Emergency Stop Requirements in a Robot Cell
What an emergency stop must do
An emergency stop is a complementary protective measure: it stops a hazardous process, it is initiated by a single human action, and it must not create a new hazard. It is not a substitute for guarding, and not a normal production stop.
| Requirement | Detail | Common error |
|---|---|---|
| Action | One action, clearly identifiable | Multiple steps or hidden button |
| Reset | Manual reset, no automatic restart | Auto-restart after release |
| Stopping category | Defined by the risk assessment | Category assumed, not analysed |
| Coverage | Every operator position and access | Only the main panel has one |
Stop category and power
Category 0 removes power immediately; category 1 stops under control then removes power. The choice depends on the mechanics: an axis that can fall or lose position may need a controlled stop before power removal. Document which category applies to which drive, and why.
Test and record
Test each emergency stop device during commissioning, after any change to the safety circuit, and at a defined interval afterwards. Record the measured stopping time for each device, because that value feeds the separation distance calculations for scanners and mats.