulation (DES) is the most common tool used in manufacturing sector for solving complex problems. Through systematic literature review, the need for a conceptual framework for decision support in FMS using DES has been identified. Within this thesis, the conceptual framework (CF) for decision support for FMS using DES has been proposed. The CF is designed based on decision-making areas identified for FMS development in literature and through industry stakeholder feedback: set-up, flexibility and schedule configuration. The CF has been validated through four industrial simulation case studies developed as a part of implementation of a new FMS plant in automotive sector. The research focuses on: (1) a method for primary data collection for simulation validated through a case study of material handling robot behaviour in FMS; (2) an approach for evaluation of optimal production set-up for industrial FMS with DES; (3) a DES based approach for testing FMS flexibility levels; (4) an approach for testing scheduling in FMS with the use of DES. The study has supported the development of systematic approach for decision making in FMS development using DES. The approach provided tools for evidence based decision making in FMS

Systematic specification of requirements for assembly process control system in the pharmaceutical industry

Abstract. Pharmaceutical manufacturing is one of the most strictly regulated fields in the world. Manufacturers of pharmaceutical products are juridically obliged to monitor the safety and quality of products. Any defects and manufacturing errors affecting the product are demanded to be traceable due to patient safety. Regulative bodies have set strict demands for data integrity in manufacturing records. The main objective of this thesis is to evaluate whether the proposed supervisory control and data acquisition software can adhere to current prevailing regulatory framework. The evaluation of the proposed supervisory control and data acquisition software focuses on handling of electronic records and electronic signatures. Features like user management, alarm and event management, reporting, and locally set requirements in the target company are investigated and reflected to the prevailing regulations concerning data integrity. The results showed that the proposed software is, when properly configured, compliant to prevailing regulations regarding electronic records and electronic signatures. In addition, the proposed software is capable of the requirements set by the target company.Systemaattinen vaatimusmäärittely kokoonpanoprosessin ohjausjärjestelmälle lääketeollisuudessa. Tiivistelmä. Valmistava lääketeollisuus on yksi maailman eniten säädellyin teollisuuden ala. Lääkinnällisten tuotteiden valmistaja on lainmukaisesti vastuussa tuotteidensa laadusta ja valmistuksen valvomisesta. Tuotteiden laatu- ja valmistusvirheiden vaaditaan olevan jäljitettävissä potilasturvallisuuden vuoksi. Sääntelyviranomaiset ovat asettaneet tiukat vaatimukset tuotantokoneiden elektronisille tallenteille. Tämän diplomityön tavoitteena on arvioida noudattaako ehdotettu ohjausjärjestelmä nykyisiä säädöksiä. Ohjausjärjestelmän arviointi keskittyy eletronisten tallenteiden ja elektronisten allekirjoitusten toteutukseen ohjelmassa. Arvioinnin perustana käytetään sääntelyviranomaisten viimeisimpiä säädöksiä. Arviointi kohdistuu ohjelmiston käyttähallintaan, hälytys- ja tapahtumahallintaan, raportointiin ja paikallisesti asetettuihin vaatimuksiin tiedon eheyden näkökulmasta. Arviointi osoitti, että oikein konfiguroituna ehdotettu ohjausjärjestelmä noudattaa nykyisiä säännöksiä elektronisten tallenteiden ja elektronisten allekirjoitusten osalta. Ohjelmisto pystyy myös vastaamaan yrityksen paikallisesti asetettuihin vaatimuksiin. Ohjelmistoa voi kuitenkin käyttää vastoin nykyisiä sääntelyviranomaisten laatimia säädöksiä ilman riittävää asiantuntevuutta