Jean-François Pétin

Pragmatic approach for modular control synthesis and implementation

Within the framework of Supervisory Control Theory, synthesis algorithms enable automatic generation of control rules from behavioural models of the process to be controlled and of goals to be achieved. The paper highlights a pragmatic use of these algorithms within an automation engineering context and focuses on two key issues: process and goals modelling, and supervisory controller implementation. In this way, the approach presented combines the synthesis techniques and algorithms with an object-oriented automation method that supplies guidelines for the analysis, design and implementation of a modular control system. This pragmatic approach is applied to the synthesis and implementation of the control of an assembly station. The paper highlights the difficulties of the modelling step and its great influence on the synthesis result itself, and also demonstrates the feasibility of the synthesis approach through a successful implementation in conformance with the International Electrotechnical Commission 61131-3 standard.

Distributed intelligent actuation and measurement (IAM) system within an integrated shop-floor organisation

Abstract The world of instrumentation is undergoing a major evolution shift as embedded intelligence and field-bus communication allow a migration of functionality into all parts of distributed automation systems. This innovative architecture allows an integrated shop-floor organisation by providing Control, Maintenance and technical Management (CMM) activities with a common and efficient representation of the process. On the basis of the industrial research and development initiated by European projects, evolution based on intelligent field devices and leading towards more adaptive automation systems is discussed. An engineering framework, as needed to structure the system models in line with the distribution and integration requirements, is suggested through a case study based on the level control system of our pilot laboratory.

Design and validation of a product-driven control system based on a six sigma methodology and discrete event simulation

Recent trends in industry towards autonomous and just-in-time production systems, and the latest developments in auto-ID technologies, have created new opportunities for enhancing reactivity and agility on the shop floor. To take advantage of these opportunities, a Product-driven System (PDS) concept can be seen as an innovative control concept that advocates that a product can be an active actor throughout its lifecycle by associating the material flow with the product information. We propose a methodological approach that contributes to the design and validation of such a system. More specifically, this work focuses on an infrastructure that satisfies PDS control requirements. The feasibility of our proposed approach was evaluated by the development of an industrial case at the Trane Company using six sigma methodology and discrete event simulation.

Control Synthesis for Product-Driven Automation

Abstract We study the problem of controlling a flexible manufacturing cell by means of automatically computed supervisors. Such a flexible control can be seen as a modular combination of product-driven supervisors and components-driven ones, mainly for control integration in a Manufacturing Execution System. Our method associates a top-down synthesis approach based on customized product specification and a bottom-up synthesis approach based on standardised components on the shelves. Practical result is a routings supervisor devoted to each product occurrence which is consistent with the manufacturing stations supervisors. Copyright

Formal Specification Method for Systems Automation

Abstract Currently automatic control deals with the theoretical modelling techniques applied to formally define the behaviour of a control system when the system goals and the process behaviour to be controlled are well defined. Although these approaches are efficient in the design and implementation phases for controlling the dynamics of automatized systems, other tools are also required in the early stages of the process of engineering a system. This paper deals with a specification method aimed at proving that the system goals, as required by the users, are formally refined towards the real target automation system with completeness, consistency, unambiguousness and correctness guarantees. Our specification method is based on the B language to globally verify, from formal constructs, the predicate:Control Systems Requirements ^ Process Systems Requirements Production System Requirements. A case study illustrates our approach and opens issues on the way to industrial practice.

Formal Specification for Manufacturing Systems Automation

Abstract Automatic synthesis of control systems deals currently with theoretical modelling techniques aiming to formally define the behaviour of a control system when process behaviours and system requirements are well defined. Theses approaches are not efficient in practice when system requirements and behavioural models are more or less refined all along the life cycle of a manufacturing automation concurrent process. Our approach aims to formally satisfy the following predicate : Control Systems Requirements Process Systems Requirements ⇒ Manufacturing System Requirements , at each phase of a system engineering process. This paper deals with the system specification phase by applying the B formal method to globally verify this automation paradigm.

Formal Engineering Methods for Modelling and Verification of Control Systems

Abstract This paper highlights the benefits of formal methods to improve the quality and efficiency of process control engineering, according to two key aspects: the definition of a formal engineering framework which allows the re-usability of specifications at a high level of abstraction and the ability to prove some properties of the process control models. An introductory example presents a formal structuring framework using the B method and highlights the main temporal requirements for modelling and proving control systems in this framework. Taking into account these temporal modalities requires an extension of the B model. An attempt using TLA is suggested and discussed.

USING SYSML FOR IDENTIFICATION AND REFINEMENT OF MACHINERY SAFETY PROPERTIES

Abstract In the context of the development of systems subjected to strong dependability and safety properties, standards such as the IEC 61508 recommend the use of formal verification tools. In this way, conceptual and practical approaches related to computer sciences and automatic control, such as model checking, theorem proving, control synthesis, have been widely explored. However, in spite of the consensus that early phases of a system definition are the most important in ensuring that the target system will satisfy the users requirements, most of these models and tools address the design and implementation phases where the identification and formalisation of system properties remain tricky. This machinery-dedicated paper combines system specification models supported by SysML to identify the system properties and architecture with model checker. This method is based on the refinement of system global requirements and their projection on the system components to formalise local properties to be proved by the model checker. A mechanical press case study illustrates this approach.

Using Coloured Petri Nets for integrated reliability and safety evaluations

Abstract Integrated Deterministic and Probabilistic Dependability Analysis (IDPDA) is respectively required for safety properties verification and reliability & availability assessment of critical systems. This paper presents an approach towards IDPDA using Coloured Petri Nets (CPN). Contributions are related to: (a) hierarchical modelling guidelines that cover deterministic and probabilistic features of a physical system under control, (b) coupling Monte-Carlo simulation with CPN model checking that requires a previous determinisation of the CPN stochastic model. Our approach is illustrated using a toy case study.

Dynamic adaptation of IEEE 802.11e priorities for improving temporal performance and safety of a Wireless Networked Discrete Control system

This paper deals with Discrete Control Systems whose implementation is distributed among devices communicating through a Wireless Network. The use of wireless communication in these applications, called Wireless Networked Discrete Control System (WNDCS), offers many advantages, but the undeterministic behaviour of the network may have a negative impact on the temporal performance and safety of the control applications. This paper focuses on WNDCS communicating through IEEE 802.11e. It presents an algorithm that adapts the flow communication priorities according to the control states in order to increase the WNDCS quality of service and safety.