Universal Robots Forum

Error C403A0: Danger of clamping between the robot lower arm and tool

I receive this error when the flange gets close the lower arm (the link between the elbow joint and wrist 1 joint), event though there is at least 1,5cm between my tool and the arm. This error engage the protective stop mode.

Error C403A0: Danger of clamping between the robot lower arm and tool

Example of a configuration triggering the error:

  • 136.46°
  • 4.19°
  • 63.94°
  • 98.65°
  • -133.19°
  • -10.6°

I guess that the controller makes assumptions on the end effector shape, certainly for safety reasons, and prevents collisions between this shape and the arm links (note that I haven’t set any tool geometry or anything related to this in the safety settings).

In my case, I need to disable it, as I already handle collisions myself with the actual end effector shape.

Where does this error come from? I do not have anything related in my safety parameters (which are set to the default). Is there a way to disable it? If not, can I know precisely the conditions to trigger it (size of a collide box, joint limits, etc…)?

I use the UR5 e-series 5.8.

This error is in place because the UR robot is a collaborative robot. You will not be able to bypass this safety feature.

Avoiding this pinch point is a part of the collaborative nature of the cobot. The 1.5 cm sounds about right to prevent hand pinches.

Update: after multiple tests, we estimated that the security can be modeled by a cylinder around the forearm, and a sphere centered the flange with a padding of approximately 30mm. When those two shapes collides, the error is triggered.

This was later confirmed by Universal Robots, who precised the exact conditions: the error is triggered when a cylinder of radius 37,5mm around the forearm and a sphere of radius 37,5mm around the flange are at a distance of less than 28mm.

We entered those shapes in our trajectory planner and never encountered the error again.