45 research outputs found
Towards a new methodology for design, modelling, and verification of reconfigurable distributed control systems based on a new extension to the IEC 61499 standard
In order to meet user requirements and system environment changes, reconfigurable control systems must dynamically adapt their structure and behaviour without disrupting system operation. IEC 61499 standard provides limited support for the design and verification of such systems. In fact, handling different reconfiguration scenarios at runtime is difficult since function blocks in IEC 61499 cannot be changed at run-time. Hence, this thesis promotes an IEC 61499 extension called reconfigurable function block (RFB) that increases design readability and smoothly switches to the most appropriate behaviour when a reconfiguration event occurs. To ensure system feasibility after reconfiguration, in addition to the qualitative verification, quantitative verification based on probabilistic model checking is addressed in a new RFBA approach. The latter aims to transform the designed RFB model automatically into a generalised reconfigurable timed net condition/event system model (GRTNCES) using a newly developed environment called RFBTool. The GR-TNCES fits well with RFB and preserves its semantic. Using the probabilistic model checker PRISM, the generated GR-TNCES model is checked using defined properties specified in computation tree logic. As a result, an evaluation of system performance and an estimation of reconfiguration risks are obtained. The RFBA methodology is applied on a distributed power system case study.Dynamische Anforderungen und Umgebungen erfordern rekonfigurierbare Anlagen und Steuerungssysteme. Rekonfiguration ermöglicht es einem System, seine Struktur und sein Verhalten an interne oder externe Änderungen anzupassen. Die Norm IEC 61499 wurde entwickelt, um (verteilte) Steuerungssysteme auf Basis von Funktionsbausteinen zu entwickeln. Sie bietet jedoch wenig Unterstützung für Entwurf und Verifikation. Die Tatsache, dass eine Rekonfiguration das System-Ausführungsmodell verändert, erschwert die Entwicklung in IEC 61499 zusätzlich. Daher schlägt diese Dissertation rekonfigurierbare Funktionsbausteine (RFBs) als Erweiterung der Norm vor. Ein RFB verarbeitet über einen Master-Slave-Automaten Rekonfigurationsereignisse und löst das entsprechende Verhalten aus. Diese Hierarchie trennt das Rekonfigurationsmodell vom Steuerungsmodell und vereinfacht so den Entwurf. Die Funktionalität des Entwurfs muss verifiziert werden, damit die Ausführbarkeit des Systems nach einer Rekonfiguration gewährleistet ist. Hierzu wird das entworfene RFB-Modell automatisch in ein generalised reconfigurable timed net condition/event system übersetzt. Dieses wird mit dem Model-Checker PRISM auf qualitative und quantitative Eigenschaften überprüft. Somit wird eine Bewertung der Systemperformanz und eine Einschätzung der Rekonfigurationsrisiken erreicht. Die RFB-Methodik wurde in einem Softwarewerkzeug umgesetzt und in einer Fallstudie auf ein dezentrales Stromnetz angewendet
Anpassen verteilter eingebetteter Anwendungen im laufenden Betrieb
The availability of third-party apps is among the key success factors for software ecosystems: The users benefit from more features and innovation speed, while third-party solution vendors can leverage the platform to create successful offerings.
However, this requires a certain decoupling of engineering activities of the different parties not achieved for distributed control systems, yet.
While late and dynamic integration of third-party components would be required, resulting control systems must provide high reliability regarding real-time requirements, which leads to integration complexity.
Closing this gap would particularly contribute to the vision of software-defined manufacturing, where an ecosystem of modern IT-based control system components could lead to faster innovations due to their higher abstraction and availability of various frameworks.
Therefore, this thesis addresses the research question:
How we can use modern IT technologies and enable independent evolution and easy third-party integration of software components in distributed control systems, where deterministic end-to-end reactivity is required, and especially, how can we apply distributed changes to such systems consistently and reactively during operation?
This thesis describes the challenges and related approaches in detail and points out that existing approaches do not fully address our research question.
To tackle this gap, a formal specification of a runtime platform concept is presented in conjunction with a model-based engineering approach.
