Algorithmic Decomposition of Railway Objects for Distributed Interlocking System

The SCADA system applications in management of Yuvacik Dam and Reservoir

A railway interlocking system (RIS) plays a vital role in the safe transportation of a railway system. It is responsible for the safe routes of trains making sure that each train movement follows the other in a proper and safe sequence. Detailed verifications and evaluations are mandatory before deploying an RIS, since it is a safety critical system (SCS). But the increasing complexity of the RIS tends to limit the capability of the classic approval methods. As a result, the formalization of RIS becomes important to both the development of computer interlocking software and the third-party testing of the RIS facilities. Petri nets are a powerful formal tool that have been applied to many railway applications. Considering the large scale and the space complexity of interlocking systems, this paper introduces a feasible method for modeling the RIS by hierarchical colored Petri net (HCPN), which aim at providing a formal verification and logic evaluation of the French RIS. The paper describes how the signaling control logical and the railway road layout are specified and constructed into the HCPN. First, the architecture of RIS and the hierarchical structure of the model framework are introduced. Then, several basic RIS components are established as Petri nets to illustrate how to map RIS components into HCPN. As a case study, a section of a typical French station is modeled. It includes interlocking routes and signaling control principles. This paper takes place in the framework of the ANR project ‘PERFECT’. As this method has already received recognition from French railway experts, the future research contains consistency checking with some other parts of the specification, such as operation rules, which allows the authors to find out the crux of some existing problems and to discover some potential safety hazards.

Distributed control and optimization form the backbone of many critical control systems, with typical examples including sensor networks, power grids, and intelligent transportation systems. As these systems grow in scale and complexity, ensuring the privacy of individual agents becomes increasingly essential. Privacy protection is no longer an optional add-on; it is a crucial element in the design of these systems. Sensitive data, such as states, measurements, and decisions, must be shielded from unauthorized access or malicious attacks, while still allowing the system to function effectively. This special issue aims to explore novel techniques and strategies that protect privacy in distributed control and optimization, showcasing how these approaches can be seamlessly integrated into real-world applications. The diverse contributions in this issue demonstrate the growing importance of privacy in the evolving field of distributed control systems. RNC7747 introduces a privacy-preserving method for coverage control in multi-agent systems with limited communication ranges, ensuring efficient operation without compromising agents' privacy. RNC7798 proposes a privacy-preserving consensus mechanism based on pulse-coupled oscillators, helping maintain privacy while agents coordinate in distributed networks. RNC7778 presents privacy preservation techniques for cloud-based cooperative LQG control systems, enabling privacy protection even when leveraging cloud resources. RNC8051 discusses achieving privacy-preserving average consensus in unreliable network environments, ensuring privacy despite communication challenges. RNC7929 introduces a novel approach to open privacy-preserving consensus via state decomposition, allowing agents to reach consensus while maintaining privacy. RNC7966 investigates leader-follower consensus in multi-agent systems with distributed event-triggered observations, ensuring privacy during agent coordination in real-time systems. RNC7789 discusses the tradeoff between privacy protection strength and control performance in control systems. RNC8029 proposes a new privacy mechanism for distributed average consensus on time-varying directed graphs. RNC7776 investigates event-triggered distributed optimization with differential privacy, reducing communication costs while safeguarding sensitive data. RNC7885 develops an event-triggered privacy-preserving optimization method for directed communication networks, emphasizing privacy during optimization tasks. RNC7791 focuses on robust optimization for virtual power plant scheduling under uncertainty, incorporating privacy preservation into the optimization process. RNC7730 explores prescribed-time distributed optimization with set constraints, offering time guarantees while maintaining privacy in dynamic optimization scenarios. RNC7926 provides a privacy-preserving algorithm for constrained resource allocation with communication delays, crucial for real-time decision-making in distributed systems. RNC7848 presents an adaptive event-triggered control strategy for cyber-physical systems under DoS and deception attacks, ensuring privacy and system security. RNC8068 addresses initial state privacy in nonlinear systems on Riemannian manifolds, offering methods to protect privacy in complex, high-dimensional control systems. RNC7906 focuses on dynamic consensus-based formation control for multi-robot systems, preserving privacy through output masking techniques while achieving coordination. RNC7688 introduces a periodic dynamic encoding mechanism for stealthy attack detection in distributed state estimation, focusing on security and privacy under attack scenarios. RNC70033 tackles robust consensus Kalman filtering for distributed state-saturated systems, incorporating dynamic-disturbed saturation levels and censored measurements to ensure privacy under uncertain conditions. The contributions in this special issue span a broad spectrum of topics related to privacy in distributed control and optimization. As distributed systems continue to evolve, these papers contribute to the ongoing conversation about balancing privacy protection with efficient system operation, highlighting the importance of privacy as a key consideration in the design and optimization of future distributed control systems. The authors declare no conflicts of interest.

