Today is...
Tuesday, November 21, 2017
Welcome to Control.com, the global online
community of automation professionals.
Featured Video...
Featured Video
A demonstration of EtherCAT control of linear motors using the CTC EtherCAT master.
Our Advertisers
Help keep our servers running...
Patronize our advertisers!
Visit our Post Archive
Cobots Collaborative Robots
Looking for people's experiences with Cobot robot/PLC integration

We're looking at introducing cobots/collaborative robots (Universal Robots - UR100) into our manufacturing facility. They will be integrated with AB5000 controlled equipment. Anyone have experience? My chief concern is from a safety/inspection viewpoint. The literature I've read on the actual robot shows that they are relatively easy to program as a "stand alone" unit. What should I watch for when meshing it with the PLC system?

Hi BillyMac,

I'm with a robot integrator that will soon be adding the UR line of robots into our systems as an official integrator. I can't speak much for UR robots yet, but your question seems to be more about safety, integration with AB PLCs, and general experience and I think I can help a little there.

First of all, depending on how complex your system is going to be, find an integrator. If this is a casual project where you'll have as much time as you want to figure out what your new USD $50K robot can do, go for it and learn about it from the ground up. I'm guessing that's not the case and you'll need to have a good idea about cycle rates, uptime, safety and risk assessment, labor savings and other ROI related items. An integrator can help you answer those questions and you can hold their feet the fire if they don't meet expectations!

You mentioned safety and right now there is much discussion going on between the non-collaborative robot camp and the collaborative robot camp about safety. A cobot will stop its motion when it detects a 'collision' with something, but there is still some pressure involved before the servo current gets beyond its threshold to signal a collision (some cobots use a separate pressure sensor to determine this along with servo current and following error). This is pretty negligible in your demo when you stop it with your hand, but imagine that you stopped it with your head, or with your hand laying sandwiched between the robot and a solid surface like a steel table. Also, your tooling on the robot needs to be flesh friendly too, no sharp corners or pinch hazard grippers. You can cut your risk down by not having people work near it or using area sensors that cut the speed down when someone approaches, etc. UR can probably help you with some of these answers before you decide to purchase. When I spoke with the reps they were very transparent about where the possible risk was and had good ideas to mitigate it.

With that out of the way, meshing with your AB5000 PLCs is pretty easy if we're talking about CompactLogix or ControLogix hardware. UR robots, if I recall - because I VERY specifically asked, can communicate over Ethernet I/P along with your PLCs. A hard part may be figuring out how to set up EI/P if you haven't before, but you'll have plenty of I/O after that. I believe UR robots also speak Modbus and blah blah blah, and if you really don't want to mess with it you can use good old discrete I/O - but you'll be fairly limited.

One bit of advice I would give about integrating robots with PLCs is to let the PLC control everything peripheral to the robot and report anything critical back to it. For example, the next part is ready to pick, or the case exchange is done and an empty box is in position ready to be filled. Let the robot worry about the I/O on its tooling only. PLC software is super easy to monitor a bunch of stuff seemingly at the same time (although technically line by line). Robot software will execute line by line which is great for sequential motions and actions, but you usually have to run parallel threads or use special commands to monitor an input while your moving through positions. Too many asynchronous things to monitor and the program can get hectic. If you don't need to watch and command a bunch of I/O asynchronously, then maybe a stand-alone robot is what you want.

Good Luck!

-Illogibot