The engineering approach decouples the engineering steps of component definition, integration, and deployment.
The runtime platform supports this approach by isolating the components, while still offering predictable end-to-end real-time behavior.
Independent evolution of software components is supported through a concept for synchronous reconfiguration during full operation, i.e., dynamic orchestration of components.
Time-critical state transfer is supported, too, and can lead to bounded quality degradation, at most.
The reconfiguration planning is supported by analysis concepts, including simulation of a formally specified system and reconfiguration, and analyzing potential quality degradation with the evolving dataflow graph (EDFG) method.
A platform-specific realization of the concepts, the real-time container architecture, is described as a reference implementation.
The model and the prototype are evaluated regarding their feasibility and applicability of the concepts by two case studies.
The first case study is a minimalistic distributed control system used in different setups with different component variants and reconfiguration plans to compare the model and the prototype and to gather runtime statistics.
The second case study is a smart factory showcase system with more challenging application components and interface technologies.
The conclusion is that the concepts are feasible and applicable, even though the concepts and the prototype still need to be worked on in future -- for example, to reach shorter cycle times.Eine große Auswahl von Drittanbieter-Lösungen ist einer der Schlüsselfaktoren für Software Ecosystems:
Nutzer profitieren vom breiten Angebot und schnellen Innovationen, während Drittanbieter über die Plattform erfolgreiche Lösungen anbieten können.
Das jedoch setzt eine gewisse Entkopplung von Entwicklungsschritten der Beteiligten voraus, welche fĂĽr verteilte Steuerungssysteme noch nicht erreicht wurde.
Während Drittanbieter-Komponenten möglichst spät -- sogar Laufzeit -- integriert werden müssten, müssen Steuerungssysteme jedoch eine hohe Zuverlässigkeit gegenüber Echtzeitanforderungen aufweisen, was zu Integrationskomplexität führt.
Dies zu lösen würde insbesondere zur Vision von Software-definierter Produktion beitragen, da ein Ecosystem für moderne IT-basierte Steuerungskomponenten wegen deren höherem Abstraktionsgrad und der Vielzahl verfügbarer Frameworks zu schnellerer Innovation führen würde.
Daher behandelt diese Dissertation folgende Forschungsfrage:
Wie können wir moderne IT-Technologien verwenden und unabhängige Entwicklung und einfache Integration von Software-Komponenten in verteilten Steuerungssystemen ermöglichen, wo Ende-zu-Ende-Echtzeitverhalten gefordert ist, und wie können wir insbesondere verteilte Änderungen an solchen Systemen konsistent und im Vollbetrieb vornehmen?
Diese Dissertation beschreibt Herausforderungen und verwandte Ansätze im Detail und zeigt auf, dass existierende Ansätze diese Frage nicht vollständig behandeln.
Um diese Lücke zu schließen, beschreiben wir eine formale Spezifikation einer Laufzeit-Plattform und einen zugehörigen Modell-basierten Engineering-Ansatz.
Dieser Ansatz entkoppelt die Design-Schritte der Entwicklung, Integration und des Deployments von Komponenten.
Die Laufzeit-Plattform unterstĂĽtzt den Ansatz durch Isolation von Komponenten und zugleich Zeit-deterministischem Ende-zu-Ende-Verhalten.
Unabhängige Entwicklung und Integration werden durch Konzepte für synchrone Rekonfiguration im Vollbetrieb unterstützt, also durch dynamische Orchestrierung.
Dies beinhaltet auch Zeit-kritische Zustands-Transfers mit höchstens begrenzter Qualitätsminderung, wenn überhaupt.
Rekonfigurationsplanung wird durch Analysekonzepte unterstützt, einschließlich der Simulation formal spezifizierter Systeme und Rekonfigurationen und der Analyse der etwaigen Qualitätsminderung mit dem Evolving Dataflow Graph (EDFG).
Die Real-Time Container Architecture wird als Referenzimplementierung und Evaluationsplattform beschrieben.
Zwei Fallstudien untersuchen Machbarkeit und NĂĽtzlichkeit der Konzepte.
