Luxury car manufacturers are facing the challenge of transitioning their customers to electric mobility without compromising on comfort levels. While efforts to enhance efficiency have traditionally focused on powertrain and aerodynamics, the rise in efficiency of electric drive trains has highlighted the significance of low-voltage power consumers. To address this, our study proposes a data-driven modelling strategy that leverages real-time in-car communication data to gain insights into the power consumption behavior of low-voltage power consumers across various real-world driving scenarios. Our methodology involves a selection process for simulation-worthy consumers, an appropriate regression algorithm, feature selection techniques, and Key Performance Indicators to assess the models’ quality and efficiency.By utilizing our data-driven modelling strategy, we can provide an individual and transparent evaluation of each power consumer, enabling automotive development engineers to optimize their vehicles’ power distribution network and deliver an unparalleled driving experience.

Energy efficiency is crucial for the quick and widespread adoption of electric-powered vehicles because higher energy consumption results in a reduced electrical range. To leverage energy efficiency potentials in the low-volt power net of the vehicle complex and intertwined software-hardware interde-pendencies as well as operation strategies need to be optimized by the engineers. Since these systemic dependencies are not transparent and the amount of information exchanged among power consumers is high, a data-driven approach for root-cause explanation and analysis is investigated. We thus propose to make use of in -car communication data to determine the function-related causes of energy consumption of control units and their actuators with the help of Explainable AI (XAI). Therefore, we apply a step-wise experimental procedure validating the suitability of XAI methods with a virtual, thus transparent power consumer first before applying them to real-world automotive data. We demonstrate the suitability of four selected XAI methods for power consumers of the electrical system of a passenger car attaining acceptable results in terms of quality and efficiency. This expedites automated and reliable data-driven knowledge generation in the domain of automotive energy efficiency.

This article deals with reconfigurable uniprocessor systems powered by a renewable energy source under real-time and resource sharing constraints. A reconfigurable system is defined as a set of implementations, each of which is encoded by real-time periodic software tasks. Reconfiguration is a flexible runtime scenario that adapts the current system’s implementation to any related environment evolution under well-defined conditions. A task is characterized by an effective calculated deadline that should be less than a maximum deadline defined in user requirements. The main problem is how to calculate the effective deadlines of the different periodic tasks in the different implementations under possibly the predicted renewable energy source and the sharing of resource constraints. We propose an offline method based on three solutions to calculate the deadlines of tasks. The first serves to compute the deadlines ensuring the real-time system feasibility and also minimizes the number of context switches by assigning the highest priority to the task with the smallest maximum deadline. The second computes the deadlines ensuring the respect of energy constraints, and the third computes the deadlines ensuring the respect of resource sharing constraints. These three solutions calculate the possible deadlines of each task in the hyperperiod of the corresponding implementations. We develop a new simulator called DEAD-CALC, that integrates a new tool called RANDOM-TASK for applying and evaluating the proposed solutions. The conducted experimentation proves that this methodology provides deadlines with affecting neither the load nor the processor speed while reducing the calculation time.Note to Practitioners—Real-time software is particularly difficult to design since, in addition to ever more complex functional constraints, it has to satisfy a set of stringent nonfunctional requirements, such as deadlines. In fact, the violation of deadlines can lead to breakdowns, data loss, and so on, which can be catastrophic for critical applications. This article presents the DEAD-CALC project for computing efficiently the deadlines of reconfigurable real-time devices to run possibly under energy and resource sharing constraints in all the system implementations. A device, in the software level, is a superset of implementations, each of which (i.e., a set of periodic software tasks) is activated and executed at a particular time according to user requirements. DEAD-CALC reduces the development time by computing the deadlines to be certainly respected without any additional feasibility analysis of the device. The calculation can only consider the real-time aspects, or both the harvesting energy and resource sharing constraints, giving the user the ability to configure the system under different conditions. DEAD-CALC is a visual environment that can be simply used by designers to compute and display these deadlines, with a few clicks, in arranged tables, and in a short time. This project can be a future reference for industrial partners who will be focusing on various real-time applications design, such as the intelligent manufacturing industry, intelligent transportation systems, embedded systems, wireless sensor networks, smart grids, medical control devices, and military platforms.

