Functional Safety

Relying on automated protective functions to bring equipment to a safe state after a fault, with the reliability of that response quantified.

Functional safety is the part of overall safety that depends on automated protective functions acting correctly — for example, emergency stop, safe torque off, and speed monitoring. Its overarching standard is IEC 61508 (first edition 1998–2000, second edition 2010), which expresses reliability with Safety Integrity Levels SIL 1–4 — the higher the level, the lower the allowed probability of dangerous failure; the machinery-specific IEC 62061 and automotive ISO 26262 both derive from it. Robotics more often cites ISO 13849-1 (currently the 2023 fourth edition), expressed with Performance Levels PL a–e and architecture Categories B, 1–4, where Categories 3 and 4 require redundant channels. The process runs hazard analysis → set a target level for each safety function → prove that level is met through redundancy, self-diagnosis, and verification. It's about whether hardware and the control system reliably stop when something goes wrong — a different concern from embodied safety, which is about a large model ‘doing the wrong thing.’

ExampleMany collaborative arms design their emergency-stop and protective-stop functions to ISO 13849-1's PL d, Category 3: two independent channels cross-check each other, and either channel failing can still cut motor torque.

Related

Emergency Stop · Protective Stop · Safe Torque Off (STO) · ISO 13849 Performance Level (PL a–e, Category B–4) / Safety Integrity Level (SIL, IEC 62061/61508) · ISO 10218-1/-2:2025 Robotics — Safety Requirements · Embodied Safety

Sources

Wikipedia: Functional safety
Wikipedia: IEC 61508
Wikipedia: ISO 13849

As of

2023