Die erste verwendet verschiedene Varianten und Rekonfigurationen eines minimalistischen verteilten Steuerungssystems, um Modell und Prototyp zu vergleichen sowie Laufzeitstatistiken zu erheben.
Die zweite Fallstudie ist ein Smart-Factory-Demonstrator, welcher herausforderndere Applikationskomponenten und Schnittstellentechnologien verwendet.
Die Konzepte sind den Studien nach machbar und nützlich, auch wenn sowohl die Konzepte als auch der Prototyp noch weitere Arbeit benötigen -- zum Beispiel, um kürzere Zyklen zu erreichen
Design, Application and Evaluation of a Multi Agent System in the Logistics Domain
The increasing demand for flexibility of automated production systems also
affects the automated material flow systems (aMFS) they contain and demands
reconfigurable systems. However, the centralized control concept usually
applied in aMFS hinders an easy adaptation, as the entire control software has
to be re-tested, when manually changing sub-parts of the control. As adaption
and subsequent testing are a time-consuming task, concepts for splitting the
control from one centralized to multiple, decentralized control nodes are
required. Therefore, this paper presents a holistic agent-based control concept
for aMFS, whereby the system is divided into so-called automated material flow
modules (aMFM), each being controlled by a dedicated module agent. The concept
allows the reconfiguration of aMFS, consisting of heterogeneous, stationary
aMFM, during runtime. Furthermore, it includes aspects such as uniform agent
knowledge bases through metamodel-based development, a communication ontology
considering different information types and properties, strategic route
optimization in decentralized control architecture and a visualization concept
to make decisions of the module agents comprehensible to operators and
maintenance staff. The evaluation of the concept is performed by means of
material flow simulations as well as a prototypical implementation on a
lab-sized demonstrator.Comment: 13 pages, https://ieeexplore.ieee.org/abstract/document/9042827
A Semantic Interoperability Model Based on the IEEE 1451 Family of Standards Applied to the Industry 4.0
The Internet of Things (IoT) has been growing recently. It is a concept for connecting
billions of smart devices through the Internet in different scenarios. One area being
developed inside the IoT in industrial automation, which covers Machine-to-Machine (M2M) and industrial communications with an automatic process, emerging the
Industrial Internet of Things (IIoT) concept. Inside the IIoT is developing the concept of
Industry 4.0 (I4.0). That represents the fourth industrial revolution and addresses the
use of Internet technologies to improve the production efficiency of intelligent services
in smart factories. I4.0 is composed of a combination of objects from the physical world and the digital world that offers dedicated functionality and flexibility inside and outside of an I4.0 network.
The I4.0 is composed mainly of Cyber-Physical Systems (CPS). The CPS is the integration
of the physical world and its digital world, i.e., the Digital Twin (DT). It is responsible for realising the intelligent cross-link application, which operates in a self-organised and
decentralised manner, used by smart factories for value creation. An area where the CPS
can be implemented in manufacturing production is developing the Cyber-Physical Production System (CPPS) concept. CPPS is the implementation of Industry 4.0 and CPS in manufacturing and production, crossing all levels of production between the
autonomous and cooperative elements and sub-systems. It is responsible for connecting
the virtual space with the physical world, allowing the smart factories to be more intelligent, resulting in better and smart production conditions, increasing productivity,
production efficiency, and product quality. The big issue is connecting smart devices with
different standards and protocols. About 40% of the benefits of the IoT cannot be
achieved without interoperability. This thesis is focused on promoting the
interoperability of smart devices (sensors and actuators) inside the IIoT under the I4.0 context.
The IEEE 1451 is a family of standards developed to manage transducers. This standard reaches the syntactic level of interoperability inside Industry 4.0. However, Industry 4.0
requires a semantic level of communication not to exchange data ambiguously. A new
semantic layer is proposed in this thesis allowing the IEEE 1451 standard to be a complete framework for communication inside the Industry 4.0 to provide an interoperable network interface with users and applications to collect and share the data from the industry field.A Internet das Coisas tem vindo a crescer recentemente. É um conceito que permite
conectar bilhões de dispositivos inteligentes através da Internet em diferentes cenários.