Analysis of electrical energy metering profiles has experienced a substantial increase of research activity in recent years. This smart metering is a tool for monitoring energy usage and users' behaviors as a pre-requisite for substantial energy savings. Instead of having a sensor at each appliance, non-Intrusive Load Monitoring (NILM) provides a cheaper solution by disaggregating the load data from a single meter using digital signal processing. Different algorithms have been successfully applied to a variety of load scenarios. Load data for small office appliances is available in the BLOND data set (Building-Level Office eNvironment Dataset) such as laptops, computer monitors, etc. The potential energy saving of each small appliance cannot be neglected, particularly in large companies/institutesIn this paper, a recurrent neural network (RNN) with long-short term memory (LSTM) is designed, trained, and validated for NILM on small power office equipment provided in the BLOND data set. A comparison to combinatorial optimization and factorial hidden Markov models using five metrics for performance testing shows good results for the proposed RNN.

With the increasing awareness of climate change and the declining prices of renewable energy sources (RESs), societies are transforming themselves to access cheap and clean energy. Solar and Wind are the two most abundantly available energy resources that can be accessed in remote areas where it is infeasible for a national grid to supply electricity. However, the RESs are intermittent in nature show high variability in output power, and become more volatile without the integration of the national grid. In this paper, we address such a problem of RESs uncertainty in an islanded microgrid, incorporating both supply-side and demand-side energy management techniques. We propose a model predictive time-ahead rolling horizon based optimization approach, that generates cost-optimal scheduling signals for various energy supply entities and flexible load demands. The objective of this work is to; 1) minimize the operating cost of the power generators, 2) minimize electricity cost for the energy consumers, and 3) maximize the consumers' satisfaction level. The numerical results show that our optimization strategy ensures the supply and demand balance applying cost-efficient decisions under any uncertain circumstances using error-correcting rolling time horizon based strategy.

A developing concept of distributed energy resources (DERs) demonstrates high power in-feed from renewable energy sources (RESs). RESs mainly include solar and wind resources. Presently, the problem faces from these RESs, is their uncertain behavior of producing energy. This is due to the reason of varying wind speed and solar irradiations. The RESs can be incorporated at any scale in the power network and can be handled through centralized or de-centralized grid control mechanism. In this paper, we present a model of nano-grid, representing a medium scale smart home. It integrates roof-top photovoltaic (PV) panels, energy storage devices (ESDs) and smart loads along with grid-supplied energy. A cost minimization problem is proposed, that reduces the accumulated cost of energy consumed by a smart home. Hence, we adopt a power scheduling scheme, establishing an optimal strategy of supplying cost-effective energy to the user's load demands. It ensures, i) high utilization factor of installed PV; ii) cost-effective ESDs operations; iii) low-cost infeed from a grid, considering home area power network (HAPN) system constraints. Our scheduling scheme is based on mixed integer linear programming (MILP) framework, providing day-ahead optimal scheduling decisions for various energy supply entities. Simulation results demonstrate the real outlook of our implemented strategy, utilizing a cost-effective optimal blend of distinct energy sources.

