ISO 26262-compliant safety concept design tool using SCDL

  • Target Industries : Mainly automotive industry
  • Target Category : Functional Safety Design Division

ISO 26262-compliant safety concept design tool using SCDL

"Safilia" is a modeling tool for design safety concepts and facilitate information sharing between designers and developers. The Safety Concept Description Language (SCDL) is based on specifications and standards developed by the Safety Concept Notation Study Group SCN-SG. Safety concepts are described in block diagrams to improve mutual understanding and easy information sharing.

Safilia benefits and use-cases

Safilia is expected to be used during the design phase of the V process, by product designers creating safety concepts, using a standardized notation to share safety concepts accross departments and organizations. If a defect is found during a safety assessment after the completion of the prototype model (because of poor communication of the design or its purpose), this can lead to a re-design or a change in specifications and cause a big setback in the schedule. Safilia enables early creation and assessment of safety designs based on a standardized notation, in order to prevent such cases.
  • Feature 1
    Current issues with safety design
    The introduction of the automotive functional safety standard ISO 26262 has raised safety design issues. One of these is that the safety concepts from the system designers is not properly conveyed. For example, the safety design task sharing between multiple systems, and the lack of mutual understanding of the safety design between OEMs and suppliers, or between hardware and software engineers, greatly affect the development schedule and the completeness and readability of the safety design. The biggest challenge in realizing this "safety concept" is the "description method."
  • Feature 2
    Safety Concept
    Safety concepts are one of the key results of the design phase, and are required by ISO 26262. THe forn the base of the Safety Architecture of a system. Designing them is the biggest challenge found in the automotive industry's efforts to comply with standards. Many issues arise during the decomposition and the co-dependance analysis of safety requirements, and it is necessary to design and communicate these "safety concepts" correctly.
  • Feature 3
    "Safilia," a tool to design safety concepts
    Safilia is a modeling tool to design safety concepts and facilitates information-sharing between designers and developers. Safety concept are written in block diagrams within the Safilia editor. This graphical language helps sharing the safety designs and avoid misunderstandings. This tool is developed by Change Vision Co., Ltd., and is promoted and sold by GAIO Technology Co., Ltd.

Safilia's concept description language

  • Function 01

    Requirement Architecture notation

    • Describe hierarchical relationships and interactions between safety requirements (SRs), as well as the redundancy and independence requirements between requirements (or requirement groups).
  • Function 02

    Element Architecture notation

    • Define and describe the inclusion relationship of elements (EL). The nested structure of the elements is represented by inclusive diagrams, which is the basis for visualizing the safety requirements assignment and ASIL scopes.
  • Function 03

    Assignement of safety requirements (SR) to elements (EL)

    • By overlaying the requirement architecture and element architecture on the same diagram, the assignement of the safety requirements (SR) to elements (EL) can be described intuitively, also showing the ASIL for the each element. ASIL mapping is optimized so that an element is assigned the highest ASIL of its safety requirements.
  • Function 04

    Decomposition notation

    • Describe the decomposition of safety requirements (SR) and their pairing into groups. Independence requirements, the grouping of safety requirements, and their pairing can all be graphically described.
  • Function 05

    FFI (Freedom From Interference) Notation

    • Describe the statement that two functions of different safety level can not interfere with each other. Safilia includes features to show that a safety requirement will not violated, or that the non-interference relationship is guaranteed.
  • Function 06

    Interface specification definition

    • This feature is used to identify places where inter-requirement interactions cross Element boundaries and to examine the interface. Specifications defined in an external file can be linked to an Interface, and a list of all Interfaces is available.
  • Function 07

    Safety analysis feature

    • Combine SCDL diagrams and tables to perform the safety analyses efficiently and according to the standard's intended purposes.
  • Function 08

    [New Feature] Failure-related modeling

    • In Safilia Designer, we modeled the relationship between failures for easier visualization of which failures to take safety measures against. This enables the linking of failures and their related requirements.
      In addition, chains of dependant failures can now be displayed graphically by importing FMEA data created during earlier safety analysis.
      Based on the existing safety analysis results (FMEA), it is possible to show a failure chain in SCDL, explain the safety analysis results, select the candidate safety mechanism, and confirm that the failure is not transmitted.
  • Function 09

    [New Feature] SysML linking feature

    • With Safilia Integrator, existing system designs can be reused to create safety concept diagrams or to reflect the results of safety design/safety analyses into the system design.
      In Safilia R5, GUI usability for the SysML linking have been drastically improved for shorter SysML<->SCDL conversion times.
  • Function 010

    [New Features] Guide word feature

    • In Safilia Designer, a check for missing guide words can be run to prevent analysis omissions and identify potential SG-related malfunctions.
      HAZOP or custom guide words are searched for, and any missing is highlighted on the SCDL diagrams.

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