Uma área que está sendo desenvolvida dentro da Internet das Coisas é a automação
industrial, que abrange a comunicação máquina com máquina no processo industrial de
forma automática. Essa interligação, representa o conceito da Internet das Coisas
Industrial. Dentro da Internet das Coisas Industrial está a desenvolver o conceito de
Indústria 4.0 (I4.0). Isso representa a quarta revolução industrial que aborda o uso de
tecnologias utilizadas na Internet para melhorar a eficiência da produção de serviços em
fábricas inteligentes. A Indústria 4.0 é composta por uma combinação de objetos do
mundo fĂsico e do mundo da digital que oferece funcionalidade dedicada e flexibilidade
dentro e fora de uma rede da IndĂşstria 4.0.
O I4.0 Ă© composto principalmente por Sistemas CiberfĂsicos. Os Sistemas CiberfĂsicos
permitem a integração do mundo fĂsico com seu representante no mundo digital, por
meio do GĂ©meo Digital. Sistemas CiberfĂsicos sĂŁo responsáveis por realizar a aplicação
inteligente da ligação cruzada, que opera de forma auto-organizada e descentralizada,
utilizada por fábricas inteligentes para criação de valor. Uma área em que o Sistema
CiberfĂsicos pode ser implementado na produção manufatureira, isso representa o
desenvolvimento do conceito Sistemas de Produção CiberfĂsicos. Esse sistema Ă© a
implementação da IndĂşstria 4.0 e Sistema CiberfĂsicos na fabricação e produção. A
cruzar todos os nĂveis desde a produção entre os elementos e subsistemas autĂłnomos e
cooperativos. Ele Ă© responsável por conectar o espaço virtual com o mundo fĂsico,
permitindo que as fábricas inteligentes sejam mais inteligentes, resultando em condições
de produção melhores e inteligentes, aumentando a produtividade, a eficiência da
produção e a qualidade do produto. A grande questão é como conectar dispositivos
inteligentes com diferentes normas e protocolos. Cerca de 40% dos benefĂcios da Internet
das Coisas não podem ser alcançados sem interoperabilidade. Esta tese está focada em
promover a interoperabilidade de dispositivos inteligentes (sensores e atuadores) dentro
da Internet das Coisas Industrial no contexto da IndĂşstria 4.0.
O IEEE 1451 Ă© uma famĂlia de normas desenvolvidos para gerenciar transdutores. Esta
norma alcança o nĂvel sintático de interoperabilidade dentro de uma indĂşstria 4.0. No
entanto, a IndĂşstria 4.0 requer um nĂvel semântico de comunicação para nĂŁo haver a
trocar dados de forma ambĂgua. Uma nova camada semântica Ă© proposta nesta tese
permitindo que a famĂlia de normas IEEE 1451 seja um framework completo para
comunicação dentro da Indústria 4.0. Permitindo fornecer uma interface de rede
interoperável com utilizadores e aplicações para recolher e compartilhar os dados dentro
de um ambiente industrial.This thesis was developed at the Measurement and Instrumentation Laboratory (IML)
in the University of Beira Interior and supported by the portuguese project INDTECH
4.0 – Novas tecnologias para fabricação, que tem como objetivo geral a conceção e
desenvolvimento de tecnologias inovadoras no contexto da IndĂşstria 4.0/Factories of the Future (FoF), under the number POCI-01-0247-FEDER-026653
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
Evaluation of OPC UA technology in order to minimize systems unavailability by improving M2M connectivity
Eventually the industrial automation engineer is challenged to optimize a M2M communication process. For this, it is essential to observe the infrastructure offered by the company and the resources available in legacy equipment. Developing a simple, economically viable solution that makes use of open communication standards is highly recommended. Alternatives that do not require large investments gain a significant dimension; another important factor in this decision is that the chosen solution should be able to operate harmoniously with existing legacy systems. By doing so, the company will be in a position to gradually pursue the Industry 4.0 concept and to preserve the most investments already made. This paper aims to describe OPC UA technology, test it in a controlled environment in order to meet a real production demand and justify how and why its differentiated characteristics are recommended for Industry 4.0 applications. http://dx.doi.org/10.18226/23185279.v7iss2p4