IEC 61499 provides a standardized approach for the development of distributed control systems. The standard introduces a component architecture, based on function blocks that are event-triggered components processing data and signals. However, it gives only limited support for the design of reconfigurable architectures. In particular, handling of several reconfiguration scenarios is quite heavy on this level since a scenario changes the execution model of the system due to requirements. To this end, a new IEC 61499-based model named reconfigurable function blocks (RFBs) is proposed. An RFB processes the reconfiguration events and switches directly to the suitable configuration using a hierarchical state machine model. The latter represents the reconfiguration model which reacts on changes in the environment in order to find an adequate reconfiguration scenario to be executed. Each scenario presents a particular sequence of algorithms, encapsulated in another execution control chart slave which represents the control model of an RFB. This hierarchy simplifies the design and separates the reconfiguration logic from control models. To verify its correctness and alleviate its state space explosion problem in model checking, this paper translates an RFB system automatically into a generalized model of reconfigurable timed net condition/event systems (GR-TNCES), a Petri net class that preserves the semantics of an RFB system. In this paper, along with verification of deterministic properties, we also propose to quantify and analyze some probabilistic properties. As a case study, we consider a smart-grid system, interpreting permanent faults in it as reconfiguration events, and we characterize them with the expected occurrence probability and the corresponding repair time. A tool chain ZiZo is developed to support the proposed approach.

This paper deals with the reconfigurable real-time systems that should be adapted to their environment under real-time constraints. The reconfiguration allows moving from one implementation to another by adding/removing/modifying parameters of real-time software tasks which should meet related deadlines. Implementing those systems as threads generates a complex system code due to the large number of threads, which may lead to a reconfiguration time overhead as well as the energy consumption and the memory allocation increase. Thus this paper proposes a multiobjective optimization approach for reconfigurable systems called MO2R2S for the development of a reconfigurable real-time system. Given a specification, the proposed approach aims to produce an optimal design while ensuring the system feasibility. We focus on three optimization criteria: 1) response time; 2) memory allocation; and 3) energy consumption. To address the portability issue, the optimal design is then transformed to an abstract code that may in turn be transformed to a concrete code which is specific to a procedural programming (i.e., POSIX) or an object-oriented language (i.e., RT-Java). The MO2R2S approach allows reducing the number of threads by minimizing the redundancy between the implementation sets. By an experimental study, such optimization permits to decrease the memory allocation by 28.89%, the energy consumption by 40.2%, and the response time by 61.32%.

The conceptual framework of future power grid incorporates self-automated power flow components. It incorporates high penetration of intermittent renewable energy and variable users' load demands. To establish an efficient real-time power flow mechanism, a realization of the exact amount of energy generation and consumption is inevitable. Hence, we propose a novel framework of a smart micro-grid (SMG), that keeps balance among generation and consumption. It empowers day-ahead supply and demand prediction mechanism along with real-time intelligent energy management (IEM) system. Practically, day-ahead predictions are attained with certain level of errors. These errors are due to the difference in predicted and measured data, also known as uncertainties. Lyapunov optimization under various IEM strategies using flexible loads and battery storage is considered to exploit these uncertainties. The proposed scheme comprises of subsequent steps: 1) the day-ahead predicting solar power and user load demands; 2) the day-ahead procurement of grid power to balance the overall load demands; 3) differentiating real-time uncertainties into user's unused excess power and unserved load demands; 4) real-time balancing of supply and demands by scheduling flexible loads and battery storage, considering the cost effective SMG operations. Our IEM system effectively demonstrates the results of the proposed framework by balancing the user demand arrivals with various energy supplies.

Current industrial systems need to interact with the surrounding environment in order to provide more efficiency. In such systems, used software applications must be strong enough to answer run-time needs. Context-aware applications seem to be an appropriate solution that can satisfy adaptation to the continuous changes. Safe reconfigurations require the respect of tasks deadlines and the avoidance of blocking. However, existing solutions are still insufficient and lack many important services. In this paper, we propose a new context-aware framework for developing control applications in dynamically changing environment. We focus on respecting real-time as well as functional constraints. The proposed framework structure provides simple reconfiguration handling and boosts the awareness of applications. This paper describes the definition of the proposed framework and its design. To prove the validation of the new approach, we have performed a case study and simulations.

This paper presents an extension to the IEC 61499 standard called Reconfigurable Function Block. The major goal is to optimize the design of a network of Function Blocks by encapsulating several reconfiguration scenarios in one function block. We define the events triggering the reconfiguration and we attach a probability to each event to express its uncertainty. In order to verify the system and to evaluate its performances, we model it with a class of Petri nets. The proposed approach is applied to a medical platform BROS as a case study throughout a developed software tool called ZiZo v3.

