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- An IEC 61499 Replication for Distributed Control ApplicationsPublication . Santos, Adriano A; Silva, A. Ferreira da; Sousa, Mário de; Magalhaes, PessoaModern industrial environment control programs are distributed among several devices. The IEC 61499 standard defines function blocks with which distributed control applications may be developed, and how these are interpreted and executed. Its functionality and the inherent support for dynamic reconfiguration provide the required infrastructure for Industry 4.0 and industrial IoT applications. However, by their distributed nature new challenges are posed, especially about how modes of failure are handled. To avoid system malfunctions and breakdowns due to partial failures, the authors propose a new framework were the concept of replication can be applied maintaining internal state synchronised. This paper presents an example of how the replication framework on the FORTE IEC 6499 execution platform can be developed and voting strategies, along with the results obtained in the implementation with the standard communication SIFBs available on the Eclipse 4diacTM.
- Teaching Control Pneumatic and Electro-pneumatic Circuits – A New MethodPublication . Silva, António Ferreira da; Santos, Adriano A.Karnaugh map is a method to simplify a logical equation, or convert a truth table in the corresponding logic circuit. This paper presents an alternative way to use the Karnaugh maps that minimizes the logical conditions of command for pneumatic circuits, whether the command is pneumatic or electric. In the last case, the method also permits the control of the circuit through a programmable controller (PLC). In practice, ensure a series of sequential movements in an automatic cycle is to find the set of equations which are executed ensure the realization of the desired sequence. The application of the method itself becomes dispensable analysis of speed or course of the cylinders (irrelevant features to the materialization of the command sequence). It means therefore that the control cylinders equations that will allow his movements (called output variables) are function only of two types of variables (input variables), the position of each cylinder (end-of-stroke valves) and if necessary memory variables. The proposed methodology ensures not only the desired sequential cycle, as well as the minimization of the variables necessary for control commands. To simplify substantially the explanation of the method, it is assumed that each pneumatic cylinder is associated with two end-of-stroke valves for detecting its position. The description as well as the applicability of the proposed methodology will be illustrated using a concrete problem of industrial automation. The methodology described here, will extend its use not only in industrial applications, but also the educational level in terms of engineering schools allowing a particular use in the automation of laboratories in the field of pneumatic control circuits and sequential electro (it is currently teaching in automation course unit of mechanical engineering in ISEP).
- Methodology for manipulation of Karnaugh maps designing for pneumatic sequential logic circuitsPublication . Santos, Adriano A; Silva, António Ferreira daThis paper presents an alternative way to use the Karnaugh maps, which minimises logical conditions used for ON/OFF control, in either pneumatic and electro pneumatic circuits. In the last case, the methodology allows the control of the circuit through a programmable logic controller (PLC). In this kind of processes, controlling pneumatic cylinders is a problem that not only depends on the state of the information present but also in terms of knowledge of past actions. In practice, ensuring a series of sequential movements in an automatic cycle is to find the set of equations that should be executed to ensure the realisation of the desired sequence. It means therefore that the equations that will allow the movements of each cylinder are functions only of two types of input variables, the position of each cylinder and if necessary, memory variables. One of the major merits that arise from the use of the proposed method is the simplicity of obtaining electrical schematic command circuit. The proposed methodology ensures not only the desired sequential cycle, as well as the minimisation of the variables necessary for control commands.
- IEC 61499 REPLICATION FOR FAULT TOLERANT SYSTEMPublication . Santos, Adriano A.; Sousa, Mário de; Magalhães, Pessoa; Silva, António Ferreira daThe IEC 61499 was developed thinking about the new generation of distributed control and automation systems. This provides essential resources for the development of distributed systems such as encapsulation, portability and reconfiguration. In this sense, and to ensure confidence in the operation should be implemented fault tolerance techniques dealing with hardware failures and errors off software associated with us where the distributed application runs. In this paper, we propose an approach to deal with failures in distributed systems tolerance problems, based on a replication model based on replication software/hardware as a means to achieve confidence in the operation.
- Electro Pneumatic Control versus GrafcetPublication . Santos, Adriano A; Silva, António Ferreira daThe classic methodologies of electro-pneumatic control are essentially based on the Cascade method and a methodology supported by Karnaugh Map. If in the first method, the resolution of pneumatic problem is basically performed by dividing the working sequence in groups, in the second method, the approach is made by the minimization of the control logic equations converting the truth table, to the corresponding logical circuit. In this paper we present an alternative form of a PLC programming, using the Cascade and Karnaugh methods, replacing the classic technique supported by the Grafcet modelling.