A formal modeling and verification approach for real-time system

Automatic train protection (ATP) system is a safety critical application for railway signaling with high logic complexity, and it is typically embedded and real-time demanded. As the computational complexity of ATP system, traditional software development method cannot accommodate effectively. In this paper, we propose a novel model-based development (MBD) scheme for ATP system. We argue that high quality software development in ATP system should not only rely on function design, but also on safety verification. A model-based development life cycle and verification approach are described. Furthermore, we present a case study, which is using the tool of SCADE suite. The approach can shorten the development period, enhance system safety, and meet challenges in safety critical software development.

Communication based Train Control(CBTC) system, the latest train control technology, has been widely applied throughout the world, because it has a number of advantages such as improved driving headway, reduction of the maintenance cost and so on. The technical core of CBTC is to ensure the safe space between trains through the real-time train tracking. Korean Radio-based Train Control System(KRTCS) has been developed as a Korean CBTC standard since 2010. KRTCS is comprised of Automatic Train Supervision(ATS), wayside/onboard Automatic Train Protection(ATP), onboard Automatic Train Operation(ATO), Electronic Interlocking(EI) and wayside equipment such as transponder tags, precision stop maker, communication network, etc. In the paper, we present system configuration of KRTCS and design and development scheme of Automatic Train Protection(ATP) communication interface for KRTCS. Communication between each component is performed using the protocol defined in the form of variable messages. Messages are divided into periodic or non-periodic messages. This study describes onboard and wayside ATP functional design and communication message and procedure for each function.

Railways are an energy-efficient mode of transportation. Even so, efforts are being made to attain even further energy savings. The latest train-car model of the Shinkansen bullet train, while achieving enriched functionality and improved performance, has attained a 49% energy reduction compared with the 0-series Shinkansen train-cars that debuted at the start of Shinkansen's operation. Also, in the underlying train control system, technologies that will lead to energy reduction have been developed. In order to achieve further energy savings and higher-performance train control, we are developing a new train control system known as Automatic Train Protection and Block System (sometimes referred to ATP-Block system here). This new control system produces a high energy-saving effect compared with conventional signal systems based on ground equipment. We believe that realization of low-cost, highly functional energy-saving Railways will bring back users of automobiles and airlines to Railways, contributing to global energy saving and helping to prevent environmental destruction.

The railway industry is an essential global logistics and passenger travel industry that is recognized for its efficiency and safety. However, the risks of accidents, derailments, and collisions on tracks remain a significant concern. Accidents can cause severe economic disruption. This study introduced a real-time and robust track-segmentation system for railway environments using computer vision and deep learning. The primary goal is to develop an advanced driver assistance system that provides real-time alerts to locomotive operators when obstacles are detected within designated regions of interest (ROIs). The research approach involves extracting a dynamic ROI in front of the locomotive’s track area, enabling a targeted and efficient analysis. Research focused on instance segmentation capabilities for precise track segmentation and ROI extraction. A specially curated dataset was created for the training and evaluation. This dataset is designed for railway track segmentation and categorized into four classes: ‘left minor, ‘right minor, ‘major, and ‘front minor, indicating different hazard levels. The dataset size and diversity were enhanced using data augmentation techniques. This study examines advanced algorithms using a custom dataset. It evaluates the performance and accuracy of the track segmentation. The ultimate goal was to determine the most suitable model for developing a reliable and fast-track segmentation system. This has enhanced the safety and efficiency of railways. This goal aligns with the Indian Railways’ modernization initiatives under the Gati Shakti Project, focusing on accident prevention through the deployment of Kavach, which is an Automatic Train Protection (ATP) that enhances train speeds.

