Mirroring Robot Movement

Samuel_Bouchard

Hi @Ryan_Weaver , how did you do this master-slave with 2 URs? Was it for a specific application?

Ryan_Weaver

@Samuel_Bouchard & @Enric

Here it is!  (attached)  

¡Disfrutad!

Ryan_Weaver

Hi @Samuel_Bouchard - I'm actually working on a white paper on the topic, so stay tuned!  The inspriation came from a customer who wanted to get two robots working together, so I figured this was the epitomy of that.  I used the Modbus Server on the UR5 to read the standard Modbus register outputs from the UR10 for joint positions.  There are some tricks to it, but I'll detail it all in the white paper and post the link here when it's complete. 

Enric

Well @Ryan_Weaver
I hope your white paper to try it!

  

Enric

Ohh yes!!

matthewd92

@Ryan_Weaver That is really cool.  Great example of using the real time feedback of the UR for control.  Thanks for the white paper as well, really concise.  We did a proof of concept last year for a customer for a dual armed UR3 that had a small portion of the program that had coordinated motion.  The rest of the time the robots were doing different tasks.  When they needed to coordinate we used the modbus register to let them communicate with each other but this would have been so much better!  Basically we let the master tell the slave it was time to move, they would both move and then the master would wait for the slave to say that motion was complete and then it started again until the motions were totally complete.

Did you see any issues with differences in joint kinematics between the two causing the actual positions to not be the exact same?

Ryan_Weaver

@matthewd92  Since we were moving based on joint angles and not TCP location, the "poses" of the robots should have been identical, but the TCP locations would have been some scaled ratio of each other's.  It would have been interesting to give this a try using the TCP location as the driver instead, having the UR10 follow the UR5.  

Thanks for the feedback!

David_Levasseur

Very clever @Ryan_Weaver, thanks for sharing.

Filip

Hi! 
Does anyone of you have maybe a written program already? The link posted in the PDF document is not working. And the program i tried to write myself does not work properly. 
Thank you very much for your help.

Ryan_Weaver

Hi @Filip - thanks for the note that the PDF isn't working.  We are actually releasing the full public version of this eBook this week, but here is the link ahead of time:
https://info.universal-robots.com/multi-robot-communication

Enjoy!

matthewd92

@Ryan_Weaver thanks, the link in the e-book works.  The link in the pdf returns a file not found error.  Looks like the pdf was missing the port number in the file link.

Ryan_Weaver

@matthewd92 - no problem!  I actually think the link was broken, the file was being hosted on our FTP (still is) but it was in a temporary location.