Collision Detected

When error [2.9011] occurs, the robot stops because it has judged that the external force on the robot exceeded the configured safety limit.

• The error appears repeatedly under the same conditions, even though no real collision seems to take place — often at the first start of the day or after a long stop.
• It appears together with an axis dropping or sagging.
• It appears during a sudden movement in recovery jog or another special mode.
• It repeats in applications where the payload, the tool or the center of gravity changes.

[2.9011] Control algorithm category

Collision has been detected.

The robot does not measure external force directly. It estimates it from the joint torque, the motor current and a model of the robot's own weight and inertia. That is why the error can also appear without a real collision, when the robot's response no longer matches what the model expects.

• Real contact, or repeated light interference — contact with a jig, equipment, a cable or a hose, including during recovery jog or automatic return. Contact light enough to go unnoticed is still enough to raise the error.
• Payload, tool or center of gravity mismatch — a heavy or offset tool is fitted but the payload setting does not match it, so normal motion is read as external force.
• Collision sensitivity not suited to the application — the threshold is lower than the application needs.
• Wear in a joint — often shown by an axis dropping, abnormal noise or vibration. This needs service.
• A chain of errors — 2.9011 appears after another position, control or torque error such as 4.1025, 5.7072 or 5.7073.
• Residual vibration after a blended motion — on some models, an axis carrying a long moment arm can keep vibrating slightly after a blend ends, and that is read as an external force.

• Reproduce the position and work step where the error occurs, and inspect the surroundings closely — cable track, air hose, sensor bracket, jig, tooling, doors and covers.
• Check that the payload setting (mass, center of gravity) matches the actual tool and workpiece, and that a long tool, heavy jig or asymmetric load has not been fitted while the setting is still the default.
• If a function in the program changes the payload, check that the value matches the real load at that point.
• Record when the error happens (time of day, after a long stop, temperature change), and at which step, axis, posture and speed.
• If collisions happen only at the end of a blended motion with nothing nearby, remove the blend on that path as a test. If the error disappears, contact your distributor — a program adjustment is available.
• If the collision sensitivity is higher than the application needs, lower it in the safety settings, within what your risk assessment allows.
• If an axis drops, the robot makes unusual noise, or a joint feels hotter than usual, stop using the robot and contact your distributor.

See also Position Following Error with Large Blend Values – Why Does It Occur? and What Is JTS Calibration and When Is It Needed?

• Robot model and serial number
• Software version of the controller
• All error codes shown with 2.9011, and the date and time
• The payload and tool settings, and a photo of the tool
• When and where the error happens — step, axis, posture, speed
• The controller log exported right after the error, and a video of the motion if possible

• 2.9015 TCP force has exceeded user limit
• 5.7060 Collision has been detected (safety controller)
• 5.7059 Joint torque has exceeded user limit in at least one joint
• 4.1025 Position Following Error
• 5.7072 Motor torque value does not match the value converted from three-phase current
• 5.7073 Joint position control error