Glossary · Stopping functions and safe states
Stopping distance
In machine safety, stopping distance is the distance traveled by hazardous motion after initiation of a stop. It depends on speed, load, braking and the condition of the machine.
- Machine safety
- Risk assessment
In one sentence
Stopping distance is how far hazardous motion continues after a stop is initiated, a key input for AGV fields and safety distances.
Example
An AGV carrying a full pallet needs 1.2 m to stop from full speed on a dry floor; the warning and protective fields of its safety laser scanner are sized from that value plus margins.
How it applies
- Machine safety: For mobile machines and linear axes, stopping distance sets the size of protective fields, for example for a safety laser scanner. Use worst-case conditions: maximum load, speed and brake wear.
- Integrated systems: Stopping distance changes when speed parameters, payload or floor conditions change. Treat those parameters as safety-relevant configuration.
- Technical documentation: State the conditions under which the stopping distance was determined and the conditions that invalidate it, such as wet floors or heavier loads.
- Evidence: Measure it at commissioning and in periodic verification, and keep the results with the calculation.
Stopping distance vs. stopping time
Stopping time is the elapsed time until motion ceases; stopping distance is the path covered in that time. ISO 13855 calculations use time, while protective fields for moving machines are often sized by distance.