After upgrading our E-series UR10 from Polyscope 5.11.1 to 5.11.5 we hear strange clicking sounds from the motors when the robot is moving. One of our customers has observed the same behaviour.
In the release notes of 5.11.5 there are some changes regarding motor controller improvements:
- Motor control improvements:
- 25% improvement in overshoot and stabilization of motions
- Reduction to joint wear increases average joint life over time.
- No change to cycle times or motion profiles
- This improvement applies to all e-Series robots
I’m not sure I understand how these clicking sounds will help in stabilization and reduction to joint wear; is it the normal behaviour ‘by design’ or is it a new issue? Is it safe to use the robot?
Thanks in advance.
Any particular movements that cause these clicking sounds? Speed/Payload/Installation parameters?
Can you provide a serial number for a robot with this issue?
Thanks for bringing this up.
Our robot serial number is 20185000412, payload is ca. 2.2 kg, a vacuumgripper with no workpiece attached. The sounds can be heard when accelerating and decelerating, and also when using blend between waypoints. It’s independent of the current robot program, but higher accelerations make the sound louder. It’s something like the motors reversing and then forward.
A short video is attached; here I used my headset on the top of the base joint to record the sounds directly.
click.mp4.zip (1.3 MB)
Maybe it’s completely normal, just unusual?
Thank you for the additional information. Another two questions that I hope you can help me with:
- Does the problem persist if you downgrade to 5.11.1?
- Does the problem persist if you remove the vacuumgripper attachments?
The robot shouldn’t start clicking because of a software update.
After downgrading to 5.11.1 the sounds disappear almost completely, although we can still hear a few very quiet clicks during acceleration and deceleration, but significantly less frequently than with 5.11.5. (Probably we did not notice this sound at all before the first upgrade.)
I haven’t tested without the gripper yet.
Does it make sense to run the same test program with both versions and make flight reports for further analysis?
Okay, I don’t think it is necessary to dismount the gripper then.
If you can generate flight reports for both cases it would be great! (5.11.1 and 5.11.5, both with gripper)
Meanwhile I will try to see what we can reproduce at our facilities.
We have removed the blue plastic covers from the joints and tried to localize the source of the chattering. It sounds like it does not come from any of the motors, but from the upper arm aluminium tube, approximately where the sticker with the serial number is located. Most likely some floating cables inside the tube are colliding to the metal parts, as a result of improvements in servo control and faster changes in the speed vector in version 5.11.5. We assume this sound is harmless and won’t damage the robot. Let us know if you agree.
Thank you for investigating.
It sounds like a probable cause and effect, although a bit surprising.
I agree with your assessment.