Characterization of trade-off preferences between non-functional properties
Efficient design and evolution of complex software intensive systems rely on the ability to make informed decisions as early as possible in the life cycle. Such informed decisions should take both the intended functional and non-functional properties into account. Especially regarding the latter, it is both necessary to be able to predict properties and to prioritize them according to well-defined criteria. In this paper we focus on the latter problem, that is to say how to make trade-offs between non-functional properties of software intensive systems. We provide an approach based on the elicitation of utility functions from stake-holders and subsequent checks for consistency among these functions. The approach is exploitable through an easy-to-use GUI, which is also presented. Moreover, we describe the setup and the outcome of our two-fold validation based on exploratory elicitations with students and practitioners
Distributed Planning for Self-Organizing Production Systems
FĂĽr automatisierte Produktionsanlagen gibt es einen fundamentalen Tradeoff
zwischen Effizienz und Flexibilität. In den meisten Fällen sind die Abläufe
nicht nur durch den physischen Aufbau der Produktionsanlage, sondern auch durch
die spezielle zugeschnittene Programmierung der Anlagensteuerung fest
vorgegeben. Änderungen müssen aufwändig in einer Vielzahl von Systemen
nachgezogen werden. Das macht die Herstellung kleiner StĂĽckzahlen unrentabel.
In dieser Dissertation wird ein Ansatz entwickelt, um eine automatische
Anpassung des Verhaltens von Produktionsanlagen an wechselnde Aufträge und
Rahmenbedingungen zu erreichen. Dabei kommt das Prinzip der Selbstorganisation
durch verteilte Planung zum Einsatz. Die aufeinander aufbauenden Ergebnisse der
Dissertation sind wie folgt:
1. Es wird ein Modell von Produktionsanlagen entwickelt, dass nahtlos von der
detaillierten Betrachtung physikalischer Produktionsprozesse bis hin zu
Lieferbeziehungen zwischen Unternehmen skaliert. Im Vergleich zu
existierenden Modellen von Produktionsanlagen werden weniger limitierende
Annahmen gestellt. In diesem Sinne ist der Modellierungsansatz ein Kandidat
für eine häufig geforderte "Theorie der Produktion".
2. FĂĽr die so modellierten Szenarien wird ein Algorithmus zur Optimierung der
nebenläufigen Abläufe entwickelt. Der Algorithmus verbindet Techniken für die
kombinatorische und die kontinuierliche Optimierung: Je nach Detailgrad und
Ausgestaltung des modellierten Szenarios kann der identische Algorithmus
kombinatorische Fertigungsfeinplanung (Scheduling) vornehmen, weltweite
Lieferbeziehungen unter Einbezug von Unsicherheiten und Risiko optimieren und
physikalische Prozesse prädiktiv regeln. Dafür werden Techniken der
Monte-Carlo Baumsuche (die auch bei Deepminds Alpha Go zum Einsatz kommen)
weiterentwickelt. Durch Ausnutzung zusätzlicher Struktur in den Modellen
skaliert der Ansatz auch auf groĂźe Szenarien.
3. Der Planungsalgorithmus wird auf die verteilte Optimierung durch unabhängige
Agenten ĂĽbertragen. DafĂĽr wird die sogenannte "Nutzen-Propagation" als
Koordinations-Mechanismus entwickelt. Diese ist von der Belief-Propagation
zur Inferenz in Probabilistischen Graphischen Modellen inspiriert. Jeder
teilnehmende Agent hat einen lokalen Handlungsraum, in dem er den
Systemzustand beobachten und handelnd eingreifen kann. Die Agenten sind an
der Maximierung der Gesamtwohlfahrt ĂĽber alle Agenten hinweg interessiert.
Die dafĂĽr notwendige Kooperation entsteht ĂĽber den Austausch von Nachrichten
zwischen benachbarten Agenten. Die Nachrichten beschreiben den erwarteten
Nutzen fĂĽr ein angenommenes Verhalten im Handlungsraum beider Agenten.
