Problems with XM540-W270-R

Technical Support
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1

I am using a Dynamixel XM540-W270-R servo with the dynamixel_interface package on ROS noetic (available on GitHub). I had set the max torque to 0.35 (where 1.0 represents the maximum torque). I use the servos in current_based_position control.

At first, the servo was stalling for about 1–2 minutes, during which it became noticeably hot. To prevent damage, I changed its position so that it was no more stalling.

However, after turning it off, I noticed that I could no longer rotate the servo by hand as I could before. Additionally, the servo started drawing 2–3 times more current than usual, and its effort values were significantly higher compared to my other XM540-W270-R servos.

In Dynamixel Wizard, I can still control the servo, and it behaves mostly as expected—except for the excessively high current draw (twice/three times the normal current). However, when I try to control it using dynamixel_interface on ROS Noetic, the servo exhibits erratic behavior.

I have a robotic arm with four XM540-W270-R servos, arranged in two daisy-chained pairs. All other servos respond normally, but the previously stalled servo behaves unpredictably:

When commanded, it gets extremely hot.
It takes around two minutesbefore it responds to commands.

Despite this issue, I can still communicate with the servo through Dynamixel Wizard without errors. However, its high current draw remains a concern.

Does someone know if this is fixable and if so how?

2

This sounds to me like there was some damage to the motor during the mentioned stall condition. 1-2 minutes at full stall is a pretty significant time to stay obstructed.

If you would like your hardware repaired by ROBOTIS, you can submit an RMA request to your region’s ROBOTIS retailer.

When submitting your items for RMA service please be advised: in the event that the units are not covered under warranty you will be responsible for the cost of shipping + repairs (labor/components) before ROBOTIS may return the RMA units.

To proceed with RMA service fill out the the appropriate form from the list above to open a request with your region’s RMA team. In addition, you may find the troubleshooting self-checklist useful to assist in filling out the RMA request form.

3

Hello Jonathon,

it was not at full stall but at 35% of the max stall torque.