Doosan Cobot — Collision Stop & Safety Recovery

Doosan · beginner · 20 min

When a Doosan cobot detects a collision it does a Floating Reaction then a Safe Operating Stop. Clear the obstruction, recover, and if it keeps tripping, review the collision sensitivity and stop mode.

ℹ️ A collision stop is the cobot protecting people and parts. On collision it briefly complies with the force (Floating Reaction) then holds position (SOS) — recover by clearing the cause, not by lowering safety.

What happens on a collision

When a Doosan cobot detects a collision, it engages Floating Reaction — a function that complies with the external force for 0.25 second at the moment of detection to soften the contact — and then engages a Safe Operating Stop (SOS), holding position safely. Collision sensitivity is the detection criterion, in percent: the higher the value, the smaller the external force at which the robot stops.

Stop modes

Doosan cobots use different stop modes for safety violations, and which one applied affects recovery:

• STO — cuts off motor power immediately.
• SS1 — cuts off motor power after the motion stops.
• RS1 — a reactive stop after collision; this mode applies only to a Collision violation.

Knowing the mode tells you whether power was cut (STO/SS1) or the robot reacted and held (RS1).

Step-by-step recovery

1. Read the violation on the teach pendant / DART-Studio — it names the collision (or other safety) violation and which stop mode was applied.
2. Clear the obstruction. Remove whatever the robot contacted, or move the robot clear of the object. The cobot won't stay recovered while it's still in contact/force.
3. Recover. Acknowledge the collision and re-enable the robot per your workflow. If power was cut (STO/SS1), you re-enable servos; for RS1 the robot reacted and can resume once acknowledged.
4. Continuing violation? Use Safety Recovery Mode. If there's an error with a continuing safety violation (or you need to pack/move the robot), use Safety Recovery Mode to configure the robot's position and angle safely, and Backdrive Mode to physically move joints, to get the robot out of the violating position.

If it keeps tripping

Repeated collision stops during normal motion usually mean the collision sensitivity is set too high for the task (it stops on very small forces) — review the sensitivity against the real application. Adjust the sensitivity and the motion (speed/path near obstacles) rather than disabling collision detection. Any change to safety settings must be re-validated per your risk assessment.

Step-by-step summary

1. Read the violation + stop mode (STO / SS1 / RS1).
2. Clear the obstruction / move the robot off the contact.
3. Acknowledge and re-enable (re-power servos if STO/SS1).
4. Continuing violation: Safety Recovery Mode + Backdrive to reposition.
5. Frequent trips: review collision sensitivity and motion; re-validate.

Never do this

Don't just crank collision sensitivity down to zero to stop nuisance trips — that removes the protection. Tune it to the task and fix the motion or fixturing causing the contact.