Ladder Metamodeling & PLC Program Validation through Time Petri Nets

International audienceLadder Diagram (LD) is the most used programming language for Programmable Logical Controllers (PLCs). A PLC is a special purpose industrial computer used to automate industrial processes. Bugs in LD programs are very costly and sometimes are even a threat to human safety. We propose a model driven approach for formal verification of LD programs through model-checking. We provide a metamodel for a subset of the LD language. We define a time Petri net (TPN) semantics for LD programs through an ATL model transformation. Finally, we automatically generate behavioral properties over the LD models as LTL formulae which are then checked over the generated TPN using the model-checkers available in the Tina toolkit. We focus on race condition detection. This work is supported by the topcased project, part of the french cluster Aerospace Valley (granted by the french DGE), cf. http://www.topcased.or

A new approach to the development and maintenance of industrial sequence logic

This thesis is concerned with sequence logic as found in industrial control systems, with the focus being on process and manufacturing control systems. At its core is the assertion that there is a need for a better approach to the development of industrial sequence logic to satisfy the life-cycle requirements, and that many of the ingredients required to deliver such an approach are now available. The needs are discussed by considering the business case for automation and deficiencies with traditional approaches. A set of requirements is then derived for an integrated development environment to address the business needs throughout the control system life-cycle. The strengths and weaknesses of relevant control system technology and standards are reviewed and their bias towards implementation described. Mathematical models, graphical methods and software tools are then assessed with respect to the requirements for an integrated development environment. A solution to the requirements, called Synect is then introduced. Synect combines a methodology using familiar graphical notations with Petri net modelling supported by a set of software tools. Its key features are justified with reference to the requirements. A set of case studies forms the basis of an evaluation against business needs by comparing the Synect methodology with current approaches. The industrial relevance and exploitation are then briefly described. The thesis ends with a review of the key conclusions along with contributions to knowledge and suggestions for further research

PLC Control and Matlab/Simulink Simulations – A Translation Approach

Postprint (published version

Flexible manufacturing system utilizing computer integrated control and modeling

In today\u27s fast-automated production, Flexible Manufacturing Systems (FMS) play a very important role by processing a variety of different types of workpieces simultaneously. This study provides valuable information about existing FMS workcells and brings to light a unique concept called Programmable Automation. Another integrated concept of programmable automation that is discussed is the use of two feasibility approaches towards modeling and controlling FMS operations; the most commonly used is programmable logic controllers (PLC), and the other one, which has not yet implemented in many industrial applications is Petri Net controllers (PN). This latter method is a unique powerful technique to study and analyze any production line or any facility, and it can be used in many other applications of automatic control. Programmable Automation uses a processor in conventional metal working machines to perform certain tasks through program instructions. Drilling, milling and chamfering machines are good examples for such automation. Keeping the above issues in concem; this research focuses on other core components that are used in the FMS workcell at New Jersey Institute of Technology, such as; industrial robots, material handling system and finally computer vision

Implementation and automation of a sequencing batch reactor with a logo-oba6 programmable low-cost controller

Implementación y automatización de un reactor secuenciado por lotes con controlador programable de bajo costoEl artículo resume los resultados obtenidos en la implementación y automatización de un reactor secuenciado por lotes (SBR). Inicialmente, se explica el principio de funcionamiento, se justifica la utilización de este tipo de reactores y sus aplicaciones. Posteriormente, se describe el diseño tanto de hardware como de software para la operación automática del reactor, haciendo énfasis en las características y limitaciones de este tipo de sistema. Además, utilizando una técnica de diseño formal (redes de petri), se desarrolla un programa que requiere estrategias de programación especiales. Por último, se presentan los análisis, resultados y conclusiones.AbstractThis paper summarizes the results obtained in the implementation and automation of a sequencing batch reactor (SBR). First, the operating principle and the justification of the use of this type of reactor, as well as its applications, are explained. Subsequently, the design of both hardware and software for the automatic operation of the reactors is described, emphasizing the features and limitations of this type of system. Additionally, a formal design technique (petri networks) is used to develop a program that allows versatile, reliable and user-friendly operation, although it requires special programming strategies. Finally, the analysis, results, and conclusions are presented.Keywords: Automation, PLC, Sequencing batch reactor (SBR), programming, removal of environmental pollutants, wastewater treatment

The DS-Pnet modeling formalism for cyber-physical system development

This work presents the DS-Pnet modeling formalism (Dataflow, Signals and Petri nets), designed for the development of cyber-physical systems, combining the characteristics of Petri nets and dataflows to support the modeling of mixed systems containing both reactive parts and data processing operations. Inheriting the features of the parent IOPT Petri net class, including an external interface composed of input and output signals and events, the addition of dataflow operations brings enhanced modeling capabilities to specify mathematical data transformations and graphically express the dependencies between signals. Data-centric systems, that do not require reactive controllers, are designed using pure dataflow models. Component based model composition enables reusing existing components, create libraries of previously tested components and hierarchically decompose complex systems into smaller sub-systems. A precise execution semantics was defined, considering the relationship between dataflow and Petri net nodes, providing an abstraction to define the interface between reactive controllers and input and output signals, including analog sensors and actuators. The new formalism is supported by the IOPT-Flow Web based tool framework, offering tools to design and edit models, simulate model execution on the Web browser, plus model-checking and software/hardware automatic code generation tools to implement controllers running on embedded devices (C,VHDL and JavaScript). A new communication protocol was created to permit the automatic implementation of distributed cyber-physical systems composed of networks of remote components communicating over the Internet. The editor tool connects directly to remote embedded devices running DS-Pnet models and may import remote components into new models, contributing to simplify the creation of distributed cyber-physical applications, where the communication between distributed components is specified just by drawing arcs. Several application examples were designed to validate the proposed formalism and the associated framework, ranging from hardware solutions, industrial applications to distributed software applications