<abstract><p>Decision-making in a railway station regarding the compatibility of the positions of the switches of the turnouts and the indications (proceed/stop) of the railway colour light signals is a safety-critical issue that is considered very labor-intensive. Different authors have proposed alternative solutions to automate its supervision, which is performed by the so-called railway interlocking systems. The classic railway interlocking systems are route-based and their compatibility is predetermined (usually by human experts): only some chosen routes are simultaneously allowed. Some modern railway interlocking systems are geographical and make decisions on the fly, but are unsuitable if the station is very large and the number of trains is high. In this paper, we present a completely new algebraic model for decision-making in railway interlocking systems, based on other computer algebra techniques, that bypasses the disadvantages of the approaches mentioned above (its performance does not depend on the number of trains in the railway station and can be used in large railway stations). The main goal of this work is to provide a mathematical solution to the interlocking problems. We prove that our approach solves it in linear time. Although our approach is interesting from a theoretical perspective, it has a significant limitation: it can hardly be adopted in an actual interlocking implementation, mainly due to the heavy certification requirements for this kind of safety-critical application. Nevertheless, the results may be useful for simulations that do not require certification credit.</p></abstract>

Choosing the Event-B formal method to model and develop distributed railway interlocking systems can give us a great advantage over the general purpose programming languages, especially in case of the safety analysis of these systems. Despite its many benefits, Event-B suffers from an efficient reuse mechanism, which is highly disadvantageous in the development of large interlocking systems. In this paper we propose a structured approach to modelling and developing large geographical interlocking systems, combining the communication models of session types with the railway entity models of Event-B. This work combines Event-B with a component-based reuse strategy realized with session types and consists of an Event-B extension with communication primitives to enable communication between the railway entities, a projection of session type specifications and a verification mechanism for these specifications to ensure global safety by the local verification of entities.

Multi-Agent Model-Based Optimization for Future Electrical Grids

Railway interlocking systems take the role of managing train traffic by locking routes and are responsible for light signalling and switch positioning. Their correct operation is highly relevant for safety as they prevent trains from taking conflicting paths which could lead to severe accidents. In addition, as interlocking systems organise traffic at infrastructure nodes, their failure can have considerable negative impact on train delays and profitability.Electronic interlocking systems in Germany are isolated electrical systems. Insulation faults can cause safety-critical unintended interlocking behaviour and are responsible for a significant amount of interlocking-related delay minutes. The goal of the present research is to prevent system failures by early detecting abnormal behaviour of the insulation resistance and by localising elements related to incipient insulation faults.In Germany specific measurement devices continuously observe the insulation resistance of the entire electrical interlocking system. If the observed insulation resistance drops below a defined threshold an alarm is raised. As part of a research project and proof-of-concept, the monitoring device of the electronic interlocking at Plattling, Bavaria, has been equipped with an additional data logger to record the observed insulation resistance for a period of 18 months. Furthermore, status messages of the interlocking control system are available for a period of 20 days. Observed systematic influences on the insulation resistance such as weather conditions and interlocking operations are presented. Time-series modelling of insulation resistance as well as classification with regard to normal/abnormal behaviour based on weather condition and railway control notifications, respectively, give promising results.KeywordsRailway infrastructureElectronic interlockingCondition monitoringTime series modellingInsulation faults

