https://www.mdu.se/

Automation is gaining importance in many domains, such as vehicle platoons, smart manufacturing, smart cities, and defense applications. However, the automated system must guarantee safe operation in any critical situation without humans in the loop as a fall-back solution. Additionally, autonomy can cause new types of hazards that need to be identified and analyzed.This paper studies cases from the transportation domain where autonomous vehicles are integrated into workflows in an open-surface mine for efficient material  transportation. In this application many individual systems collaborate to form a system-of-system (SoS) to achieve the mission goals. The complexity of such an SoSand the dependencies between the constituent systems complicate the safety analysis. In an SoS there exist several causes leading to new emergent hazards, failure of identification of which could lead to catastrophes.

In this paper, we describe an SoS-centric process called 'SafeSoS', capable of identifying emergent hazards, through  structuring the complex characteristics of an SoS  on three hierarchical levels to enable better comprehension and analysis. We describe the process in detail and apply the process to an industrial transportation system from the earth-moving machinery domain.As part of the SafeSoS process, we utilize model-based formalisms to describe the characteristics of the application and the constituent systems, which form the input for analyzing the safety of the resulting SoS.We apply the safety analysis methods HiSoS, SMM, FTA, FMEA and Hazop to the industrial SoS with the purpose to identify emergent hazards. As a result of our work, we show how to identify and analyze emergent hazards by the help of our SafeSoS approach. 

Safety-critical systems may fail dangerously with severe consequences to the health of the involved humans, costly equipment, the environment, or other valuable assets of a stakeholder. For these classes of systems, the developers are obliged to analyze each potentially hazardous situation thoroughly. In addition, any identified hazardous situation needs to be considered for risk reduction measures, including adjustments of the system's design, additional safeguards if the hazards cannot entirely be removed by design, or warning information to users.  

An essential activity in the development process is the safety analysis, where hazards related to the system under development are identified, and the risks are evaluated and classified. This classification stipulates the rigor of complying with safety standard requirements and directing the development and verification activities. Several techniques for safety analysis have been identified in the literature and are applied in industrial development processes.

The technical evolution enables moving from developing single systems with specific features towards attaching several independent systems to a system-of-systems.On top of the trend towards connectedness, there is also a trend towards more and more automation. In the vehicle domain, autonomous vehicles can collaborate to achieve specific goals, like transporting goods in warehouses, transporting containers in automated ports, or transporting material in off-road environments.

Autonomy brings in new challenges when ensuring product safety and functional safety for single systems due to the lack of a human operator as a fallback solution.Further, when autonomous vehicles collaborate in a fleet, the safety analysis becomes more complex since their interaction and interoperability bring forth new hazards not identifiable with a safety analysis of a single system. Our research aims to bridge this gap and provide solutions for specifying a system-of-systems and finding and developing suitable safety analysis methods.

To understand the challenges and current practices, we have studied industrial projects where systems-of-systems are developed. We have applied safety analysis methods to our industrial cases and found limitations of finding hazards related to a system-of-systems. As part of our research, we have developed extensions to the safety analysis methods to support the analysis of a system-of-systems. We have developed the Safe System-of-Systems (SafeSoS) method which is a structured and hierarchical process to discover and document a system-of-systems characteristics on three primary abstraction levels. Additionally, we utilize model-based formalism to describe the System-of-Systems’ characteristics on each level. Our research results support engineers in the industry when designing a safety-critical system-of-systems.

Safety-critical systems may fail dangerously with severe consequences to the health of the involved humans, costly equipment, the environment, or other valuable assets of a stakeholder. For these classes of systems, the developers are obliged to analyze each potentially hazardous situation thoroughly. In addition, any identified hazardous situation needs to be considered for risk reduction measures, including adjustments of the system's design, additional safeguards if the hazards cannot entirely be removed by design, or warning information to users.  An essential activity in the development process is the safety analysis, where hazards related to the system under development are identified, and the risks are evaluated and classified. This classification stipulates the rigor of complying with safety standard requirements and directing the development and verification activities. Several techniques for safety analysis have been identified in the literature and are applied in industrial development processes.The technical evolution enables moving from developing single systems with specific features towards attaching several independent systems to a system-of-systems.On top of the trend towards connectedness, there is also a trend towards more and more automation. In the vehicle domain, autonomous vehicles can collaborate to achieve specific goals, like transporting goods in warehouses, transporting containers in automated ports, or transporting material in off-road environments.Autonomy brings in new challenges when ensuring product safety and functional safety for single systems due to the lack of a human operator as a fallback solution.Further, when autonomous vehicles collaborate in a fleet, the safety analysis becomes more complex since their interaction and interoperability bring forth new hazards not identifiable with a safety analysis of a single system. Our research aims to bridge this gap and provide solutions for specifying a system-of-systems and finding and developing suitable safety analysis methods.To understand the challenges and current practices, we have studied industrial projects where systems-of-systems are developed. We have applied safety analysis methods to our industrial cases and found limitations of finding hazards related to a system-of-systems. As part of our research, we have developed extensions to the safety analysis methods to support the analysis of a system-of-systems. We have developed the Safe System-of-Systems (SafeSoS) method which is a structured and hierarchical process to discover and document a system-of-systems characteristics on three primary abstraction levels. Additionally, we utilize model-based formalism to describe the System-of-Systems’ characteristics on each level. Our research results support engineers in the industry when designing a safety-critical system-of-systems.

