Detecting a person in the workspace requires immediate slowing or stopping

What it is

A protective response to workspace intrusion makes the robot enter validated restricted motion or a protective stop once a person crosses a risk-assessed boundary, before hazardous contact becomes possible. “Immediate” means deterministic enough for the stopping-distance budget; it does not always mean removing power.

Why it happens

After a crossing, remaining margin is the separation minus travel during sensing, logic, drive, and mechanical braking. A response later than this chain cannot be rescued by a prominent warning. Slowing is valid only where residual speed, effective mass, pinch points, and payload have all been shown acceptable; otherwise motion or hazardous energy must be stopped.

Studying it

Entry speed and direction, robot pose, payload, occlusion, and brake condition can vary while measuring boundary-to-safe-output latency, actual stop distance, minimum separation, misses, and near misses. Independent instruments should be time-aligned with controller logs, including single sensing or actuation faults. Unvalidated extremes use test bodies, not exposed participants.

Where it stops holding

This response addresses detectable entry, not blind spots, ejected parts, stored-energy release, or a person already inside at startup. Collaborative operation may permit proximity under defined conditions, not unrestricted continued motion. Emergency stop is complementary and cannot replace automatic safeguarding.

Applying it

• Compute the boundary from the worst entry direction and complete stopping chain, including perception, control, and braking delay.
• Define when each zone permits restricted motion, controlled stop, or energy isolation; loss of protective sensing must lead safe.
• Test maximum payload, weakest braking, occlusion, and oblique entry, verifying that the hazard cannot be reached before the protective response.

Related

• Same group: X5.05.2 Response must distinguish accidental intrusion from authorized collaborative entry · X5.05.3 Normal speed must resume only after confirming that the person has fully left or is safely separated · X5.05.4 Frequent false stops encourage operators to bypass safeguards
• Adjacent: X5.01 Physical safety boundaries · X5.03 Emergency stop
• Search terms: protective stop · safeguarded space · stopping distance