Allow Freedrive after Collision


Use External/Internal Freedrive button to close safety popups. Hence, allowing to move the Cobot away when beeing clamped.

What is it?

This functionality allows the operator to get out of a clamped situation, while being unable to reach the control panel.

Why is it needed?

This feature is a needed safety functionality. From that kind of view, UR should have big interest to develop this feature. When an operator is clamped, there is no convenient way he can get out of the situation. Even when we install our own physical button to activate the freedrive mode, it would not work after a collision. It would always be necessary to close the safety popup on the panel first. When the operator is not able to reach the panel while he is clamped, he is stuck. He could possibly force the cobot to move while in error state, but that could damage the cobot.

Additional remarks

I tried to find a way to do this by myself. It would be possible to do it in combination with the Dashboard Server. The problem is, that the “remote mode” would need to be actived all the time. Also, an additional PC would be needed.

Correct me if I’m wrong here, but I think the ability to backdrive the servos is for this exact reason. You should be able to shove the robot out of your way (albeit not as easily as freedrive) if you get clamped, regardless of the freedrive state. They use absolute encoders so I don’t believe you really run any risk of damaging the robot in this case. It’s been designed with these types of scenarios in mind.

You could write a CAP that runs the dashboard server even without being in remote mode, and add a button on the end of arm that sends the “clear protective stop” dashboard command through it. You’d probably have to get creative to “cheat it” by setting itself to remote, clearing the popup, then setting back to manual. Definitely less convenient than an official solution from UR

What situation do you have that allows an operator access to Freedrive without the pendant? I assume some sort of external freedrive switch?

I remember seeing a demo at a RIA trade show. It was before I had programmed a UR so I dont remember all the code they used,

Generally though, They had a top level While loop for external forces under threshold, then run normal. Above that threshold, it would go to freedrive, then i think it would wait 10sec and restart.

Hi Eric,

sorry for the late reply. Many thanks for your answer!

Yes, we could probably do it with the way you described. Just thought there may be more people who think that it would be a good feature. The way it is today, it is not very user-friendly. To add a more convenient way and add safety functionalities would be great.

Yes, we are using an external freedrive switch. Probably we will try the dashboard solution later this year. I would come back to post a solution.

Best regards

So it is something that would fire before the actual safety limits, right?

Best regards