4. Es wird eine Beschreibung der wiederverwendbaren Fähigkeiten von Maschinen
und Anlagen auf Basis formaler Beschreibungslogiken entwickelt. Ausgehend von
den beschriebenen Fähigkeiten, sowie der vorliegenden Aufträge mit ihren
notwendigen Produktionsschritten, werden ausfĂĽhrbare Aktionen abgeleitet. Die
ausfĂĽhrbaren Aktionen, mit wohldefinierten Vorbedingungen und Effekten,
kapseln benötigte Parametrierungen, programmierte Abläufe und die
Synchronisation von Maschinen zur Laufzeit.
Die Ergebnisse zusammenfassend werden Grundlagen fĂĽr flexible automatisierte
Produktionssysteme geschaffen -- in einer Werkshalle, aber auch ĂĽber Standorte
und Organisationen verteilt -- welche die ihnen innewohnenden Freiheitsgrade
durch Planung zur Laufzeit und agentenbasierte Koordination gezielt einsetzen
können. Der Bezug zur Praxis wird durch Anwendungsbeispiele hergestellt. Die
Machbarkeit des Ansatzes wurde mit realen Maschinen im Rahmen des EU-Projekts
SkillPro und in einer Simulationsumgebung mit weiteren Szenarien demonstriert
Agent-based manufacturing — review and expert evaluation
The advent of smart manufacturing and the exposure to a new generation of technological enablers have revolutionized the way manufacturing process is carried out. Cyber-Physical Production Systems (CPPS) are introduced as main actors of this manufacturing shift. They are characterized for having high levels of communication, integration and computational capabilities that led them to a certain level of autonomy. Despite the high expectations and vision of CPPS, it still remains an exploratory topic. Multi-Agent Systems (MAS) have been widely used by software engineers to solve traditional computing problems, e.g., banking transactions. Because of their high levels of distribution and autonomous capabilities, MAS have been considered by the research community as a good solution to design and implement CPPS. This work first introduces a collection of requirements and characteristics of smart manufacturing. A comprehensive review of various research applications is presented to understand the current state of the art and the application of agent technology in manufacturing. Considering the smart manufacturing requirements and current research application, a SWOT analysis was formulated which identifies pros and cons of the implementation of agents in industry. The SWOT analysis was further validated by an industrial expert evaluation and the main findings and discussion of the results are presented
A framework for flexible integration in robotics and its applications for calibration and error compensation
Robotics has been considered as a viable automation solution for the aerospace industry to address manufacturing cost. Many of the existing robot systems augmented with guidance from a large volume metrology system have proved to meet the high dimensional accuracy requirements in aero-structure assembly. However, they have been mainly deployed as costly and dedicated systems, which might not be ideal for aerospace manufacturing having low production rate and long cycle time. The work described in this thesis is to provide technical solutions to improve the flexibility and cost-efficiency of such metrology-integrated robot systems.
To address the flexibility, a software framework that supports reconfigurable system integration is developed. The framework provides a design methodology to compose distributed software components which can be integrated dynamically at runtime. This provides the potential for the automation devices (robots, metrology, actuators etc.) controlled by these software components to be assembled on demand for various assembly applications.
To reduce the cost of deployment, this thesis proposes a two-stage error compensation scheme for industrial robots that requires only intermittent metrology input, thus allowing for one expensive metrology system to be used by a number of robots. Robot calibration is employed in the first stage to reduce the majority of robot inaccuracy then the metrology will correct the residual errors. In this work, a new calibration model for serial robots having a parallelogram linkage is developed that takes into account both geometric errors and joint deflections induced by link masses and weight of the end-effectors.
Experiments are conducted to evaluate the two pieces of work presented above. The proposed framework is adopted to create a distributed control system that implements calibration and error compensation for a large industrial robot having a parallelogram linkage. The control system is formed by hot-plugging the control applications of the robot and metrology used together. Experimental results show that the developed error model was able to improve the 3 positional accuracy of the loaded robot from several millimetres to less than one millimetre and reduce half of the time previously required to correct the errors by using only the metrology. The experiments also demonstrate the capability of sharing one metrology system to more than one robot