This paper introduces a method for modeling and simulation of a production system with different energy modes. We aim to save the energy in an assembly automobile production line platform using sensitive sensors. A new prototype model is proposed using an extension of Petri nets called GR-TNCES (generalized reconfigurable timed net condition event systems). We also present a simulation of this model with a proposed tool ZIZO to show the energy gain compared to standard production line model.

This paper presents a detailed comparison between Peltier elements (also called thermoelectric coolers (TEC)) and thermoelectric generators (TEG) for the usage as thermoelectric power generators. Whereas the former is normally known for cooling applications or heat pump uses, it can also be used as generator. Today, thermoelectric energy harvesting systems find more and more utilization, e.g. in wireless sensors or exhaust pipes. The efficiency of thermoelectric materials for the low temperature sector (between 0 °C and 200 °C) is actually not very high, but the costs for TEGs are. As TECs and TEGs consist of the same thermoelectric material for this temperature sector (Bi2Te3), the upcoming question is in which temperature range and under which conditions expensive TEGs can be replaced by cheap TECs. Therefore, in this contribution, TECs and TEGs are tested and compared under the same conditions.

The Functional Mock-up Interface (FMI) is the result of a research program initiated by Daimler AG, further industrial companies, and several institutes, with the aim of enabling the exchange of dynamic simulation models between different simulation tools as well as their co-simulation. The upcoming release of the second version of this standard in 2014 is the motivation for the current investigation into possible uses in the process industry. The standard is therefore presented and discussed in general, but with focus on the needs of the process industry. This article also illustrates how a Functional Mock-up Unit (FMU) can be coupled to widely-used simulation tools and presents a concept for its coupling and implementation. The concept uses the open and well-defined Shared-Memory-Gateway provided by the SIMIT Simulation Framework.

The interconnection of distributed generation units has a significant impact on the performance of an energy system. In this paper, challenges in designing grid-connected and islanded distributed energy systems (DES) are described and a concept of simulation models in the component-oriented modeling language Modelica®is presented, wherein simulation models are divided into physically detailed and physically abstracted models.

In a field test at Saarland University, a decision tool named OWLracle has been developed. It supports university managers in comparing benefit and costs of different methods of energy saving. They include building automation as well as economic and psychological incentives. In order to guarantee transferability to other university properties, appropriate typicals are required. To this end, the paper defines common Building Types, Room Types, and User Types, representative of German universities. Furthermore, it introduces a BCVTB-based implementation of OWLracle, integrating Modélica® libraries of Room and User Types and EnergyPlus models of Building Types. 27 combinations of Building, Room and User Type are compared with respect to their total energy consumption.

Energy engineering is an emerging topic in manufacturing plants due to environmental and economic reasons. It is not enough to save energy during the utilization of products, but the production should be considered as well. Moreover, idle times during production should be taken into account by switching the systems and the subsystems into modes that require less energy inputs. Furthermore energy related properties should be considered as early-as-possible in the plant process development, because in this phase the influence on the later energy consumption is considerable. Hence, methods for energy optimization in production are combined with virtual plant engineering to consider energy aspects as early as possible in plant design. Both engineering domains contribute to an integrated process for energy engineering in the virtual factory.

In waste water pumping stations, centrifugal pumps driven by induction motors are used to transport the collected effluent to the treatment plants. Those pumps can be controlled either using frequency converters or on-and-off control using soft starters. In this paper a method for modeling wastewater pumping stations using the component oriented modeling language Modelica is presented. The model provides a valuable simulation tool to validate and judge on the different control schemes of these stations. This approach is applied successfully on a real pumping station located at the northern part of Gaza. The derived model facilitates tuning the control parameters and allows better understanding of the system dynamics.