Train Interface Unit (TIU) is the key execution unit of on board Automatic Train Protection (ATP) system. ATP system achieves the control of the train and information exchange with the train via TIU. Developing a TIU which fits for different train platform and is in compliance with the safety integrity level (SIL) 4 can greatly facilitate the system installation and lower operation and maintenance cost. This thesis has designed a TIU for a series of standard train platform. Based on the system design, four key technologies of TIU, include relay and Multifunction Vehicle Bus (MVB) interface, safety communication, emergency brake (EB) interface and service brake (SB) interface, are in-depth in anatomist. Through the thorough analysis and evaluation of the safety and real-time performance, we can get the conclusion that the TIU sub-system meets the requirements of the practical use.

A description is presented of an expert system called ADES (ATP design expert system) for the design of automatic train-protection (ATP) systems. (An ATP system is a railway signaling system consisting of a set of logic circuits that control the safe movements of trains within a railway station.) Artificial intelligence techniques proved feasible to address this particular design problem, and ADES, which uses artificial intelligence techniques, makes it possible to design good control circuits to meet operational requirements rapidly by using well-structured, explicitly represented knowledge on ATP. ADES' inference engine works as a partial evaluator for the knowledge representation language KARL which is used to write design rules. Since every circuit produced by the expert system is still expressed in KARL, the KARL interpreter has also been used as a simulator for a designed circuit. Prototypes of the inference engine and the KARL interpreter have been implemented as extended Prolog metainterpreters. >

Automatic train protection (ATP) is an important equipment with a safety requirement of SIL 4 for Chinese Train Control System, whose safety is usually guaranteed by testing. Test cases generation method is an important basis and research focus of ATP. Taking Petri Net as the modelling tool, a test cases generation method of ATP is proposed. First, according to the technical specification, performing a fault mode analysis, ATP Petri Net testing model is established. Then, the test cases are generated automatically by searching the reachability tree of the testing model. Finally, taking the SOM function of ATP as an example, testing model is established and test cases are generated. By comparing the test cases generated by this method and the existing test cases, the correctness and effectiveness of this method is verified.

Requirements-based testing is one of the most commonly used ways to ensure the correctness of software, especially for embedded control software in safety-critical domains such as spacecraft and railway systems. Many industrial standards such as the DO-333 and EN50128 also request rigorous requirements-based software testing. To test embedded control software effectively and efficiently, generating high-quality test cases automatically is extremely important. However, existing methods for generating test cases from requirements require intensive manual efforts and expertise. To address this problem, we proposed an automatic requirements-based software testing method for embedded control software. To obtain automatic test case generation and precise test oracles derivation, requirements specification should be precise and readable for the industrial practitioners. Therefore, we use the light-weight domain-specific formal description language, CASDL (Casco Accurate Specification Description Language) for the industrial practitioners to define software requirements into formal specifications at the first step. Based on the formal specification, we propose an algorithm to automatically generate test inputs that satisfy the MC/DC criteria suggested by typical industrial standards and precise test oracles can be derived by "running" the specification with such test inputs. To this end, we proposed an algorithm for simulating the formal specification to generate the test oracles, i.e., the expected outputs corresponding to the test inputs. To facilitate the application of this method in the industry, we have built a tool that can automatically perform the overall testing process. To validate and evaluate its effectiveness in real industrial projects, we have applied it in testing a real Automatic Train Protection (ATP) system provided by our industrial partner, the Casco Signal Co., Ltd (one of the largest railway control system companies in China). In the case study on ATP requirements, our approach generated test cases for 129 requirement items following MC/DC criteria and caught 40 inconsistencies between Casco's requirements and implementation.

RFM module is widely used for the classification of customer value. The classification results based on big data are often used as portrait of customer loyalty and customer value evaluation. In this paper, RFM model is introduced innovatively to analyse the fault of on board ATP (Automatic Train Protection) system. Through the fault value classification, it can effectively predict the impact of a certain type of fault on operation. For one thing, the operation departments and equipment providers can pre-process the corresponding failures according to the evaluation results, so as to reduce operational losses. For another thing, it can be used as the basis for dealing with big data of ATP faults.

