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

Technical Questions
1

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.

1 Like
2

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.

3

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.

1 Like
4

@hla Thank you for reporting how you solved the error.
We are experiencing a similar issue and are also doing our own collision detection so the detection within the robot seems unecessary and less precise than our own.
We will implement a similar fix to our collision detection.

5

Hello everyone!
I’ve encountered a similar issue with UR10e robot. However, I can’t seem to fit this 28mm between the two surfaces. Is it possible that these radii (37.5mm) may vary compared to UR5e for spheres and cylinders? How should the radii be interpreted? Is it the radius of the arm +37.5mm, or should the arm be replaced with a 37.5mm cylinder? I have the same question regarding spheres: how is the radius defined?
The “safety distance” on the real device seems much more like 4-5 cm compared to @hla’s 1.5 cm .
Software version: 5.12.2