This contribution defines for the first time “safety automata”, a specification language for safety control functions. This fills an important gap in the method tool box of the automation engineer. The definition has a profound potential to broaden the use of automata and their well-known advantages in industrial applications. The advantages and application of safety automata are explained by example via the function block SF_Equivalent of the PLCopen specification. Stepwise, the authors illustrate the specification of this function block by means of safety automata, the transformation rules to implement the automata in fully functional PLC code, and finally the generation of test cases that allow checking both the automata and the PLC code.

Model Driven Development (MDD) has been proved as a quite successful paradigm in general-purpose computing and is currently exploited in the embedded systems domain. On the other hand, the majority of industrial automation systems is developed based on the IEC 61131 standard. This standard defines a model and a set of programming languages for the development of industrial automation software and it is supported by the majority of the commercial tools in this domain. This work proposes an MDD process to increase the productivity and reliability of the development process of industrial automation systems. Piping and instrumentation diagrams are considered as source of requirements for process control engineering and SysML is used to reduce the gap between these diagrams and the 61131 based design specs of the control system. The foundation for a SysML profile to facilitate the exploitation of SysML in this domain is described. This profile will allow the developer to work in higher layers of abstraction than the one supported by IEC 61131 and effectively move from requirement specifications into the implementation model of the system.

The nine papers in this special section focus on information technology in automation.

Numerical simulation of stiff and hybrid systems is widely used in various engineering domains. Numerical solvers, originally designed for purely continuous problems, are not sufficient for these systems. Modern simulation environments provide necessary modifications and extensions to solve the problem. The implementation details of solvers and run time systems greatly affect the performance of simulations regarding accuracy, velocity of simulation, compactness of results, and efficiency. Since no all-powerful solver exists, we assess four popular solvers (DASSL, LSODAR, DOPRI5, RADAU IIA), included in the all-purpose simulator Dymola®for different problems with continuous, stiff, and hybrid behavior. Key traits, including the number of steps, accuracy, CPU time and the event handling capability, are examined and advice for solver selection is given.

This paper presents a novel two-step approach for modeling forward and backward network delays in networked control systems (NCS). The first step is to build a colored Petri net (CPN) structural model for the simulation of Ethernet based networked control systems. The modular model captures the most important features of industrial networked control systems, such as client/server input/output scanning and cyclical execution of the control algorithm on a programmable logic controller (PLC). CPN tools software is used to build and simulate the model with different parameter sets. This first easy to build model is used in a second step to identify a compact phenomenological model from an extensive set of simulation results. In this second step a finite state Markov chain delay model (FSMD) is used to capture the delay patterns generated with the CPN model. The resulting model is more compact than the CPN model and due to its mathematical form it can be integrated in existing design and analysis methods for NCS.

This paper presents a novel colored Petri net model for the simulation of fully-switched Ethernet based networked control systems (NCS). The model of the NCS is built from models of the automation system components (e.g. PLC, Ethernet Switch, IO Module) in a structure conserving way. CPNtools software is used to build and simulate the models. The proposed approach is used to study the overall response time of a given NCS as well as the two delays between actuator and controller and between sensor and controller respectively. These delays are often used in the design of controllers for NCS. An analysis of the results using periodograms shows a high amount of regularity in the delays that possibly can be exploited for controller design.

The reactivity of Networked Automation Systems (NAS) has direct influence on safety and quality aspects. It can be determined by a response time analysis, which itself can be calculated using probabilistic model checking (PMC). The analysis of a NAS has to account for several coupled components, each of them exhibiting its own behavior. Consequently, in this article the influences of (1) the controllerpsilas execution behavior including its network interface card (cyclic vs. interrupt based) and (2) the communication model (Producer-Consumer vs. Client-Server) on the response time behavior will be analyzed. For this purpose the systems are represented by abstract models using probabilistic timed automata. Probabilistic model checking is used to compare the reactivity of different possible combinations of the basic behaviors.