Automatic train protection (ATP) system of urban railway transit is very important for safe operation, where the effective transmission of train control information is the most significant factor. In the research of nationalization for the ATP system, carried out by the Ministry of Constructions and Ministry of Railways of China, the frequency shift keying (FSK) approach is adopted to modulate the train control information, as it does not need to estimate the phase of the carrier wave. This paper introduces a computer simulation method of FSK, and solves some of the key techniques, such as how to make the FSK simulation into a real-time system with continuous phase as well as dynamically changed the codes and frequencies of FSK. The computer simulated FSK was implemented in an ATP simulation system and was shown to be effective.

It is an effective way to enhance the safety of train control system by using safety redundant architectures.This paper consider the typical safety redundant architectures, including double hot standby, 2-out-of-2, 2*2-out-of-2, and 2-out-of-3, establishes models for these architectures by Markov chain.Then the safety of different architectures are simulated using Matlab.The simulation results can provide a certain reference when choosing redundant architectures in real engineering.

GSM-Railways (GSM-R) is the current standard for railway voice and data communication. GSM-R provides railway specific voice services, such as Railway Emergency Call (REC). GSM-R provides also the European Train Control System (ETCS), which offers in-cab signaling and Automatic Train Protection (ATP). Despite these features and services, GSM-R has various major shortcomings. Therefore, alternative technologies are considered to replace GSM-R and become the next generation railway mobile communication network. 3GPP Long Term Evolution (LTE) is a likely candidate for GSM-R replacement. LTE is more efficient, flexible and offers much higher capacity, which allows the railway network to provide new communication-based applications for railways. Most of the research on LTE in railways has been focused on data-based railway applications (ETCS signaling and other). Nevertheless, voice communication is still a crucial service for railways. Regardless of its advantages, LTE can only become a railway communication technology if it provides voice communication fulfilling railway requirements. This paper presents how Voice over LTE (VoLTE) can be used to build railway communication services. Examples of Railway Emergency Call and One-to-One Call are provided. Service performance, in terms of call setup times and voice transmission quality, is analyzed in simulation scenarios modelling two railway scenarios in Denmark.

Global System for Mobile Communications-Railway (GSM-R) is the current standard for railway voice and data communication. It provides railway-specific voice services, such as railway emergency calls (RECs), as well as the European Train Control System (ETCS), which offers in-cab signaling and automatic train protection. Despite these features and services, GSM-R has major shortcomings. Therefore, alternative technologies are being considered to replace GSM-R and become the next-generation railway mobile communication network.

The task of checking if a computer system satisfies its timing specifications is extremely important. These systems are often used in critical applications where failure to meet a deadline can have serious or even fatal consequences. This paper presents an efficient method for performing this verification task. In the proposed method a real-time system is modeled by a state-transition graph represented by binary decision diagrams. Efficient symbolic algorithms exhaustively explore the state space to determine whether the system satisfies a given specification. In addition, our approach computes quantitative timing information such as minimum and maximum time delays between given events. These results provide insight into the behavior of the system and assist in the determination of its temporal correctness. The technique evaluates how well the system works or how seriously it fails, as opposed to only whether it works or not. Based on these techniques a verification tool called Verus has been constructed. It has been used in the verification of several industrial real-time systems such as the robotics system described below. This demonstrates that the method proposed is efficient enough to be used in real-world designs. The examples verified show how the information produced can assist in designing more efficient and reliable real-time systems.

A new tool for integrating formal methods, particularly model checking, in the development process of component-based real-time systems specified in UML is proposed. The described tool, TANGRAM (Tool for Analysis of Diagrams), performs automatic translation from UML diagrams into timed automata, which can be verified by the UPPAAL model checker. We focus on the CORBA Component Model. We demonstrate the overall process of our approach, from system design to verification, using a simple but real application, used in train control systems. Also, a more complex case study regarding train control systems is described.