Distributed implementation of Grafcets through IEC 61499

Comunicación presentada en 25th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA), 2020A Grafcet is a standardized model for describing the behavior of systems which is popular among automation engineers. As the Grafcet standard excludes implementation details, the models are typically translated to automation software. Such software was traditionally programmed in one of the languages specified in IEC 61131-3. Nowadays, automation software is increasingly modelled in IEC 61499 which facilitates designing distributed control systems. In this paper, we define a standardized translation methodology, so that automation engineers can benefit from the advantages of IEC 61499 while continuing to use Grafcet. We discuss the differences between Grafcet and IEC 61499. We translated a Grafcet model into an IEC 61499 application to illustrate the process and derive guidelines for application designers. For the core concepts of Grafcet, we present the corresponding structure in IEC 61499

Simulation and Control of a Cyber-Physical System under IEC 61499 Standard

IEC 61499 standard provides an architecture for control systems using function blocks (FB), languages, and semantics. These devices can be interconnected and communicate with each other. Each device contains several resources and algorithms with a communication FB at the end, which can be created, configured, and deleted without affecting other resources. Physical element can be represented by a FB that encapsulates the functionality (data/events, process, return data/events) in a single module that can be reused and combined. This work presents a simplified implementation of a modular control system using a low-cost device. In the prototyping of the application, we use 4diac to control, model and validate the implementation of the system on a programmable logic controller. It is proved that this approach can be used to model and simulate a cyber-physical system as a single element or in a networked combination. The control models provide a reusable FB design.We acknowledge the financial support of CIDEM, R&D unit funded by FCT – Portuguese Foundation for the Development of Science and Technology, Ministry of Science, Technology and Higher Education, under the Project UID/EMS/0615/2019, and it was supported by FCT, through INEGI and LAETA, under project UIDB/50022/2020.info:eu-repo/semantics/publishedVersio

Usage of IEC 61131 and IEC 61499 standards for creating distributed control systems

This publication deals with the application of standards for industrial automation during distributed control systems design. Control systems design consists of a choice between two approaches based on the standards, IEC 61131 and IEC 61499. The question is which of the standards to use for distributed control systems design. The most commonly used standards are briefly listed in the introduction section. Then follows a more detailed description of the IEC 61131 and IEC 61499 standards, future development of the IEC 61499 standard and its usage during the creation of distributed control systems. Further on are lists and descriptions of existing commercial and research software tools, which are necessary in implementing this standard. The main section deals with the methodology for standard application comparison and criteria selection for comparing. This methodology is then verified on real control systems. The final section includes methodology generalization for suitable approach selection, resulting in recommendations for which standard to choose during creation of distributed control systems

Practice of Industrial Control Logic Programming using Library Components

This chapter discusses Programmable Logic Controller (PLC) programming practice, particularly the use of library components, in the automotive industry. A study of program structure and use of library components at two European car manufacturers is presented. The main purpose of the study is to provide understanding of current PLC programming in industry

Método de implementação do controle de sistemas e eventos discretos com aplicação da teoria de controle supervisório

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica.A literatura indica que, de forma geral, a prática industrial corrente para desenvolvimento de sistemas de controle em sistemas de dinâmica dirigida a eventos discretos é empírica e não adota métodos formais de modelagem do sistema nem de síntese do controlador. Esta Tese de Doutorado apresenta um método de implementação do controle de sistemas a eventos discretos. Este método permite que a implementação seja realizada concentrada em um único controlador, possivelmente um controlador lógico programável (CLP), ou distribuída em um conjunto de controladores. A lei de controle, denominada supervisor, é obtida pela aplicação da Abordagem Modular Local da Teoria de Controle Supervisório. Para aplicar esta teoria o comportamento livre do sistema e as especificações de controle são representados através de autômatos. O método de implementação é um procedimento sistemático para conversão do modelo que descreve o comportamento livre do sistema e do supervisor no programa de aplicação do CLP. Este programa de aplicação resulta em conformidade com a norma internacional IEC 61131-3. A literatura discute os diversos problemas que podem ocorrer quando os resultados da Teoria de Controle Supervisório são implementados. O método de implementação apresentado nesta Tese permite considerar tais problemas. São apresentadas propriedades que, se satisfeitas, garantem que a ocorrência de tais problemas não se manifesta. Um aspecto fundamental para a distribuição do controle é a comunicação entre os controladores. Esta Tese apresenta um modelo de comunicação entre CLPs. Este modelo garante a satisfação de um conjunto de propriedades relevantes à distribuição do controle. Este modelo emprega um serviço de comunicação definido na norma internacional IEC 61131-5. The literature indicates that, generally, the current industrial practice of developing control systems of discrete event dynamic systems is empirical and does not apply either formal methods of system modeling or of control synthesis. This Thesis presents a discrete event systems control implementation method. This method allows the implementation to be carried out concentrated in a single controller, possibly a programmable logic controller (PLC), or distributed in a set of controllers. The control law, named supervisor, is obtained applying the Local Modular Approach of the Supervisory Control Theory. In order to apply this theory the system free behavior and the control specifications are both represented by automata. The implementation method is a systematic procedure to convert the free behavior system model and the supervisor into the PLC application program. This application program results in conformity with the international standard IEC 61131-3. The literature discusses the several problems that may arise when the results of the Supervisory Control Theory are to be implemented. The implementation method presented in this Thesis allows to consider such problems. It is presented a set of properties that, when satisfied, guarantee that such problems do not occur. An essential aspect to the control distribution is the communication between controllers. This Thesis presents a PLC communication model that fulfils a set of properties important to control distribution. This model adopts a communication service defined by the international standard IEC 61131-5