Technological advancements in communication and embedded computing lead to the increasing application of decentralized structures in automation and control. The decentralization adds new behavior in the form of - often non-deterministic - delays to the resulting networked control systems (NCS). To analyze a closed loop control system including network communication, simulation is a viable approach. In this work a library for the simulation of controller and network hardware to be used in combination with process models in closed loop is presented. The library is implemented in the Modelica language. To allow easy application a structure conserving component based modeling approach is followed. The applicability is shown by analyzing the performance of a robotics control system where communication is realized alternatively with Ethernet and CAN bus.

Several interpretations and implementations of the IEC 61499 standard have been published. The interpretations have been made with a certain desired run-time behavior in mind. One group of interpretations focuses on providing a well analyzable behavior whereas the others have been proposed to increase runtime performance. However, there has not been an interpretation of the standard having usability in mind. In this contribution a new interpretation of IEC 61499, explicitly focused on usability for beginners in the domain of distributed control, is presented and compared to already published interpretations. Applicability of the interpretation is shown by an implementation based on .NET.

The introduction of Ethernet and Internet technologies in the fieldbuses of automation systems widely facilitates vertical integration. Control functions can coexist more easily with higher level functions such as supervision, production reporting or maintenance. But what does the response time of the control function become when architecture components -e.g. controllers, remote input-output modules or fieldbuses -are requested in parallel by other functions? In this paper, we focus on switched Ethernet-based fieldbuses using Modbus TCP/IP. The evaluation of the impact of vertical integration on the response time of control functions is obtained from a series of measurements on a real system. A great number of response times were measured with a specific automated equipment that we developed. Three types of load on the control architecture are studied: traffic on fieldbuses, requests on controllers and requests on remote input-output modules. The analysis of the measurement results shows which level of vertical integration can be reasonably allowed, taking into account the required response times.

The onward dispersion of Ethernet based structures with decentralized and distributed multi-user environments in automation leads towards networked automation systems (NAS). The new modern structures are less expensive and at the same time more flexible than classical ones. However, they induce non-deterministic delays. Hence, the detailed analysis of the resulting response time is not only prerequisite for the responsible use; it also enables to check dependability properties prior-to changes or expansions of the system. To do so, a new modeling language -DesLaNAS -is introduced, which accounts for the special needs of modeling NAS. Based on probabilistic model checking for the analysis, the influence of different components and of net-based behavior modes like resource-sharing and synchronization on the resulting response time is discussed.

The distributed control applications of today are usually assumed to be run on a hardware consisting of heterogeneous processing elements. A standard like IEC 61499 attempts to provide an unanimous software infrastructure for these applications. An important research interest thereof is to find possible deployment of the components of the distributed application on these heterogeneous nodes. Since most of such applications are hard real-time ones the complexity of the problem is further increased by strict temporal restrictions. This paper addresses this issue as algorithms are presented for finding feasible and optimal solutions of such deployment problems. Moreover, the problems are also considered in the context of two different - while conforming to the standard - execution semantics realized in certain implementations of IEC 61499.

Evaluation of response times in Networked Automation System (NAS), especially ether net-based NAS, is a new challenge in automation domain. This paper presents a feasible simulation approach for this issue. A model library of typical NAS structure is built using Modelica/Dymola. Modular modeling concept is implemented to enable a better representation of system structure. The presented toolbox allows users to explore the temporal behavior of the system by simulation. The modeling is described in some detail. Comparisons with concerned tools are performed to reveal potential improvement. A case study shows how simulation of NAS with process model in closed loop is arranged. Use of the tools is presented in an example.

In case of failures in a PLC controlled process the problem of diagnosis arises. Today this is often a manual task. Whenever the failure in the controlled system is not directly related to an actuator, its sources have to be tracked back through the PLC program to the corresponding sensors. This process can be very time consuming. The presented work aims at providing a means for determining this effort and to assist the diagnosis process. To do so, software quality measures are studied. The evaluation of these measures on a program shows the most complex parts and hence gives hints on possible improvements. During the calculation of the measures graphical representations of some dependency relations are derived. These can be used as an aid for the engineer in the actual diagnosis process. Two case studies illustrate the presented approach.

