Cobot Videos

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  • It depends on what you're trying to do.

    Cobots are really not much different from their "big iron" cousins, except that the safety standards that apply have various caveats. The required Risk Assessments can be more complicated, sometimes.

    The big issue is understanding how easy it is to accidentally make your Cobot non-collaborative. Too many people think that just buying a Cobot means they can do without fencing or other safety equipment. But if you put a sharp knife, a pointer screwdriver, a welding torch, or a chainsaw on your Cobot... well, your Cobot isn't a Cobot anymore, and you need to treat it just like Big Iron. The number of people I've seen buy Cobots and think they can just disregard all safety concerns....

    Many Cobots have options to turn their Collaborative mode off, temporarily. Doing this safely requires safety-rated interlocks, because a Cobot in non-Collaborative mode is just as dangerous as a Big Iron robot in the same weight class.

    Cobots are limited to modest payloads, and low speeds, unless you turn off Collaborative mode. So don't expect high speeds.

    Cobots generally program much the same as the Big Iron, although their joints may be arranged somewhat differently (this varies by brand). The main difference tends to be that Cobots can be "jogged" by holding the "deadman" and physically pushing the robot into position before hitting the Record button. Some Cobots are actually stupidly hard to jog accurately from the pendant, making the push&pull programming a necessity rather than a handy option (URs, I'm looking at you here).

    Running with Scissors: Putting Sharp Pointy Tools on Your Collaborative Robot
    David McMillan gives a humorous account of safely programming a collaborative robot to place a screw, while volunteering to act as crash test dummy.

  • Thanks for the reply and article (great read by the way). Your point about people using cobots in a non-collaborative way is a good one, as previously I've heard tell of the promise of safety and such when using a cobot, but not so much about the contexts in which they get used (or especially how that might affect its collaboration capabilities). Ultimately, this promise/notion of inherent safety when using them is one of the reasons I've started looking into them as I wanted to get an understanding of when they are used, how, and what differs between them and the big iron alternatives (in terms of how people approach problems using them). So thanks for the info!

  • Glad I could help a bit.

    Another thing about Cobots (or, at least, the ones I've used so far), is that to achieve their Collaborative rating, they are very fussy about their payloads. For example, every Cobot I've used, after a collision fault or a reboot, requires an operator to manually acknowledge that the programmed payload is still attached, and that no external forces are acting on the Cobot (ie, no one is touching it). This is b/c the Cobot must perform a degree of recalibration or checking of its internal torque sensors, which are what detects collisions. This means that these sensors are part of the critical safety chain of the Cobot, and as such no quick/easy bypasses are permitted. For some Cobots, doing an axis calibration may require the robot to point straight up ("candlestick pose") in order to separate gravity effects.

    Dressing a Cobot has challenges as well. Thick cables, heavy hoses, spring-loaded retractors -- Cobots cannot tell the difference between these forces and a collision. So dressing needs to be light, neat, and you must avoid motions that pull on the dressing, or might wrap it around the wrist. Sticking to the Cobot's internal power/communications lines is strongly recommended, and you need to design your EOAT accordingly.

    Another wrinkle of having the robot's internal sensors be part of the safety chain -- Cobots are less maintainable by end users, in general. So far, I've never seen motor replacement on a Cobot performed by anyone but a certified tech from the robot manufacturer, and some maintenance can only be done by shipping the robot back to the factory. In contrast, replacing motors on Big Iron is usually not a big deal.

    One Cobot I worked with was used as a demo model, mounted on a cart... and we found that moving that cart across a bumpy floor would throw the contact sensing so badly out of calibration that it had to be sent back to the factory. A smaller Cobot (10kg payload) came from the manufacturer in a high-strenth carboard "carrying frame", with hand-holes, and the instructions were explicit that simply picking the robot up by hand would void the warranty -- instead, the crate and padding had to be broken down in a specific order, then the robot could only be lifted (by hand) using the cardboard carrying frame (which supported all the axes in their shipping positions), and there were all sorts of warnings about how jostling the robot carelessly could render it useless. Once it was bolted down to its permanent stand, it could take more abuse, but between crate and stand, it was vulnerable.

    So: read the instructions completely before opening the crate! Cobots are just easier to break than Big Iron, even the small Big Iron.

  • SkyeFire Little question for you, lets say I would like Fanuc has the DCS to make it so you can make the Cobot Speed up and make it not a cobot and what if the robot did a task then moved back and hit like a light current and would go back to being slow. Think that would work or somthing

  • What you describe is possible. The devil is in the details, of course. But as long as you had a safety-qualified means of ensuring that the Cobot could not reach a human while operating in non-Collaborative mode, you should be able to do this.

    Details are important, though. Let's say you use a light curtain to switch the Cobot back to Collaborative mode when it approaches an area it shares with the operator. The placement of that light curtain would have to take the Cobot's non-Collaborative stopping distance into account, so that the operator would be safe even if the Cobot hit the curtain at maximum non-Collaborative speed and got E-Stopped by the curtain.

    Likewise, any other fencing or guarding would have to be designed to deal with the robot in non-Collaborative mode.

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