OPTIMIZATION OF PRODUCTION LINES USING ADVANCED CNC INTERPOLATION METHODS AND DISTRIBUTION OF CONTROL LOGIC

These days, information technology really makes the difference in manufacturing industry. High performance computers allow to realize control algorithms of increasing complexity and high speed reliable computer networks allows the communication between different devices and realization of advanced distributed control applications. In this thesis, we focus on the optimization of the production lines using two different approaches. First we focus on the improvement of a single workstation of the production line, then we focus on the improvement of the interactions between various stations of the production line.. A typical workstation that can be found in a production line is the machine tool for manufacturing workpieces. Advances in manufacturing technologies allow to increase quality and efficiency in production lines, but also ask for new and increasing requirements on the motion planning and control systems. The increase of CPU processing power has permitted, in traditional CNC systems, the introduction of NURBS interpolation capabilities, thus determining a further increase in machining quality and efficiency. This has posed new and still unsolved issues, such as the need to satisfy multiple opposite constraints like limiting chord error, acceleration and jerk and offering real-time guarantees. In addition, the ability of privileging the production throughput by relaxing one or more of the previous constraints in a simple way has emerged as another requirement of modern manufacturing plants. Nevertheless, none of the existing NURBS interpolators have these characteristics. In this thesis, we propose a NURBS interpolator that is able to satisfy all the manufacturing technology requirements and is able to respect, thanks to its bounded computational complexity, the position control real-time constraints. Such interpolator is easily reconfigurable, i.e. it can relax some of the constraints and can be adapted in order to include constraints that were not originally considered. Performances of the proposed algorithm have been evaluated both by simulations and by real milling experiments. However, improvements in productivity of a the machine tool can be neutralized if the various workstations of the production line are not properly synchronized. Distributed control allows to improve the coordination of different workstations but its design is challenging. The IEC 61499 standard has been developed to ease the modeling and design of distributed control systems, providing advanced concepts of software engineering (such as abstraction, encapsulation, reuse) to the world of control engineering. The introduction of such standard in already existing control environments poses challenges, since the widespread IEC 61131-3 programming standard is not compatible with the new standard. In order to solve this problem, this thesis presents an architecture that permits to integrate modules of the two standards, allowing to exploit the benefits of both. The proposed architecture is based on coexistence of control logic of both standards. Each standard interacts with some particular interfaces that encapsulate information and functionalities to be exchanged with the other standard. A methodology of integration of 61131-3 modules in a 61499 distributed solution based on such architecture is also developed, and it is described via a case study to prove feasibility and benefits

Development of insect production automation: Automated processes for the production of Black Soldier Fly (Hermetia illucens)

In recent years, Black Soldier Fly (Hermetia illucens) has received attention as an attractive approach for recycling biowaste into value products. The production of Black Soldier Fly (BSF) uses biowaste as the input feedstock for the growing of BSF larvae in order to produce nutrient-rich larvae feedstock products and organic fertilizers. However, most of the operations in BSF production are still carried out manually, which limits production volume. This makes BSF products less competitive than other traditional feedstock products. Thus, this thesis aims to develop automated processes for the mass production of BSF larvae. In order to eliminate the dependence on manual work and to make feasible the industrialization of production, a six-step strategy was implemented. The sequence of steps was as follows: determining the requirements and specifications of the BSF production; calculating the desired capacity of processes; selecting machinery; designing automated processes; proposing a method of machinery integration; and designing state machines for automation software programming. The solution developed here consists of four components: a list of machinery with capacity analysis; a designed floor layout and 3D visualization of all production processes; a proposed automation control system for the integration of machinery; and composite function blocks of IEC 61499 standard for automation software programming. This thesis shows that the availability of current technologies makes feasible the automation of the BSF production process. In terms of further work, the selection of processing machines should be verified; and both the programming of automation software and the use of simulation could improve the design of the production automation

Tehokas kommunikaatio rajoitetun kaistanleveyden kaukovalvonta sovelluksissa

Serial radio modems are long-standing but usable technology and they are still widely used in data communication in many applications. Slow transmission speed, point-to-point connections and signal attenuation are the negative aspects of serial modems. Old and new radio modem models are still compatible with each other because they have not changed greatly over the years. Radio modems can transfer many transmission protocols therefore user can select the most suitable protocol for the application. The goal of this thesis was to improve the usage of serial radio modems in communication between PLCs. Data transfer speed generally cannot be increased thus only necessary data should be transferred through radio modems. The protocol that was used in this thesis was Modbus RTU which is supported by numerous process control devices. Radio network enables reading and writing data to remote automation systems using Modbus RTU. Every device in the network has to be polled individually and round times of large networks can increase to tens of seconds. The basic idea in improving the communication rate is that every station in the network was read sequentially but stations can jump the queue if needed. This thesis studied how different data should be divided in the communication. It is not necessary to use cyclical data transfer method for all the data and therefore some data could only be transferred when needed. Performance of the communication system was tested using existing remote monitoring system. The new communication system is similar to existing one therefore performance of the new implementation can be verified. The performance of both systems were measured and results have been presented in the last chapter

Authentication Layer for IEC 61113-3 Applications

Mid 2010, the Stuxnet ICS attack targeted the Siemens automation products, and after this attack the ICS security was thrust into spotlight, automation products suppliers started to re-examine their business approach to cyber security. The OPC Foundation made also significant changes and improvements on its new design OPC-UA to increase security of automation applications but, what is still missing and seems to be not resolved any time soon is having security in depth for industrial automation applications. In this paper, we propose a simple but strong security control solution, what we will call a logic application level security particularly for SCADA and DCS. This proposed method is based on message integrity and should not be viewed as the main, nor the only level of protection that an industrial automation system is expected to have, but can be a low-level security procedure that avoids intelligent attacks such as Stuxnet