New technological trends lead to the increasing use of network technologies in automation. Especially the Ethernet with TCP/IP and wireless networks find growing acceptance. The resulting networked automation systems (NAS) display properties such as stochastic delays and information loss, which are not known in classical automation structures. When control quality is to be assessed, these properties have to be determined. In this paper, the determination is achieved in a modeling approach based on probabilistic timed automata (PTA). The derived models allow the analysis of delays using probabilistic model checking (PMC). A case study illustrates how the results of the analysis can be applied to increase the product quality in a manufacturing system controlled by an NAS.

Development of distributed control applications within a standard framework was actually the strongest motivation behind the introduction of IEC 61499. Yet, scarcity of its application is due to the fact that the development is more complex as compared to the existing languages and standards. This paper addresses an UML-based development process for IEC 61499 which attempts to consider the aspects related to the utilization of the unique features that this standard brought into the field of industrial control applications. Reliability is an important consideration in this particular realm of software development and apart from formal verification tests are often performed to verify the software components. An automatic test-case generation methodology is introduced to complement the proposed development process.

This paper presents a method to assess response time of automation system architectures including industrial switched Ethernet networks using client/server protocols. The method relies upon modeling the behavior of the components of these architectures in the form of hierarchical timed colored Petri nets and upon simulation of these models. A case study exemplifies the method and shows how it can facilitate design of automation systems including this kind of industrial Ethernet networks.

This paper proposes Unified Modeling Language (UML) as modeling tool for distributed control systems (DCSs) according to the IEC 61499 standard. The reason behind using this model is a demand to describe the system considering the whole development process. The object-oriented (OO) concept in UML along with its supporting tools is a good candidate for this purpose. However, IEC 61499 is built on the use of interconnected function blocks (FBs) as a modeling paradigm. A mapping concept from UML into FB-based systems and its implementation are presented. As a result, the UML model using class diagrams, packages, and state diagrams can be transformed automatically to models according to IEC 61499. The proposed process leads to a combination of previously disjoint design levels in the system development.

Programmable logic controllers (PLCs) are still the workhorse of industrial automation. The programming and adaptation of the software for PLCs - i.e. the implementation of the control algorithms - are expensive and cumbersome tasks. Today the re-implementation of an existing PLC program on a new platform, as it is supported by industrial tools on a low level, requires considerable manual re-working by a specialist. Known re-implementation processes do not allow a fully automatic transfer to a new platform. Furthermore they lack re-documentation of the code which makes it hard to understand and to follow the implemented algorithms. To avoid these problems, this paper proposes a re-implementation concept for existing PLC programs based on formal methods. An application of this concept to a lab system is presented to assess its applicability

Functionality based control is an approach that improves the quality of the design process in distributed controlled systems (DCSs) by combining object-oriented concepts with re-configurability on function level. The basic functions are implemented in function blocks and then the overall functionality is derived by the use of a supervising scheduler. This paper presents an approach to model the basic functionalities in manufacturing systems using Unified Modeling Language (UML). A transformation of the UML description into an IEC 61499 compliant format is given. The approach is illustrated using the functionality based control (FBC) of a laboratory plant

The introduction of non-deterministic networks to the automation field leads to new questions in the analysis of the resulting systems often called networked control systems (NCS). To determine reaction times not only the cycle times of the controllers but also the network delays have to be taken into account. The problem further increases in reliability analysis. Here the failures of a variety of components have to be considered. For this purpose probabilistic model checking (PMC) is a promising formal approach. This paper investigates the application of existing techniques and tools from PMC to the analysis of delay times in NCS under the consideration of component failures. A key idea in the presented approach is that the nature of signals in automation systems is taken into account. A case study shows how properties, relevant for the reliable functioning of an automation system, can be checked