Autonomous vehicles grow importance in many domains and depending on the domain and user needs, autonomous vehicles can be designed as stand-alone solutions as in the automotive domain or as part of a fleet with a specific purpose as in the earth moving machinery domain. Contemporary hazard analysis methods primarily focus on analyzing hazards for single systems. Such an analysis requires knowledge about typical usage of a product, and it is evaluated among others if an operator is able to handle a critical situation. Each hazard analysis method requires specific information as input in order to conduct the method. However, for system-of-systems it is not yet clear how to analyze hazards and provide the required information. In this paper we describe a use case from the earth moving machinery domain where autonomous machines collaborate as a system-of-systems to achieve the mission. We propose a hierarchical process to document a system-of-systems and propose the use of model-based development methods. In this work we discuss how to utilize the provided details in a hazard analysis. Our approach helps to design a complex system-of-systems and supports hazard analysis in a more effective and efficient manner.

In this paper we present AdaptiveFlow as a platform for designing system of systems. A model-based development approach is proposed and tools are provided for formal verification and performance evaluation. The actor-based language, Timed Rebeca, is used for modelling, and the model checking tool Afra is used for checking the safety properties and also for performance evaluation. We investigate the efficiency of our approach and the applicability of the developed platform by conducting experiments on a case study based on the Electric Site Research Project of Volvo Construction Equipment. In this project, a fleet of autonomous haulers is utilised to transport materials in a quarry site. We used three adaptive policies as plugins to our platform and examined these policies in different scenarios.

Product lines in industry are often based on an engineer’s focus on fast and feasible product instantiation rather than a precise product line development method and process as described in literature. When considering functional safety, we need a precise model that includes evidence for the safety of each variant of the product.Functional safety standards provide guidance to develop safety critical products and require that evidence is collected to prove the safety of the product. But today’s functional safety standards do not provide guidance on how to achieve functional safety in product lines. At the same time arguments need to be collected during development so that each product configuration is safe and is fulfilling the requirements of the standards. Providing these arguments requires tracing safety-related requirements and dependencies through the development process taking the impact of variability in different development artifacts into consideration.

In this thesis, we study the challenges of developing safety critical products in product lines. We explore industrial practices to achieve functional safety standard compliance in product lines by interviewing practitioners from different companies and by collecting the reported challenges and practices. This information helps us to identify improvement areas and we derive requirements that a product line engineering method needs to fulfill. Based on these findings we analyze variability management methods from the software product line engineering research domain to identify potential candidate solutions that can be adapted to support safety critical products. We provide an approach for capturing functional safety related characteristics in a model-based product line engineering method. We apply our method in an industrial case demonstrating the applicability.

Produktlinjer inom industrin är oftast baserade på ingenjörernas vilja att snabbt och enkelt utveckla nya varianter, snarare än på någon precis utvecklingsmodell för produktlinjer beskriven i litteraturen. För att visa på funktionssäkerhet krävs en precis modell som innehåller argumenten för att påvisa säkerheten hos alla varianter av produkten. Funktionssäkerhetsstandarder ger en vägledning för att utveckla säkerhetskritiska produkter och kräver att belägg samlas för att bevisa produktens säkerhet. Men dagens funktionssäkerhetsstandarder beskriver inte hur man uppnå funktionssäkerhet i produkt linjer. Argument behöver samlas under utveckling som bevisar att varje produktkonfiguration är säker och uppfyller kraven i standarden. Detta kräver i sin tur att spåra beroenden till säkerhetsrelaterade krav genom utvecklingsprocessen och visa hur de påverkas av variabilitet. I denna avhandling studerar vi utmaningarna med att utveckla säkerhetskritiska produkter i produktlinjer. Vi undersöker industrins metoder för att uppnå funktionssäkerhet genom att intervjua experter från olika företag och sammanställa utmaningar och praxis. Denna information hjälper oss att identifiera förbättringsområden och vi beskriver de krav som en tilltänkt produktlinjeteknik måste uppfylla. Baserat på dessa resultat vi analyserar varianthanteringsmetoder som beskrivs inom området produktlinjemetoder (eng: product line engineering), för att identifiera potentiella kandidatlösningar vilka kunde anpassas för att stödja säkerhetskritiska produkter. Vi presenterar en metod för att hantera funktionssäkerhetsrelaterade egenskaper i en modellbaserad metod för att hantera produktlinjer. Vi tillämpar vår metod i ett industriellt fall för att demonstrera tillämpligheten.

Today's industrial product lines in the automotive and construction equipment domain face the challenge to show functional safety standard compliance and argue for the absence of failures for all derived product variants. The product line approaches are not su cient to support practitioners to trace safety-related characteristics through development. We aim to provide aid in creating a safety case for a certain con guration in a product line such that overall less e ort is necessary for each con guration. In this paper we 1) discuss the impact of functional safety on product line development, 2) propose a model-based approach to capture safety-related characteristics during concept phase for product lines and 3) analyze the usefulness of our proposal.

Reuse of already developed parts and concepts is a common approach in industry to reduce the time to market and reduce the development efforts. Industrial product lines are often grown over time and structured approaches to support decision-making and manage the complexity are lacking. When developing safety-critical products through product lines, evidence must be provided for all possible product configurations. The lack of a structured product line approach taking the functional safety dimension into consideration makes it challenging for practitioners to provide the required evidence. In this paper we (1) identify requirements that a variability management approach will need to fulfill, (2) discuss existing approaches and their limitations, (3) propose potential extension, (4) apply our approach in an industrial use case and (5) discuss its applicability and future work.

Developing safety critical products demands a clear safety argumentation for each product in spite of whether it has been derived from a product line or not. The functional safety standards do not explain how to develop safety critical products in product lines, and the product line concept is lacking specific approaches to develop safety critical products. Nonetheless, product lines are well-established concepts even in companies developing safety critical products. In this paper we present the results of an exploratory study interviewing 15 practitioners from 6 different companies. We identify typical challenges and approaches from industry and discuss their suitability. The challenges and approaches brought out by this study help us to identify and enhance applicable methods from the product line engineering domain that can meet the challenges in the safety critical domain as well.