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Safilia : ISO26262 edition, SCDL safety concept design tool

Safety concept modeling tool for ISO26262
Based on Safety Concept Description Language (SCDL)
Graphical block diagramming feature
Clearly share safety concept information between designers and developers


Overview

"Safilia" is a tool to assist Safety Concept Design using the Safety Concept Design Language (SCDL). It follows the specifications and standards decided by the Safety Concept Notation Study Group (SCN-SG), which oversees the development of SCDL and promotes its diffusion.

Safety Design - Current Challenges

With the introduction of automotive functional safety standard ISO26262, challenges related to safety design are increasing. One such challenge is that the safety concept designed by the safety designer is not being accurately conveyed to other team members. This can, for example, have a significant impact on the safety design's division of roles across multiple systems and between OEM and suppliers, the lack of mutual understanding of the safety design between hardware/software engineers, the development efficiency and safety design completeness and the objective description of the safety design. Thus, the "notation" when implementing the "safety concept" has become a major challenge.

The Safety Concept

The safety concept is an important design artifact for ISO26262, and is equivalent to the safety architecture design concept. This design is a major challenge for safety regulation conformity within the automotive industry. With frequent design problems being detected during decomposition of the safety requirements and co-analysis, correctly designing the safety concept and obtaining a mutual understanding is a necessity.

Safilia: the Tool to Support Safety Concept Design

Safilia is a modelling tool to support the design of the safety concept, and promote the sharing of safety design information between designers and developers. With the tool's editor, block diagrams are used to describe the safety concept. In this way the safety concept can be shared to reach a common consensus between teams. Safilia is developed by Change Vision CO., LTD. and marketed by GAIO TECHNOLOGY CO., LTD.

Safilia: Use Phase and Effect

It is assumed that Safilia will be used at the design phase of the V-model development process when designing the safety concept. The objective is to share the safety concept within the organization or department using a unified notation. Prototype models designed without sufficient information sharing of the safety concept can lead to safety defects being detected, resulting in a large amount of rework due to having to return and make changes to the specifications and design. By using Safilia, it is possible to establish and evaluate the safety design at the early stages using a standardized notation, thereby avoiding rework related losses.

Safilia: Description Features

[First Version]

Requirement Architecture
Element Architecture
Safety Requirement to Element Arrangement
Decomposition
Freedom From Interference (FFI)
Interface

[Future Updates]

Analysis
Software Layer Architecture
State transition connector/condition branch connector definition

Requirement Architecture

The requirement architecture describes the hierarchical relationship and mutual relationship between safety requirements. The interaction between safety requirements, redundancy relationship between requirements (groups) and independence requirements are specified.

Safety requirement diagram, layer definition
(Japanese version)

Definition of interactions between requirements
(Japanese version)

Element Architecture

The element architecture describes the inclusive relation of the elements. It represents the element's nested structure by inclusive diagram, and is a foundation on which to visualize the safety requirements placement and ASIL spread range.


(Japanese version)

Safety Requirement to Element Arrangement

By merging the display of the Requirement Architecture and Element Architecture, it is possible to describe the arrangement of the safety requirement to the elements. Here, the mapping of the ASIL for each element will be described. Safilia includes an ASIL optimization feature for ASIL mapping that will automatically the assign safety requirement's ASIL to elements. If safety requirements with different ASIL are arranged to an element, the highest ASIL will be automatically assigned to the element.


(Japanese version)

Decomposition

Describe the safety requirement decomposition and the the group combination. Use this feature to describe items such as the safety requirements group, the independence requirements and the safety requirement group combination.


(Japanese version)

Freedom From Interference

When integrating features with different safety related levels, it is necessary to demonstrate that there is no interference between them. Features are included such as drawing relationship lines to indicate there are no violations with safety requirements and that the features are free from interference.


(Japanese version)

Interface

Indicate locations where interactions between requirements cross over element boundary lines in order to examine the interface. Associate the interface to external files where the specifications are defined. Also, it is possible to display the interface in a table.


(Japanese version)


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