The developer of logic control systems is faced with increasing complexity of the functions to be implemented and, at the same time, increasing demands on the reliability of the resulting software. To analyze the reliability of such complex systems formal methods can be applied. One area of the corresponding research is focused on the application of model checking techniques to Programmable Logic Controllers (PLCs). In this paper a new method to formalize PLC programs together with a model of the cyclic behavior of the PLC is presented. The control systems behavior is modeled, and then the program, written in Instruction List, is formalized and integrated into the model. The formalization in SMV language is suitable for verification using BDD and SAT techniques. Both techniques are compared using first results of a case study.

IEC 61499 ushers in a new trend of software development in the area of Industrial Process Measurement and Control System (IPMCS). This new standard simplifies the development of distributed IPMCS applications through inclusion of re-usability, encapsulation and modularity. IEC 61499, due to its close resemblance with Object-Oriented (OO) paradigm also paves the way to integrate modeling techniques like UML into the development process of the distributed IPMCS applications. Yet a remarkable challenge is there to integrate or re-design the systems, elements or components designed using a monolithic language like the ones on Programmable Logic Controllers (PLCs). In this work it is attempted to share the experiences faced while attempting to migrate a PLC controlled centralized laboratory application into an IEC 61499 compliant distributed control application. The targeted distributed control system consists of network-enabled controllers where the IEC 61499 compliant control sub-applications should run. It needs to be mentioned that the development process did not start from analysis of the specification of the instrument to be controlled but rather from a formal specification of it written in Signal Interpreted Petri Nets (SIPN).

Outlines an approach for applying model-checking to logic control algorithms in a way that is easy to understand and to apply by non-specialists. Non-specialists in this case means the designers of PLC programs (mostly control engineers and technicians) because they often have only restricted knowledge in computer science. A graphical design approach (based on signal interpreted Petri nets, SIPN) is used to generate a controller for a benchmark problem. This controller is then checked against a set of semi-verbally formulated properties, and improved to fulfill them. The combination of the graphical SIPN design approach and the semi-verbal specification language results in a very transparent and easy to apply approach to the design and verification of PLC software.

A detailed generic model of the control design process is introduced and discussed. It is used for surveying different formal approaches in the context of PLC programming. The survey focuses on formal methods for verification and validation (V&V). The varying works in this area are categorized using three criteria: the general approach (A) to the task (model based, constraint based or without a model), the formalism (F) (Petri net, automata, etc.,) used to state the formal description, and the method (M) (model-checking, reachability analysis, etc.,) used to analyze the properties. Based on these three criteria (A-F-M) a three letter code for V&V approaches is introduced. Some works from the multitude of V&V research are presented and categorized using this new system.

In the area of automatic control, more and more tasks formerly solved using special hardware are being solved using software. Hence, when discussing quality in automation, it is necessary to measure the quality of a software product. Software quality is a field of major interest for researchers and practitioners. However, in the area of control engineering, it is rarely studied. In previous publications the authors introduced the concept of transparency and defined corresponding metrics to measure the quality of logic controllers. In addition to these metrics, known complexity metrics from computer science are adapted to the area of logic control design and it is shown how the concepts of complexity and transparency are related. The metrics are introduced using the signal interpreted Petri net, but they are also valid for other Petri net types.

Interpreted Petri nets (IPN) are an extension of the basic Petri net (PN) framework. They are ordinary PN with additional components to model the information flow to and from the PN. This contribution gives a general overview of the control design process. Furthermore, it shows how the different tasks in this process, especially analysis, verification and validation, can be successfully solved within the formal IPN framework.

In this contribution we present the basic concepts of a senior course on logic process control based on Petri nets. This course is an introduction to basic design concepts and description formalisms of industrial logic control systems. It is mandatory for all students of electrical engineering specializing in the field of automation. One of the examples used throughout the course to illustrate the main concepts is presented. A discussion of the educational experiences is included.