Modelling and simulation of distributed time critical communication and control systems in vehicles or vehicle networks

Cybersecurity for industrial control systems: A survey

Industry 4.0 is the German vision for the future of manufacturing, where smart factories use information and communication technologies to digitise their processes to achieve improved quality, lower costs, and increased efficiency. It is likely to bring a massive change to the way control systems function today. Future distributed control systems are expected to have an increased connectivity to the Internet, in order to capitalize on new offers and research findings related to digitalization, such as cloud, big data, and machine learning. A key technology in the realization of distributed control systems is middleware, which is usually described as a reusable software layer between operating system and distributed applications. Various middleware technologies have been proposed to facilitate communication in industrial control systems and hide the heterogeneity amongst the subsystems, such as OPC UA, DDS, and RT-CORBA. These technologies can significantly simplify the system design and integration of devices despite their heterogeneity. However, each of these technologies has its own characteristics that may work better for particular applications. Selection of the best middleware for a specific application is a critical issue for system designers. In this paper, we conduct a survey on available standard middleware technologies, including OPC UA, DDS, and RT-CORBA, and show new trends for different industrial domains.

While networks of cooperating embedded devices are becoming more and more present in today's digital world, the development of software at process control and management levels must face the heterogeneity and dynamic of the components of these distributed systems. This paper presents a service oriented model that enhances interoperability between low-level devices and control level applications. This model has been applied to the development of a prototype application named FoxController that can be deployed on embedded systems and is compliant to the Devices Profile for Web Service (DPWS) specifications. FoxController simplifies the setting up of flexible and distributed data acquisition and control systems.

An open distributed control system (DCS), which consists of many devices and an open network interconnecting them, is now used in many automation areas. For assuring control performance under heavy traffic on the network, simulation of a DCS is required. For this purpose, we propose an object-oriented design pattern approach as a uniform, efficient and accurate method of modeling and simulating a DCS. Four design patterns are proposed. Device constructor and composite-device-constructor patterns describe classes and mechanisms for uniformly structuring device models composed of many kinds of sensors and actuators. A statechart pattern defines classes and the state-transition execution mechanism for realizing the behavior of sensors and actuators in a device. The event-chain pattern defines classes and the event dispatching mechanism among sensors and actuators in both an intra-device and inter-device manner. The systematic implementation procedures from these patterns to the executable Java code of the DCS simulation model are also discussed. Finally the effectiveness of our approach was proved by developing the Java-based DCS modeler and simulator used in building automation.

In this paper, we define an approach to Distributed Control Systems (DCS) that employs an Architecture Description Language to design and analyze agent based distributed control systems. The ADL is used as a Software Engineering method to simplify the complex task of calculating resource utilization of the distributed system. This approach is then applied to the problem of command and control of remote missile launchers in a battlefield. We use this example to provide compelling reasoning that ADL can analyze real-time distributed systems using the agent software model.

This papers introduces a current research on avionic distributed control systems, using smart components. The research focus on fuel management systems. The nearest experimental target is real flight testing into three years. For safety reasons the new distributed system has to react with pertinent reconfigurations when there are problems in the system, as detected by the smart components. Likewise, it is possible that the fuel plant changes, for instance when extra tanks are added, so the distributed control system has to reconfigure its functionality. The specific experimental platform for the research is an helicopter. The paper describes the control problem, the control distribution concept, the smart components, and the present research for reconfiguration.

This paper deals with multilevel control and optimization of a chiller system. The system consists of multiple chillers, feed pumps, and cooling towers. A multilevel control structure is presented. The first level contains control loops for chilled water temperature, vane position, and condenser water temperature. Second level controls provide supervisory adjustments of set points of first level controls. Third level is optimum load allocation of chillers and pumps. A fourth level supervisory deals with the coordination of conflicting goals of subsystems to provide a load strategy. Performance analysis (monitoring, trouble shooting) are also presented. A digital and distributed control system is utilized for implementation. The distributed system has a flexible architecture compatible for each level of control sophistication. It offers simple function blocks for digital control of first-level loops, as well as, the higher levels without any need of computer programming.