I have very strange problem with UR20 and UR10e.
UR20 goes to the protective stop even if the speed and acceleration are very low - default (movel : a=1.2, v=0.25; movej : a=0.6, v=0.8). In the beginning I thought that problem could be in the Tool payload, CoG and Inertia matrix, but even I removed the tool and set payload, CoG and inertia matric as 0, UR20 still couldn’t move basic movement and went to the protective stop.
In basic movement I mean going 40cm from left to right and right to left, without any chance of robot touching itself or anything.
Popup message always showed that Base Joint detected the collision or deviation from the path.
I have the same issue with UR10e, but with higher distance and higher speed (a=2, v=1.5).
We have an experience of working with UR10e with much higher speed and acceleration (a=3.5, v=2.8) and we never had any issue.
Problem of incorrect tool payload, cog and inertia matrix practically is eliminated, as we work with the same tool with another UR10e-s.
Herewith, we tested to measure payload with the robot, while tool wasn’t attached to the tool flange. Robot scaled 1.2 kg of nothing. So, is there a chance that problem is in sensors of the robot?
one option I can recommend you doing, would to analyze the joint data with the UR Log Viewer.
You can either export the support files via the Log Tab and review the Flight reports or record the program, which triggers the protective stops.
Follow the documentation on how to view the individual log data. Attached you can find a screen shot from a recording we made some time ago. The graph in the blue rectangle shows the correspondent actual joint current, target joint current and allowed current window. The goal should be to have actual and target current aligning, while staying as far away from the allowed current window as possible.
In this sample it does not align at all and would be a quite bad case. Review your joints current windows and you may spot the part in the program triggering the protective stop - which are normally connected with not being able to follow a path due to reaching the current window for a particular joint.
To better define the spot, which triggered the protective job you should also observe the Safe Mode ( green arrow ). Seeing this graph change indicates a change in the safe mode, which could link to the protective stop.
How sturdy is the robot mounted? If there is any sort of flex to the mounting, it will certainly cause these issues. the fact it’s always the base leads me to suspect it’s not mounted rigid enough according to the specs in the manual.
Thank you for your replies.
I found out that if I move the robot joints and warm them up, they do not go to the protective stop. So, after the installation, first thing what I do is to move all the joints as much degree as possible (-360 to 360).
