ISO 26262 — Functional Safety (Road Vehicles)
How ISO 26262 functional safety concepts are supported in NexoGraph.
ISO 26262 (Road vehicles — Functional safety) is the international standard for functional safety of electrical and electronic systems in road vehicles. It covers the complete safety lifecycle from concept through decommissioning and applies to all vehicle categories.
NexoGraph supports ISO 26262 by providing the traceability infrastructure required to demonstrate a complete, consistent safety case from hazard to verified safety requirement.
Core Concepts
| Concept | Definition |
|---|---|
| Item | System or combination of systems that implements a function at the vehicle level |
| Hazard | Potential source of harm caused by malfunctioning behaviour of the item |
| Risk | Combination of probability of occurrence of harm and severity of that harm |
| Safety Goal | Top-level safety requirement derived from hazard analysis |
| ASIL | Automotive Safety Integrity Level — A (lowest) through D (highest), plus QM |
| Functional Safety Requirement (FSR) | Safety requirement at the functional level, allocated to the item |
| Technical Safety Requirement (TSR) | Safety requirement at the technical level, allocated to system elements |
HARA — Hazard Analysis and Risk Assessment
The HARA process classifies hazards by severity (S0–S3), exposure (E0–E4), and controllability (C0–C3) to derive the ASIL for each safety goal.
NexoGraph Alignment
| ISO 26262 artefact | NexoGraph approach |
|---|---|
| Safety Goal | Requirement entity with isSafetyGoal: true attribute; ASIL stored as a field |
| Functional Safety Requirement | Requirement entity; reference relation to parent Safety Goal for traceability |
| Technical Safety Requirement | Requirement entity allocated to a subsystem Package |
| Item | Top-level Package representing the system under development |
| ASIL allocation | Attribute on Requirement; propagated through decomposition relations |
Traceability Chain
NexoGraph's reference relations enforce the traceability chain required by ISO 26262 Part 4 (§8):
StakeholderNeed → Safety Goal (Requirement) → FSR (Requirement) → TSR (Requirement)Every safety requirement can be traced back to its originating hazard-derived safety goal, satisfying the standard's bidirectional traceability obligation.
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